Background: Previous studies provide evidence that breast cancers occurring in different age and ethnic groups are not evenly distributed with regard to their biologic, pathologic and clinical characteristics. We evaluated the distributions of 11 pathological and biological variables between African-American (AA) and white patients and between three different age groups (20-39, 40-59 and 60-74 years). We examined whether racial differences existed across levels of age.
Methods: Data were obtained from the Carolina Breast Cancer Study (CBCS), a population-based, case-control study of breast cancer in North Carolina. Eighty hundred and sixty one women with a first diagnosis of invasive breast cancer participated in Phase I of the CBCS. Diagnostic paraffin blocks were obtained from 807 cases. One representative block was scored for histologic type and grade (architectural, nuclear, mitotic and overall). Medical chart review yielded tumor size, lymph node status, distant metastases, stage, hormone receptor status (ER/PR) and DNA ploidy.
Results: Pathologically advanced tumors (large size, high grade, high stage, ER/PR negative) were significantly more common in young and AA women. Racial differences varied by age. Among younger, AAs and whites differed only with respect to ER/PR status, while among older women AAs and whites differed only with respect to stage at diagnosis.
Conclusions: The results of this study confirm the presence of poorer prognosis breast cancer among AA and younger women. They also highlight the need for age and race to be considered together when evaluating pathologic and biologic characteristics of disease and when making inferences regarding tumor aggressiveness.