Effect of a Detailed Family History of Melanoma on Risk for Other Tumors: A Cohort Study Based on the Nationwide Swedish Family-Cancer Database

Using the Swedish Family-Cancer Database, we assessed the effect of a detailed family history of melanoma on risk for other tumors (other than melanoma). Among 248,011 individuals with a family history of melanoma, 43,931 other tumors were diagnosed from 1958 to 2010. Standardized incidence ratios (SIRs) were calculated for other tumors in patients who had a family history of melanoma, as compared with those without. A detailed family history of melanoma was investigated according to an increasing number of melanomas in either 1 or ⩾2 first-degree relatives (FDRs). Associations were considered significant when there were at least two independently significant SIRs or a statistically significant trend of increasing SIRs with increasing number of melanomas in relatives. The applied criteria for significant associations were convincingly met by pancreatic, breast, prostate, and squamous cell skin tumors and ependymoma, although there was significant but not overwhelming evidence for thyroid, parathyroid, lung, and unknown primary tumors, meningioma, mycosis fungoides, and myeloid leukemia. To our knowledge, no studies have previously considered a detailed family history of melanoma and the use of internal validation to assess familial associations of melanoma with other tumors. We established associations for 12 other tumors, and the associations for myeloid leukemia, parathyroid, and unknown primary tumors are, to our knowledge, previously unreported.