Familial Cancer Clustering in Patients with Prolactinoma.

People are at higher risk for malignancy as they get older or have a strong family history of cancer. This study aims to collect family history of cancer in a large cohort of patients with pituitary adenomas (PA) in outpatient clinic from years 2005-2017. Overall, 46.6% of 1062 patients with PA had a family member affected with cancer. Breast cancer in family members was reported in 15.3% of patients with prolactinomas which was significantly higher than in families of patients with non-functioning pituitary adenomas (NFPA) (10.0%) or acromegaly (6.8%) (p = 0.004). Lung cancer in family members was reported in 12.1% of patients with prolactinomas, significantly higher than in families of NFPA patients (7.0%, p = 0.049). Colorectal cancer in relatives of patients with PA was reported with any type of PA. Furthermore, patients with a positive family history of malignancy were diagnosed with PA at an earlier age than patients with a negative family history (43.6 ± 15.9 vs 46.0 ± 16.4 years, p = 0.015). Female patients with prolactinoma are more commonly diagnosed before the age of 25 years. Forty-two percent of patients with PA diagnosed before the age of 25 years had a second- and third-degree relative with cancer, significantly higher than patients with PA diagnosed later in life (25.8%, p < 0.001). Breast, lung, and colon cancers in second- and third-degree relatives were reported in significantly higher proportion of patients with PA diagnosed before the age of 25 years, compared with patients with PA diagnosed later in life (breast cancer: 10.9 vs 6.1%, p = 0.033; lung cancer: 10.9 vs 5.8%, p = 0.02; colon cancer: 9.5 vs 4.0%, p = 0.004). These results suggest familial cancer clustering in patients with prolactinoma and young patients with PA (younger than 25 years at diagnosis of PA). In particular, there is a strong association between prolactinoma and family history of breast and lung cancers. Further research of possible shared genetic susceptibility of prolactinoma and breast and lung cancers is needed.