Disease-free probability after the first primary ductal carcinoma in situ of the breast: a comparison between African-American and White-American women

Compelling evidence about the differences in the biology and behavior of invasive breast cancer between African-American (AA) and White-American (WA) women motivate inquiry into comparing the clinicopathology of non-invasive breast cancer (ductal carcinoma in situ, DCIS). AA and WA women diagnosed with their first primary DCIS between 1990 and 1999 were identified from the institutional tumor registry. Data on method of presentation, treatment, and patient characteristics were retrieved from electronic medical records. Patients were followed up through the medical records until the diagnosis of a subsequent cancer or the last day of contact with the institution. A total of 100 (29.6%) AAs and 236 (70.4%) WAs with the mean age of 60 (SD ± 13) and 57 (SD ± 12), respectively, contributed to this study. DCIS was detected during routine screening mammography for 81% (n = 81) of AAs and 88.4% (n = 206) of WAs (P = 0.073). Differences in the distributions of grade, margin status, necrosis, or treatment modalities were not statistically significant between AAs and WAs. Analysis of competing risks Cox proportional hazard multivariate modeling yielded a significant 8-year cumulative risk of a second cancer for AAs but only in the ipsilateral breast (HR = 3.96, 95% CI 1.42–11.04, P = 0.01). Despite comparable clinical presentation and treatment, 8 years after the initial treatment, AAs experienced a higher risk of second breast cancer in ipsilateral but not in the contralateral breast. The observed excess risk of a second cancer in the ipsilateral breast may suggest of intrinsic differences in the biology of cancer.