Benign Breast Disease: Emerging Findings in a Diverse Population

B enign breast disease (BBD), diagnosed when a woman has a breast biopsy for a palpable or mammographic abnormality but findings are benign, has been shown to be an important risk factor for subsequent breast cancer (1). Several previously published studies reported the risk of breast cancer with varying types of BBD: Dupont and Page reported that women with nonproliferative disease did not have increased breast cancer risk unlike women with atypical hyperplasia who had significantly higher breast cancer risk (2). We reported our findings in the Mayo BBD cohort that the relative risk for breast cancer in the cohort overall was 1.56 (95% CI 1.45–1.68) and that the increased risk persisted for at least 25 years after the initial biopsy (3). Previous studies on BBD and breast cancer risk have been reported on populations of women that were predominantly Caucasian (2–5). Current knowledge on BBD in the AfricanAmerican population is limited. African-American women are known to be diagnosed with breast cancer at earlier ages and at more advanced stages and experience a 15% higher mortality than Caucasians (6). It is immensely important that future studies incorporate data from the African-American (A-A) population to further our understanding of risks in this population. The current study by Worsham and colleagues begins to fill the gap in our knowledge by providing hitherto unavailable information on BBD in the A-A population (7). Worsham et al. report their findings on a cohort of women with BBD, 28% of 4,537 eligible women were African-American and 63% were aged <50 years at biopsy. Incident breast cancers were identified through examination of tumor registries of Henry Ford Health system, the Detroit SEER registry and the State of Michigan cancer registry and follow-up information was available on 95% of the cohort (median duration of follow-up, not reported). They report an overall breast cancer incidence rate of 452 (95% confidence interval 394–519) per 100,000 person years. It is important to note that for the AA population, the BC incidence rate was 420 (95% CI 320–551) per 100,000 person years, and not significantly different from the non A-A population. The distribution of histologic lesions (nonproliferative, proliferative, ADH, and ALH) was also similar between the A-A and the non–A-A populations. Interestingly, nonproliferative lesions were seen in 39% of this cohort unlike the Mayo BBD cohort where it comprised 67% of the lesions seen. This may be a reflection of the classification (current study included mild ductal hyperplasia as proliferative lesions whereas the Mayo study considered it as nonproliferative lesion), clinical practice during the study period (current study from 1981 through 1994, whereas the Mayo study included BBD diagnosed from 1967 through 1991), or study population (primary care versus mainly referral population). In addition, the cohort in this study had predominantly younger population of women with 63% being 49 years or younger. The authors state that marital status was not a factor for breast cancer incidence from BBD. However, marital status has generally, not been considered a risk factor for breast cancer. It would have strengthened the paper considerably to include information regarding the distribution of other factors that affect breast cancer risk such as family history, and age at first parity. The authors use incidence rate ratios to describe risk, finding that risk for women with atypical ductal hyperplasia and atypical lobular hyperplasia Address correspondence and reprint requests to: Lynn C. Hartmann, MD, Medical Oncology, Mayo Clinic, 200 1st St. SW, Rochester, MN 55905, USA, or e-mail: hartmann.lynn@mayo.edu.