To assess the clinical value of peritoneal washing cytology (PWC) in women with BRCA1 or BRCA2 mutations and women from a family with hereditary breast and/or ovarian cancer (HBOC) undergoing risk-reducing salpingo-oophorectomy (RRSO) in detecting primary peritoneal cancer (PPC) or occult ovarian/fallopian tube cancer. Here, BRCA1 is linked to ovarian cancer.