Prevalent versus incident breast cancers: benefits of clinical and radiological monitoring in women with pathogenic BRCA1/2 variants

Women with pathogenic germline BRCA1 or BRCA2 variants have a higher risk of breast cancer than in the general population. International guidelines recommend specific clinical and radiological breast follow-up. This specific breast screening program has already been shown to be of clinical benefit, but no information is available concerning the use of prognostic factors or specific survival to guide follow-up decisions. We evaluated "high-risk" screening in a retrospective single-center study of 520 women carrying pathogenic germline variants of the BRCA1 or BRCA2 gene treated for breast cancer between January 2000 and December 2016. We compared two groups of women: the incidental breast cancer group (IBCG) were followed before breast cancer diagnosis (N = 103), whereas the prevalent breast cancer group (PBCG) (N = 417) had no specific follow-up for high risk before breast cancer diagnosis. Breast cancers were diagnosed at an earlier stage in the IBCG than in the PBCG: T0 in 64% versus 19% of tumors, (p 0.00001), and N0 in 90% vs. 75% (p 0.00001), respectively. Treatment differed significantly between the 2 groups: less neoadjuvant chemotherapy (7.1% vs. 28.5%, p 0.00001), adjuvant chemotherapy (47.7% vs. 61.9%, p = 0.004) and more mastectomies (60% vs. 42% p 0.0001) in the IBCG vs PBCG groups respectively. Overall and breast cancer-specific mortality were similar between the two groups. However, the patients in the IBCG had a significantly longer metastasis-free survival than those in the PBCG, at three years (96.9% [95% CI 93.5-100] vs. 92.30% [95% CI 89.8-94.9]; p = 0.02), suggesting a possible long-term survival advantage.