Salivary Gland Cancer inBRCA-Positive Families

Abstract

Although an association between breast cancer and salivary gland cancers has been noted for decades, this is the first study, to our knowledge, to evaluate the possible linkage of BRCA gene mutations and this malignant neoplasm. To compare the prevalence of salivary gland cancers in a large BRCA gene mutation database with background rates in the general population. This is a retrospective review (June 1, 2012, through April 31, 2013) of pedigrees from patients with breast cancer in The Clinical Cancer Genetics Program at The Ohio State University Wexner Medical Center. A total of 5754 individuals were identified from 187 pedigrees, and their medical histories were reviewed for diagnoses of salivary gland tumors and BRCA testing. The pedigrees were restricted to provide a cohort of individuals with reasonable accuracy in family history by considering 3 generations of each pedigree, starting with the proband's generation and adding 1 generation above and below. The youngest generation was replaced with another older generation if there were no BRCA-related cancers or BRCA mutations recorded. Nonblood relatives of the proband (ie, stepparents and stepsiblings) were also excluded. The rate of salivary gland cancers in the Clinical Center Genetics Program was compared with background incidence rates. After applying the restrictions to the 187 pedigrees in the database, 5754 individuals were included in the cohort. Two parotid gland cancers, 2 salivary gland cancers not otherwise specified, and 1 adenoid cystic carcinoma were identified. One of these cancers likely did not segregate with the BRCA mutation, and another individual tested negative for the BRCA mutation, resulting in a rate of 3 of 5754 (0.052%).The observed rate of 3 of 5754 cases (0.052%) of head and neck cancers in BRCA-positive probands and likely carriers is significantly higher than the background incidence rate of 3 of 100,000 (0.003%) per year (P < .001). We believe this is a significant observation that, when considered alongside other similarities between salivary glands and breast tissue, warrants further investigation into the nature of a possible linkage between germline BRCA mutations and salivary gland cancer.