Purpose: Breast cancer diagnosed in women 35 years of age or less accounts for <2% of all breast cancer cases. Clinical and pathologic characteristics of early onset breast cancer are not well defined in BRCA mutation carriers and non-carriers.
Methods: 194 women diagnosed with breast cancer at 35 years of age or less who had BRCA1/2 mutation testing were included in the study. Logistic regression models were fit to determine the associations between clinical variables and BRCA status.
Results: Thirty-two (17%) and 12 (6%) patients had BRCA1 and BRCA2 mutations, respectively. BRCA1-carriers had a higher likelihood of a positive family history (FH) of breast and/or ovarian cancer (P = 0.001), or first-degree relatives diagnosed with breast cancer at <50 years old (P = 0.001) compared to non-carriers. BRCA2-carriers were more likely to have a FH of male breast cancer compared to noncarriers (P = 0.02). Among BRCA2-carriers, the age at first full-term pregnancy was younger in ER-negative cases compared with ERpositive cases (19.5 vs. 28.5 years old; P = 0.01). BRCA1-carriers with a later age at menarche were more likely to have a later stage at diagnosis (P = 0.04). Non-carriers with a lower BMI were more likely to have lymph node involvement (P = 0.03).
Conclusions: Several associations were identified between reproductive risk factors or BMI and disease characteristics. Further characterization may result in a better understanding of the trends in young onset breast cancer in BRCA-carriers and non-carriers.
Keywords: BMI; BRCA; Breast cancer; Family history; Male breast cancer; Parity.
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