Familial versus Sporadic Breast Cancer: Different Treatments for Similar Tumors?

Objective: It is unclear if and to what extent family history of breast/ovarian cancer or BRCA1/2-mutation carriership influences breast cancer treatment strategy. We investigated whether treatment differed between patients from BRCA1/2 families and those unselected for family history. Methods: We included 478 BRCA1/2-related patients referred for genetic testing before or after diagnosis. Two references were used: 13,498 population-based and 6896 hospital-based patients. Surgical treatment and adjuvant chemotherapy use was analyzed using logistic regression models, stratified by tumor size, nodal status, age at and period of diagnosis, and estrogen receptor status (ER). Results: BRCA1/2 cases aged 35 - 52 years at diagnosis and/or with tumors < 2 cm were more likely to have undergone a modified radical mastectomy (Odd Ratios (OR) ranging from 2.8 to 5.1) compared to the references. This effect was most pronounced in patients treated after 1995 (OR 5.7 to 10.3). Compared to the reference groups, chemotherapy was more often administered to BRCA1 and ER-negative BRCA1/2-cases irrespective of age and nodal status (OR 1.9 to 24.3). Conclusion: After 1995 treatment of BRCA1/2-associated patients consisted notably of more mastectomies and adjuvant chemotherapy than their population-based counterparts with the same tumor characteristics. There is a need to be aware of such differences in daily practice and interpretation of survival studies on BRCA1/2 mutation carriers.