Incidence and familial risks in pituitary adenoma and associated tumors.

Reliable data on familial risks are important for clinical counseling and cancer genetics. We wanted to study incidence trends and familial risks for pituitary adenomas and associated tumors through parental and sibling probands, using the nation-wide Swedish Family-Cancer Database on 10.5 million individuals, containing families with parents and offspring. Cancer data were retrieved from the Swedish Cancer Registry from years 1958 to 2002, including 3239 pituitary tumor patients. Familial risk for offspring was defined through standardized incidence ratio (SIR), adjusted for many variables. The incidence of pituitary adenoma has increased moderately from 1958 to the 1990s and declined thereafter. There were only three offspring-parent pairs with a concordant pituitary tumor, the SIR was not significant. Parental skin cancer (SIR 1.60) and leukemia (1.90, chronic lymphatic leukemia 2.59) were associated with offspring pituitary adenoma diagnosed at any age up to 70 years. There was a strong association of pituitary adenomas with nervous system hemangiopericytomas, SIR 182. The only significant association among siblings was between pituitary tumors and breast cancer (1.46). The risk of pituitary adenoma was marginally increased in individuals whose siblings were diagnosed with colorectal cancer. The results suggest an association of pituitary adenomas with nervous system hemangiopericytomas and breast and colorectal cancers, in addition to some other tumor types. Whether these associations can be explained by the recently identified pituitary adenoma predisposing gene, AIP, remains to be established.