Clinicopathologic features of breast cancers that develop in women with previous benign breast disease.

BACKGROUND: Women with benign breast disease (BBD) have an increased risk of developing breast cancer (BC). Nearly 30% of all BCs develop in women with prior BBD. Information regarding features of the expected number of BCs after BBD would enhance individualized surveillance and prevention strategies for these women. In the current study, the authors sought to characterize BCs developing in a large cohort of women with BBD. METHODS: The current study cohort included 13,485 women who underwent breast biopsy for mammographic or palpable concerns between 1967 and 2001. Biopsy slides were reviewed and classified as nonproliferative disease, proliferative disease without atypia, or atypical hyperplasia. BCs were identified by follow-up questionnaires, medical records, and Tumor Registry data. BC tissues were obtained and reviewed. RESULTS: With median follow-up of 15.8 years, 1273 women developed BC. The majority of BCs were invasive (81%), of which 61% were ductal, 13% were mixed ductal/lobular, and 14% were lobular. Approximately two-thirds of the BC cases were intermediate or high grade, and 29% were lymph node positive. Cancer characteristics were similar across the 3 histologic categories of BBD, with a similar frequency of ductal carcinoma in situ, invasive disease, tumor size, time to invasive BC, histologic type of BC, lymph node positivity, and human epidermal growth factor receptor 2 positivity. Women with atypical hyperplasia were found to have a higher frequency of estrogen receptor-positive BC (91%) compared with women with proliferative disease without atypia (80%) or nonproliferative disease (85%) (P = .02). CONCLUSIONS: A substantial percentage of all BCs develop in women with prior BBD. The majority of BCs after BBD are invasive tumors of ductal type, with a substantial number demonstrating lymph node positivity. Of all the BCs in the current study, 84% were estrogen receptor positive. Prevention therapy should be strongly encouraged in higher-risk women with BBD.

Complex fibroadenoma and breast cancer risk: a Mayo Clinic Benign Breast Disease Cohort Study.

The purpose of this study is to examine the breast cancer risk overall among women with simple fibroadenoma or complex fibroadenoma and to examine the association of complex fibroadenoma with breast cancer through stratification of other breast cancer risks. The study included women aged 18-85 years from the Mayo Clinic Benign Breast Disease Cohort who underwent excisional breast biopsy from 1967 through 1991. Within this cohort, women who had fibroadenoma were compared to women who did not have fibroadenoma. Breast cancer risk (observed versus expected) across fibroadenoma levels was assessed through standardized incidence ratios (SIRs) by using age- and calendar-stratified incidence rates from the Iowa Surveillance, Epidemiology, and End Results registry. Analyses were performed overall, within subgroups of involution status, with other demographic characteristics (age, year of biopsy, indication for biopsy, and family history), and with histologic characteristics, including overall impression [nonproliferative disease, proliferative disease without atypia (PDWA), or atypical hyperplasia]. Fibroadenoma was identified in 2136 women [noncomplex, 1835 (85.9%); complex, 301 (14.1%)]. SIR for noncomplex fibroadenoma was 1.49 (95% CI 1.26-1.74); for complex fibroadenoma, it was 2.27 (95% CI 1.63-3.10) (test for heterogeneity in SIR, P = .02). However, women with complex fibroadenoma were more likely to have other, concomitant high-risk histologic characteristics (e.g., incomplete involution and PDWA). In analyses stratified by involution status and PDWA, complex fibroadenoma was not an independent risk marker for breast cancer. Complex fibroadenoma does not confer increased breast cancer risk beyond other established histologic characteristics.