BRCA-1 and BRCA-2 mutations as prognostic factors in clinical practice and genetic counselling

Women in general have a 10% risk of developing breast cancer and a 2–3% chance of ovarian cancer in their life-times. Mutations in BRCA-1 and BRCA-2 are present in only a small portion (5–10%) of all breast cancers. Carriers of mutations in these genes have a greater risk of cancer, especially before menopause in the case of BRCA-1 carriers. In addition, their risk of contralateral breast cancer is significantly higher than for the general population (4.2–53% vs. 2%). The grade of contralateral tumours in these patients is more aggressive. BRCA-2 hereditary breast cancer seems more heterogeneous than the BRCA-1 phenotype, and not clearly different from sporadic forms. However, since 20–30% of carriers of BRCA mutations never develop breast or ovarian cancer, there must be other ‘risk modifiers’. Survival is better for carriers of hereditary ovarian cancer. Patients with these mutations are referred for genetic counselling, a complex process which includes: an informative dialogue between the proband and the geneticist, drawing up a family history, informed consent, evaluation of risk, genetic testing and possible involvement of healthy family members.