Breast Cancer is Common in Women With Ovarian Malignant Mixed Mullerian Tumors

Ovarian malignant mixed Mullerian tumors (MMMTs) are uncommon cancers. The purpose of the study was to determine the rate of metachronous or synchronous breast cancer as well as the rate of truncating germline BRCA1 and/or BRCA2 mutations in a series of women with these uncommon tumors.

Records were reviewed to identify all women with MMMTs treated by the gynecologic oncology service. The stage, grade, histology, survival, and rate of coexistent breast cancer were determined. Tumor and/or peripheral blood was tested for BRCA1 and BRCA2 truncating mutations.

Twenty-four patients with MMMTs were found. Tumor and paired peripheral blood was available on 20 patients and 4 more patients had only peripheral blood available. Family pedigrees were available on all 24 patients. Fifteen of 24 (62.5%) patients were found to have metachronous or synchronous breast cancers with 9 of 15 (60%) having bilateral breast cancer. No BRCA1 or BRCA2 mutations were found (somatic or germline) in this cohort.

Although an uncommon tumor, MMMTs are often found in women with breast cancer. Despite this finding, BRCA1 or BRCA2 germline mutations are not common in this population.

Ovarian MMMTs are frequently found in women with cancer but are not frequently associated with defects in BRCA1 or BRCA2.