BC occurrence (including both invasive and ductal carcinoma in situ) was lower in the BRRM than in the surveillance group [8 (1%) vs. 268 (27%) for BRCA1, and 0 (0%) vs. 144 (19%) for BRCA2 mutation carriers; Table 1]. This evidence concerns the gene BRCA1 and ductal breast carcinoma in situ.