Racial disparities in initiation of adjuvant endocrine therapy of early breast cancer

Endocrine therapy initiation among women diagnosed with ductal carcinoma in situ from 2001 to 2018

PURPOSE

Trials demonstrating benefits of tamoxifen for women with ductal carcinoma in situ (DCIS) were published > 20 years ago; yet subsequent uptake of endocrine therapy was low. We estimated endocrine therapy initiation in women with DCIS between 2001 and 2018 in a community setting, reflecting more recent years of diagnosis than previous studies.

METHODS

This retrospective cohort included adult females ≥ 20 years diagnosed with first primary DCIS between 2001 and 2018, followed through 2019, and enrolled in one of three U.S. integrated healthcare systems. We collected data on endocrine therapy dispensings (tamoxifen, aromatase inhibitors [AIs]) from electronic pharmacy records within 12 months after DCIS diagnosis. Using generalized linear models with a log link and Poisson distribution, we estimated endocrine therapy initiation rates over time and by patient, tumor (including estrogen receptor [ER] status), and treatment characteristics.

RESULTS

Among 2020 women with DCIS, 587 (29%) initiated endocrine therapy within 12 months after diagnosis (36% among 1208 women with ER-positive DCIS). Among women who used endocrine therapy, 506 (86%) initiated tamoxifen and 81 (14%) initiated AIs. Age-adjusted endocrine therapy initiation declined from 34 to 21% between 2001 and 2017; between 2015 and 2018, AI use increased from 8 to 35%. Women less likely to initiate endocrine therapy were ER-negative or had borderline/unknown or no ER test results, ≥ 65 years at diagnosis, Black, and received no radiotherapy.

CONCLUSION

One-third of women diagnosed with DCIS initiated endocrine therapy, and use decreased over time. Understanding why women eligible for endocrine therapy do not initiate is important to maximizing disease-free survival following DCIS diagnosis.

Factors and Beliefs Affecting Women Diagnosed With Breast Cancer to Initiate Cancer Treatment: A Systematic Review

BACKGROUND

Initiating treatment within the optimal time is critical for women with breast cancer. A delay in cancer treatment initiation can result in increased morbidity and mortality and decreased overall survival.

OBJECTIVE

This systematic review aims to investigate the literature for the factors and beliefs affecting women diagnosed with breast cancer with regard to initiating cancer treatment.

METHODS

The PubMed, CINAHL, and PsycINFO databases were searched using the terms of breast cancer, initiating or seeking treatment, and beliefs. The Johns Hopkins Evidence-Based Practice Research Evidence Appraisal Tool was used to evaluate the included articles.

RESULTS

Sixteen articles were included in this review. The addressed factors were classified as (1) patient-related factors, (2) disease-related factors, (3) provider-related factors, and (4) system-related factors. The identified beliefs were cultural beliefs and perceived barriers to initiating treatment.

CONCLUSION

Although the literature reported multiple factors and beliefs that impact the time of initiating treatment among women with breast cancer, more research is needed to fully understand the beliefs influencing treatment initiation. It is essential to address and screen the factors and beliefs identified for women diagnosed with breast cancer to enhance treatment initiation early and prevent any possible delay. Interventions can be developed to overcome the factors and beliefs that may lead to late treatment initiation. Advocacy for new policies should be in action to reduce the disparities associated with treatment initiation among women with breast cancer.

Differences in 21-Gene and PAM50 Recurrence Scores in Younger and Black Women With Breast Cancer

PURPOSE

Genomic tests, such as the Oncotype Dx 21-gene and Prosigna risk of recurrence (ROR-P) assay, are commonly used for breast cancer prognostication. Emerging data suggest variability between assays, but this has not been compared in diverse populations.

MATERIALS AND METHODS

RNA sequencing was performed on 647 previously untreated stage I-III estrogen receptor-positive/human epidermal growth factor receptor 2-negative tumors in the Carolina Breast Cancer Study, which oversampled Black and younger women (age <50 years at diagnosis), using research versions of two common RNA-based prognostic assays: ROR-PR and the 21-gene recurrence score (RSR). Relative frequency differences and 95% CIs were estimated for associations with race and age, and hazards of 5-year local or distant recurrence were modeled with Cox regression. Proliferation and estrogen module scores from each assay, representing broad activity of genes in those pathways, were examined to guide interpretation of differences between tests.

RESULTS

Among both younger and older individuals, Black women had higher frequency of intermediate and high ROR-PR scores than non-Black women. Race was not significantly associated with RSR in either age group. High (hazard ratio [HR], 4.67 [95% CI, 1.73 to 12.70]) and intermediate (HR, 2.12 [95% CI, 0.98 to 4.62]) ROR-PR scores were associated with greater risk of recurrence, but RSR did not predict recurrence. RSR emphasized estrogen over proliferation modules, whereas ROR-PR emphasized proliferation. Higher proliferation scores were associated with younger age and Black race in both assays. Modifications to the RSR algorithm that increased emphasis on proliferation improved prognostication in this diverse population.

CONCLUSION

ROR-PR and the 21-gene RSR differentially emphasize estrogen-related and proliferative biology. The emphasis of 21-gene RS on estrogen-related biology and lower endocrine therapy initiation among Black women may contribute to poorer prognostic ability in heterogeneously treated populations.

Availability of Cranial Prostheses for Black Patients at Comprehensive Cancer Centers

PURPOSE

For patients who seek to camouflage cancer-related hair loss, cranial prostheses such as wigs and hair pieces exist. We sought to determine the availability of yaki-textured, type IV curls, and afro wigs at boutiques in Comprehensive Cancer Centers (CCCs).

METHODS

The 56 CCCs in the United States were surveyed to see whether they had an affiliated wig boutique for patients experiencing hair loss. Boutique workers were then asked a series of seven questions regarding cranial prostheses options for patients seeking yaki-textured, type IV curls, and afro wigs. The availability of wigs was compared with US Census data on population size and density of Black residents.

RESULTS

Of the 56 CCCs, 27 (46%) institutions had active affiliated hair boutiques. We were able to reach 19 (70%) of the 27 boutiques, of which 53% (n = 10) offered yaki-textured wigs, 37% (n = 7) offered type IV curls or afro wigs, and 47% (n = 9) offered neither. Two additional boutiques offered in-store catalogs for Black patients who were interested in naturally appearing wigs. Although two institutions offered a wig bank that was free to all patients, neither had yaki-textured or afro wigs in stock. There was no significant relationship between population size or density of Black residents and availability of these wigs.

CONCLUSION

Many Black patients undergoing cancer treatment interested in cranial prosthesis do not have consistent access to wigs with textures comparable with type IV hair at CCCs. With increased inventory of racially inclusive wigs, partnerships with third-party vendors, and support for the previous authorization process, we can better support Black patients experiencing cancer-related hair loss.

Simulating the population impact of interventions to reduce racial gaps in breast cancer treatment

BACKGROUND

Inequities in guideline-concordant treatment receipt contribute to worse survival in Black patients with breast cancer. Inequity-reduction interventions (eg, navigation, bias training, tracking dashboards) can close such treatment gaps. We simulated the population-level impact of statewide implementation of inequity-reduction interventions on racial breast cancer inequities in North Carolina.

METHODS

Using registry-linked multipayer claims data, we calculated inequities between Black and White patients receiving endocrine therapy (n = 12 033) and chemotherapy (n = 1819). We then built cohort-stratified (endocrine therapy and chemotherapy) and race-stratified Markov models to simulate the potential increase in the proportion of patients receiving endocrine therapy or chemotherapy and subsequent improvements in breast cancer outcomes if inequity-reducing intervention were implemented statewide. We report uncertainty bounds representing 95% of simulation results.

RESULTS

In total, 75.6% and 72.1% of Black patients received endocrine therapy and chemotherapy, respectively, over the 2006-2015 and 2004-2015 periods (vs 79.3% and 78.9% of White patients, respectively). Inequity-reduction interventions could increase endocrine therapy and chemotherapy receipt among Black patients to 89.9% (85.3%, 94.6%) and 85.7% (80.7%, 90.9%). Such interventions could also decrease 5-year and 10-year breast cancer mortality gaps from 3.4 to 3.2 (3.0, 3.3) and from 6.7 to 6.1 (5.9, 6.4) percentage points in the endocrine therapy cohorts and from 8.6 to 8.1 (7.7, 8.4) and from 8.2 to 7.8 (7.3, 8.1) percentage points in the chemotherapy cohorts.

CONCLUSIONS

Inequity-focused interventions could improve cancer outcomes for Black patients, but they would not fully close the racial breast cancer mortality gap. Addressing other inequities along the cancer continuum (eg, screening, pre- and postdiagnosis risk factors) is required to achieve full equity in breast cancer outcomes.

Economic Hardship and Associated Factors of Women With Early-Stage Breast Cancer Prior to Chemotherapy Initiation

INTRODUCTION

Economic hardship (EH) can negatively influence cancer outcomes. Little is known about the factors that are associated with higher levels of EH among patients with breast cancer (BC). This paper describes EH in women with early-stage BC prior to or at their first chemotherapy treatment (baseline) and explores whether there are differences by race, area deprivation, stress, symptom distress, and social support.

PATIENTS AND METHODS

A descriptive comparative/correlational design was employed using baseline data of a multisite, longitudinal, multimethod study comparing the symptom experience and management prior to prescribed chemotherapy for women with early-stage BC. Participants completed measures for EH, perceived stress, symptom distress, and social support. Race was measured by self-report. Area deprivation indices (ADI) measuring neighborhood economic factors were calculated from publicly available websites.

RESULTS

Participants (N = 248; age = 52.9 ± 12.3 years) were 62% White and 38% Black, 54% partnered, and 98% insured. Compared to White patients, Black patients reported higher (worse) EH (1.2 ± 3.0 vs. -0.7 ± 2.4), lived in areas of greater deprivation (80.1 ± 2.1 vs. 50.5 ± 23.5),and were more likely to report inadequate household income (Black: 30.5%; White: 11.1%). Adjusting for race and age, being Black (P< .001), living in an area of greater deprivation (P = .049), higher perceived stress (P = .008), lower perceived appraisal (P = .040), and less tangible support (P < .001) contributed to greater EH. Worse symptom distress trended toward greater EH (P = .07).

CONCLUSIONS

This study emphasizes the importance of incorporating baseline holistic assessment to identify patients most likely to experience EH during early-stage BC treatment.

From Race to Racism and Disparities to Equity: An Actionable Biopsychosocial Approach to Breast Cancer Outcomes

PURPOSE

Racial disparities in outcomes of breast cancer in the United States have widened over more than 3 decades, driven by complex biologic and social factors. In this review, we summarize the biological and social narratives that have shaped breast cancer disparities research across different scientific disciplines in the past, explore the underappreciated but crucial ways in which these 2 strands of the breast cancer story are interwoven, and present 5 key strategies for creating transformative interdisciplinary research to achieve equity in breast cancer treatment and outcomes.

DESIGN

We first review the key differences in tumor biology in the United States between patients racialized as Black versus White, including the overrepresentation of triple-negative breast cancer and differences in tumor histologic and molecular features by race for hormone-sensitive disease. We then summarize key social factors at the interpersonal, institutional, and social structural levels that drive inequitable treatment. Next, we explore how biologic and social determinants are interwoven and interactive, including historical and contemporary structural factors that shape the overrepresentation of triple-negative breast cancer among Black Americans, racial differences in tumor microenvironment, and the complex interplay of biologic and social drivers of difference in outcomes of hormone receptor positive disease, including utilization and effectiveness of endocrine therapies and the role of obesity. Finally, we present 5 principles to increase the impact and productivity of breast cancer equity research.

RESULTS

We find that social and biologic drivers of breast cancer disparities are often cyclical and are found at all levels of scientific investigation from cells to society. To break the cycle and effect change, we must acknowledge and measure the role of structural racism in breast cancer outcomes; frame biologic, psychosocial, and access factors as interwoven via mechanisms of cumulative stress, inflammation, and immune modulation; take responsibility for the impact of representativeness (or the lack thereof) in genomic and decision modeling on the ability to accurately predict the outcomes of Black patients; create research that incorporates the perspectives of people of color from inception to implementation; and rigorously evaluate innovations in equitable cancer care delivery and health policies.

CONCLUSIONS

Innovative, cross-disciplinary research across the biologic and social sciences is crucial to understanding and eliminating disparities in breast cancer outcomes.

Randomized phase III trial evaluating motivational interviewing and text interventions to optimize adherence to breast cancer endocrine therapy (Alliance A191901): the GETSET protocol

BACKGROUND

Hormone receptor-positive (HR +) breast cancer is the most common type of breast cancer in the USA but has excellent long-term outcomes in recent decades, in part due to effective oral endocrine therapy (ET). ET medications are typically prescribed for 5 to 10 years, depending on the risk of recurrence, and must be taken daily. One limiting factor to ET efficacy is nonadherence, with high-risk groups for nonadherence including younger women and Black women.

METHODS

The Alliance for Clinical Trials in Oncology (Alliance) trial A191901 is an ongoing, four-arm (text message reminder (TMR), motivational interviewing (MI), TMR plus MI, or enhanced usual care) randomized clinical trial that tests the efficacy and effect of two interventions (TMR and/or MI) on improved ET adherence, patient-reported outcomes (PROs), and resource use requirements among HR + breast cancer survivors. Participants are randomized in a 1:1:1:1 ratio to the four arms. With an assumed loss to follow-up of approximately 11%, we plan to recruit 1180 participants. Randomization is stratified based on age and race to ensure balance between the arms, and we oversample younger and Black women, with each group representing 30% of the study population. Participants randomized to an intervention will actively participate in the intervention for 9 months, and all participants will be followed for adherence data and PRO endpoints, through the use of the Pillsy cap medication event monitoring system and Alliance ePRO survey app (i.e., Patient Cloud). The primary analysis will compare Pillsy-measured ET adherence among study arms at 12 months.

DISCUSSION

This multisite study will not only define strategies to improve adherence to breast cancer oral therapies, but it will also potentially support strategies in large cooperative research groups that can increase delivery and tolerability of ET, involve diverse patient populations in clinical research, and engage patients effectively in interventional studies, using remote and cost-effective delivery methods.

TRIAL REGISTRATION

Clinicaltrials.gov NCT04379570 . Registered on 7 May 2020.

Reduced racial disparity in receipt of optimal locoregional treatment for women with early-stage breast cancer

INTRODUCTION

Racial disparities in breast cancer treatment contribute to Black women having the worst breast cancer survival rates in the U.S. We investigated whether differences in receipt of optimal locoregional treatment (OLT), defined as receipt of mastectomy, breast-conserving surgery, or no surgery when contraindicated, existed between Black and White women with early-stage breast cancer from 2008-2018.

METHODS

In this retrospective cohort study, data from the Surveillance, Epidemiology, and End Results (SEER) Program Incidence Database was utilized to identify tumor cases from Black and White women aged 20-64 years old with stage I-II breast cancer. Logistic regression analyses were used to evaluate the associations between race and receipt of OLT as well as potential effect modification by tumor characteristics, and year of diagnosis.

RESULTS

Among 177,234 women diagnosed with early-stage breast tumors, disparities in OLT between Black and White women were present from 2008-2010 (2008: 82.1% Black vs. 85.7% White, p<0.001; 2009: 82.1% Black vs. 85.8% White, p<0.001; 2010: 82.2% Black vs. 87.2% White, p<0.001). This disparity was eliminated between 2010-2011 (86.3% Black vs. 87.5% White, p = 0.15), and did not reoccur during the remainder of the study period. From 2010-2011, more Black women received radiation therapy following breast-conserving surgery (43.4% to 48.9%; p = 0.001), which accounted for an overall increased receipt of OLT.

CONCLUSION

Increased receipt of radiation therapy with breast-conserving surgery appeared to drive a substantial increase in OLT for Black women from 2010-2011 that lasted throughout the study period. Further research on the underlying mechanisms that reduced this disparity is warranted.

Racial and regional disparities in deaths in breast cancer

Breast cancer is the second most diagnosed malignancy in American women with a lifetime occurrence of 1 in 8 women in the United States. There has been a dearth of research focusing on regional differences in breast cancer mortality with respect to race in the US. It is crucial to identify regions that are lagging to uplift the outreach of breast cancer care to certain races. Data for this study were obtained from the 2016-2018 Nationwide Inpatient Sample. In-hospital mortality, race and hospital regions for the patients with the primary diagnosis of Malignant Neoplasms of Breast were studied. Baseline characteristics of participants were summarized using descriptive statistics. The patient population was stratified as per race, hospital region, gender, therapy received and family history. Logistic regression was performed to derive the odds ratio while adjusting for different variables. 99, 543 patients with metastatic breast cancer were identified. African Americans (AAs) were found to have the highest reported deaths at 5.54%, followed by Asians and Pacific Islanders at 4.80% and Caucasians 4.09% (p < 0.0001). The odds of dying were significantly higher in the AA population when compared to Caucasian population (OR 1.391 (1.286-1.504)), and the odds were consistently higher across all regions of the US. In terms of regional disparities with respect to race, AA's had highest mortality in the south whereas all other races had the highest mortality in the west. It was seen that races identifying as "others" had significantly higher odds of dying in the Northeast. It is crucial to identify racial differences in the various regions across the US in order to implement appropriate outreach strategies to tackle these disparities.

Use of endocrine therapy for estrogen receptor-positive breast cancer among American Indians and Alaska natives

BACKGROUND

American Indian/Alaska Native (AI/AN) women with estrogen receptor-positive (ER +) breast cancer have higher mortality compared to non-Hispanic whites (NHW). The purpose of this study is to compare rates of initiation of endocrine therapy (ET) between AI/AN and NHW and further determine survival outcomes for ER + breast cancer.

METHODS

We used the National Cancer Database to identify patients diagnosed with ER + breast cancer, stage I-III, between 2004 and 2017. Multivariable logistic regression was performed to determine factors associated with initiation of adjuvant ET. Overall survival was estimated using the Kaplan-Meier analysis and Cox proportional hazards modeling.

RESULTS

We identified a total of 771,619 patients (AI/AN, n = 2473; NHW, n = 769,146). Compared to NHW, AI/AN patients were more likely to live in rural areas, be younger, and have tumors that were higher grade, node positive, and larger. Initiation of adjuvant ET was high in both groups and not significantly different between AI/AN and NHW. Independent predictors of ET initiation included rural location, age, higher tumor grade, node-positive disease, larger tumor size, and progesterone receptor-positive status. Initiation of ET was significantly associated with improved overall survival among all patients. Overall survival was significantly worse among the AI/AN population.

CONCLUSION

AI/AN race was significantly and independently associated with worse overall survival after diagnosis of ER + breast cancer. We did not find a significant difference in the initiation of adjuvant ET between AI/AN and NHW. Exact reasons why AI/AN women with ER + breast cancer have higher mortality rates remain elusive but are probably multifactorial.

Survival Disparities in US Black Compared to White Women with Hormone Receptor Positive-HER2 Negative Breast Cancer

Black women in the US have significantly higher breast cancer mortality than White women. Within biomarker-defined tumor subtypes, disparate outcomes seem to be limited to women with hormone receptor positive and HER2 negative (HR+/HER2-) breast cancer, a subtype usually associated with favorable prognosis. In this review, we present data from an array of studies that demonstrate significantly higher mortality in Black compared to White women with HR+/HER2-breast cancer and contrast these data to studies from integrated healthcare systems that failed to find survival differences. Then, we describe factors, both biological and non-biological, that may contribute to disparate survival in Black women.

Accuracy of tumor registry versus pharmacy dispensings for breast cancer adjuvant endocrine therapy

PURPOSE

Accounting for endocrine therapy use for breast cancer treatment is important for studies of survivorship. We evaluated the accuracy of Surveillance, Epidemiology, and End Results (SEER) breast cancer endocrine therapy data compared with pharmacy dispensings from an integrated health system.

METHODS

We included women with non-metastatic hormone receptor positive primary breast cancer diagnosed between 1995 and 2017 enrolled in Kaiser Permanente Washington, linking their data with SEER. We used pharmacy dispensings for endocrine therapy within one year following diagnosis as our reference standard. We calculated kappa (concordance), positive predictive value (PPV), and negative predictive values (NPV) overall and stratified by woman and tumor characteristics of interest.

RESULTS

Of 5,055 women, mean age at diagnosis was 62 years (interquartile range = 53-71); 53% had localized stage, 56% received lumpectomy with radiation, and 31% received chemotherapy. SEER data alone identified 67% of women as having received endocrine therapy; this increased to 75% with pharmacy dispensings. SEER's concordance with pharmacy dispensings was 0.68 (PPV = 91%; NPV = 76%). PPV did not vary by tumor or women characteristics; however, NPV declined with younger age at diagnosis (64% in < 45 years vs. 86% in 75+ years), increasing tumor stage (49% in regional stage vs. 91% in DCIS), and chemotherapy treatment (41% in those with chemotherapy vs. 83% in those without chemotherapy).

CONCLUSION

Pharmacy dispensings enable more complete endocrine therapy capture, particularly in women with more advanced tumors or who receive chemotherapy. We determined woman, tumor, and treatment characteristics that contribute to underascertainment of endocrine therapy use in tumor registries.

Endocrine therapy initiation among women with stage I-III invasive, hormone receptor-positive breast cancer from 2001-2016

PURPOSE

This retrospective cohort study examined patterns of endocrine therapy initiation over time and by demographic, tumor, and treatment characteristics.

METHODS

We included 7777 women from three U.S. integrated healthcare systems diagnosed with incident stage I-III hormone receptor-positive breast cancer between 2001 and 2016. We extracted endocrine therapy from pharmacy dispensings, defining initiation as dispensings within 12 months of diagnosis. Demographic, tumor, and treatment characteristics were collected from electronic health records. Using generalized linear models with a log link and Poisson distribution, we estimated initiation of any endocrine therapy, tamoxifen, and aromatase inhibitors (AI) over time with relative risks (RR) and 95% confidence intervals (CI) adjusted for age, tumor characteristics, diagnosis year, other treatment, and study site.

RESULTS

Among women aged 20+ (mean 62 years), 6329 (81.4%) initiated any endocrine therapy, and 1448 (18.6%) did not initiate endocrine therapy. Tamoxifen initiation declined from 67 to 15% between 2001 and 2016. AI initiation increased from 6 to 69% between 2001 and 2016 in women aged ≥ 55 years. The proportion of women who did not initiate endocrine therapy decreased from 19 to 12% between 2002 and 2014 then increased to 17% by 2016. After adjustment, women least likely to initiate endocrine therapy were older (RR = 0.81, 95% CI 0.77-0.85 for age 75+ vs. 55-64), Black (RR = 0.93, 95% CI 0.87-1.00 vs. white), and had stage I disease (RR = 0.88, 95% CI 0.85-0.91 vs. stage III).

CONCLUSIONS

Despite an increase in AI use over time, at least one in six eligible women did not initiate endocrine therapy, highlighting opportunities for improving endocrine therapy uptake in breast cancer survivors.

The impact of race and ethnicity in breast cancer-disparities and implications for precision oncology

Breast cancer is the most commonly diagnosed cancer worldwide and is one of the leading causes of cancer death. The incidence, pathological features, and clinical outcomes in breast cancer differ by geographical distribution and across racial and ethnic populations. Importantly, racial and ethnic diversity in breast cancer clinical trials is lacking, with both Blacks and Hispanics underrepresented. In this forum article, breast cancer researchers from across the globe discuss the factors contributing to racial and ethnic breast cancer disparities and highlight specific implications of precision oncology approaches for equitable provision of breast cancer care to improve outcomes and address disparities.

Racial Disparities and Diagnosis-to-Treatment Time Among Patients Diagnosed with Breast Cancer in South Carolina

OBJECTIVES

Diagnosis-to-treatment interval is an important quality measure that is recognized by the National Accreditation Program for Breast Centers, and the American Society of Breast Surgeons and the National Quality Measures for Breast Care. The aim of this study was to assess factors related to delays in receiving breast cancer treatment.

METHODS

This retrospective cohort study (2002 to 2010) used data from the South Carolina Central Cancer Registry (SCCCR) and Office of Revenue and Fiscal Affairs (RFA) to examine racial differences in diagnosis-to-treatment time (in days), with adjuvant hormone receipt, surgery, chemotherapy, and radiotherapy assessed separately. Chi-square tests, and logistic regression and generalized linear models were used to compare diagnosis-to-treatment days.

RESULTS

Black women on average received adjuvant hormone therapy, surgery, chemotherapy, and radiotherapy 25, 8, 7, and 3 days later than their White counterparts, respectively. Black women with local stage cancer had later time to surgery (OR: 1.6; CI: 1.2-2.2) compared with White women with local stage cancer. Black women living in rural areas had higher odds (OR: 2.0; CI: 1.1-3.7) of receiving late chemotherapy compared with White women living in rural areas. Unmarried Black women also had greater risk (OR: 2.0; CI: 1.0-4.0) of receiving late radiotherapy compared to married White women.

CONCLUSIONS

To improve timely receipt of effective BrCA treatments, programs aimed at reducing racial disparities may need to target subgroups of Black breast cancer patients based on their social determinants of health and geographic residence.

Adherence to Endocrine Therapy and Racial Outcome Disparities in Breast Cancer

The disparity in outcomes of breast cancer for Black compared with White women in the U.S. is well known and persistent over time, with the largest disparities appearing among women with hormone receptor-positive (HR+) cancers. The racial gap in breast cancer survival first emerged in the 1980s, a time of significantmen treatment advances in early-stage breast cancer, including the introduction of adjuvant endocrine therapy. Since that time, the gap has continued to widen despite steady advances in treatment and survival of breast cancer overall. Although advanced stage at presentation and unfavorable biology undoubtedly contribute to racial differences in survival of HR+ breast, treatment disparities are increasingly acknowledged to play a key role as well. The recent recognition of racial differences in endocrine therapy use may be a key explanatory factor in the persistent racial gap in mortality of HR+ disease, and may be a key focus of intervention to improve breast cancer outcomes for Black women. IMPLICATIONS FOR PRACTICE: Black women with hormone receptor-positive breast cancer experience the greatest racial disparity in survival among all breast cancer subtypes. This survival gap appears consistently across studies and is not entirely explained by differences in presenting stage, tumor biology as assessed by genomic risk scores, or receipt of chemotherapy. Recent research highlights lower adherence to endocrine therapy (ET) for Black women. Health systems and individual providers should focus on improving communication about the importance of ET use, sharing decisions around ET, providing appropriate support for side effects and other ET-related concerns, and equitably delivering survivorship care, including ET adherence assessment.

Initiation and adherence to adjuvant endocrine therapy among urban, insured American Indian/Alaska Native breast cancer survivors

BACKGROUND

It has been shown that racial/ethnic disparities exist with regard to initiation of and adherence to adjuvant endocrine therapy (AET). However, the relationship among American Indian/Alaska Native (AIAN) individuals is poorly understood, particularly among those who reside in urban areas. We evaluated whether AET initiation and adherence were lower among AIAN individuals than those of other races/ethnicities who were enrolled in the Kaiser Permanente of Northern California (KPNC) health system.

METHODS

We identified 23,680 patients from the period 1997 to 2014 who were eligible for AET (first primary, stage I-III, hormone receptor-positive breast cancer) and used KPNC pharmacy records to identify AET prescriptions and refill dates. We assessed AET initiation (≥1 filled prescription within 1 year of diagnosis) and AET adherence (proportion of days covered ≥80%) every year up to 5 years after AET initiation.

RESULTS

At the end of the 5-year follow-up period, 83% of patients were AET initiators, and 58% were AET adherent. Compared with other races/ethnicities, AIAN women had the second-lowest rate of AET initiation (non-Hispanic Black [NHB], 78.0%; AIAN, 78.6%; Hispanic, 83.0%; non-Hispanic White [NHW], 82.5%; Asian/Pacific Islander [API], 84.7%), the lowest rate of AET adherence after 1 year and 5 years of follow-up (70.3% and 50.8%, respectively), and the greatest annual decline in AET adherence during the 4- to 5-year period of follow-up (a 13.8% decrease in AET adherence [from 64.6% to 50.8%]) after initiation of AET. In adjusted multivariable models, AIAN, Hispanic, and NHB women were less likely than NHW women to be AET adherent. At the end of the 5-year period, total underutilization (combining initiation and adherence) in AET-eligible patients was greatest among AIAN (70.6%) patients, followed by NHB (69.6%), Hispanic (63.2%), NHW (58.7%), and API (52.3%) patients, underscoring the AET treatment gap.

CONCLUSION

Our results suggest that AET initiation and adherence are particularly low for insured AIAN women.

Adoption and effectiveness of de-escalated radiation and endocrine therapy strategies for older women with low-risk breast cancer

PURPOSE

Recent clinical trials support de-escalation of adjuvant radiation therapy following lumpectomy in some older women with low-risk HR+ breast cancers planning to take endocrine therapy. The adoption of these findings into clinical practice, and the effectiveness of de-escalated therapy in real-world populations, remain under investigation.

MATERIALS AND METHODS

We evaluated use of adjuvant radiation therapy and/or endocrine therapy among older women with T1-2 node-negative, HR+ breast cancer in the United States between 2007 and 2011. The study included patients from the Surveillance, Epidemiology and End Results-Medicare linked database and the North Carolina Cancer Information and Population Health Resource database.

RESULTS

Radiation therapy was received by 65.5% of patients, with no decrease over time. Older women and those with T2 (compared to T1) tumors were less likely to receive radiation therapy. In propensity-adjusted analyses, both radiation therapy alone (HR 0.75, 95% CI 0.67-0.84) and radiation + endocrine therapy (HR 0.62, 95% CI 0.54-0.69) were associated with significantly lower recurrence risk compared to endocrine therapy alone. Non-adherence to endocrine therapy was common (37%) and similar across groups. With a median follow-up of 48 months (range 13-84), we were not able to detect an association of non-adherence with recurrence risk in endocrine therapy-containing treatment arms.

CONCLUSION

Most older women with stage I HR+ breast cancers continue to receive radiation, at higher rates than patients with node-negative stage II tumors. These findings suggest that while multiple evidence-based treatment options exist in these patients, improvements are needed to ensure that radiation therapy is applied equitably and rationally.

A population-based comparison of treatment patterns, resource utilization, and costs by cancer stage for Ontario patients with hormone receptor-positive/HER2-negative breast cancer

PURPOSE

To update and expand on data related to treatment, resource utilization, and costs by cancer stage in Canadian patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) breast cancer (BC).

METHODS

We analyzed data for adult women diagnosed with invasive HR+/HER2- BC between 2012 and 2016 utilizing the publicly funded health care system in Ontario. Baseline characteristics, treatment received, and health care use were descriptively compared by cancer stage (I-III vs. IV). Resource use was multiplied by unit costs for publicly funded health care services to calculate costs.

RESULTS

Our study included 21,360 patients with stage I-III plus 813 with stage IV HR+/HER2- BC. Surgery was performed on 20,510 patients with stage I-III disease (96.0%), with the majority having a lumpectomy, and radiation was received by 15,934 (74.6%). Few (n = 1601, 7.8%) received neoadjuvant and most (n = 15,655, 76.3%) received adjuvant systemic treatment. Seven hundred and fifty eight patients with metastatic disease (93.2%) received systemic therapy; 542 (66.7%) received endocrine therapy. Annual per patient health care costs were three times higher in the stage IV vs. stage I-III cohort with inpatient hospital services representing nearly 40% of total costs.

CONCLUSION

The costs associated with metastatic HR+/HER2- BC reflect a significant disease burden. Low endocrine treatment rates captured by the publicly funded system suggest guideline non-adherence or that a fair portion of Ontarian patients may be incurring out-of-pocket drug costs.

Cancer stem cells: Culprits in endocrine resistance and racial disparities in breast cancer outcomes

Breast cancer stem cells (BCSCs) promote endocrine therapy (ET) resistance, also known as endocrine resistance in hormone receptor (HR) positive breast cancer. Endocrine resistance occurs via mechanisms that are not yet fully understood. In vitro, in vivo and clinical data suggest that signaling cascades such as Notch, hypoxia inducible factor (HIF), and integrin/Akt promote BCSC-mediated endocrine resistance. Once HR positive breast cancer patients relapse on ET, targeted therapy agents such as cyclin dependent kinase inhibitors are frequently implemented, though secondary resistance remains a threat. Here, we discuss Notch, HIF, and integrin/Akt pathway regulation of BCSC activity and potential strategies to target these pathways to counteract endocrine resistance. We also discuss a plausible link between elevated BCSC-regulatory gene levels and reduced survival observed among African American women with basal-like breast cancer which lacks HR expression. Should future studies reveal a similar link for patients with luminal breast cancer, then the use of agents that impede BCSC activity could prove highly effective in improving clinical outcomes among African American breast cancer patients.

Do Histopathology and Clinical Outcomes of Breast Atypia Vary by Race/Ethnicity?

BACKGROUND

The clinical behavior of breast cancer varies by racial and ethnic makeup (REM), but the impact of REM on the clinical outcomes of breast atypia remains understudied. We examined the impact of REM on risk of underlying or subsequent carcinoma following a diagnosis of breast atypia.

METHODS

In this retrospective, single-institution chart review, adult women diagnosed with breast atypia (atypical ductal hyperplasia, atypical lobular hyperplasia, or lobular carcinoma in situ) were stratified by REM. Regression modeling was used to estimate risk of underlying or subsequent carcinoma.

RESULTS

We identified 539 patients with breast atypia, including 15 Hispanic (2.8%), 127 non-Hispanic black (23.6%), and 397 non-Hispanic white women (73.7%). Diagnoses included 75.1% atypical ductal hyperplasia (n = 405), 4.6% atypical lobular hyperplasia (n = 25), and 20.2% lobular carcinoma in situ (n = 109). Rates for each type of atypia did not vary by REM (P = 0.33). Of those with atypia on needle biopsy, the rate of underlying carcinoma at excision was 17.3%. After adjustment, REM was not associated with greater risk for carcinoma at excision (P = 0.41). Of those with atypia alone on surgical excision, the rate of a subsequent carcinoma diagnosis was 15.4% (median follow-up 49 mo). REM was not associated with a long-term risk for carcinoma (P = 0.37) or differences in time to subsequent carcinoma (log-rank P = 0.52). Chemoprevention uptake rates were low (10.6%), especially among Hispanic (0%) and non-Hispanic black (3.8%) patients (P = 0.01).

CONCLUSIONS

Among patients with atypia, REM does not appear to influence type of histologic atypia, risk for carcinoma, or clinical outcome, despite differences in chemoprevention rates.

Racial and Geographic Disparities in Endocrine Therapy Adherence Among Younger Breast Cancer Survivors

OBJECTIVES

African American (AA) women with breast cancer (BrCA) have higher mortality than any other race. Differential mortality has been attributed to nonadherence to endocrine therapy (ET). ET can lower the risk of dying by one third; yet 50% to 75% of all women are nonadherent to ET. Despite the wealth of research examining adherence to ET, understanding which groups of women at risk for poor adherence is not well established. The aim of this investigation was to describe ET adherence by race and geographic location among a cohort of younger BrCA survivors.

MATERIALS AND METHODS

Cancer registry records were linked to administrative data from Medicaid and a private insurance plan in South Carolina. Inclusion criteria included: European American (EA) or AA race, 3 years of continuous enrollment in the insurance plan after diagnosis, and BrCA diagnosis between 2002 and 2010. Adherence was measured by computing a medication possession ratio (MPR) based upon refill service dates and the number of pills dispensed. Adjusted least squared means were calculated by racial and geographic group using analysis of covariance methods.

RESULTS

The average MPR for EA women was significantly higher at 96% compared with 92% for AA women (P<0.01). After adjustment for years on hormone therapy, age, and number of pharmacies utilized, rural AA women had an average MPR of 90% compared with 95% for EA women (P<0.01).

CONCLUSIONS

AA women residing in rural areas demonstrate significantly lower adherence compared with their EA counterparts. Interventions are needed to improve adherence that may ameliorate AA mortality disparities.

Examining breast cancer disparities in African Americans with suggestions for policy

Breast cancer is a commonly diagnosed malignancy and the second leading cause of cancer-related death among American women today. The literature suggests that African American Women (AAW) are more likely to die from the disease each year compared to their White counterparts. A biological basis for this disparity exists-early age of onset, more advanced stage of the disease, more aggressive histological changes, and worse survival. Even though mechanisms underlying these disparities are poorly understood, recent studies suggest that the poorer breast cancer outcome observed in AAW may, in part, result from underlying molecular factors. The present review was undertaken to investigate if AAW do, in fact, develop a more aggressive form of breast cancer compared to other racial groups based on molecular level differences and social determinants. This review also addresses health policy changes that may be implemented to aid in eliminating this disparity.

Integrating biology and access to care in addressing breast cancer disparities: 25 years' research experience in the Carolina Breast Cancer Study

Purpose of Review

To review research on breast cancer mortality disparities, emphasizing research conducted in the Carolina Breast Cancer Study, with a focus on challenges and opportunities for integration of tumor biology and access characteristics across the cancer care continuum.

Recent Findings

Black women experience higher mortality following breast cancer diagnosis, despite lower incidence compared to white women. Biological factors, such as stage at diagnosis and breast cancer subtypes, play a role in these disparities. Simultaneously, social, behavioral, environmental, and access to care factors are important. However, integrated studies of biology and access are challenging and it is uncommon to have both data types available in the same study population. The central emphasis of Phase 3 of the Carolina Breast Cancer Study, initiated in 2008, was to collect rich data on biology (including germline and tumor genomics and pathology) and health care access in a diverse study population, with the long term goal of defining intervention opportunities to reduce disparities across the cancer care continuum.

Summary

Early and ongoing research from CBCS has identified important interactions between biology and access, leading to opportunities to build greater equity. However, sample size, population-specific relationships among variables, and complexities of treatment paths along the care continuum pose important research challenges. Interdisciplinary teams, including experts in novel data integration and causal inference, are needed to address gaps in our understanding of breast cancer disparities.

Application of the Champion Health Belief Model to determine beliefs and behaviors of Turkish women academicians regarding breast cancer screening: A cross sectional descriptive study

BACKGROUND

Breast cancer is an important cancer type and the most common malignancy among women in both developed and developing countries and the second leading cause of cancer death in women worldwide. This study aimed to examine the projected risk of breast cancer in Turkish women academician, determine the levels of their breast cancer screening behaviors and uncover the relationship between their health beliefs and screening behaviors.

METHODS

This cross-sectional descriptive study was conducted from March to July 2018 in the province of Aydın, Turkey with a total of 200 female academicians. The data were collected using questionnaires filled out by the participants and the Turkish version of the Champion Health Belief Model Scale. Data were analyzed using t test, ANOVA, Chi-square and logistic regression performed with Statistical Package for Social Sciences version 20.

RESULTS

The mean age of the female academics was 36.1 ± 0.53 years. The female performing breast self-examination had higher perceived sensitivity (OR = 2.88, 95% Cl 1.32, 2.66) benefits to breast self-examination (OR = 0.90, 95% Cl 0.82, 0.99), self-efficacy (OR = 0.87, 95% Cl 0.81, 0.93) health motivation (OR = 1.74, 95% Cl 0.50, 0.90), benefit to mammography (OR = 0.97, 95% Cl 0.88, 1.08), lower barrier to mammography (OR = 1.05, 95% Cl 1.0, 1.09) than women who did not. Female academics with clinical breast examination had higher self-efficacy (OR = 0.91, 95% Cl 0.86, 0.97) and lower barrier to mammography (OR = 1.06, 95% Cl 1.02, 1.10) than women who did not. The female with take mammography had higher sensitivity (OR = 0.84, 95% Cl 0.72, 0.98), lower barrier to breast self-examination (OR = 1.08, 95% Cl 1.02, 1.15) and lower barrier to mammography (OR = 1.09, 95% Cl 1.04, 1.14) than female who did not.

CONCLUSIONS

Female academicians in Turkey exhibit positive attitudes towards breast self-examination, clinical breast examination and mammography as they have higher perceived sensitivity against breast cancer, self-efficacy and fewer barriers. Long-term community-based programs should be extended to different groups of women from a variety of socio-demographic environments.

Breast Cancer Incidence and Mortality by Molecular Subtype: Statewide Age and Racial/Ethnic Disparities in New Jersey

The objective of this study was to assess breast cancer incidence and mortality rates by molecular subtype for cases diagnosed in New Jersey. Data on all primary, histologically confirmed, invasive breast cancers diagnosed among women between January 1, 2008 and December 31, 2013 were retrieved from the New Jersey State Cancer Registry. Age-adjusted incidence rates were calculated for each subtype, by ageandrace/ethnicity. Logistic regression models, Cox proportional hazards models, and Kaplan Meier curves were used to describe the relative risks for breast cancer incidence, mortality, and survival, respectively. In this population-based sample of 32,770 breast cancer cases, non-Hispanic Blacks (NHBs) had the highest triple-negative breast cancer (TNBC) incidence rate (17.8 per 100,000, 95% CI 16.5-19.2) compared to other races/ethnicities. NHBs had also higher odds of TNBC (OR 2.1, 95% CI 1.95-2.36) and higher hazards of death when diagnosed with TNBC (HR 1.28, 95% CI 1.05-1.56), luminal A (HR 1.64, 95% CI 1.41-1.91), or luminal B (HR 1.54, 95% CI 1.10-2.15) than non-Hispanic Whites (NHWs). Younger women (20-39 years) had higher odds of TNBC (OR 1.77, 95% CI 1.54-2.02) and luminal B (OR 1.56, 95% CI 1.35-1.80) compared to women 50-64 years; minority women had higher odds of non-luminal HER2-expressing and lower odds of luminal A than NHWs. TNBC was associated with the poorest survival rates. These findings highlight a need for enhanced screening to promote earlier diagnosis and improve breast cancer outcomes, particularly in minorities and younger women, which will be essential for achieving health equity.

Race and delays in breast cancer treatment across the care continuum in the Carolina Breast Cancer Study

BACKGROUND

After controlling for baseline disease factors, researchers have found that black women have worse breast cancer survival, and this suggests that treatment differences may contribute to poorer outcomes. Delays in initiating and completing treatment are one proposed mechanism.

METHODS

Phase 3 of the Carolina Breast Cancer Study involved a large, population-based cohort of women with incident breast cancer. For this analysis, we included black women (n = 1328) and white women (n = 1331) with stage I to III disease whose treatment included surgery with or without adjuvant therapies. A novel treatment pathway grouping was used to benchmark the treatment duration (surgery only, surgery plus chemotherapy, surgery plus radiation, or all 3). Models controlled for the treatment pathway, age, and tumor characteristics and for demographic factors related to health care access. Exploratory analyses of the association between delays and cancer recurrence were performed.

RESULTS

In fully adjusted analyses, blacks had 1.73 times higher odds of treatment initiation more than 60 days after their diagnosis in comparison with whites (odds ratio [OR], 1.73; 95% confidence interval [CI], 1.04-2.90). Black race was also associated with a longer treatment duration. Blacks were also more likely to be in the highest quartile of treatment duration (OR, 1.69; 95% CI, 1.41-2.02), even after adjustments for demographic and tumor characteristics (OR, 1.31; 95% CI, 1.04-1.64). A nonsignificant trend toward a higher recurrence risk was observed for patients with delayed initiation (hazard ratio, 1.44; 95% CI, 0.89-2.33) or the longest duration (hazard ratio, 1.17; 95% CI, 0.87-1.59).

CONCLUSIONS

Black women more often had delayed treatment initiation and a longer duration than whites receiving similar treatment. Interventions that target access barriers may be needed to improve timely delivery of care.

Does race predict survival for women with invasive breast cancer?

BACKGROUND

Black women with breast cancer have lower survival rates and higher recurrence rates in comparison with white women. This study compared treatment and survival outcomes for black and white women at a highly specialized tertiary care cancer center.

METHODS

An institutional review board-approved, retrospective institutional database review was performed to identify all black women treated for invasive breast cancer between 2005 and 2010. Women with a prior history of breast cancer, stage IV cancer, or bilateral breast cancer were excluded. White women had similar exclusion criteria applied and were then matched to black women 1:1 by age and diagnosis year. Clinicopathologic and treatment variables were compared by race. Kaplan-Meier methodology was used to estimate overall survival (OS) and disease-free survival (DFS); a multivariable analysis was conducted with Cox regression models.

RESULTS

The study group consisted of 1332 women (666 black). The median tumor size was larger in black women (1.6 vs 1.3 cm; P < .001). Black women had more nodal disease (41.1% vs 32%; P < .001) and had tumors that were more frequently an estrogen receptor-negative (32.9% vs 15%; P < .001), progesterone receptor-negative (47.1% vs 30.2%; P < .001), or triple-negative (TN) subtype (24% vs 8.9%; P < .001) in comparison with white women. Black women also had inferior DFS and OS; race was not an independent prognostic indicator in the multivariable analysis.

CONCLUSIONS

Black women had more advanced disease and adverse prognostic indicators at diagnosis, but race was not an independent predictor of outcome. Black women were significantly more likely to have TN breast cancer. Further research is necessary to understand the differences in tumor biology associated with race.

Endocrine Therapy Nonadherence and Discontinuation in Black and White Women

BACKGROUND

Differential use of endocrine therapy (ET) by race may contribute to breast cancer outcome disparities, but racial differences in ET behaviors are poorly understood.

METHODS

Women aged 20-74 years with a first primary, stage I-III, hormone receptor-positive (HR+) breast cancer were included. At 2 years postdiagnosis, we assessed nonadherence, defined as not taking ET every day or missing more than two pills in the past 14 days, discontinuation, and a composite measure of underuse, defined as either missing pills or discontinuing completely. Using logistic regression, we evaluated the relationship between race and nonadherence, discontinuation, and overall underuse in unadjusted, clinically adjusted, and socioeconomically adjusted models.

RESULTS

A total of 1280 women were included; 43.2% self-identified as black. Compared to white women, black women more often reported nonadherence (13.7% vs 5.2%) but not discontinuation (10.0% vs 10.7%). Black women also more often reported the following: hot flashes, night sweats, breast sensitivity, and joint pain; believing that their recurrence risk would not change if they stopped ET; forgetting to take ET; and cost-related barriers. In multivariable analysis, black race remained statistically significantly associated with nonadherence after adjusting for clinical characteristics (adjusted odds ratio = 2.72, 95% confidence interval = 1.75 to 4.24) and after adding socioeconomic to clinical characteristics (adjusted odds ratio = 2.44, 95% confidence interval = 1.50 to 3.97) but was not independently associated with discontinuation after adjustment. Low recurrence risk perception and lack of a shared decision making were strongly predictive of ET underuse across races.

CONCLUSIONS

Our results highlight important racial differences in ET-adherence behaviors, perceptions of benefits/harms, and shared decision making that may be targeted with culturally tailored interventions.

Using Group-based Trajectory Models and Propensity Score Weighting to Detect Heterogeneous Treatment Effects: The Case Study of Generic Hormonal Therapy for Women With Breast Cancer

BACKGROUND

We extend an interrupted time series study design to identify heterogenous treatment effects using group-based trajectory models (GBTMs) to identify groups before a new policy and then examine if the effects of the policy has consistent impacts across groups using propensity score weighting to balance individuals within trajectory groups who are and are not exposed to the policy change. We explore this by examining how adherence to endocrine therapy (ET) for women with breast cancer was impacted by reducing copayments for medications by the introduction of generic ETs among women who do not receive a subsidy (the "treatment" group) to those that do receive a subsidy and are not exposed to any changes in copayments (the "control" group).

METHODS

We examined monthly adherence to ET using the proportion of days covered for women diagnosed with breast cancer between 2008 and 2009 using SEER-Medicare data. To account for baseline trends, we characterize adherence for 1 year before generic approval of ET using GBTMs, within each groups we generate inverse probability treatment weights of not receiving a subsidy. We compared adherence after generic entry within each GBTM using a modified Poisson model.

RESULTS

GBTMs for adherence in the 1-year pregeneric identified 6 groups. When comparing patients who did and did not receive a subsidy we found no overall effect of generic introduction. However, 1 of the 6 identified adherence groups postgeneric adherence increased [the "consistently low" (risk ratio=1.91; 95% confidence interval=1.34-2.72)].

CONCLUSIONS

This study describes a new approach to identify heterogenous effects when using an interrupted time series research design.

A systematic review of interventions to improve adherence to endocrine therapy

PURPOSE

Adherence to endocrine therapy for hormone positive breast cancer is a significant problem, especially in minority populations. Further, endocrine therapy reduces recurrence and thus mortality. However, little data are available on interventions to improve adherence. The authors conducted a systematic review to examine the impact of interventions, strategies, or approaches aimed to improve endocrine therapy adherence among women with breast cancer. A secondary aim was to determine if interventions had any cultural modifications.

METHODS

Two of the authors examined articles published between 2006 and 2017 from a wide variety of databases using Covidence systematic review platform.

RESULTS

In total, 16 eligible studies met criteria for review including 4 randomized controlled trials, 4 retrospective studies, and 8 with various observational designs. Eligible studies used a broad range of definitions for adherence and measured adherence by self-report, medical records, claims data, and combinations of these. All used 80% medication possession ratio as a standard for adherence. Patient information/education was the most frequent intervention strategy but did not demonstrate a significant effect except in one study. Significant results were noted when education was combined with communication strategies.

CONCLUSIONS

Researchers need a standard definition for adherence and a reliable measure that is feasible to use in a variety of studies. While education may be a necessary component of an intervention, when used alone, it is not a sufficient approach to change behavior.

A systematic review of interventions to improve adherence to endocrine therapy

PURPOSE

Adherence to endocrine therapy for hormone positive breast cancer is a significant problem, especially in minority populations. Further, endocrine therapy reduces recurrence and thus mortality. However, little data are available on interventions to improve adherence. The authors conducted a systematic review to examine the impact of interventions, strategies, or approaches aimed to improve endocrine therapy adherence among women with breast cancer. A secondary aim was to determine if interventions had any cultural modifications.

METHODS

Two of the authors examined articles published between 2006 and 2017 from a wide variety of databases using Covidence systematic review platform.

RESULTS

In total, 16 eligible studies met criteria for review including 4 randomized controlled trials, 4 retrospective studies, and 8 with various observational designs. Eligible studies used a broad range of definitions for adherence and measured adherence by self-report, medical records, claims data, and combinations of these. All used 80% medication possession ratio as a standard for adherence. Patient information/education was the most frequent intervention strategy but did not demonstrate a significant effect except in one study. Significant results were noted when education was combined with communication strategies.

CONCLUSIONS

Researchers need a standard definition for adherence and a reliable measure that is feasible to use in a variety of studies. While education may be a necessary component of an intervention, when used alone, it is not a sufficient approach to change behavior.

Trastuzumab uptake in HER2-positive breast cancer patients: a systematic review and meta-analysis of observational studies

Overexpression of the HER2 gene is predictive of treatment benefit with trastuzumab therapy for breast cancer (BC) patients. The study objective was to investigate whether all eligible patients with HER2-positive BC initiated trastuzumab therapy. A systematic search was conducted through PubMed, Web of Science PsycINFO, Cumulative Index to Nursing and Allied Health Literature (CINAHL) and Cochrane Library. From 2651 studies identified, 107 observational studies were included for full text review, of which 26 met the inclusion criteria and an additional 7 studies were identified through citation searching. Two independent reviewers extracted data for accuracy and completeness. From 33 observational studies, 14,644 patients were exposed to trastuzumab therapy. Age range varied across studies; the youngest cohort had a median age of 50 and the oldest had a median age of 84. Sample sizes ranged from 11 to 1928 and included patients from 10 countries. Studies were heterogenous and few studies accounted for confounders. We identified large variability in uptake of trastuzumab in HER2-positive early BC patients (9.1-100%) and metastatic BC patients (50.8-84.0%). The pooled uptake was 71.3% (95% CI 64.6-77.9%), with high heterogeneity (I² = 99.05%). The most conservative predictors of higher uptake included younger age (OR 2.09; 95% CI 1.36-3.20) and lower Charlson Comorbidity Index of patients (OR 1.62; 95% CI 1.32-1.99). In addition, tumour characteristics including higher tumour grade (OR 1.73; 95% CI 1.23-2.45), larger tumour size (OR 1.80; 95% CI 1.54-2.10), advanced tumour stage (OR 2.07; 95% CI 1.44-2.96) and hormone receptor negative tumor (OR 1.54; 95% CI 1.35-1.77) were associated with higher uptake. The uptake of trastuzumab therapy varied widely between studies and across subgroups suggesting that there may be some inequalities in the use of this agent. However, our findings should be interpreted with caution due to study heterogeneity and potential confounding, and thus additional studies of individual level data which control for confounders are needed to understand more about inequalities in uptake.

Financial Impact of Breast Cancer in Black Versus White Women

Purpose Racial variation in the financial impact of cancer may contribute to observed differences in the use of guideline-recommended treatments. We describe racial differences with regard to the financial impact of breast cancer in a large population-based prospective cohort study. Methods The Carolina Breast Cancer Study oversampled black women and women younger than age 50 years with incident breast cancer in North Carolina from 2008 to 2013. Participants provided medical records and data regarding demographics, socioeconomic status, and financial impact of cancer at 5 and 25 months postdiagnosis. We report unadjusted and adjusted financial impact at 25 months postdiagnosis by race. Results The sample included 2,494 women who completed follow-up surveys (49% black, 51% white). Since diagnosis, 58% of black women reported any adverse financial impact of cancer ( v 39% of white women; P < .001). In models adjusted for age, stage at diagnosis, and treatment received, black women were more likely to report adverse financial impact attributable to cancer (adjusted risk difference [aRD], +14 percentage points; P < .001), including income loss (aRD, +10 percentage points; P < .001), health care-related financial barriers (aRD, +10 percentage points; P < .001), health care-related transportation barriers (aRD, +10 percentage points; P < .001), job loss (aRD, 6 percentage points; P < .001), and loss of health insurance (aRD, +3 percentage points; P < .001). The effect of race was attenuated when socioeconomic factors were included but remained significant for job loss, transportation barriers, income loss, and overall financial impact. Conclusion Compared with white women, black women with breast cancer experience a significantly worse financial impact. Disproportionate financial strain may contribute to higher stress, lower treatment compliance, and worse outcomes by race. Policies that help to limit the effect of cancer-related financial strain are needed.

Unmet Needs in Clinical Research in Breast Cancer: Where Do We Need to Go?

This CCR Focus highlights areas in breast cancer research with the greatest potential for clinical and therapeutic application. The articles in this CCR Focus address the state of the science in a broad range of areas with a focus on "hot" although sometimes controversial topics, unanswered questions, and unmet need. From mutational signatures, the cancer genomic revolution, and new inroads in immunotherapy for breast cancer to unique concerns of vulnerable populations as well as national and global health disparities, these works represent much of the promise of breast cancer research as well as the challenges in the coming years. Each review focuses not only on recent discoveries but also on putting the topic in context, including limitations to overcome. This overview is designed to further contextualize the highlighted issues within the broader research landscape. We also present new information from a poll of ALLIANCE for Clinical Trials in Oncology Breast Committee members regarding the most needed and viable potential future National Cancer Institute (NCI)-supported clinical trials in breast cancer. The great challenge is to translate the potential benefits of greater scientific knowledge reflected in this CCR Focus section into improvements in outcomes for individuals and populations with breast cancer. A unifying theme across the six articles contained in this CCR Focus is the increasingly recognized value and necessity of collaboration across disciplines from bench to bedside to populations. Only continued and iteratively amplified scientific, clinical, and governmental commitment to creating, testing, and implementing new knowledge will reduce the global morbidity and mortality of breast cancer. Clin Cancer Res; 23(11); 2611-6. ©2017 AACRSee all articles in this CCR Focus section, "Breast Cancer Research: From Base Pairs to Populations."

Evaluation of the Quality of Adjuvant Endocrine Therapy Delivery for Breast Cancer Care in the United States

Importance

Randomized trials in breast cancer have demonstrated the clinical benefits of adjuvant endocrine therapy (AET) in preventing recurrence and death. The examination of concordance with AET guidelines at a national level as a measure of quality of care is important.

Objective

To investigate temporal trends and factors related to receipt of AET for breast cancer.

Design, Setting, and Participants

This retrospective cohort study included 981 729 women with breast cancer in the National Cancer Database from January 1, 2004, to December 31, 2013. Women with stages I to III breast cancer who received all or part of their treatment at the reporting institution were included in the analysis.

Main Outcomes and Measures

Temporal changes in AET receipt (estimating the annual percentage change) and AET practice patterns (using logistic regression) and the effect of AET guideline concordance on survival of women with hormone receptor-positive (HR+) breast cancer (using the multivariable Cox proportional hazards model).

Results

Of the 981 729 eligible patients (mean [SD] age, 60.8 [13.3] years), 818 435 had HR+ and 163 294 had HR-negative (HR-) cancer. Among the patients with HR+ cancer, receipt of AET increased over time, from 69.8% in 2004 to 82.4% in 2013. Among patients with HR- cancer, receipt decreased from 5.2% in 2004 to 3.4% in 2013. Hospital-level adherence (≥80% of patients with HR+ cancer received AET) increased from 40.2% in 2004 to 69.2% in 2013. Receipt of AET varied significantly by age (lower in patients ≥80 years), race (lower in African American and Hispanic participants), geographic location (lower in West South Central, Mountain, and Pacific census regions), and receptor status (lower in patients with estrogen receptor-negative and progesterone receptor-positive cancer). Surgery and radiotherapy were the factors most significantly associated with appropriate AET receipt (only 45.0% in patients who received lumpectomy without radiotherapy). Receipt of AET was associated with a 29% relative risk reduction in mortality. Based on this effectiveness estimate, if all patients with HR+ cancer received AET, approximately 14 630 lives would have been saved over 10 years.

Conclusions and Relevance

From 2004 to 2013, underuse and misuse of AET have decreased for patients with breast cancer, but optimal use has not been achieved, and significant variation in care remains. The involvement of surgery and radiotherapy were among the most significant factors associated with optimal use, which underscores the benefits of team-based care to support guideline-concordant therapy.

Medical costs of treating breast cancer among younger Medicaid beneficiaries by stage at diagnosis

BACKGROUND

Younger women (aged 18-44 years) diagnosed with breast cancer often face more aggressive tumors, higher treatment intensity, and lower survival rates than older women. In this study, we estimated incident breast cancer costs by stage at diagnosis and by race for younger women enrolled in Medicaid.

METHODS

We analyzed cancer registry data linked to Medicaid claims in North Carolina from 2003 to 2008. We used Surveillance, Epidemiology, and End Results (SEER) Summary 2000 definitions for cancer stage. We split breast cancer patients into two cohorts: a younger and older group aged 18-44 and 45-64 years, respectively. We conducted a many-to-one match between patients with and without breast cancer using age, county, race, and Charlson Comorbidity Index. We calculated mean excess total cost of care between breast cancer and non-breast cancer patients.

RESULTS

At diagnosis, younger women had a higher proportion of regional cancers than older women (49 vs. 42%) and lower proportions of localized cancers (44 vs. 50%) and distant cancers (7 vs. 9%). The excess costs of breast cancer (all stages) for younger and older women at 6 months after diagnosis were $37,114 [95% confidence interval (CI) = $35,769-38,459] and $28,026 (95% CI = $27,223-28,829), respectively. In the 6 months after diagnosis, the estimated excess cost was significantly higher to treat localized and regional cancer among younger women than among older women. There were no statistically significant differences in excess costs of breast cancer by race, but differences in treatment modality were present among younger Medicaid beneficiaries.

CONCLUSIONS

Younger breast cancer patients not only had a higher prevalence of late-stage cancer than older women, but also had higher within-stage excess costs.

Impact of patient race and geographical factors on initiation and adherence to adjuvant endocrine therapy in medicare breast cancer survivors

To evaluate variations in the use of adjuvant endocrine therapy (AET) by race and geography, this research examined their influence on initiation and adherence to AET in female Medicare enrollees with breast cancer, diagnosed between 2007 and 2011.Using SEER (Surveillance, Epidemiology, and End Results Program)-Medicare data from 2007 to 2001, logistic regressions with random intercept for county of residence were used to predict AET initiation during 1st year and AET adherence assessed by the medication possession ratio (MPR) during year after initiation in a sample of fee-for-service medicare beneficiaries. Part D enrollment was required for the examination of adherence. Independent variables examined were race (black, white, or other) and geographical indicators (area deprivation, non-metropolitan status, and physician shortage).Overall, 23% of patients did not initiate AET within 1 year and 26% of the initiation sample was not adherent to AET, with average follow-up time among initiators of 141 days and an average MPR of 0.84. Significant heterogeneity (P < .01) was found between SEER sites, with initiation rates as low as 69% for Washington and as high as 81% for New Jersey; MPR adherence varied from 77% in New Jersey to 68% in Utah.Blacks had lower initiation, enrollees not in Medicaid had lower adherence, lower area deprivation counties had lower initiation, earlier SEER-Medicare years had both later initiation and nonadherence, and significant (P < .05) variations between SEER sites remained after accounting for area deprivation index, metropolitan status, and physician shortage. Subgroup analysis showed particular pockets of lower initiation for blacks with stage III tumors, on chemotherapy and lower adherence for blacks in youngest age group, with stage III tumors, tamoxifen use and blacks/others in oldest age group.Black women and women living in states with more rurality in the United States were less likely to receive guideline-recommended AET, which necessitates future efforts to alleviate these disparities to improve AET use and ultimately pursue more survival gains through optimizing adjuvant treatment use among cancer survivors.

High Initiation of Adjuvant Hormonal Therapy Among Uninsured Stages I-III Breast Cancer Patients Treated in a Safety-Net Healthcare System

OBJECTIVE

Despite benefits of adjuvant hormonal therapy (AHT), many eligible breast cancer patients do not complete therapy as recommended. Patterns of AHT use have not been well studied among uninsured breast cancer patients who fall into coverage gaps or are ineligible for public insurance programs.

METHODS

We identified 291 patients newly diagnosed with stages I-III hormone receptor-positive breast cancer from January 2008 to December 2012. All patients were treated at a safety-net healthcare system and enrolled in an income-based medical assistance program that fills AHT prescriptions at low cost. We extracted and linked cancer registry, pharmacy claims, and medical record data to assess AHT initiation (defined as a new AHT prescription ≤18 months since diagnosis) and sociodemographic and healthcare utilization variables. Log-binomial regression was used to identify correlates of initiation.

RESULTS

Overall, 239 (82%) patients initiated AHT. Tamoxifen (42%) and anastrozole (55%) were most commonly prescribed. The mean copay was $4.90 for tamoxifen and $6.00 for anastrozole. Although crude analyses revealed small, statistically significant prevalence ratios for race/ethnicity (Hispanic vs. white, other vs. white), year of diagnosis (2008 vs. 2012), primary care visit before diagnosis (any vs. none), and smoking status (current vs. never), there were no significant correlates of initiation in the adjusted model.

CONCLUSION

Safety-net healthcare systems providing access to AHT (i.e., through reduced copays) could improve the number of eligible patients initiating therapy. Continuity and integration of care in these settings may reduce disparities frequently observed in uninsured, low-income breast cancer populations.

African American Race is an Independent Risk Factor in Survival from Initially Diagnosed Localized Breast Cancer

BACKGROUND: African American race negatively impacts survival from localized breast cancer but co-variable factors confound the impact.

METHODS: Data sets were analyzed from the Surveillance, Epidemiology and End Results (SEER) directories from 1973 to 2011 consisting of patients with designated diagnosis of breast adenocarcinoma, race as White or Caucasian, Black or African American, Asian, American Indian or Alaskan Native, Native Hawaiian or Pacific Islander, age, stage I, II or III, grade 1, 2 or 3, estrogen receptor or progesterone receptor positive or negative, marital status as single, married, separated, divorced or widowed and laterality as right or left. The Cox Proportional Hazards Regression model was used to determine hazard ratios for survival. Chi square test was applied to determine the interdependence of variables found significant in the multivariable Cox Proportional Hazards Regression analysis. Cells with stratified data of patients with identical characteristics except African American or Caucasian race were compared.

RESULTS: Age, stage, grade, ER and PR status and marital status significantly co-varied with race and with each other. Stratifications by single co-variables demonstrated worse hazard ratios for survival for African Americans. Stratification by three and four co-variables demonstrated worse hazard ratios for survival for African Americans in most subgroupings with sufficient numbers of values. Differences in some subgroupings containing poor prognostic co-variables did not reach significance, suggesting that race effects may be partly overcome by additional poor prognostic indicators.

CONCLUSIONS: African American race is a poor prognostic indicator for survival from breast cancer independent of 6 associated co-variables with prognostic significance.

Understanding CKD among patients with T2DM: prevalence, temporal trends, and treatment patterns-NHANES 2007-2012

OBJECTIVE

To describe the estimated prevalence and temporal trends of chronic kidney disease (CKD) treatment patterns, and the association between CKD and potential factors for type 2 diabetes mellitus (T2DM) in different demographic subgroups.

RESEARCH DESIGN AND METHODS

This was a cross-sectional analysis of adults with T2DM based on multiple US National Health and Nutrition Examination Survey (NHANES) datasets developed during 2007-2012. CKD severity was defined according to the Kidney Disease: Improving Global Outcomes (KDIGO) 2012 guidelines using the CKD Epidemiology Collaboration (CKD-EPI) equation: mild to moderate=stages 1-3a; moderate to kidney failure=stages 3b-5. Multivariable logistic regression analyses were performed to assess the associations between CKD and potential factors.

RESULTS

Of the adult individuals with T2DM (n=2006), age-adjusted CKD prevalence was 38.3% during 2007-2012; 77.5% were mild-to-moderate CKD. The overall age-adjusted prevalence of CKD was 40.2% in 2007-2008, 36.9% in 2009-2010, and 37.6% in 2011-2012. The prevalence of CKD in T2DM was 58.7% in patients aged ≥65 years, 25.7% in patients aged <65 years, 43.5% in African-Americans and Mexican-Americans, and 38.7% in non-Hispanic whites. The use of antidiabetes and antihypertensive medications generally followed treatment guideline recommendations. Older age, higher hemoglobin A1c (HbA1c), systolic blood pressure (SBP), and having hypertension were significantly associated with CKD presence but not increasing severity of CKD.

CONCLUSIONS

CKD continued to be prevalent in the T2DM population; prevalence remained fairly consistent over time, suggesting that current efforts to prevent CKD could be improved overall, especially by monitoring certain populations more closely.

Disparities in Use of Human Epidermal Growth Hormone Receptor 2-Targeted Therapy for Early-Stage Breast Cancer

PURPOSE

Trastuzumab is a key component of adjuvant therapy for stage I to III human epidermal growth factor receptor 2 (HER2)-positive breast cancer. The rates and patterns of trastuzumab use have never been described in a population-based sample. The recent addition of HER2 information to the SEER-Medicare database offers an opportunity to examine patterns of trastuzumab use and to evaluate possible disparities in receipt of trastuzumab.

METHODS

We examined a national cohort of Medicare beneficiaries with incident stage I to III HER2-positive breast cancer diagnosed in 2010 and 2011 (n = 1,362). We used insurance claims data to track any use of trastuzumab in the 12 months after diagnosis as well as to identify chemotherapy drugs used in partnership with trastuzumab. We used modified Poisson regression analysis to evaluate the independent effect of race on likelihood of receiving trastuzumab by controlling for clinical need, comorbidity, and community-level socioeconomic status.

RESULTS

Overall, 50% of white women and 40% of black women received some trastuzumab therapy. Among women with stage III disease, 74% of whites and 56% of blacks received trastuzumab. After adjustment for tumor characteristics, poverty, and comorbidity, black women were 25% less likely to receive trastuzumab within 1 year of diagnosis than white women (risk ratio, 0.745; 95% CI, 0.60 to 0.93).

CONCLUSION

Approxemately one half of patients 65 years of age and older with stage I to III breast cancer do not receive trastuzumab-based therapy, which includes many with locally advanced disease. Significant racial disparities exist in the receipt of this highly effective therapy. Further research that identifies barriers to use and increases uptake of trastuzumab could potentially improve recurrence and survival outcomes in this population, particularly among minority women.

Racial/Ethnic Disparities in Perioperative Outcomes of Major Procedures: Results From the National Surgical Quality Improvement Program

OBJECTIVE

To determine the association between race/ethnicity and perioperative outcomes in individuals undergoing major oncologic and nononcologic surgical procedures in the United States.

BACKGROUND

Prior work has shown that there are significant racial/ethnic disparities in perioperative outcomes after several types of major cardiac, general, vascular, orthopedic, and cancer surgical procedures. However, recent evidence suggests attenuation of these racial/ethnic differences, particularly at academic institutions.

METHODS

We utilized the American College of Surgeons National Surgical Quality Improvement Program database to identify 142,344 patients undergoing one of the 16 major cancer and noncancer surgical procedures between 2005 and 2011.

RESULTS

Eighty-five percent of the cohort was white, with black and Hispanic individuals comprising 8% and 4%, respectively. In multivariable analyses, black patients had greater odds of experiencing prolonged length of stay after 10 of the 16 procedures studied (all P < 0.05), though there was no disparity in odds of 30-day mortality after any surgery. Hispanics were more likely to experience prolonged length of stay after 5 surgical procedures (all P < 0.04), and were at greater odds of dying within 30 days after colectomy, heart valve repair/replacement, or abdominal aortic aneurysm repair (all P < 0.03). Fewer disparities were observed for Hispanics, than for black patients, and also for cancer, than for noncancer surgical procedures.

CONCLUSIONS

Important racial/ethnic disparities in perioperative outcomes were observed among patients undergoing major cancer and noncancer surgical procedures at American College of Surgeons National Surgical Quality Improvement Program institutions. There were fewer disparities among individuals undergoing cancer surgery, though black patients, in particular, were more likely to experience prolonged length of stay.

Racial disparities in breast cancer diagnosis and treatment by hormone receptor and HER2 status

BACKGROUND

African American and Hispanic women are more likely to be diagnosed with aggressive forms of breast cancer. Disparities within each subtype of breast cancer have not been well documented.

METHODS

Using data from 18 SEER cancer registries, we identified 102,064 women aged 20 years or older, diagnosed with invasive breast cancer in 2010-2011, and with known stage, hormone receptor (HR), and HER2 status. Associations between race/ethnicity and cancer stage and receipt of guideline-concordant treatment were evaluated according to HR/HER2 status.

RESULTS

Overall, African American and Hispanic women were 30% to 60% more likely to be diagnosed with stage II-IV breast cancer compared with non-Hispanic whites. African American women had 40% to 70% higher risks of stage IV breast cancer across all four subtypes. American Indian/Alaska Native women had a 3.9-fold higher risk of stage IV triple-negative breast cancer. African American and Hispanic whites were 30% to 40% more likely to receive non-guideline-concordant treatment for breast cancer overall and across subtypes.

CONCLUSIONS

Women in several racial/ethnic groups are more likely to be diagnosed with more advanced stage breast cancer. African American and American Indian/Alaska Native women in particular had the highest risk of being diagnosed with stage IV triple-negative breast cancer. African American and Hispanic women were also consistently at higher risk of not receiving guideline-concordant treatment across subtypes.

IMPACT

These findings provide important characterization of which subtypes of breast cancer racial/ethnic disparities in stage and treatment persist.

Are There Differences in Treatment and Survival Between Poor, Older Black and White Women with Breast Cancer?

OBJECTIVES

To explore differences in treatment and survival outcome between poor, older black and white women with breast cancer.

DESIGN

Retrospective cohort study.

SETTING

Public safety net hospital.

PARTICIPANTS

Women aged 65 and older diagnosed with breast cancer from 1999 to 2008 (n = 1,000).

MEASUREMENTS

Breast cancer treatments that black and white women sought were compared using the Pearson chi-square test. All-cause mortality of black and white women was compared using hazard ratios derived from a multivariate Cox proportional hazards model.

RESULTS

There was no significant difference between older black and white women in surgical treatment, radiation therapy, chemotherapy, or hormone therapy over the study period. Race was not a significant predictor of survival in the Cox proportional hazards model that controlled for stage of cancer, age at diagnosis, dual-eligibility status, comorbid conditions, body mass index, smoking history, mammogram screening, and treatment for breast cancer.

CONCLUSION

Race did not appear to affect treatment or mortality in a cohort of older women with low socioeconomic status. This may be associated with similar healthcare delivery and equivalent access to health care for the older black and white women in this study.

Race-associated biological differences among Luminal A breast tumors

African-American (AA) women have higher breast cancer-specific mortality rates. A higher prevalence of the worse outcome Basal-like breast cancer subtype contributes to this, but AA women also have higher mortality even within the more favorable outcome Luminal A breast cancers. These differences may reflect treatment or health care access issues, inherent biological differences, or both. To identify potential biological differences by race among Luminal A breast cancers, gene expression data from 108 CAU and 57 AA breast tumors were analyzed. Race-associated genes were evaluated for associations with survival. Finally, expression of race- and survival-associated genes was evaluated in normal tissue of AA and CAU women. Six genes (ACOX2, MUC1, CRYBB2, PSPH, SQLE, TYMS) were differentially expressed by race among Luminal A breast cancers and were associated with survival (HR <0.8, HR >1.25). For all six genes, tumors in AA had higher expression of poor prognosis genes (CRYBB2, PSPH, SQLE, TYMS) and lower expression of good prognosis genes (ACOX2, MUC1). A score based on all six genes predicted survival in a large independent dataset (HR = 1.9 top vs. bottom quartile, 95% CI: 1.4-2.5). For four genes, normal tissue of AA and CAU women showed similar expression (ACOX2, MUC1, SQLE, TYMS); however, the poor outcome-associated genes CRYBB2 and PSPH were more highly expressed in AA versus CAU women's normal tissue. This analysis identified gene expression differences that may contribute to mortality disparities and suggests that among Luminal A breast tumors there are biological differences between AA and CAU patients. Some of these differences (CRYBB2 and PSPH) may exist from the earliest stages of tumor development, or may even precede malignancy.

Racial/Ethnic and socioeconomic disparities in endocrine therapy adherence in breast cancer: a systematic review

We examined the current literature to understand factors that influence endocrine therapy (ET) adherence among racial/ethnic and socioeconomic subpopulations of breast cancer patients. We searched PubMed and PsycINFO databases for studies from January 1, 1978, to June 20, 2014, and January 1, 1991, to June 20, 2014, respectively, and hand-searched articles from relevant literature reviews. We abstracted and synthesized results within a social ecological framework. Fourteen articles met all inclusion criteria. The majority of included articles reported significant underuse of ET among minority and low-income women. Modifiable intrapersonal, interpersonal, and community-level factors are associated with ET use, and these factors vary across subgroups. Both race/ethnicity and socioeconomic status are associated with ET use in most settings. Variation in factors associated with ET use across subgroups indicates the need for more nuanced research and targeted interventions among breast cancer patients.