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Predictors of inactive lifestyle among adult survivors of childhood cancer
A report from the Childhood Cancer Survivor Study
Article first published online: 17 FEB 2009
Copyright © 2009 American Cancer Society
Volume 115, Issue 9, pages 1984–1994, 1 May 2009
How to Cite
Ness, K. K., Leisenring, W. M., Huang, S., Hudson, M. M., Gurney, J. G., Whelan, K., Hobbie, W. L., Armstrong, G. T., Robison, L. L. and Oeffinger, K. C. (2009), Predictors of inactive lifestyle among adult survivors of childhood cancer. Cancer, 115: 1984–1994. doi: 10.1002/cncr.24209
- Issue published online: 20 APR 2009
- Article first published online: 17 FEB 2009
- Manuscript Accepted: 24 OCT 2008
- Manuscript Revised: 20 SEP 2008
- Manuscript Received: 29 JUL 2008
- National Cancer Institute (Bethesda, Md). Grant Number: CA 55,727
- American Lebanese Syrian Associated Charities
- childhood cancer;
- physical activity;
Participation in physical activity is important for childhood cancer survivors, because inactivity may compound cancer/treatment-related late effects. However, some survivors may have difficulty participating in physical activity, and these individuals need to be identified so that risk-based guidelines for physical activity, tailored to specific needs, can be developed and implemented. The objectives of the current study were to document physical activity patterns in the Childhood Cancer Survivor Study (CCSS) cohort, to compare the physical activity patterns with siblings in the CCSS and with a population-based sample from the Behavioral Risk Factor Surveillance System, and to evaluate associations between diagnosis, treatment, and personal factors in terms of the risk for an inactive lifestyle.
Percentages of participation in recommended physical activity were compared among survivors, siblings, and population norms. Generalized linear models were used to evaluate the associations between cancer diagnosis and therapy, sociodemographics, and the risk for an inactive lifestyle.
Participants included 9301 adult survivors of childhood cancer and 2886 siblings. Survivors were less likely than siblings (46% vs 52%) to meet physical activity guidelines and were more likely than siblings to report an inactive lifestyle (23% vs 14%). Medulloblastoma (35%) and osteosarcoma (27%) survivors reported the highest levels of inactive lifestyle. Treatments with cranial radiation or amputation were associated with an inactive lifestyle as were being a woman, black race, older age, lower educational attainment, underweight or obese status, smoking, and depression.
Childhood cancer survivors were less active than a sibling comparison group or an age- and sex-matched population sample. Survivors who are at risk for an inactive lifestyle should be considered high priority for developing and testing of intervention approaches. Cancer 2009. © 2009 American Cancer Society.
The need for long-term medical follow-up and interventions to address or prevent cancer/treatment-related late effects increase as the number of individuals who survive childhood cancer continues to increase. Both individualized medical follow-up for long-term survivors of childhood cancer and the adoption of a healthy lifestyle that includes physical activity are encouraged by pediatric professional medical organizations, including the American Society of Pediatric Hematology and Oncology, the International Society of Pediatric Oncology, and the American Academy of Pediatrics.1, 2
In the general population, physical activity decreases the risk of both all-cause mortality and mortality related to cardiovascular disease3-8 and is associated inversely with the risk of developing breast,9, 10 endometrial,9 colon,11-13 and lung cancers.14, 15 Physical activity also is associated with a decreased risk of developing dyslipidemia and insulin resistance,16 osteoporosis,17-19 and cognitive decline.20, 21 An active lifestyle has demonstrated benefits even among those who have substantial functional loss.22-24 Some evidence exists to support the contention that a healthy lifestyle that includes an adequate amount of physical activity has the potential to prevent or attenuate many of the long-term problems experienced by childhood cancer survivors.25 Late effects that have been associated with an inactive lifestyle include early mortality,26 cardiovascular disease,27 lipid abnormalities,28 osteoporosis,28 cognitive decline,29 and physical performance limitations.30
Because of the heterogeneous nature of histologies and treatments experienced by childhood cancer survivors, there is a need to provide a comprehensive documentation of specific risk factors for an inactive lifestyle in this population. Certain groups of cancer survivors may benefit from targeted interventions that address their unique limitations so they can modify their lifestyle choices. Others may have treatment-related late effects that are amenable to existing programs designed to improve physical health, such as those that target obesity,31 diabetes,32, 33 or cardiovascular disease.34 This report documents the physical activity patterns in the Childhood Cancer Survivor Study (CCSS) cohort, compares physical activity patterns between survivors and siblings, and evaluates the association between diagnosis, treatment, and demographic/personal factors and risk for inactive lifestyle. For external validation of the use of the sibling comparison group, physical activity patterns among both siblings and survivors are compared with an age- and sex-matched population reference group from the Behavioral Risk Factor Surveillance Survey (BRFSS). These analyses are designed to provide initial information for the eventual development of evidence-based, risk-based guidelines and interventions for physical activity promotion among long-term childhood cancer survivors.
MATERIALS AND METHODS
Details of the CCSS study have been published elsewhere.35 Briefly, eligible participants were ≥5-year cancer survivors who were diagnosed between 1970 and 1986 at age <21 years at 1 of 26 institutions. Eligible diagnoses included leukemia, Hodgkin disease, non-Hodgkin lymphoma, central nervous system (CNS) malignancies, Wilms tumor, neuroblastoma, soft tissue sarcoma, and bone tumors. Of the 20,346 eligible individuals, 14,357 survivors were contacted and enrolled successfully. A comparison group of 3899 siblings also was recruited and completed the same baseline questionnaire that the survivors completed in 1995/1996. Survivor and sibling participants who completed the 2003 follow-up questionnaire had their treatment records abstracted, and those aged ≥18 years in 2003 were eligible for these analyses. The entire set of study questionnaires and the medical record abstraction form can be found at www.stjude.org/ccss accessed February 6, 2009.
Outcome of Interest
The primary outcome of interest for these analyses was activity status indicated on the 2003 CCSS Questionnaire. On the basis of participants' answers to 6 questions from the BRFSS36 about physical activity and 1 question about participation in physical activity over the past month (Fig. 1), this outcome was summarized as 1) a binary variable that classified the participant as an individual who either met or did not meet the Centers of Disease Control and Prevention (CDC) guidelines for physical activity (30 minutes of moderate intensity physical activity on ≥5 days of the week or 20 minutes of vigorous intensity physical activity on ≥3 days of the week),37 and 2) a binary variable that classified an inactive lifestyle if the participant indicated that they did not participate in any leisure-time physical activity over the past month. In addition, a 3-to-1 population-based sample was selected that was frequency matched on age and sex from individuals who answered the same 6 questions on the 2003 BRFSS to serve as a comparison group for both survivors and siblings.38
Independent (Explanatory) Variables
Diagnosis and treatment variables were abstracted from the medical record and included the following: cancer diagnosis, age at diagnosis, surgery status (classified as amputation, other surgery, or none), chemotherapy (classified as anthracyclines, other chemotherapy, or none), and radiation (classified as cranial radiation, chest radiation, other radiation, or none). Demographic and personal factors for both survivors and members of the sibling comparison group were obtained from the 2003 CCSS Questionnaire.
Explanatory variables from the 2003 CCSS Questionnaire included race, current age, highest level of educational attainment, employment status, annual household income, height and weight, smoking status, and depression. Body mass index (BMI) was calculated by dividing self-reported weight in kilograms by height in meters squared and was grouped as underweight (BMI <18.5 kg/m2), normal weight (BMI 18.5-24.9 kg/m2), overweight (BMI 25-29.9 kg/m2), and obese (BMI ≥30 kg/m2). Depression was assessed and classified according to the respondent's score on the 18-item Brief Symptom Inventory (BSI).39 A T-score of ≥63 on the BSI was classified as depression.40
Descriptive statistics were calculated for demographic and personal factors and were compared between survivors and siblings. The frequencies and percentages of survivors and siblings who did not meet CDC guidelines for physical activity and who reported an inactive lifestyle were compared in separate multivariate models, which were adjusted for demographic and personal factors. The proportion of survivors within each cancer diagnosis by sex stratification who did not meet CDC guidelines for physical activity and who reported an inactive lifestyle also were compared with the proportion of siblings in separate, age-adjusted models. All comparisons between survivors and siblings used relative risk regression models (generalized estimating equations) to account for potential intrafamily correlations.41, 42 The impact of treatment variables on not meeting CDC guidelines for physical activity and for an inactive lifestyle were evaluated in analyses that were limited to survivors only using generalized linear models (log-link and a binomial error term)43 stratified by sex and adjusted for age at questionnaire completion and age at diagnosis.
The frequency of survivors, siblings, and the BRFSS sample who did not meet CDC guidelines for physical activity and who reported an inactive lifestyle was calculated and compared between survivors, both overall and by diagnosis, and for the BRFSS sample using chi-square statistics. Percentages were compared between siblings and the BRFSS sample in generalized linear regression models43 that were adjusted for age and sex.
Data were evaluated to assure that the assumptions of each procedure were met before statistical testing. Results of multivariate analyses are reported as risk ratios with 99% confidence intervals [CI]. Although analyses were hypothesis driven, because of the large sample size and the multiple comparisons conducted, confidence intervals are reported to 1 decimal place in the tables, adjusted to reflect a P value cutoff point of .001. SAS version 9.1 (SAS Institute, Inc., Cary, NC) was used for all analyses.
There were 9301 survivors and 2886 siblings who were aged ≥18 years when they completed the 2003 CCSS Questionnaire. This represents 76% of living adult survivors and siblings who were eligible to participate in this survey. Nonparticipants included 2385 survivors and 458 siblings who either actively or passively declined participation and 905 survivors and 27 siblings who were lost to follow-up. Among both survivors and siblings who completed the 2003 CCSS Questionnaire, 12,139 answered the question about inactive lifestyle (99.6%), and 11,805 (96.9%) answered the questions about physical activity. Participant survivors did not differ from nonparticipant survivors by diagnosis or age at diagnosis. Participant survivors and siblings were older, more likely to be women, and more likely to report their race as white than nonparticipant survivors or siblings (P < .001 for all).
The characteristics of the cancer survivors and the sibling comparison group are provided in Table 1. Cancer survivors were more likely to be men and aged ≤40 years than siblings. Siblings were more likely to have graduated from college, to be working or caring for a home and family, and to have an annual household income >$20,000. Cancer survivors were more likely than siblings to be underweight and to be never-smokers. Cancer survivors reported less exercise than siblings. Over half of cancer survivors (52%) and slightly less than half of siblings (47%) reported that they did not meet CDC guidelines for physical activity.
|Characteristic||Survivors, N=9301||Siblings, N=2886||P*|
|Age group, y|
|High school graduate||4888||52.6||1356||47||<.0001|
|Working/caring for home or family||7450||80.1||2628||91.1|
|Unemployed/looking for work||429||4.6||68||2.4||<.0001|
|Unable to work||717||7.7||37||1.3|
|Annual household income, $US|
|Body mass index, kg/m2|
|Normal weight, 18.5-24.9||4020||43.2||1261||43.7|
|Height and/or weight not indicated||364||3.9||87||3|
|Meets guidelines for physical activity|
The associations between cancer survivor status, specific demographic and lifestyle factors, and activity status are shown in Table 2. After adjusting for demographic and lifestyle factors, cancer survivors were 1.2 times more likely (99% CI, 1.1-1.3) to report that they did not meet CDC guidelines for physical activity and 1.6 times more likely (99% CI, 1.4-1.8) to report no physical activity during the previous month (inactive lifestyle) than siblings. In the same adjusted models, being a woman, black race, older age, an inability to work, and being either underweight or obese also were associated positively with not meeting CDC guidelines for physical activity and with an inactive lifestyle. Individuals with higher levels of education were less likely to report an inactive lifestyle than those who did not finish high school. Current smokers compared with never smokers and individuals who had BSI scores ≥63 compared with those who had BSI scores <63 were more likely to report an inactive lifestyle.
|Characteristic||Did Not Meet Physical Activity Guidelines: Total, N=11,805||Inactive Lifestyle: Total, N=12,139|
|No.||%*||RR†||99% CI†||No.||%*||RR†||99% CI†|
|Age group, y|
|High school graduate||5997||53.6||0.9||0.8-1.0||6227||24.6||0.8||0.6-1.0|
|Working/caring for home or family||9794||51.6||1.0||10,042||18.9||1.0|
|Unemployed/looking for work||479||56.2||1.0||0.9-1.2||494||27.1||1.3||1.0-1.6|
|Unable to work||712||73.2||1.2||1.1-1.3||750||43.5||2.1||1.7-2.5|
|Annual household income, $US|
|Body mass index|
|Depression at time of survey|
Table 3 shows the associations between specific cancer diagnoses and activity status by sex. Among women, survivors of brain tumors and leukemia were the least likely to meet guidelines for physical activity. Among men, survivors of CNS tumors and osteosarcoma were the least likely to meet CDC physical activity guidelines. Both men and women survivors in every diagnostic category were more likely than siblings to report an inactive lifestyle. Amputation and cranial radiation also were associated with not meeting CDC physical activity guidelines and with an inactive lifestyle (Table 4).
|Variable||Did Not Meet Physical Activity Guidelines: Total, N=11,805||Inactive Lifestyle: Total, N=12,139|
|No.||%*||RR†||99% CI†||No.||%*||RR†||99% CI†|
|Acute lymphoblastic leukemia||1333||58.1||1.2||1.1-1.3||1377||25.3||1.9||1.6-2.2|
|Acute myeloid leukemia||127||58.3||1.2||1.0-1.4||131||19.1||1.4||1.0-2.0|
|Other or unspecified leukemia||83||56.6||1.2||1.0-1.4||87||25.3||1.9||1.3-2.8|
|Other CNS tumor||74||55.4||1.2||0.9-1.4||77||31.2||2.3||1.6-3.2|
|Wilms tumor (kidney tumors)||472||54.0||1.1||1.0-1.3||482||20.3||1.6||1.3-2.0|
|Osteosarcoma/other bone tumor||258||59.7||1.2||1.1-1.3||265||29.8||1.9||1.5-2.4|
|Soft tissue sarcoma||382||56.8||1.2||1.1-1.3||393||23.4||1.6||1.3-2.0|
|Acute lymphoblastic leukemia||1314||48.0||1.1||1.0-1.2||1357||20.7||1.6||1.3-1.9|
|Acute myeloid leukemia||100||49.0||1.1||0.9-1.3||102||20.6||1.6||1.0-2.3|
|Other or unspecified leukemia||96||49.0||1.1||0.9-1.3||98||20.4||1.5||1.0-2.3|
|Other CNS tumor||105||61.0||1.3||1.1-1.5||107||31.7||2.3||1.7-3.2|
|Wilms tumor (kidney tumors)||370||46.5||1.0||0.9-1.2||386||19.7||1.6||1.2-2.0|
|Osteosarcoma/other bone tumor||251||57.4||1.2||1.1-1.3||258||23.3||1.6||1.2-2.1|
|Soft tissue sarcoma||410||50.7||1.1||1.0-1.2||423||22.5||1.6||1.3-2.0|
|Variable||Did Not Meet Physical Activity Guidelines: Total, N=8993||Inactive Lifestyle: Total, N=9264|
|No.||%*||RR†||99% CI†||No.||%*||RR†||99% CI†|
|Amputation of lower limb||196||69.9||1.3||1.2-1.5||202||31.2||1.6||1.2-2.0|
|Chemotherapy including anthracyclines||1545||58.8||1.1||1.0-1.2||1596||24.1||1.1||1.0-1.3|
|Chemotherapy without anthracyclines||1695||56.3||1.0||0.9-1.1||1731||23.5||1.1||1.0-1.3|
|Any cranial radiation||1227||62.4||1.2||1.1-1.3||1273||28.4||1.5||1.3-1.7|
|Chest radiation without cranial radiation||760||54.1||1.0||0.9-1.1||774||21.7||1.0||0.8-1.2|
|Amputation of lower limb||228||54.4||1.3||1.1-1.5||234||25.2||1.4||1.0-1.9|
|Chemotherapy including anthracyclines||1693||49.8||1.0||0.9-1.1||1742||19.2||0.8||0.7-1.0|
|Chemotherapy without anthracyclines||1594||49.5||1.0||0.9-1.1||1659||21.8||0.9||0.8-1.1|
|Any cranial radiation||1297||54.5||1.2||1.1-1.3||1344||24.6||1.3||1.1-1.6|
|Chest radiation without cranial radiation||681||501||1.1||1.0-1.2||699||20.3||1.0||0.9-1.3|
Figure 2 illustrates the proportion of individuals who met CDC guidelines for physical activity and the proportion of individuals who reported no leisure-time physical activity over the past month for survivors, siblings, and the BRFSS sample. Survivors were less likely to meet the CDC guidelines for physical activity than the BRFSS reference group, and siblings were less likely to report an inactive lifestyle than the BRFSS group.
The current analysis of physical activity status among a large, heterogeneous cohort of adult survivors of childhood cancer indicates that they are less active than either the siblings in the study or the general population of similar age and sex. Although the findings are statistically significant, the percentage differences in individuals who do not meet CDC physical activity guidelines probably are not clinically meaningful. What is more important is that the prevalence of no activity over than past month is 60% higher among childhood cancer survivors compared with siblings. Our results characterize the features of survivors who are in particular need of interventions that promote physical activity. These include survivors who are women, black, older, underweight or obese, and survivors of CNS or bone tumors, especially those who received cranial radiation or underwent an amputation.
Our study population reports less physical activity than other groups of childhood cancer survivors, including adolescents and young adults,44-46 but more physical activity than a smaller group of childhood cancer survivors comprised of nearly 50% CNS tumor survivors.47 Keats et al45 reported average participation in combined moderate and vigorous physical activities ≥5 times per week, 36 to 42 minutes per session, among 51 adolescent survivors. In that cohort, CNS tumor survivors comprised 13%, and osteosarcoma survivors comprised 8.5%. Tercyak et al46 reported adequate physical activity among 80% of 75 childhood cancer survivors ages 11 to 21 years. Just over half of those individuals were women, and 52% were leukemia survivors. Finnegan et al44 indicated that 81% of childhood cancer survivors who were recruited over the Internet reported being physically active. Those survivors were younger (ages 18-37 years) than our cohort and mostly were well educated, Caucasian women. The proportions of CNS tumor survivors (13% vs 10%) and bone tumor survivors (8% vs 11%) in our cohort were similar to the proportions reported by Finnegan et al, respectively. A small group of adult survivors of childhood cancer in Queensland, Australia were less active, with only 36% reporting sufficient physical activity.47 That group of individuals included a greater percentage of CNS tumor survivors (43%) and more women (61%) than our study.
Our study is the first to our knowledge reporting differences among percentages of individuals who met the nationally recommended guidelines for physical activity in a large, heterogeneous cohort of cancer survivors, siblings, and a population-based comparison group. Our study included all diagnoses in the CCSS cohort and differed from a previous CCSS report in which the analyses were limited to survivors of acute lymphoblastic leukemia.48 Our data analyses included data summarized by Florin et al48 and confirmed and extend the findings that being a woman and receiving cranial radiation are associated with inadequate physical activity. Our analyses also included siblings of cancer survivors, who reported physical activity levels similar to those reported in the population-based group from the BRFSS, dispelling the notion that siblings of cancer survivors who participate in research introduce either healthy or sick participant bias into the study design.49
The demographic and treatment-related risk factors identified in our analyses are supported by other investigators who have demonstrated lower than expected levels of physical activity among adults who were treated for CNS malignancies and bone tumors during childhood, particularly among women survivors. Odame et al50 reported reduced physical activity levels in a group of 25 survivors of childhood CNS tumor who were ages 5 to 29 years at evaluation, with scores on 2 different activity indices lower among those who received cranial radiation compared with those who did not receive cranial radiation. Gerber et al51 evaluated 30 survivors of pediatric sarcoma and reported that 67% had activity levels below the 50th percentile for their age and sex. Problems were most pronounced among those with lower-extremity or trunk lesions and among women.
Several study limitations should be considered in the interpretation of these results. First, physical activity was evaluated with self-report data that could not be validated. However, over- and under-reporting of physical activity were evaluated in 1 study that compared self-reported physical activity on the BRFSS survey with objective monitoring using motion sensors and a heart rate monitor.52 The authors of that report observed 80% agreement between the 2 methods of classifying individuals who did or did not meet the national recommendations for physical activity. In addition, 2 of the personal/demographic variables in our model that influenced physical inactivity, obesity and employment status, were measured simultaneously with the physical activity outcomes. Therefore, we cannot be sure of the direction of these associations. Participants may have an inactive lifestyle because they are obese or may be obese because they have an inactive lifestyle. Participants may have an inactive lifestyle because they are busy looking for a job, or they may be unemployed and sedentary because disability prevents their participation in either activity. Finally, these analyses include cancer survivors who were treated between 1970 and 1986. Because therapy has evolved in response to the documentation of medical late effects, fewer children are receiving cranial radiation or amputation as part of treatment. Not all of our results may be generalizable to children who are treated with more contemporary therapy. However, this information is applicable to the large cohort of young adult survivors of childhood cancer who were treated on earlier protocols and to the groups of individuals who still receive chemotherapy that promotes obesity, cranial radiation, and extensive lower-extremity surgical procedures.
In summary, childhood cancer survivors were less likely than members of a sibling comparison group or an age- and sex-matched group of BRFSS survey participants to meet the nationally recommended guidelines for physical activity. Women survivors, survivors with obesity or chronic disease, survivors who received cranial radiation, and those whose treatment required extensive surgical intervention may benefit from targeted interventions that address unique barriers to participation in regular physical activity.
Conflict of Interest Disclosures
Supported by grant CA 55,727 (L. L. Robison, principal investigator) from the National Cancer Institute (Bethesda, Md) with additional support provided to St. Jude Children's Research Hospital by the American Lebanese Syrian Associated Charities.
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