Risk of breast cancer among Japanese women with a positive family history.

191 Background: Most breast cancer cases are sporadic, rather than associated with inherited gene mutations, such as BRCA1 and BRCA2. However, women with a family history of breast cancer are at increased risk of developing breast cancer compared to those women without any family history, even if they lack these gene mutations.,We analyzed 10892 patients including bilateral breast cancer cases (total of 11398 breast cancers) who underwent surgery at our hospital between 1962 and 2009. We excluded 295 cases whose family history data were not available. Clinical and pathological differences between following patient groups were tested; 9528 patients or 9955 cancers (88%) with negative family history (FH-), 896 patients or 951 cancers (8%) who had at least one first-degree relative with breast cancer (1FH+), 468 patients or 492 cancers (4%) who had second-degree relative with breast cancer (2FH+), and 1364 patients or 1443 cancers (12%) with family history regardless of first- or second-degree relative (FH+). Significance was established at a p-value of < 0.05.,Among the family members, sisters were more likely to have treated for breast cancer (38% in FH+ group), followed by mothers (27%), aunts (26%), grandmothers (7%), and daughters (2%). The incidence of developing contralateral breast cancer was significantly higher in 1FH+ group, compared to patients in FH- and 2FH+ groups. No other factors showed any significant difference, including the incidence of cancer in other organs, pathological characteristics, and age of onset, although BRCA1 and BRCA2 mutation may be associated with increased risk of developing breast cancer at younger age. Outcome studies with available data did not show any significant difference in overall survival between FH+ and FH- patients.,A Japanese woman with a positive family history has a higher risk of developing breast cancer than women without any close relatives with breast cancer, similar to the results reported in Western countries where prevalence of breast cancer is higher. Regular checkup of contralateral breast is important for those patients whose first-degree relatives have also been diagnosed with breast cancer.