Background: Having a family history (FH) of cancer is recognized as one of the most important factors inpredicting personal cancer risk. Since reports on cancer FH from developing countries are limited, the presentstudy was conducted to provide a first report on the prevalence of familial cancers in Iran. Methods: Crosssectionalanalysis performed on self-reported FH of cancers based on data from a large population based studyin Tehran, the capital of Iran. Each participant was shown a list of site-specific cancers and asked if a relative hadbeen diagnosed with any cancer on the list, completing the question by specifying the age of diagnosis. Results:Stomach cancer (4.6%) was the most common condition noted for family members, followed by the cancers ofthe breast (4.2%), lung (3.5%), liver (3.1%), leukemia (3.0) and colorectum (2.8%). The most frequent cancerreported by the responders was breast (1.8%) in first degree relatives (FDR) and stomach (1.8%) and stomach(2.8%) in second degree relatives (SDR). A FH of cancer was more commonly reported by younger persons andfemales. Of all respondents with a positive FH, 28.2% had at least one affected person diagnosed at age under50 years in their FDRs. Conclusion: A substantial proportion of individuals in the Iran report having a familymember affected by cancer, and thus may be recommended for early cancer screening services.
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