Familial association of prostate cancer with other cancers in the Swedish family-cancer database

BACKGROUND. Familial associations between cancer sites may implicate true familial clustering which is relevant for the identification of new cancer syndromes and for clinical counseling. METHODS. We used the nation-wide Swedish Family-Cancer Database, containing 10,553 sons and 107,518 fathers with prostate cancer among a total of 170,000 cancer patients in the 0- to 70-year-old offspring generation and over 800,000 cancer patients in the parental generation. We calculated familial standardized incidence ratios (SIRs) and confidence intervals (CIs) for prostate cancers and other cancers in family members. RESULTS. SIRs for prostate cancer were increased in sons when mothers were diagnosed with breast and ovarian cancers, and when siblings were diagnosed with Hodgkins disease (1.78, N = 18,95% Cl 1.05-2.82) and leukemia (1.39,43,1.01-1.88). Liver cancer and melanoma were also in excess in the high-risk families. CONCLUSIONS. The present analysis, the largest yet carried out, found many novel associations implying familial links between prostate cancer and other sites.