Lifestyle, dietary pattern and colorectal cancer: a case-control study.

Background: In Iran, not only the incidence of colorectal cancer (CRC) is increasing but also the age of patients at diagnosis is alarmingly dropping. We need urgent actions to better understand the epidemiology of CRC and the contributing factors for such pattern in Iranian population. The aim of our study was to determine the potential contribution of lifestyle, including dietary pattern, to CRC in a large Iranian province.

Methods: A hospital based case-control study was performed on 572 participants (275 cases and 297 controls). Patients in the case group were newly diagnosed with CRC in a referral hospital and patients in the control group were selected from those patients with non-malignancy diseases who were admitted to the same hospital. Control group was frequency matched to the case group for gender and age.

Results: Based on the results of multivariable logistic regression analysis, direct associations were observed between usual pattern of defecation (OR_{> 3rd /every day} =4.74, 95% CI: 1.78-12.59), chicken consumption (OR_{sometimes or always/occasionally} = 6.33, 95% CI:3.23-12.43), family history of CRC (OR_yes/no =5.79, 95% CI: 2.72-12.31), and alcohol consumption (OR_yes/no =6.03, 95% CI: 2.14-16.98) with the odds of CRC among the study population. On the other hand, taking multivitamins (OR_yes/no=0.09, 95% CI:0.04-0.20), consumption of coffee (OR_{always/occasionally} =0.29, 95% CI: 0.12-0.69), taking vitamins D supplement (OR_yes/no =0.38,95% CI:0.22-0.66), and consumption of garlic (OR_{sometimes/occasionally} =0.53,95% CI: 0.30-0.95) significantly reduced the odds of CRC.

Conclusions: We revealed potentially significant effects of several lifestyle related factors with CRC risk in Iranian population. More studies are required to understand the mechanism of action of the associated factors in developing CRC.