A population-based study of familial cutaneous melanoma.

We studied familial risks in cutaneous melanoma by comparing the occurrence of melanoma, or discordant cancer, in two generations, based on the Swedish Family-Cancer Database of 9.6 million individuals. Offspring were from 0 to 61 years of age. Cancers were obtained from the Swedish Cancer Registry for the years 1958 to 1996. The study was based on 30,170 cases of melanoma. Among these, 196 offspring came from families where a parent also presented with melanoma. The overall familial hazard ratio (FHR) was 2.47 when a parent had melanoma; an early age of onset increased the risk. Multiple primary melanomas in parents increased the FHR in offspring, being 2.23 for one, 9.10 for two and up to 83 for more than two melanomas in the parent. The number of affected offspring increased the risk of melanoma in the parents, from 3.05 when one was affected to 5.12 and 151 when two or three offspring were affected, respectively. Melanoma risk to a sibling with an affected proband was 3.56. Melanoma in one generation was associated with an increased occurrence of squamous cell carcinoma of the skin in the other generation. Other weaker associations were found to pancreatic, breast, testicular and nervous system cancers and non-Hodgkin lymphomas.