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Keywords:

  • healthcare disparities;
  • socioeconomic factors;
  • health policy;
  • early detection of cancer;
  • breast cancer

Abstract

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. Acknowledgements
  7. CONFLICT OF INTEREST DISCLOSURES
  8. REFERENCES

BACKGROUND:

This study assessed the relationship between area-level poverty and stage of breast cancer at diagnosis among low-income women when screening mammography was available at no cost.

METHODS:

The authors identified women diagnosed with breast cancer from 1999 to 2005 through the Massachusetts Cancer Registry, and compared the odds of advanced stage disease for women with low incomes (n = 546) for whom screening mammography and diagnostic services were available at no cost through the Massachusetts Breast and Cervical Cancer Early Detection Program, relative to a nonparticipating comparison group (n = 1287) residing in the same neighborhoods with similar distribution of age, race, and ethnicity as Massachusetts Breast and Cervical Cancer Early Detection Program participants. Among Massachusetts Breast and Cervical Cancer Early Detection Program participants, the odds of advanced stage disease were estimated by mammography use.

RESULTS:

Although screening mammography was available at no cost, only 36% of program participants diagnosed with breast cancer used screening mammography. Stage of breast cancer at diagnosis was not associated with area-level poverty among Massachusetts Breast and Cervical Cancer Early Detection Program participants. For the comparison group, advanced stage disease was more likely for residents in high-poverty areas, relative to low-poverty areas (49% vs 37%, P < .01). The adjusted odds of advanced stage disease at diagnosis was greater for women aged 41 to 49 years, compared with those aged 50 to 64 years (P = .01).

CONCLUSIONS:

Programs that ensure breast cancer screening and diagnostic services are available at no cost to low-income women can mitigate the adverse effect of area-level poverty on stage of breast cancer. However, such programs require effective strategies to encourage use of screening mammography to promote diagnosis at an earlier stage. Cancer 2010. © 2010 American Cancer Society.

A substantial body of evidence demonstrates a greater risk for advanced stage breast cancer at diagnosis and correspondingly worse survival rates in neighborhoods of lower socioeconomic status,1-9 and among lower-income women.10-12 Yet there is a paucity of research that examines whether greater risk of advance stage disease at diagnosis is because of characteristics of women within neighborhoods, characteristics of the neighborhood itself, or a combination of these factors. Such knowledge can inform the development of intervention strategies to reduce social disparities in stage of breast cancer.13, 14

Access to screening mammography is a fundamental determinant of the stage of breast cancer at diagnosis and can vary between persons within neighborhoods or across neighborhoods based on individual-level or area-level socioeconomic factors.15-17 Lower-income, uninsured women experience greater barriers to screening mammography because of the cost of services and a limited number of healthcare providers that offer free care or accept Medicaid.12, 15, 18-20 Access to mammography can also vary across areas, because primary care providers and mammography facilities are less likely to locate in lower-income neighborhoods.5, 8, 21-24

The relationship between socioeconomic status and stage of breast cancer is complex.14, 17 The most effective interventions to improve use of screening mammography for lower-income women may need to address barriers at both the individual level and area level.21-23 However, progress on this lingering issue will require policy solutions and additional evidence to support funding of such solutions. Unfortunately, patient-level income is not routinely collected in cancer registers, so there are limited data available to study this important topic.15

The purpose of this study was to assess the relationship between socioeconomic status and stage of breast cancer at diagnosis among low-income women when screening mammography was available at no cost. Further understanding of this topic is relevant to the development of effective interventions to reduce disparities in stage of breast cancer for low-income women. We examined the following research questions: 1) Is area-level poverty associated with stage of breast cancer at diagnosis among low-income women when screening mammography is available at no cost? and 2) Is use of screening mammography associated with stage of breast cancer at diagnosis among low-income women when screening mammography is available at no cost?

MATERIALS AND METHODS

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. Acknowledgements
  7. CONFLICT OF INTEREST DISCLOSURES
  8. REFERENCES

Study Design and Data Sources

We identified women diagnosed with breast cancer in Massachusetts during 1999 to 2005 through the Massachusetts Cancer Registry. Stage of disease at diagnosis was examined among a retrospective cohort of low-income women enrolled in the Massachusetts Breast and Cervical Cancer Early Detection Program and a comparison group of women who did not participate in this program but had similar exposure to area-level poverty and similar distributions of age, race, and ethnicity as program participants.

The Massachusetts Cancer Registry is a population-based cancer registry that collects information from hospitals and other facilities on newly diagnosed cases of cancer among state residents. Data obtained from the cancer registry included tumor size, regional lymph node status, and the presence or absence of distant metastases for incident cases of breast cancer, date of diagnosis, age at diagnosis, race, Hispanic ethnicity, and Census tract associated with women's addresses.

The Breast and Cervical Cancer Early Detection Program is a national program that funds free breast and cervical cancer screening and diagnostic services for low-income women.25 The Massachusetts program reaches women across the state through arrangements with contractors to conduct outreach and health education, and to ensure that clinical staff are available at various facilities to provide case management, screening, and diagnostic services to eligible women. Eligibility criteria for the Massachusetts program include income <250% of the Federal poverty level, and uninsured or underinsured. Services are targeted to women 40 to 65 years of age, but women outside this age range are not refused care if they meet other eligibility criteria. We collected dates of service for screening mammograms from the Massachusetts Breast and Cervical Cancer Early Detection Program.

This research protocol used existing, deidentified data that were thus deemed exempt from review by the Harvard School of Public Health Human Subjects Committee. The study protocol was approved by the Massachusetts Department of Public Health Research and Data Access Review Committee.

Data Linkages

To identify Massachusetts Breast and Cervical Cancer Early Detection Program participants, the Massachusetts Cancer Registry linked the records of women diagnosed with ductal carcinoma in situ and invasive breast cancer during 1999 to 2005 to records of participants in the Massachusetts Breast and Cervical Cancer Early Detection Program. Records were linked by name, birth date, Social Security number, town of residence, and Zip Code using Link Plus, a probabilistic record linkage program developed at the Centers for Disease Control and Prevention.26

Study Population

A total of 40,398 women in Massachusetts were diagnosed with ductal carcinoma in situ or invasive breast cancer during 1999 to 2005 (934 Massachusetts Breast and Cervical Cancer Early Detection Program participants and 39,464 nonparticipants). We excluded women missing Census tract data or information on stage at diagnosis. Women with race/ethnicity other than non-Hispanic white, non-Hispanic black, or Hispanic were also excluded, because there were too few cases to provide reliable information about these groups. To ensure women were age-eligible for routine breast cancer screening within the year preceding their diagnosis, we limited our sample to women aged 41 years and older. Figure 1 summarizes the exclusion criteria for Massachusetts Breast and Cervical Cancer Early Detection Program participants and the comparison group of nonparticipants. Missing stage was associated with race, area-level poverty, and age. However, the absolute value of the observed difference was minimal for race and area-level poverty (0%-3%). The proportion of women excluded for missing stage in the comparison group was almost 2× the proportion excluded among Massachusetts Breast and Cervical Cancer Early Detection Program participants because stage was missing more often for women older than 65 years and because of the relatively small proportion of Massachusetts Breast and Cervical Cancer Early Detection Program participants in this age group as a result of the program eligibility criteria.

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Figure 1. Selection of study groups is shown. MBCCEDP indicates Massachusetts Breast and Cervical Cancer Early Detection Program.

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Of the 934 Massachusetts Breast and Cervical Cancer Early Detection Program participants, 388 were excluded for the following reasons: 86 (9%) missing Census tract, 73 (8%) missing stage, 68 (7%) age younger than 41 years, and 36 (4%) race/ethnicity other than non-Hispanic white, non-Hispanic black, or Hispanic. To ensure that women in our sample were eligible for screening mammography at no cost, we excluded 125 (13%) Massachusetts Breast and Cervical Cancer Early Detection Program participants who were diagnosed with breast cancer prior to receiving any breast-related service (eg, mammogram, diagnostic ultrasound, surgical biopsy, clinical breast exam, or consultation for a breast problem) through the program.

Of the 39,464 women in the cancer registry who were not Massachusetts Breast and Cervical Cancer Early Detection Program participants, 11,675 were excluded for the following reasons: 3260 (8%) missing Census tract, 5493 (14%) missing stage, 2157 (5%) age younger than 41 years, and 765 (2%) race/ethnicity other than non-Hispanic white, non-Hispanic black, or Hispanic. To limit our comparison group to women similar to Massachusetts Breast and Cervical Cancer Early Detection Program participants with regard to area-level poverty, age, race, and ethnicity, we matched the remaining 27,789 women to Massachusetts Breast and Cervical Cancer Early Detection Program participants by Census tract and identified 8274 women who resided in the same tracts. Census tracts are relatively homogeneous areas that include 4000 people on average,27 and associations between stage of breast cancer and Census tract-level poverty have been found in other studies.4, 6, 8, 28 The term Census tract is used interchangeably with the word neighborhood throughout this paper. Next, we used simple random sampling to frequency match the 8274 women in the comparison group to Massachusetts Breast and Cervical Cancer Early Detection Program participants by race/ethnicity (non-Hispanic white, non-Hispanic black, Hispanic) and age (41-49 years, 50-64 years, 65 years and older). The final study groups consisted of 546 participants in the Massachusetts Breast and Cervical Cancer Early Detection Program and 1287 women in the comparison group residing in 397 of the 1367 Census tracts in Massachusetts.

Measures

The dependent variable was stage of breast cancer at diagnosis, defined by the American Joint Committee on Cancer.29 Patient level covariates included self-reported race/ethnicity (non-Hispanic white, non-Hispanic black, Hispanic), age at diagnosis, and year of diagnosis. For the Massachusetts Breast and Cervical Cancer Early Detection Program participants, we created a dichotomous measure of timely use of screening mammography. Timely use was defined as completion of a screening mammogram within the year before the diagnosis to correspond with the American Cancer Society screening guidelines that are followed by the Breast and Cervical Cancer Early Detection Program.30 Screening mammograms were defined with Current Procedural Terminology code 76,092 (bilateral) or Healthcare Common Procedure Coding System code G0202 (direct digital image, bilateral).

Area-level poverty was based on the 2000 Census tract variable “percentage of population living below poverty.” We categorized area-level poverty as high (20% or more of the population living below poverty) or low (<20% of the population living below poverty). This measure of poverty is considered the most robust for consistently detecting socioeconomic gradients in cancer incidence.27 To disentangle the separate effects of individual-level and area-level poverty on stage of breast cancer at diagnosis, we created a variable with 4 categories based on study groups by poverty area: 1) Massachusetts Breast and Cervical Cancer Early Detection Program group residing in high-poverty areas, 2) Massachusetts Breast and Cervical Cancer Early Detection Program group residing in low-poverty areas, 3) comparison group residing in high-poverty areas, and 4) comparison group residing in low-poverty areas.

Statistical Analysis

Our analysis consisted of 3 parts. First, we used the chi-square test to examine differences in characteristics between Massachusetts Breast and Cervical Cancer Early Detection Program participants and the comparison group, unadjusted associations between characteristics of study groups and stage of breast cancer at diagnosis, and unadjusted associations between mammography use among Massachusetts Breast and Cervical Cancer Early Detection Program participants and area-level poverty, and stage of breast cancer. Second, we modeled the adjusted odds of advanced stage breast cancer at diagnosis for study group by poverty area using the 4-level variable with the comparison group residing in low-poverty areas as the reference group. To compare estimates for all groups, we also ran this model using the comparison group in high-poverty areas, and the Massachusetts Breast and Cervical Cancer Early Detection Program group in low-poverty areas as the reference groups. Third, among only the Massachusetts Breast and Cervical Cancer Early Detection Program participants, we modeled the adjusted odds of advanced stage breast cancer for women who did not have timely use of screening mammography, compared with women who completed a screening mammogram within the year before their diagnosis. Stage of breast cancer was grouped as early (ductal carcinoma in situ, stage I) or advanced (stage II, III, IV) based on the 5-year relative survival rate (100%) for ductal carcinoma in situ and stage I breast cancer.31

For our adjusted estimates of association, we used hierarchical logistic regression models to allow for residual variance between and within Census tracts. Logit coefficient estimates from multilevel models were conditional on the random effects at the level of Census tract. All adjusted models controlled for age at time of diagnosis, race/ethnicity, and year of diagnosis. All P values were 2-tailed, with P < .05 as the threshold for statistical significance. We used SAS version 9.1 (SAS Institute, Cary, NC) for all analyses.32

RESULTS

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. Acknowledgements
  7. CONFLICT OF INTEREST DISCLOSURES
  8. REFERENCES

The comparison group and Massachusetts Breast and Cervical Cancer Early Detection Program participants were similar with respect to age and race/ethnicity because of frequency matching on these characteristics. The comparison group resided in the same Census tracts as Massachusetts Breast and Cervical Cancer Early Detection Program participants, but a higher percentage of Massachusetts Breast and Cervical Cancer Early Detection Program participants resided in low-income areas relative to the comparison group, 22% versus 17% (P = .01), respectively (Table 1).

Table 1. Demographic Characteristics of Women Diagnosed With Breast Cancer in Massachusetts, 1999 to 2005
CharacteristicsMBCCEDP Group, n=546, No. (%)Comparison Group,a n=1287, No. (%)P
  • MBCCEDP indicates Massachusetts Breast and Cervical Cancer Early Detection Program.

  • P values were determined by using the chi-square test.

  • a

    Comparison group of women residing in the same census tracts as the MBCCEDP group and frequency matched on age and race/ethnicity.

Census tract-level poverty   
 High: 20.0% to 57.4% living below poverty121 (22)219 (17) 
 Low: 0.4% to <20.0% living below poverty425 (78)1068 (83).01
Age, y   
 41-49178 (33)427 (33) 
 50-64306 (56)711 (55) 
 ≥6562 (11)149 (12).95
Race/ethnicity   
 Non-Hispanic white404 (74)950 (74) 
 Non-Hispanic black62 (11)146 (11) 
 Hispanic80 (15)191 (15).99

Bivariate associations showed that stage of breast cancer at diagnosis was similar for Massachusetts Breast and Cervical Cancer Early Detection Program participants and the comparison group. However, area-level poverty was only associated with stage of breast cancer among women in the comparison group (P < .01). Age and race/ethnicity were also strongly associated with stage of disease, among women 41 to 49 years of age (P = .01) and those of non-Hispanic Black race (P = .01) experiencing the greatest risk (Table 2).

Table 2. Stage of Breast Cancer at Diagnosis for Women Diagnosed With Breast Cancer in Massachusetts, 1999 to 2005
CharacteristicsAdvanced Stage Breast Cancer (TNM Stage II, III, IV), n=1833, No. (%)P
  • MBCCEDP indicates Massachusetts Breast and Cervical Cancer Early Detection Program.

  • P values were determined by using the chi-square test.

  • a

    Comparison group of women residing in the same Census track as the MBCCEDP group and frequency matched on age and race/ethnicity.

Study group  
 MBCCEDP group229 (42).24
 Comparison groupa502 (39) 
MBCCEDP group  
 High: 20.0% to 57.4% living below poverty53 (44).65
 Low: 0.4% to <20.0% living below poverty176 (41) 
Comparison groupa  
 High: 20.0% to 57.4% living below poverty107 (49)<.01
 Low: 0.4% to <20.0% living below poverty395 (37) 
Census tract-level poverty  
 High: 20.0% to 57.4% living below poverty160 (47)<.01
 Low: 0.4% to <20.0% living below poverty571 (38) 
High: 20.0% to 57.4% living below poverty  
 MBCCEDP group53 (44).37
 Comparison groupa107 (49) 
Low: 0.4% to <20.0% living below poverty  
 MBCCEDP group176 (41).11
 Comparison groupa395 (37) 
Age, y  
 41-49270 (45).01
 50-64376 (37) 
 ≥6585 (40) 
Race/ethnicity  
 Non-Hispanic white512 (38).01
 Non-Hispanic black98 (47) 
 Hispanic121 (45) 

Most (73%) of the 546 Massachusetts Breast and Cervical Cancer Early Detection Program participants received at least 1 breast-related service through the program in the year before their diagnosis; a third of these services were screening mammograms. Smaller percentages of Massachusetts Breast and Cervical Cancer Early Detection Program participants used the program within the 2 years (7%), 3 years (7%), or ≥4 years (13%) before their diagnosis (data not shown). The unadjusted timing of screening mammography use did not differ by area-level poverty. Women who did not complete a screening mammogram within the year before their diagnosis were more likely to be diagnosed with advanced stage breast cancer, P < .01 (Table 3).

Table 3. Completion of Screening Mammograms Among MBCCEDP Participants With Diagnosis of Breast Cancer During 1999 to 2005
  Census Tract-Level Poverty 
Screening Mammogram Completed Within the Year Before DiagnosisaTotalHigh, n = 121, 20.0% to 57.4% Living Below Poverty, No. (%)Low, n = 425, 0.4% to <20.0% Living Below Poverty, No. (%)P
Yes194 (36)42 (22)152 (79) 
No352 (64)79 (22)273 (78).83
  Stage of Breast Cancer at Diagnosis 
Screening Mammogram Completed Within the Year Before DiagnosisaTotalEarly, n = 317, Ductal Carcinoma In Situ (TNM Stage I)Advanced, n = 229 (TNM Stage II, III, IV)P
  • MBCCEDP indicates Massachusetts Breast and Cervical Cancer Early Detection Program.

  • P values were determined by using the chi-square test.

  • a

    Women who did not complete a screening mammogram within the year before their diagnosis completed 1 or more of the following services through the MBCCEDP before their diagnosis: consultation, clinical breast exam, diagnostic mammogram, diagnostic ultrasound, surgical biopsy.

Yes194 (36)135 (70)59 (30) 
No352 (64)182 (52)170 (48)<.01

Table 4 reports the adjusted odds of advanced stage breast cancer at diagnosis by study group and area-level poverty (Model 1) and the adjusted odds of advanced stage breast cancer by mammography use for Massachusetts Breast and Cervical Cancer Early Detection Program participants (Model 2). In Model 1, we found that for women in the comparison group, the odds of advanced stage breast cancer were 46% greater in high-poverty areas, relative to low-poverty areas. Similar stage of breast cancer at diagnosis was found for Massachusetts Breast and Cervical Cancer Early Detection Program participants residing in low-poverty areas (odds ratio [OR], 1.20; 95% confidence interval [CI], 0.95-1.51), and high-poverty areas (OR, 1.17; 95% CI, 0.77-1.78), relative to the comparison group residing in low-poverty areas. The adjusted odds of advanced stage breast cancer were 37% greater for women aged 41 to 49 years compared with those aged 50 to 64 years. Using the comparison group residing in high-poverty areas as the reference, we found similar stage of breast cancer at diagnosis for Massachusetts Breast and Cervical Cancer Early Detection Program participants residing in low-poverty and high-poverty areas (data not shown). Model 2 showed that the adjusted odds of advanced stage breast cancer for women who did not complete a screening mammogram within the year before their diagnosis were more than twice the odds for women who completed timely screening.

Table 4. Adjusted Odds Ratios for Advanced Stage Breast Cancer at Diagnosis: Women Diagnosed With Breast Cancer in Massachusetts, 1999 to 2005
CharacteristicsModel 1, n = 1833Model 2, n = 546
OR95% CIOR95% CI
  • OR indicates odds ratio; CI, confidence interval; MBCCEDP, Massachusetts Breast and Cervical Cancer Early Detection Program; Ref, reference.

  • Model 1 includes the MBCCEDP group and the comparison group of women. Model 2 includes only the MBCCEDP group. Model 1 and Model 2 also control for year of diagnosis.

  • a

    High-poverty area where 20.0% to 57.4% of the population live below poverty.

  • b

    Low-poverty area where 0.4% to <20.0% of the population live below poverty.

  • c

    Comparison group of women residing in the same Census tracts as the MBCCEDP group and frequency matched on age and race/ethnicity.

Study groups    
 MBCCEDP group residing in high-poverty areaa1.170.77-1.780.900.55-1.48
 MBCCEDP group residing in low-poverty areab1.200.95-1.51Ref 
 Comparison groupc residing in high-poverty areaa1.461.03-2.06  
 Comparison groupc residing in low-poverty areabRef   
Age, y    
 41-491.371.11-1.691.300.87-1.93
 50-64Ref Ref 
 ≥651.090.79-1.480.950.53-1.70
Race/ethnicity    
 WhiteRef Ref 
 Black1.280.92-1.771.410.78-2.58
 Hispanic1.140.84-1.531.400.79-2.45
Screening mammogram completed within year before diagnosis
 Yes  Ref 
 No  2.051.37-3.06

DISCUSSION

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. Acknowledgements
  7. CONFLICT OF INTEREST DISCLOSURES
  8. REFERENCES

This study addressed limitations of earlier research by analyzing linked data from the Massachusetts cancer registry and the Massachusetts Breast and Cervical Cancer Early Detection Program to examine the relationship between area-level poverty and stage of breast cancer at diagnosis among low-income women when breast cancer screening and diagnostic services were available at no cost to them. Our results showed that stage of breast cancer at diagnosis was not associated with area-level poverty for Massachusetts Breast and Cervical Cancer Early Detection Program participants. In contrast, women similar to Massachusetts Breast and Cervical Cancer Early Detection Program participants with regard to exposure to area-level poverty, and characteristics of age, race, and ethnicity experienced increased risk of diagnosis with advanced stage disease in high-poverty areas. Our findings also provide new information on the increased risk of advanced stage breast cancer at diagnosis among women aged 41 to 49 years. Consistent with prior research, we demonstrated that use of screening mammography was associated with earlier stage breast cancer at diagnosis.12, 33-37 Area-level poverty attenuated the relationship between race/ethnicity and stage of breast cancer.

Two earlier studies found similar stage of breast cancer at diagnosis for low-income women enrolled in the Breast and Cervical Cancer Early Detection Program and women not enrolled in the program.38, 39 However, neither of these prior studies examined the effects of both area-level and individual-level socioeconomic measures as our study did. We found extreme values for proportions of women diagnosed with advanced stage disease among the comparison group (49% in high-poverty areas; 37% in low-poverty areas), whereas values for Massachusetts Breast and Cervical Cancer Early Detection Program participants were midrange (44% in high-poverty areas; 41% low-poverty areas). This pattern of advanced stage breast cancer across study groups and areas suggests that ensuring cancer screening and diagnostic services are available at no cost to low-income women can mitigate the effects of living in high-poverty neighborhoods.

Our study brings attention to the increased risk of advanced stage breast cancer at diagnosis among women aged 41 to 49 years. Women in this age group have lower rates of screening mammography, compared with women aged 50 to 64 years,12, 40 which may account for their higher risk of advanced stage disease at diagnosis. The American Cancer Society recommends annual screening by mammography starting at age 40 years,12 but there has been considerable debate about the benefit of this recommendation.41-43 It is not clear to what extent confusion over conflicting cancer screening guidelines is associated with underuse of mammography among younger women. However, research is needed to understand how such controversies are translated into physicians' practices and patients' use of screening services.

Although screening mammography was free and available to low-income women through the Massachusetts Breast and Cervical Cancer Early Detection Program, most women accessed the program for diagnostic services, and did not use screening mammography. Overall, rates of self-reported use of mammography is high among Massachusetts women (71%), relative to women residing in other states.12 However, national estimates of mammography use suggest that only 59% of breast cancers are detected by mammography (vs by clinical breast exams or by patient self-exams or symptoms).44 The rate of mammography-detected breast cancer is even lower for women with less than a high school education and those with annual household incomes less than $20,000.44 Taken together, this evidence implies that access to free mammography alone does not encourage the use of screening among low-income women. Also needed are effective strategies that address logistical, cultural, social, and cognitive barriers to the use of screening mammography among women in this population.14, 16, 17

We found that race/ethnicity was no longer associated with stage of breast cancer at diagnosis after accounting for area-level poverty. However, other studies have found persistent health disparities between racial/ethnic groups after accounting for socioeconomic status,8, 11, 45-47 providing evidence that measures of race/ethnicity capture more than income level. There is a critical need for disparities research to move beyond using race/ethnicity as a proxy for socioeconomic status in order to understand fully the behavioral and contextual characteristics that influence women's access to and use of breast cancer detection services.14 Through a better understanding of the social determinants of disease burden, more effective interventions can be developed to reduce health inequalities.

There are several limitations to this study. The difference in stage of breast cancer at diagnosis between high-poverty and low-poverty areas for the comparison group is likely because of the differential distribution of individual income, access to mammography, and use of mammography. Unfortunately, the absence of these data limits our ability to explain how these characteristics contributed to this finding. The decision to include 149 (27%) Massachusetts Breast and Cervical Cancer Early Detection Program participants who had a breast-related service through the Massachusetts Breast and Cervical Cancer Early Detection Program earlier than the year before their diagnosis may have biased our findings if these women were not eligible to participate in the program in the year prior to their diagnosis. However, we conducted a sensitivity analysis to examine our results when these women were excluded from the sample and determined that our findings did not change. Of potential concern in our study was that the comparison group was more likely than Massachusetts Breast and Cervical Cancer Early Detection Program participants to have women excluded because of missing stage. However, this imbalance was because of the eligibility criteria for Massachusetts Breast and Cervical Cancer Early Detection Program participants, and was not dependent on the outcome of interest.

We are not able to generalize findings from our study to all low-income, underinsured women because Breast and Cervical Cancer Early Detection Program participants may be more health conscious than nonparticipants of similar socioeconomic position. Results from our study may not apply to Breast and Cervical Cancer Early Detection Program programs in other states and regions in the country because of differences in population characteristics, program implementation, or local policies that influence access to care for low-income, uninsured populations.

This study provides new findings that suggest that public programs that ensure breast cancer screening and diagnostic services are available to low-income women at no cost can mitigate barriers to early detection of breast cancer, despite low use of screening mammography. However, our results indicate a need to implement effective strategies to promote initiation and regular use of screening mammography among low-income women, because uptake of screening mammography is low even when this service is available and free.

Acknowledgements

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. Acknowledgements
  7. CONFLICT OF INTEREST DISCLOSURES
  8. REFERENCES

The authors thank Mary Lou Woodford, RN, BSN, MBA, CCM, Director of the Women's Health Network, Massachusetts Department of Public Health, for sharing her knowledge of the Massachusetts Breast and Cervical Cancer Early Detection Program with us; and Richard Knowlton, MS, Epidemiologist, Massachusetts Cancer Registry, for identifying cancer cases from the registry and linking cases to Massachusetts Breast and Cervical Cancer Early Detection Program records.

CONFLICT OF INTEREST DISCLOSURES

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. Acknowledgements
  7. CONFLICT OF INTEREST DISCLOSURES
  8. REFERENCES

This work was supported by the National Cancer Institute Cancer Prevention and Control Fellowship (5 R25 CA057711-15 to R.L.); the National Institutes of Health, Health Disparities Research Program of the Harvard Catalyst/Harvard Clinical and Translational Science Center (1 UL1 RR 025758-01 and financial contributions from participating institutions to J.Z.A); and the National Cancer Institute, MassCONECT (5 U01 CA114644 and K05CA124415 to K.M.E). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Cancer Institute's Center to Reduce Cancer Health Disparities.

REFERENCES

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. Acknowledgements
  7. CONFLICT OF INTEREST DISCLOSURES
  8. REFERENCES
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