Risk of Colorectal Cancer in Relatives: A Case Control Study

Introduction: Although increased risk of colorectal cancer in individuals with family history of the disease has been observed consistently in past studies limited information is available on the colorectal cancer associated with family history in Iran. The purpose of this study is to define colorectal cancer risk associated with family history cancer. Methods: The present study was designed as an unmatched case control study. Cases were 393 patients that histologically confirmed colorectal carcinomas and 393 controls were randomly selected from among the healthy participants in a health survey. For the cases the family history was extracted from a standard history form completed by the patients and for the controls; it was obtained through interviews conducted by trained health care providers. Mantel-Hansel Odds Ratio was computed to remove the confounding effect of age and sex. Results: A positive family history was reported by 36.4% and 24.4% of cases and controls respectively. Colorectal cancer risk increased two-fold for subjects reporting any first degree relative with cancer. The adjusted odds ratio was 4.8 (0.95CI: 2.1-8.1) indicating that having a positive family history of colorectal cancer among relatives increases ones risk of colorectal cancer about 4.8-fold. Conclusion: According to our findings family history of cancer increases risk of CRC. As there is no current colorectal cancer screening program in Iran it is recommended that first degree relatives of patients with colorectal cancer be prioritized for screening programs