Risk of colorectal cancer in relatives: a case control study

Abstract

Background: In around 10 to 15% of all colorectal cancer (CRC) cases, a positive family history of colorectal cancer is observed . Although increased risk of colorectal cancer in individuals with a family history of the disease has been observed consistently in the past studies, limited information is available on colorectal cancer associated with family history in Iran.

Aims: The purpose of this study is to define the risk of colorectal cancer associated with a family history of cancer.

Setting and design: The present study was designed as an unmatched case control study. The cases were 393 patients with histologically confirmed colorectal carcinomas and there were 393 controls, randomly selected from among the healthy participants in a health survey.

Methods: The family history was extracted from a standard history form completed by the patient or from the record created by a health care provider.

Statistical analysis: Mantel-Heanszel Odds Ratio was computed for removing the confounding effect of age and sex.

Results: A positive family history of cancer was reported by 36.4 and 24.4% among the cases and controls, respectively. Colorectal cancer risk increased two-fold in subjects who reported having first degree relatives with cancer. The adjusted odds ratio was 4.76, indicating that having a positive family history of colorectal cancer among relatives increased one's risk of colorectal cancer about 4.5-fold.

Conclusion: According to our findings, a family history of cancer increased the risk of CRC. Due to this fact that there is no current colorectal cancer screening program in Iran, it is recommended that first degree relatives of patients with colorectal cancer should be considered as a priority group for screening programs.