An estimated 10.5 million Americans alive today have a history of cancer,1 and it is projected that this number will double by the year 2030 as the population grows and ages.2 Despite the ever increasing numbers of cancer survivors, there still is much to learn about their long-term needs and the factors that affect their quality of life (QOL). In response, the American Cancer Society (ACS) has developed and implemented a program of research, referred to collectively as the Studies of Cancer Survivors (SCS), with objectives at 2 levels. At the descriptive level, the SCS surveys are intended to generate statistical descriptions of the QOL of cancer survivors by state and to provide data for policy and other cancer control planners. At the theoretical level, the SCS surveys also attempt to add to the understanding of the variables that influence the psychosocial adjustment and QOL of long-term cancer survivors. Prior to the release of specific study results, this report describes the rationale, design, and implementation of these studies.
Previous research has shown that the overall QOL of most early-stage cancer survivors returns to levels comparable to that of individuals with no history of cancer soon after treatment is completed.3–8 A significant proportion of survivors, however, continue to experience levels of physical, emotional, and social problems that are elevated relative to the general population,9–12 with problems sometimes persisting for years after treatment ends.3, 13–15 Treatment-specific physiological problems, such as lymphedema,16–18 cognitive deficits,19, 20 pain,21, 22 fatigue,9, 23, 24 urinary or bowel dysfunction,25, 26 sexual dysfunction,27–29 infertility,30, 31 and premature menopause,32, 33 can develop during treatment and may become chronic or irreversible34–36; whereas other late effects, including second cancers,37–43 may emerge long after the completion of treatment.35, 44–46 Anxiety, depression, fears of recurrence, and concerns about passing the disease on to their offspring often surface as persistent emotional and psychological concerns for cancer survivors.34, 47–49 Cancer survivors also have reported problems with life and health insurance,34, 50, 51 employment,12, 52–55 and social reintegration.56, 57
Although a growing body of research has begun to document the problems cancer survivors experience, several factors have limited the generalizability of these findings. Most studies of QOL in long-term cancer survivors have been conducted at major cancer centers and often suffer from an under representation of minority, poor, rural, and other hard-to-reach populations.58, 59 In addition, most survivorship studies focus on a single cancer site—usually breast, prostate, or colorectal cancer—making it difficult to compare the impact of different cancers and leaving many cancers understudied. Many studies utilize populations that vary widely in terms of time since diagnosis3, 4, 21 or have limited data on diagnosis and treatment.21, 60 Finally, few studies have included survivors at multiple, well-defined time points postdiagnosis, hindering the ability to make comparisons of survivors at different phases of survivorship. Even fewer studies have enrolled cohorts of survivors who are followed longitudinally through the survivorship continuum.
The SCS surveys were designed to overcome such limitations. The SCS surveys are comprised of 3 separate but related components: SCS-I, SCS-II, and a Caregiver Study, which surveys caregivers nominated by survivors in SCS-I. The Caregiver Study will be described in a subsequent report. SCS-I is a longitudinal investigation of the predictors of adjustment to cancer and the patterns of change in survivors' QOL over an 11-year period. It surveys adults diagnosed with 1 of the 10 most highly incident cancers: prostate, breast, lung, colorectal, bladder, non-Hodgkin lymphoma (NHL), skin melanoma, kidney, ovarian, and uterine. The study over samples survivors age <55 years, because a cancer diagnosis has a greater impact on the QOL of younger adults than on that of older adults.21, 34 SCS-I is designed to survey this panel of survivors at 1 year, 2 years, 5 years, and 10 years after diagnosis.
SCS-II is intended to rapidly identify QOL issues in long-term survivors by using a cross-sectional design to sample adult survivors from 3 separate cohorts based on the length of time postdiagnosis: 2 years, 5 years, or 10 years. SCS-II includes the 6 cancers in SCS-I with good long-term survival rates (breast, prostate, colorectal, bladder, uterine, and skin melanoma) to assure sufficient samples in the cohorts further from diagnosis. The sample sizes for both studies allow for comparisons between cancer types and for investigation within a type, including understudied cancers, such as urinary bladder and NHL. Because survivors were sampled at well-defined time points—1 year, 2 years, 5 years, and 10 years postdiagnosis—these studies allow for direct comparisons of QOL at different points in the survivorship continuum.
By drawing samples from state cancer registries, which include all reportable patients diagnosed with cancer within a given state, the SCS surveys were designed to be more inclusive of demographic groups that were underrepresented in past survivorship research, such as low-income survivors. Both studies over sampled African-American and Hispanic survivors, allowing for investigation of the particular problems and concerns of these groups and comparisons between racial/ethnic groups. In an effort to better approximate the United States population, the studies included registries from each of the 4 regions defined by the Bureau of the Census. Thus, the SCS surveys were designed to add significantly to the scientific understanding of the QOL of cancer survivors.
MATERIALS AND METHODS
Institutional Review Boards, State Registry,and Survivor Eligibility Criteria
Overall approval for the SCS was obtained from the Institutional Review Board (IRB) of Emory University. Additional IRB and regulatory approvals were obtained for each registry. In both studies, state cancer registries were selected based on the following considerations: 1) to maximize coverage of the United States population, targeting states with large, diverse populations representative of the different regions of the country, with at least 1 state from each census region (West, Midwest, Northeast, and South); 2) to maximize coverage of ACS divisions, attempting to target at least 1 state per division; 3) to include state registries capable of implementing the SCS recruitment protocol; 4) to include state registries where data were available to draw a sample of eligible cancer survivors. SCS-I survivors were sampled from 10 months to 11 months after diagnosis and, thus, must have been ascertained and recorded in the registry database by that time. SCS-II included survivors 10 years after diagnosis; thus, registries must have contained data on survivors this long postdiagnosis at the time of sample selection. Table 1 lists the 11 states that were included in SCS-I and the 14 states that were included in SCS-II. Four states participated in both studies. Survivors who were included in the studies met the eligibility criteria provided in Table 2.
Table 1. Racial Stratification, Response Rates*, and Final Sample Size by State
PCR2 indicates physician consent rate; ORR2, overall recruitment rate; Final no., the number of individuals who completed a questionnaire; SCS-I and SCS-II, longitudinal and cross-sectional Studies of Cancer Survivors, respectively; W, white; O, other, B, black; NS, not stratified; H, Hispanic; NH, non-Hispanic; NA, not applicable.
PCR2 = 100 × [cases eligible for case consent/eligible cases] where eligible cases include those categorized as eligible for case consent, physician refused, and a portion of those categorized as unlocatable or no response at physician consent; ORR2 = 100 × [questionnaires completed/eligible cases] where eligible cases include those categorized as physician refused, questionnaire complete, case refused, and a portion of those categorized as unlocatable or no response at physician or case consent.63
Survivors of skin melanoma were not stratified by race except in California Regions 2 through 6, where they were stratified by H ethnicity (H or NH). The presence of a separate race stratum for H indicates that all other race strata for that registry were NH.
The state registry completed physician and patient consent, and the American Cancer Society (ACS) completed questionnaire recruitment.
Active physician consent was used. All other states used physician notification.
All consent and recruitment was completed by the state registry.
All consent and recruitment completed by ACS.
These registries include 5-y and 10-y cohorts only.
Physicians were notified through medical societies and hospitals.
SCS-I and SCS-II indicates the longitudinal and cross-sectional Surveys of Cancer Survivors, respectively; SEER, Surveillance, Epidemiology, and End Results.
1. Age ≥18 y at the time of diagnosis
1. Diagnosed during the 12-mo eligibility period (eg, April 2001 to March 2002)
1. Diagnosed in the calendar y either 2 y, 5 y, or 10 y prior to sampling
2. Diagnosed with a local, regional, or distant SEER Summary Stage cancer; for urinary bladder, in situ cases also are included
2. Diagnosed with 1 of the 10 most highly incident cancers: prostate, female breast, lung, colorectal, urinary bladder, non-Hodgkin lymphoma, skin melanoma, kidney, ovarian, or uterine cancer
2. Diagnosed with 1 of 6 highly incident cancers: prostate, female breast, colorectal, bladder, skin melanoma, or uterine cancer
3. A resident of the target state at the time ofcancer diagnosis
Note: The 12-mo eligibility period varied by registry (15 mo in NJ); all other eligibility periods fell between January 2000 and September 2003
Note: The y of diagnosis for the cohorts of 2-y, 5-y, and 10-y survivors varied by registry; sample y ranged from 1999 to 2001, from 1996 to 1998, and from 1991 to 1993 for 2-y, 5-y, and 10-y survivor cohorts, respectively
4. Survivors were ineligible if they were dead, unable to complete the survey because of mental incompetence, illness (generally terminal), or unable to communicate in English or Spanish
A separate, state-wide probability sample was drawn from the central cancer registry in each state in which either study was conducted. The exceptions were California, where separate probability samples were drawn for Regions 2, 3, 4, 5, and 6, and Washington State, where the sample was drawn from 13 counties. In both studies, the sample was stratified by cancer type. Racial stratification was not conducted within a state if the distribution of survivors by cancer type, age/cohort, and race/ethnicity lead to empty or sparse cells, because this would prohibit the calculation of meaningful parameter estimates. In contrast to other cancers, skin melanoma generally was not stratified by race/ethnicity because of the lower incidence rates and absolute numbers of this cancer among minorities.61 Table 1 lists the racial strata used in each state. In states where the sample was stratified by race/ethnicity, minorities were over sampled up to the point of achieving equal allocation across racial/ethnic groups. The SCS-I sample was stratified by age group, with survivors aged <55 years over sampled to allow adequate numbers of younger survivors for analysis. In SCS-I, the survival rates for each cancer were incorporated into the sampling strategy to ensure a sufficient sample at 2 years, 5 years, and 10 years postdiagnosis. The cancers with the best 1-year and 5-year survival rates comprised the first group (melanoma, breast, prostate, bladder and uterine), the cancers with moderate survival comprised the second group (colorectal, kidney, NHL, and ovarian), and lung cancers comprised the third group. For every 1 patient selected in the first group, 1.4 survivors were selected from the second group, and 3 survivors were selected from the lung cancer group. The selection fraction for lung cancer was a compromise that balanced needs for precise estimates of QOL in 2-year, 5-year, and 10-year lung cancer survivors; the expected number of lung cancer patients available for sampling; and overall study costs.
In SCS-II, the general design allocated the state sample size equally across each of the postdiagnosis cohorts. Within each cohort, 25% of the sample size was allocated to each of breast cancer, colorectal cancer, and prostate cancer; and 12.5% of the sample was allocated to each of the remaining cancers (melanoma, bladder cancer, and uterine cancer). This allocation strategy reflected the distribution of these 6 cancers in the United States, with more of the sample allocated to the more common cancers, producing an approximate probability proportional to size-stratified sampling plan across cancer types.
State cancer registries are required to report data 2 years after the close of a given calendar year. Because SCS-II targeted survivors ≥2 years postdiagnosis, nearly all survivors who ultimately were identified by a registry had been ascertained. SCS-I, however, targeted survivors 1 year postdiagnosis, so samples were drawn before state cancer registries had completed case ascertainment and data cleaning. Consequently, the database from which SCS-I samples were drawn did not include all eligible survivors. Efforts to increase coverage of eligible survivors in SCS-I included drawing a series of subsamples to increase time for case ascertainment and, in 1 state, the use of rapid case ascertainment. The state-level databases from which SCS-I samples were drawn contained a median of 63.2% of the survivors who ultimately were identified by the cancer registry (range, 30.9–118.5%); numbers >100% resulted from duplicate records, that is, multiple records from different facilities for a single case. Duplicates were removed after sampling.
Questionnaire Development, Pilot Testing,and Translation
The SCS surveys include instruments and scales that are used widely in psychosocial research and that are known to be valid and reliable for use with cancer patients (Table 3). In addition, for areas of interest with no established instruments, items were developed and pilot tested. Questionnaire development involved 3 major activities: 1) consultation with a panel of medical and behavioral cancer researchers, 2) administration of the questionnaire to focus groups, and 3) pilot testing the questionnaires and study protocols with samples of survivors selected from registries. The final versions of both surveys took approximately 60 minutes to complete. The questionnaires and all other study materials were translated into Spanish by a panel of experts, except where validated Spanish versions of scales already exist. These translations subsequently were tested with Spanish-speaking focus groups.
Table 3. Studies of Cancer Survivors Measures
HMO indicates health maintenance organization; PPO, preferred provider organization; SCS-I and SCS-II, longitudinal and cross-sectional Studies of Cancer Survivors, respectively; ACS, American Cancer Society.
See Baker et al, 1995, 199673, 74; Matthews et al, 2002.75
Date of birth, race, ethnicity, marital status, education, and annual household income
A short list of common medical conditions with a brief description is provided; survivors are asked to indicate which, if any, of the medical conditions they have experienced or been diagnosed with
Cancer diagnosis and treatment
Respondents are queried about the type(s) of cancer with which they were diagnosed and the y of diagnosis as well as the treatment(s) they have received for this cancer
Three questions address whether the respondent currently is covered by health insurance, and, if so, what type of plan (HMO, PPO, etc) and who provides the plan (employer, self, etc)
Satisfaction with Life Domains Scale-Cancer (SLDS-C)
The SLDS-C is a broad measure of quality of life that asks respondents to indicate their current satisfaction with 18 different life domains relevant to the quality of life of cancer patients; the scale uses a picture-response format in which satisfaction is indicated by choosing 1 of 7 faces (ranging from a “terrible” face with a deep, down-turned frown to a “delighted” face with a large smile); items can be evaluated individually, and a total score can be calculated*
Cancer Problems in Living Scale (CPILS)
The CPILS consists of 31 items related to problems that cancer survivors may have experienced since their cancer diagnosis; the respondent is asked to indicate how much of a problem each of the items has been in the last 12 mo (not a problem, somewhat of a problem, or a severe problem), and items are evaluated individually†
Modified Rotterdam Symptom Checklist (RSCL-M)
The RSCL-M asks only about physical symptoms‡; this version excludes psychological symptoms, which were redundant with the Profile of Mood States (POMS); the respondents are asked to indicate the extent to which they have been bothered by each of 30 symptoms during the past wk (not at all, a little, quite a bit, or very much); total symptom burden can be calculated as well as scores for individual items‡
Functional Assessment of Chronic Illness Therapy-Spiritual Well-being (FACIT-Sp)
The FACIT-Sp is a 12-item scale that assesses spiritual well-being; it includes 2 subscales, 1 that measures a sense of meaning and peace and 1 that assesses the role of faith in illness; respondents are asked to indicate the truth of each item (not at all, a little bit, somewhat, quite a bit, or very much); a total spiritual well-being score and 2 subscale scores can be calculated§
Medical Outcomes Study Short Form-36 (MOS SF-36)
The MOS SF-36 is a 36-item, well-tested, valid, and reliable self-report tool for assessing health-related quality of life||; scores can be obtained for each of 8 subscales (physical functioning, role-physical, bodily pain, general health, vitality, social functioning, role-emotional, and mental health) and for 2 summary measures, the Physical Component Summary score and the Mental Component Summary score; 1 question asks the respondents to rate their general health compared with 1 y ago
Multidimensional Scale of Perceived Social Support (MSPSS)
The MSPSS is a 12-item self-report inventory of perceived adequacy of social support¶; the scale provides a summary score as well as 3 subtype scores for perceived support from a significant other, family, and friends; each item is rated on a 7-point scale from very strongly disagree to very strongly agree
The POMS-37# is an alternate short form based on 37 of the 65 items in the original POMS**; sample items are “unhappy,” “lively,” and “unable to concentrate”; for each item, respondents indicate on a 5-point scale how much they had been feeling that way during the past 2 wk; scores can be derived for total negative mood and for 6 factor-based subscales (tension-anxiety, depression-dejection, anger-hostility, confusion-bewilderment, fatigue-inertia, and vigor-activity); internal consistencies of thetotal score and subscales range from 0.78 to 0.91#
Questions in both SCS-I and SCS-II ask for information about current employment status, employment at the time of diagnosis, and work problems related to cancer diagnosis (eg, laid off, passed over for promotion)
Questions in SCS-I only
Country of birth, whether the respondent is a nursing home resident, and sex
Access to care
Information is gathered on type of health care providers seen, type of treatment facilities used, and average travel time to treatment site
Respondents are asked about their satisfaction with their health insurance coverage and whether they have experienced problems with their coverage
Caregiver contact information and their relationship to the survivor were collected
Complementary and alternative treatment methods
Includes 32 items that can be organized further into 5 broad categories to access patient use of complementary and alternative medicine
Measures in SCS-II only
Lifestyle Behavior Scale
This 18-items scale was developed by the ACS Behavioral Research Center for the purposes of this study and assesses health behavior changes after cancer diagnosis; the instrument was based on previous research in lifestyle behaviors in cancer patients†† and was tested in the SCS-II pilot
Physician and Survivor Consent
Recruitment procedures varied, depending on the rules and regulations regarding recruitment in a given registry. Physicians were identified through registry records and follow-back to reporting facilities. Physicians either were contacted for written consent to recruit a given survivor (active physician consent), were sent a letter explaining that recruitment of a given survivor would begin in 3 weeks unless study personnel heard from the physician (physician notification), or were informed about the study in general through mailings and presentations to medical societies and hospitals. This last approach did not involve the identification of individual survivors. Table 1 identifies the recruitment procedures used by each registry.
Survivor recruitment also varied based on registry regulations. Twelve registries released survivors to the ACS for simultaneous consenting and surveying, whereas 16 registries consented survivors prior to releasing contact information to the ACS for survey administration. One registry simultaneously consented and administered the baseline survey. With regard to recruitment, all registries used an adaptation of Dillman's tailored design method,62 which includes 3 mailings—1) a cover letter, consent form, and/or questionnaire, 2) a reminder letter, and 3) another consent form and/or questionnaire with a different cover letter—followed by telephone follow-up.
Eligibility and Response of Sampled Cases
Although the designs of the 2 studies differ, the protocols and recruitment rates are similar. The final dispositions of all sampled survivors for both studies are presented in Figure 1. For the combined studies, 61,847 survivors were sampled, of which 9.1% were determined to be ineligible for recruitment after sampling because of missing or out-of-range values in eligibility variables, such as stage or date of birth. This left 90.9% eligible for physician consent. During recruitment, survivors were determined to be ineligible or deceased based on information obtained from the individual or a proxy (eg, medical professional or family member). Survivors were coded as unlocatable when mail was returned undeliverable, the phone number was not working, or someone indicated that the individual did not reside at that address, and additional contact information was not found despite extensive efforts. Response rates were estimated as the number of completed interviews divided by the number of eligible reporting units in the sample63; ineligible survivors were removed from the denominator. Because large portions of survivors were identified as deceased during recruitment despite efforts to update vital status before and after sampling, they were reported separately from other ineligible survivors. The physician consent rate (PCR1) of 91.9% is the proportion of survivors still eligible at this stage—excluding those ineligible or deceased at physician consent—that received physician consent and became eligible for case consent. The case recruitment rate (CRR1) of 35.1% is the proportion of participants eligible for case consent—excluding those deemed ineligible or deceased—that completed a survey. Finally, the overall recruitment rate (ORR1), 32.0%, takes into account the combined impact of physician and case consent by indicating the proportion of eligible survivors who completed a survey.
The ORR1, however, underestimates the response rate, because it assumes that everyone with unknown eligibility—that is, survivors coded no response or unlocatable—are eligible refusals. In accordance with standard survey procedures,63 response rates were recomputed after the number with unknown eligibility was adjusted downward to account for the fraction that would most likely have been ineligible. It was assumed that the fraction of ineligible survivors for the unknown eligibility group was the same as the fraction for the known eligibility group. An ineligibility fraction was calculated for each recruitment stage, and the number of survivors with unknown eligibility that were assumed ineligible was computed and removed from the response rate calculation. For example, the ineligibility fraction at the physician-consent stage is the number of survivors identified as ineligible or deceased divided by the number of survivors identified as eligible for case consent, physician refused, ineligible, or deceased. The ineligibility fraction is then applied to the survivors with unknown eligibility—no response and unlocatable—to estimate the number of ineligible survivors to be removed from the response rate calculation. Adjusting the SCS rates by using this approach results in minor changes to the PCR2 (92.0%), CRR2 (37.3%), and ORR2 (34.0%).
Response by Study Site and Cohort
The PCR2, ORR2, and numbers of completed surveys are shown for each site for both studies in Table 1, which also provides the type of physician consent and survivor recruitment used by each site. Response rate calculations reflect differences in site recruitment procedures. The sites that required active physician consent (for SCS-I, Connecticut and Ohio; for SCS-II, Colorado and Nebraska) have a much lower median PCR2 (62.0%) than sites where physician notification was used (median, 96.5%). The median ORR2 across registries is 34.9% (minimum, 15.9%; maximum, 52.1%).
Table 4 presents the distribution of survivors in final disposition for each cohort: 1 year for SCS-I and 2 years, 5 years, and 10 years for SCS-II. The 1-year cohort had higher levels of deceased and ineligible survivors than later cohorts. One trend is the increasing proportion of unlocatable survivors, which rises from 4.8% in the 1-year cohort to 10.1% in the 10-year cohort. Similarly, the proportion of survivors lost to physician consent increased from 5.9% in the 1-year cohort to 8.5% in the 10-year cohort. It also is worth noting that the 10-year cohort had a lesser proportion of survivors completing questionnaires. To rule out the possibility that differences between cohorts were caused by differences in study sites, the same comparisons were made using only data from states that recruited all cohorts, and the patterns noted here remained unchanged.
Representativeness and Descriptionof the Final Sample
Calculated by using registry data, the ORR1 for particular medical and demographic groups is presented in Table 5. For both studies, survivors who were younger (18–54 years), women, and white responded at higher rates than survivors who were older (≥55 years), men, and racial/ethnic minorities. Ovarian and breast cancer survivors had the highest response rates, and bladder and lung cancer survivors had the lowest. Survivors who were diagnosed initially with distant or in situ cancer responded at lower rates than survivors who were diagnosed initially with local or regional cancer. The same pattern was observed when these comparisons were repeated with data from the 4 states that participated in both SCS-I and SCS-II.
Table 5. Survey Response by Medical-Demographic Group*
SCS-I and SCS-II indicate the longitudinal and cross-sectional Studies of Cancer Survivors, respectively; NA, not applicable; NHL, non-Hodgkin lymphoma.
Eligible survivors are individuals who were alive and met all study eligibility criteria.
Eligible survivors who completed a questionnaire.
Eligible survivors who refused, did not respond, were unlocatable, or who had physicians who refused, were unlocatable, or did not respond.
Age at diagnosis
In situ (bladder only)
Among the respondents, 19.4% are racial/ethnic minorities (nonwhite). Based on self-reported data, 40.1% of respondents have a high school education or less, and 16.2% have an annual household income <$20,000. In SCS-I, baseline surveys were completed a median of 1.2 years after diagnosis. Respondents in the 2-year cohort of SCS-II completed surveys a median of 3.3 years after diagnosis, respondents in the 5-year cohort completed surveys a median of 6.3 years after diagnosis, and respondents in the 10-year cohort completed surveys a median of 11.3 years after diagnosis.
The longitudinal (SCS-I) and cross-sectional (SCS-II) components of the ACS SCS surveys provide unique resources for assessing the physical and psychosocial impact of cancer on long-term cancer survivors. SCS-I, which enrolls survivors 1 year after diagnosis and surveys them 3 more times, allows for the investigation of patterns of psychosocial functioning and QOL as individuals move through the survivorship continuum. Such longitudinal designs allow researchers to rule out cohort effects and increase the power of statistical tests by exploiting inherent correlations in repeated measures on an individual. In addition, the survey content and recruitment procedures for the studies were designed to be comparable, so that baseline data from SCS-I can be combined with SCS-II to create a cross-sectional dataset of survivors approximately 1 year, 3 years, 6 years, or 11 years from diagnosis. Thus, the SCS surveys allow investigation of QOL among cancer survivors at distinct time points postdiagnosis. Data from the 15,411 survivors enrolled in SCS provide a basis for identifying potential QOL correlates of long-term cancer survivors that, subsequently, can be investigated in longitudinal studies, such as SCS-I. The stratification by cancer type (10 sites in SCS-I, 6 sites in SCS-II), the over sampling of minority and younger survivors, and the inclusion of 21 geographically dispersed states representing each of the 4 regions defined by the Bureau of the Census provide unique opportunities to investigate QOL while taking medical, sociodemographic, and geographic factors into consideration.
The content of SCS provides a broad overview of survivors functioning. It consists primarily of previously developed instruments with known psychometric characteristics that are relevant to survivors from 1 year to 10 years after diagnosis. It covers 4 domains of QOL: physical (continuing effects, such as pain, fatigue, etc), psychological/emotional (depression, distress, etc), social (employment, social support), and spiritual. The self-reported QOL data are supplemented and strengthened by data from state cancer registries describing cancer type, date of diagnosis, and stage, variables for which self-report has been shown to be inaccurate in previous research.64, 65
The median overall response rate across registries for SCS is 34.9%, which is similar to the 41.2% median overall response rate across states in the 2004 Behavioral Risk Factor Surveillance System.66 Rates like these suggest that some level of response bias is likely, provided nonresponse is associated with outcomes like QOL.67 In contrast, frame undercoverage, although it may be an issue to be considered, is believed to be missing randomly and, thus, not a cause of bias. Two contributors to bias must be considered when interpreting results from SCS: First, the groups generally less likely to respond to surveys (eg, the elderly, males, and nonwhites)67 and groups with certain medical characteristics (eg, survivors of bladder cancer, cohorts at longer periods postdiagnosis) were less likely to respond in our sample. Nonresponse adjustment weights may compensate for this to some degree. Second, some researchers have observed that survivors with poor health are less likely to respond to surveys.66, 68 Systematic exclusion of survivors with poor health may lead to over-estimation of QOL. Although the extent to which this occurred in SCS is unclear, it will be considered when interpreting QOL indicators generated from SCS data. Given the large number of participants and the significant proportion of minorities, men, and low-income survivors in the final sample, it is anticipated that correlational results will be reasonably accurate.
Efforts are underway to analyze study data along several different areas of interest. A primary avenue of investigation is comparisons of QOL between 1-year, 3-year, 6-year, and 11-year survivors. Other articles will describe the QOL of survivors of understudied cancers (eg, lung, NHL) and underserved groups, such as minority and low-income survivors. Summary reports will describe QOL of survivors in the SCS sample at state levels for use by state cancer control planners in identifying issues of cancer survivors. Another ongoing effort in this program of research is the continuation of SCS-I. At the time of the current report, data collection for the 2-year survey was complete, and planning for the third survey was underway.
Sampling and Recruitment
Studies of cancer etiology must survey patients who die soon after diagnosis because of the possible relation between high-level exposure and death shortly after diagnosis, and this requires the use of costly rapid case ascertainment (frequent visits to reporting facilities to ascertain cases). In contrast, studies of long-term outcomes do not require data on patients who die shortly after diagnosis and can utilize more economic approaches. Studies of outcomes ≥2 years past diagnosis can rely on inherent ascertainment activities, because registries are required to report to their regulatory agencies—the Surveillance, Epidemiology, and End Results Program; the National Program of Cancer Registries; and the North American Association of Central Cancer Registries—at that time. When drawing samples closer to diagnosis, the cost of ascertainment can be contained by using 2-stage cluster samples to decrease the number of facilities to be visited and by making visits less frequent. For example, studies of 1-year survivors need visits to facilities only 1 or 2 times per year. Finally, the sampling design of registry-based studies should take into account the data presented in Table 4. The increasing proportion of survivors who are unlocatable or lost to physician consent in cohorts further from diagnosis probably resulted from deterioration of registry data, whereas higher rates of ineligible and deceased survivors in the 1-year cohort probably were due to sampling from an incomplete registry database.
Although the physician consent process provides data on eligibility and vital status, it increases costs and decreases response rates. Active physician consent becomes problematic as survivors move beyond initial treatment and stop seeing the physicians recorded in the registry. The SCS states that required active physician consent had lower physician consent rates (median, 62.0%) than the rate achieved by those using physician notification (96.5%), which requires fewer resources, is quicker, and places fewer burdens on health professionals. Furthermore, the majority of patients (87%) do not believe that a physician should decide whether they are approached for a study.69 Based on SCS data, state cancer registry personnel from 3 states successfully changed regulations that required active physician consent. Even physician notification can be problematic if registries do not collect physician data and if reporting facilities refuse to provide physician data despite registry IRB approval. Because of issues with physician data, 1 IRB approved informing physicians about the study through large physician groups and state medical associations rather than physician notification. In summary, physician notification is preferable to active physician consent in survivor studies; the quality of physician data is important; and regulatory bodies are amenable to changing their policy on physician notification if the evidence is persuasive.
It is known that survey salience has an impact on survey response,70 and a number of factors may have decreased the salience of SCS to survivors. Some SCS participants indicated that cancer was no longer important to them, some preferred not to be reminded of it, and others believed that their stories were uninteresting, because they had been cancer free for years; recruitment materials were developed to address these issues. The SCS surveys were conducted on a statewide basis, with recruitment materials generally featuring the ACS and the state department of health; in contrast, surveys that are identified as coming from universities, particularly local universities, usually get better response.62 Compared with single cancer studies, the salience of the SCS may have been diluted further, because the multiple cancers included did not allow survey materials to match a participant's diagnosis.
The receipt of study materials was the first time most survivors became aware that a state agency had their name, address, and information about their cancer. Many were shocked by this, which may have overshadowed consideration of study participation. For those who were contacted by telephone, explanations of the registry's objectives and the steps taken to protect patient privacy often overcame participant concerns. Sending a prenotification letter about the cancer registry before study materials are sent may attenuate the potential impact of patients learning that they are listed in a cancer registry. This would be consistent with Dillman's tailored design method,62 which posits that providing information in more digestible chunks leads to better survey response. Furthermore, prenotification increases response rates by 3% to 6% in the general populace,62 and evidence suggests that prenotification may increase participation in registry-based surveys.69
When designing registry-based studies, researchers should consider issues of ascertainment, sampling, and recruitment as well as techniques like face-to-face interviews, incentives, or community-based research to improve response rates. Because of their cancer experience and the discomfort that may be associated with the discovery of being listed in a cancer registry, recruits for registry-based studies are a unique group who may respond differently to survey design elements than the general public. The field of registry-based surveys would benefit from the integration of methodological experiments into protocols in an effort to identify improved recruitment approaches.
Probability sampling from state cancer registries has the advantage of providing full coverage of the population of survivors in a defined geographic region. The SCS show that it is practical to conduct multisite studies of the QOL of long-term cancer survivors using state cancer registries. The only comparable studies are 2 National Cancer Institute-sponsored studies that were designed to investigate the relation between cancer care practices and outcomes, including survival and QOL.71, 72 The National Cancer Institute-sponsored studies sample from state cancer registries and abstract data from medical records but collect less psychosocial data and include survivors of fewer cancers than SCS. Therefore, the inferences regarding long-term survivorship that can be drawn from the SCS are the most wide-ranging to date.
We acknowledge the efforts of the staff of participating cancer registries and the hundreds of hospitals, such as Stamford Health System, that contributed cases to these studies through the state cancer registries. Certain data used in this study came from state cancer registries (eg, the Connecticut Tumor Registry of the Connecticut Department of Health), and the authors assume full responsibility for analyses and interpretation of these data. Maxine Denniston worked tirelessly designing samples and implementing the studies. Jessica DeFrank managed Studies of Cancer Survivors-II. Donna Brogan provided sampling design and statistical consultation. We also acknowledge Corinne Crammer for editing and Jerome Yates for advice on strategy and article preparation