Racial disparity in distant recurrence-free survival in localized breast cancer patients: A pooled analysis of NSABP trials

Abstract

AbstractBackgroundBlack race is associated with worse outcome in patients with breast cancer. We evaluated distant relapse-free survival (DRFS) between Black and White women with localized breast cancer who participated in NCI-sponsored clinical trials.MethodsWe analyzed pooled data from eight National Surgical Adjuvant Breast and Bowel Project (NSABP) trials including 9,702 women with localized breast cancer treated with adjuvant chemotherapy (AC, n=7,485) or neoadjuvant chemotherapy (NAC, n=2,217), who self-reported as Black (n=1,070) or White (n=8,632). The association between race and DRFS was analyzed using log-rank tests and multivariate Cox regression.ResultsAfter adjustment for covariates including age, tumor size, nodal status, body mass index and taxane use, and treatment (AC vs. NAC), Black race was associated with an inferior DRFS in ER-positive (HR 1.24 [95% CI 1.05-1.46], p=0.01), but not in ER-negative disease (HR 0.97 [95% CI 0.83-1.14], p=0.73), and significant interaction between race and ER status was observed (p=0.03). There was no racial disparity in DRFS among patients with pathologic complete response (pCR) (Log-rank p =0.8). For patients without pCR, black race was associated with worse DRFS in ER-positive (HR 1.67 [95% CI 1.14-2.45], p=0.01), but not in ER-negative disease (HR 0.91 [95% CI 0.65-1.28], p=0.59).ConclusionBlack race was associated with significantly inferior DRFS in ER-positive localized breast cancer treated with AC or NAC, but not in ER-negative disease. In the NAC group, racial disparity was also observed in patients with residual ER-positive breast cancer at surgery, but not in those who had a pathologic complete response.Lay SummaryBlack women with breast cancer have worse outcome compared to White women. We investigated if this held true in the context of clinical trials which provide controlled treatment setting. Black women with cancer containing estrogen receptors (ER) had worse outcome than White women. If breast cancers did not contain ER there was no racial disparity in outcome. Moreover, we observed racial disparity in women who received chemotherapy before their cancer was removed, but only if they had cancer with ER and residual disease upon completion of treatment. If cancer disappeared upon pre-surgical chemotherapy, there was no racial disparity.