The goal of this study was to evaluate the racial differences in outcomes among women with metastatic TNBC. Our findings show a worst outcome for Black women with TNBC and suggest mortality difference in the metastatic subgroup. We find no statistically significant racial differences in survival but differences in treatment utilization. More NHB women underwent surgery, and less likely to receive radiation or have unknown radiation receipt status than NHW women.
Sociodemographic differences
Previous studies showed that NHB women were diagnosed with breast cancer at younger ages [5]. This study similarly showed that NHB women were diagnosed at younger mean age (NHB average age 58 vs. 61 in NHW). A higher proportion of NHB women were unmarried and resided in urban census tracts with more than half from low nSES census tracts. More NHB woman were uninsured compared to NBW woman with majority of the black woman being insured either via Medicare or private insurance. While health insurance is the most commonly mentioned and significant obstacle to seeking care [19–21], a number of other issues, such as cancer-related out-of-pocket financial problems [22], required time away from work [23] and transportation issues [24,25] may potentially have a disproportionate impact on African American women with cancer [26]. These socioeconomic characteristics are reflected in the Yost index (nSES) which we show NHB women comprising the overwhelming majority of those in the lowest tertile. Our findings are consistent with previous reports [19–25].
Management patterns in metastatic TNBC
In terms of treatment by race, more NHB women on univariate analysis received surgery (not statistically significant), fewer received or had an unknown status for radiation (p-value < .05) while there are no differences seen with chemotherapy. We also did not find a statistically significant difference in receipt of surgery, chemotherapy or radiation based on race with multivariate analysis. There are established data on treatment differences in NHB women compared to NHW in non-metastatic TNBC but there is a dearth of data in the metastatic group. NHB women with earlier stages of breast cancer have a treatment preference for breast conservation, a higher rate of chemotherapy and radiation refusal [26–28].
One divergent finding is in our sample, women with low nSES were more likely to receive surgery. In metastatic breast cancer, surgery is controversial, especially in the triple negative subtype [29]. Therefore, surgery receipt especially if it occurs antecedent to chemotherapy would be considered low value care. Previous studies have shown that low value treatment options like surgery in the metastatic setting is disproportionately performed in women of low socioeconomic classes and medical facilities with a large concentration of Black patients [30]. Patients who are poor are sometimes given care that is neither medically necessary nor useful. The lack of health literacy to comprehend and make educated decisions about their health may be the cause [31]. We show crude rates of higher surgery in NHB and on logistic regression the effect of nSES on surgery suggests potential non-guideline concordant care.
In all treatment types (surgery, chemotherapy, and radiation), both NHW and NHB woman without a married partner were less likely to definitively undergo treatment. Previous studies agree with these results and showed that breast cancer survival is impacted by marital status [32–35] suggesting lack of support from spouse and family, finances (insurance) and concerns about potential physical deformities with treatment. Furthermore, having a strong social network is linked to a higher chance of survival in several studies [36–42]. Having family, friends, and spouses for support encourages patients to seek medical attention, complete their treatments and seek support from breast cancer survivors [43–45].
Racial differences in survival
There is a median survival of 13 months vs. 15 months in NHB compared to NHW women but we did not detect a statistically significant difference. In a previous study from Arciero et al., after correcting for age, tumor grade, surgery, and radiation treatments, NHB patients exhibited lower overall survival and BCSS (breast cancer specific survival time) in both the univariate and multivariate analyses [5]. Another study explained that non-biological causes and factors unrelated to the stage at which the patient presents, such as residual treatment/healthcare inequalities due to socioeconomic and health-care system issues, could possibly account for a large amount of the mortality difference [46]. Other studies that investigated stage IV breast cancer patients identified between 1998 and 2003, found that survival for NHW women improved dramatically whereas survival for NHB women did not [4]. The survival gap has continued to increase as a result of this tendency [47].
Predictors of disease specific survival in our study population show receipt of surgery and chemotherapy to be significant. Surgery in the setting of metastatic breast cancer is controversial. Typically, it is reserved for patients showing response to chemotherapy and disease stability [29,48]. It is possible that those who received chemotherapy would also undergo surgery, with both treatments prolonging survival.
Limitations
Given the retrospective nature of this study, it has several limitations. SEER data represent individual variables such as race, while census data were used for nSES and rural/urban residence. nSES and rural/urban residence were assessed at one point in time and do not reflect potential (especially recent) changes in residence; further, it is possible that nSES does not accurately ascertain individual SES. In the models for receipt of radiation and chemotherapy, we cannot determine and exclude patients for whom treatment was not recommended to assess differences among NHB and NHW women. For chemotherapy and radiation therapy receipt, the SEER database does not distinguish between “no treatment received” and “unknown if treatment received” so those variables were combined into “no/unknown.” Further, there may be biases due to differences in whether or not treatments were received based on unmeasured factors including patient and provider preferences, patient refusal, distance traveled, hospital characteristics, and comorbidities. The data from providers detailing their recommendations would provide more meaningful assessment of racial differences in treatment. Ideally, we would know whether treatment was offered and refused, or not recommended based on patient factors such as comorbidities. Last, the categories for distant disease were not consistent in variables used by the SEER Program across the study time period so metastatic categories as clinically described may be heterogeneous.