Adherence to adjuvant endocrine therapy for breast cancer: a qualitative exploration of attribution of symptoms among post-menopausal women.

PURPOSE: Oral adjuvant endocrine therapy (AET) is an effective treatment for hormone receptor positive breast cancer to decrease recurrence and mortality, but adherence is poor. This study explored post-menopausal women's experiences with AET, with a particular focus on adherence to AET as well as distress and symptoms experienced prior to and during AET treatment. METHODS: Participants were recruited from a hospital registry, stratified by adherence to/discontinuation of AET. Telephone interviews followed a semi-structured interview guide and were recorded and transcribed verbatim. Transcripts were systematically coded using team-based coding, with analysis of themes using a grounded theory approach. RESULTS: Thirty-three participants were interviewed; ages ranged from 57 to 86 years. Participants included 10 discontinued patients and 23 patients who completed their AET course or were adherent to AET at the time of interviewing. Both adherent and discontinued patients reported symptoms throughout their AET treatment course, and both attributed symptoms to factors other than AET (e.g., older age and pre-existing comorbidities). However, discontinued patients were more likely to attribute symptoms to AET and to describe difficulty managing their symptoms, with some directly citing symptoms as the reason for discontinuing AET therapy. Conversely, adherent patients were more likely to describe the necessity of taking AET, despite symptoms. CONCLUSIONS: AET adherence was associated with beliefs about AET, symptom attribution, and symptom management. Routine symptom monitoring during AET and addressing both symptoms and patients' understanding of their symptoms may promote adherence to AET.

Medication delivery factors and adjuvant endocrine therapy adherence in breast cancer.

PURPOSE: Over 50% of breast cancer patients prescribed a 5-year course of daily oral adjuvant endocrine therapy (ET) are nonadherent. We investigated the role of costs and cancer medication delivery mode and other medication delivery factors on adherence. METHODS: We conducted a retrospective cohort study of commercially insured and Medicare advantage patients with newly diagnosed breast cancer in 2007-2015 who initiated ET. We examined the association between 12-month ET adherence (proportion of days covered by fills ≥ 0.80) and ET copayments, 90-day prescription refill use, mail order pharmacy use, number of pharmacies, and synchronization of medications. We used regression models to estimate nonadherence risk ratios adjusted for demographics (age, income, race, urbanicity), comorbidities, total medications, primary cancer treatments, and generic AI availability. Sensitivity analyses were conducted using alternative specifications for independent variables. RESULTS: Mail order users had higher adherence in both commercial and Medicare-insured cohorts. Commercially insured patients who used mail order were more likely to be adherent if they had low copayments (< $5) and 90-day prescription refills. For commercially insured patients who used local pharmacies, use of one pharmacy and better synchronized refills were also associated with adherence. Among Medicare patients who used mail order pharmacies, only low copayments were associated with adherence, while among Medicare patients using local pharmacies both low copayments and 90-day prescriptions were associated with ET adherence. CONCLUSION: Out-of-pocket costs, medication delivery mode, and other pharmacy-related medication delivery factors are associated with adherence to breast cancer ET. Future work should investigate whether interventions aimed at streamlining medication delivery could improve adherence for breast cancer patients.

Implementation-effectiveness trial of systematic family health history based risk assessment and impact on clinical disease prevention and surveillance activities.

BACKGROUND: Systematically assessing disease risk can improve population health by identifying those eligible for enhanced prevention/screening strategies. This study aims to determine the clinical impact of a systematic risk assessment in diverse primary care populations. METHODS: Hybrid implementation-effectiveness trial of a family health history-based health risk assessment (HRA) tied to risk-based guideline recommendations enrolling from 2014-2017 with 12 months of post-intervention survey data and 24 months of electronic medical record (EMR) data capture. SETTING: 19 primary care clinics at four geographically and culturally diverse U.S. healthcare systems. PARTICIPANTS: any English or Spanish-speaking adult with an upcoming appointment at an enrolling clinic. METHODS: A personal and family health history based HRA with integrated guideline-based clinical decision support (CDS) was completed by each participant prior to their appointment. Risk reports were provided to patients and providers to discuss at their clinical encounter. OUTCOMES: provider and patient discussion and provider uptake (i.e. ordering) and patient uptake (i.e. recommendation completion) of CDS recommendations. MEASURES: patient and provider surveys and EMR data. RESULTS: One thousand eight hundred twenty nine participants (mean age 56.2 [SD13.9], 69.6% female) completed the HRA and had EMR data available for analysis. 762 (41.6%) received a recommendation (29.7% for genetic counseling (GC); 15.2% for enhanced breast/colon cancer screening). Those with recommendations frequently discussed disease risk with their provider (8.7%-38.2% varied by recommendation, p-values ≤ 0.004). In the GC subgroup, provider discussions increased referrals to counseling (44.4% with vs. 5.9% without, P < 0.001). Recommendation uptake was highest for colon cancer screening (provider = 67.9%; patient = 86.8%) and lowest for breast cancer chemoprevention (0%). CONCLUSIONS: Systematic health risk assessment revealed that almost half the population were at increased disease risk based on guidelines. Risk identification resulted in shared discussions between participants and providers but variable clinical action uptake depending upon the recommendation. Understanding the barriers and facilitators to uptake by both patients and providers will be essential for optimizing HRA tools and achieving their promise of improving population health. TRIAL REGISTRATION: Clinicaltrials.gov number NCT01956773 , registered 10/8/2013.

Feasibility of a pharmacist-led symptom monitoring and management intervention to improve breast cancer endocrine therapy adherence.

BACKGROUND: Adjuvant endocrine therapy (AET) for breast cancer reduces mortality, but one-third to one-half of patients discontinue it early or are nonadherent. OBJECTIVE: We developed a pilot single-site study of patients with evidence of early nonadherence to AET to assess the feasibility of a novel, clinical pharmacist-led intervention targeting symptom and medication management. METHODS: Patients with prescription fill records showing nonadherence were enrolled in a single-arm feasibility study. Automated reminders were sent by e-mail or text with a link to symptom monitoring assessments weekly for 1 month and monthly until 6 months. Clinical oncology pharmacists used guideline-based symptom management and other medication management tools to support adherence and ameliorate symptoms reported on the assessments. Patient-reported outcome assessments included physical, mental, and social health domains and self-efficacy to manage symptoms and medications. Feasibility outcomes included completion of symptom reports and pharmacist recommendations. RESULTS: Of 19 participants who were nonadherent who enrolled and completed initial assessments, 18 completed all final study procedures, with 14 completing all assessments and no patient missing more than 3 assessments. All 18 participants reported at least one of 3 symptom types, and the majority reported attempting pharmacist recommendations. Patient-reported measures of physical, mental, and social health and self-efficacy improved, and 44% of the patients became adherent. CONCLUSION: An intervention using pharmacists in an oncology practice to systematically monitor and manage symptoms shows promise to reduce symptoms, enhance support and self-efficacy, and improve adherence to AET.

Patient-Physician Concordance for Quantitative Formats and Treatment Options and the Relationship with State Anxiety.

Patient-physician concordance about topics discussed in a clinic visit is essential for effective communication but may be difficult to achieve in cancer care. We conducted a multicenter, observational study at two Midwestern oncology clinics. A sample of 48 English-speaking or Spanish-speaking women with newly diagnosed stage 0-3 breast cancer completed surveys before and after a visit with an oncologist. Patient-physician dyads were coded as concordant if both patient and physician follow-up self-reports agreed whether (or not) specific treatments were discussed (i.e., treatment option concordance; mastectomy, lumpectomy, hormone therapy, neoadjuvant, and adjuvant chemotherapy) and whether risk was described using certain quantitative formats (i.e., quantitative format concordance; percentages, proportions out of 100 and 1000, graphs, pictures, evidence from clinical studies, cancer stage). Agreement was determined using percent agreement and prevalence-adjusted bias-adjusted kappa (PABAK). Pearson's correlations were used to determine relationships between anxiety and each measure concordance. Percent concordance was higher for treatment concordance (73.3%) compared to quantitative format concordance (64.5%), and PABAK scores tended to be higher for treatment options (PABAK = .21-.78). Both treatment and quantitative format concordance were negatively associated with pre-visit state anxiety, but only treatment concordance was statistically significant (treatment: r = - .504, p = .001; quantitative format: r = - .096, p = .523). Our study indicates moderate patient-physician concordance in early breast cancer care communication and that patient anxiety may impact the ability for patients and physicians to agree on the content communicated in a clinic visit.

Pharmacy deserts and patients with breast cancer receipt of influenza vaccines.

BACKGROUND: Yearly influenza vaccination is strongly recommended at age 65 and reimbursed by Medicare without copays or deductibles at pharmacies and clinical settings. Uptake is low among patients with a high risk for influenza complications and good access to specialist care, such as recent cancer survivors. We hypothesized that more accessible pharmacies could be associated with higher immunization uptake in such patients. OBJECTIVES: To determine whether pharmacy access is associated with influenza vaccination in subjects recently diagnosed with breast cancer, and whether this association differs by additional risk factors for influenza complications. METHODS: We examined a cohort of patients with stage 0-III breast cancer diagnosed 2011-2015 from the Surveillance, Epidemiology, and End Results-Medicare cancer registry. All retail pharmacies in the United States were identified, and pharmacy access was measured by assessing supply and demand in each census tract using a 2-stage floating catchment area approach that accounted for pharmacy driving distances recommended by the Centers for Medicare and Medicaid Services. We examined the association of pharmacy access with influenza vaccination after breast cancer diagnosis in regression models. RESULTS: More than 11% of 45,722 patients with breast cancer lived in census tracts where no pharmacies were within recommended driving distances from the population-weighted tract center. Vaccination in the year after diagnosis was less likely for patients in these very low-access tracts (adjusted odds ratio 0.92 [95% CI 0.86-0.96]), black (0.55 [0.51-0.60]) and Hispanic (0.76 [0.70-0.83]) women, and Medicaid recipients (0.74 [0.69-0.79]). Vaccination was inversely associated with per capita income in the subject's census tract, but there was no difference in the pharmacy effect by race, ethnicity, or census tract income. CONCLUSION: Very low pharmacy access is associated with modest reductions in vaccination that could be useful for policy and planning regarding vaccinator resources and outreach.

Neighborhood Characteristics and Cancer Survivorship: An Overview of the Current Literature on Neighborhood Landscapes and Cancer Care.

There is a growing literature on the association between neighborhood contexts and cancer survivorship. To understand the current trends and the gaps in the literature, we aimed to answer the following questions: To what degree, and how, has cancer survivorship research accounted for neighborhood-level effects? What neighborhood metrics have been used to operationalize neighborhood factors? To what degree do the neighborhood level metrics considered in cancer research reflect neighborhood development as identified in the Leadership for Energy and Environmental Design for Neighborhood Development (LEED-ND) guidelines? We first conducted a review guided by PRISMA extension for scoping review of the extant literature on neighborhood effects and cancer survivorship outcomes from January 2000 to January 2021. Second, we categorized the studied neighborhood metrics under six main themes. Third, we assessed the findings based on the LEED-ND guidelines to identify the most relevant neighborhood metrics in association with areas of focus in cancer survivorship care and research. The search results were scoped to 291 relevant peer-reviewed journal articles. Results show that survivorship disparities, primary care, and weight management are the main themes in the literature. Additionally, most articles rely on neighborhood SES as the primary (or only) examined neighborhood level metric. We argue that the expansion of interdisciplinary research to include neighborhood metrics endorsed by current paradigms in salutogenic urban design can enhance the understanding of the role of socioecological context in survivorship care and outcomes.

A dependent Dirichlet process model for survival data with competing risks.

In this paper, we first propose a dependent Dirichlet process (DDP) model using a mixture of Weibull models with each mixture component resembling a Cox model for survival data. We then build a Dirichlet process mixture model for competing risks data without regression covariates. Next we extend this model to a DDP model for competing risks regression data by using a multiplicative covariate effect on subdistribution hazards in the mixture components. Though built on proportional hazards (or subdistribution hazards) models, the proposed nonparametric Bayesian regression models do not require the assumption of constant hazard (or subdistribution hazard) ratio. An external time-dependent covariate is also considered in the survival model. After describing the model, we discuss how both cause-specific and subdistribution hazard ratios can be estimated from the same nonparametric Bayesian model for competing risks regression. For use with the regression models proposed, we introduce an omnibus prior that is suitable when little external information is available about covariate effects. Finally we compare the models' performance with existing methods through simulations. We also illustrate the proposed competing risks regression model with data from a breast cancer study. An R package "DPWeibull" implementing all of the proposed methods is available at CRAN.

Aromatase Inhibitor Symptom Management Practices: A Retrospective Study.

PURPOSE: Aromatase inhibitor (AI)-associated symptoms contribute to early therapy discontinuation. Although guidelines exist for management of these symptoms, little is known about the degree to which physicians address symptoms and adhere to the guidelines for treatment. PATIENTS AND METHODS: In this retrospective chart review, women with hormone receptor-positive breast cancer who were prescribed an AI between October 15, 2012, and September 14, 2017, were randomly selected from the institution's cancer registry. Patient medical records were reviewed to identify the prevalence of symptom documentation and management. Documented symptoms were categorized into musculoskeletal, vasomotor, and urogenital. Symptom treatment guidelines were compiled from the National Comprehensive Cancer Network (NCCN) and the American Cancer Society/American Society of Clinical Oncology (ACS/ASCO). Treatments were categorized as either meeting or not meeting the guidelines. Among patients with symptoms recorded, chi-square tests and time-to-event models were used to examine factors associated with treatment and factors associated with guideline-based treatment. RESULTS: Among 179 women prescribed an AI, 82% had at least one symptom and 46% had multiple symptoms. Of the 147 women with any documented symptom, 97 (66%) received some form of symptom-palliating treatment. Seventy-seven patients (52%) received guideline-based treatments or guideline-based treatments in combination with non-guideline-based treatments. There were no differences in receipt of treatment overall (ie, guideline based or non-guideline based) for either vasomotor or musculoskeletal symptoms by age, race, or stage. CONCLUSION: Although 82% of patients had symptoms documented in their medical records, just over half of those patients received guideline-based treatment.

The Use and Concurrent Use of Side Effect Controlling Medications Among Women on Aromatase Inhibitors.

Background: Women on aromatase inhibitors (AIs) as part of their breast cancer treatment often experience difficult to control side effects. Although there are several medications to manage the side effects of AI therapy, many of them are associated with their own risk, particularly sedation. The objective of this study was to describe the prescribing practices for side effect managing (SE) medications among women with breast cancer on AI therapy and to assess for combinations of medications that may present a clinical risk to patients. Methods: Retrospective data analysis using Surveillance, Epidemiology and End Results (SEER)-Medicare data of all women aged 66-90 years with stage I-III hormone positive breast cancer diagnosed between 2008 and 2014 who initiated AI therapy within 12 months of their diagnosis. We determined the percentage of patients prescribed an SE medication in the 12 months prior and in the 24 months after the initiation of AI therapy. We calculated the number of prescriptions and the number of days of overlapping (i.e., >1 SE) prescriptions, and examined predictors of overlapping prescriptions. Results: The use of SE medications was pervasive and increased after initiation of AI therapy. The most commonly prescribed medications were opiates (55.1%), selective serotonin reuptake inhibitors (22.6%), benzodiazepines (18.4%), tramadol (17.7%) and gabapentin (14.6%). In total 15.5% of patients had overlapping prescriptions; among those, 36.2% had three overlapping prescriptions. Prior use was the strongest predictor of overlapping prescriptions with an odds ratio of 7.9 (95% confidence interval: 7.17-8.77). Conclusion: Among women on AI therapy, the use of SE medications is common and many have overlapping prescriptions raising concern for potential harm from polypharmacy.

Association of Current Opioid Use With Serious Adverse Events Among Older Adult Survivors of Breast Cancer.

Importance: National efforts to improve safe opioid prescribing focus on preventing misuse, overdose, and opioid use disorder. This approach overlooks opportunities to better prevent other serious opioid-related harms in complex populations, such as older adult survivors of cancer. Little is known about the rates and risk factors for comprehensive opioid-related harms in this population. Objective: To determine rates of multiple opioid-related adverse drug events among older adults who survived breast cancer and estimate the risk of these events associated with opioid use in the year after completing cancer treatment. Design, Setting, and Participants: This retrospective cohort study used 2007 to 2016 Surveillance, Epidemiology and End Results-Medicare data from fee-for-service Medicare beneficiaries with first cancer diagnosis of stage 0 to III breast cancer at age 66 to 90 years from January 1, 2008, through December 31, 2015, who completed active breast cancer treatment. Data were analyzed from October 31, 2019, to June 10, 2020. Exposures: Repeated daily measure indicating possession of any prescription opioid supply in Medicare Part D prescription claims. Main Outcomes and Measures: Adjusted risk ratios (aRRs), estimated using modified Poisson generalized estimating equation models, for adverse drug events related to substance misuse (ie, diagnosed opioid abuse, dependence, or poisoning), other adverse drug events associated with opioid use (ie, gastrointestinal events, infections, falls and fractures, or cardiovascular events), and all-cause hospitalization associated with opioid supply the prior day, controlling for patient characteristics. Results: Among 38 310 women included in the study (mean [SD] age, 74.3 [6.3] years), there were 0.010 (95% CI, 0.008-0.011) adverse drug events related to substance misuse per 1000 person-days, 0.237 (95% CI, 0.229-0.245) other adverse drug events associated with opioid use per 1000 person-days, and 0.675 (95% CI, 0.662-0.689) all-cause hospitalizations per 1000 person-days. Opioid use was associated with increased risk of adverse drug events related to substance misuse (aRR, 14.62; 95% CI, 9.69-22.05; P < .001), other adverse drug events related to opioid use (aRR, 2.50; 95% CI, 2.11-2.96; P < .001), and all-cause hospitalization (aRR, 2.77; 95% CI, 2.55-3.02; P < .001). In a dose-response effect, individuals with high daily opioid doses had consistently higher risks of all study outcomes compared with individuals who had low opioid doses. Compared with days with no opioid exposure, the risk of any adverse drug event related to substance misuse was 3.4-fold higher for individuals with a current opioid supply ≥50 mg morphine equivalent dose per day (aRR, 3.40; 95% CI, 2.47-4.68; P < .001), while the risk was 2.3-fold higher for individuals with 1 to 49 mg morphine equivalent dose per day (aRR, 2.29; 95% CI, 1.89-2.77; P < .001). Conclusions and Relevance: These findings suggest that among older adults who survived breast cancer, continued prescription opioid use in the year after completing active cancer treatment was associated with an immediate increased risk of a broad range of serious adverse drug events related to substance misuse and other adverse drug events associated with opioid use. Clinicians should consider the comprehensive risks of managing cancer pain with long-term opioid therapy.

Parental Status in Treatment Decision Making among Women with Nonmetastatic Breast Cancer.

Background. Having dependent children may affect cancer treatment decisions. We sought to describe women's surgery and chemotherapy decisions in nonmetastatic breast cancer by parental status. Methods. We conducted a secondary analysis of the 2015 cross-sectional Share Thoughts on Breast Cancer Study, conducted in 7 Midwestern states in the United States, restricted to women of prime parenting age (aged 20-50 years) who consented to the use of their medical records (N = 225). We examined treatment decisions using data visualization and logistic regression (adjusted for age, stage, family history of breast cancer, income, education, race, health insurance, and partner status). Results. Women with dependent children received bilateral mastectomy more often than women without dependent children (adjusted odds ratio 3.09, 95% confidence interval 1.44-6.62).We found no differences in the receipt of chemotherapy by parental status. Women reported more active roles in surgery than in chemotherapy decision making. Conclusions. As a likely factor in cancer treatment decisions, parental status should be addressed in clinical practice and research. Future research should assess patients' sense of ownership in treatment decision making by treatment type.

Health Insurance Coverage Disruptions and Cancer Care and Outcomes: Systematic Review of Published Research.

BACKGROUND: Lack of health insurance coverage is associated with poor access and receipt of cancer care and survival in the United States. Disruptions in coverage are common among low-income populations, but little is known about associations of disruptions with cancer care, including prevention, screening, and treatment, as well as outcomes of stage at diagnosis and survival. METHODS: We conducted a systematic review of studies of health insurance coverage disruptions and cancer care and outcomes published between 1980 and 2019. We used the PubMed, EMBASE, Scopus, and CINAHL databases and identified 29 observational studies. Study characteristics and key findings were abstracted and synthesized qualitatively. RESULTS: Studies evaluated associations between coverage disruptions and prevention or screening (31.0%), treatment (13.8%), end-of-life care (10.3%), stage at diagnosis (44.8%), and survival (20.7%). Coverage disruptions ranged from 4.3% to 32.8% of patients age-eligible for breast, cervical, or colorectal cancer screening. Between 22.1% and 59.5% of patients with Medicaid gained coverage only at or after cancer diagnosis. Coverage disruptions were consistently statistically significantly associated with lower receipt of prevention, screening, and treatment. Among patients with cancer, those with Medicaid disruptions were statistically significantly more likely to have advanced stage (odds ratios = 1.2-3.8) and worse survival (hazard ratios = 1.28-2.43) than patients without disruptions. CONCLUSIONS: Health insurance coverage disruptions are common and adversely associated with receipt of cancer care and survival. Improved data infrastructure and quasi-experimental study designs will be important for evaluating the associations of federal and state policies on coverage disruptions and care and outcomes.

The impact of generic aromatase inhibitors on initiation, adherence, and persistence among women with breast cancer: Applying multi-state models to understand the dynamics of adherence.

PURPOSE: Clinical trials have clearly documented the survival benefit of aromatase inhibitors (AIs); however, many women fail to initiate (primary nonadherence) or remain adherent to AIs (secondary nonadherence). Prior studies have found that costs impact secondary nonadherence to medications but have failed to examine primary nonadherence. The purpose of this study is to examine primary and secondary adherence following the reduction in copays due to the introduction of generic AIs. METHODS: Using Surveillance, Epidemiology, and End Results-Medicare data, we identified 50 054 women diagnosed with incident breast cancer between 2008 and 2013. We compare women whose copays would change and those whose would not, due to the receipt of cost-sharing subsidies before and after generics were introduced using a difference-in-difference (DinD) analysis. To examine primary and secondary nonadherence, we rely on a multistate model with four states (Not yet initiated, User, Not Using, and Death). We adjusted for baseline factors using inverse probability treatment weights and then simulated adherence for 36 months following diagnosis. RESULTS: The generic introduction of AIs resulted in patients initiating AIs faster (DinD = -4.7%, 95%CI = -7.0, -2.3; patients not yet initiating treatment at 6-months), being more adherent (DinD ranging in absolute increase of 8.1%-10.4%) and being less likely to not be using the therapy (DinD range in absolute decrease of 1.2% at 6 months to 8.8% at 24 months) for women that do not receive a subsidy after generics were available. CONCLUSIONS: Introduction of generic alternatives to AIs significantly reduced primary and secondary nonadherence.

Effects of Previous Medication Regimen Factors and Bipolar and Psychotic Disorders on Breast Cancer Endocrine Therapy Adherence.

BACKGROUND: Endocrine therapy adherence remains a barrier to optimal estrogen receptor-positive breast cancer outcomes. We theorized that experience navigating difficult medication regimen factors, such as route of administration complexity, might improve subsequent adherence after stressful cancer diagnoses but not for patients with bipolar and psychotic disorders at risk of poor access and nonadherence. MATERIALS AND METHODS: We included 21,894 women aged ≥ 68 years at their first surgically treated stage I-IV estrogen receptor-positive breast cancer (2007-2013) from the Surveillance, Epidemiology, and End Results-Medicare data set, of whom 5.8% had bipolar or psychotic disorders. We required continuous fee-for-service Medicare (parts A and B) data for ≥ 36 months before and 18 months after the cancer diagnosis. The medication regimen factors in the part D claims for 4 months before included the number of all medications used, pharmacy visits, and administration complexity (medication regimen complexity index subscale). Cox regression analysis was used to model the time to initiation and discontinuation, with longitudinal linear regression for adherence to endocrine therapy. RESULTS: Women with more frequent previous medication use and pharmacy visits were more likely to initiate, 4+ medications and 2+ visits versus no medication (hazard ratio [HR], 1.47; 95% confidence interval [CI], 1.33-1.63), to adhere (6.0%; 95% CI, 4.3-7.6), and to continuously use their endocrine therapy (discontinuation HR, 0.48; 95% CI, 0.39-0.59). Medication administration complexity had modest effects. Difficult medication regimens were more common for patients with bipolar and psychotic disorders but had no statistically significant effects. CONCLUSIONS: Experience with frequent previous medication use and pharmacy visits might increase the likelihood of endocrine therapy use for most patients but not for those with bipolar and psychotic disorders.

Concurrent Opioid and Benzodiazepine Prescriptions Among Older Women Diagnosed With Breast Cancer.

Guidelines recommend using caution in co-prescribing opioids with benzodiazepines, yet, in practice, the extent of concurrent prescribing is poorly understood. Notably, no population-based studies, to our knowledge, have investigated concurrent prescribing among patients with cancer. We conducted a retrospective cohort study using data from the Surveillance, Epidemiology, and End Results (SEER) database linked with Medicare claims (2012-2016) for women diagnosed with breast cancer. We used modified Poisson regression to examine predictors of any concurrent prescriptions in the year post-diagnosis and Poisson regression to examine predictors of the number of overlapping days. We found that 13.0% of the 19 267 women in our sample had concurrent prescriptions. Women who underwent more extensive treatment and those with previous use of opioids or benzodiazepines were at increased risk for concurrent prescriptions (adjusted risk ratio of previous benzodiazepine use vs no previous use = 15.05, 95% confidence interval = 13.19 to 17.19). Among women with concurrent prescriptions, overlap was most pronounced among low-income, rural, and Hispanic women (adjusted incidence rate ratio of Hispanic vs non-Hispanic white = 1.25, 95% confidence interval = 1.20 to 1.30). Our results highlight opportunities to reduce patients' unnecessary exposure to this combination.