Background: Breast cancer is one of the most prevalent cancers among women and features increasing trends of incidence rates. Worldwide, yearly about 1.67 million of new cases and 522,000 of deaths from breast cancer are registered. The aim of this study was to determine the risk factors of breast cancer in women and to identify high risk groups.

Methods: In a case-control study, 170 women with breast cancer who were registered in cancer registration system from 2011 to 2015 at Dezful City, Iran, were compared with 170 healthy women with confirmation of mammography. After age matching of groups, the needed information about risk factors and demographic information including information, educational level, marital status, family history of breast cancer, age at menarche, parity, oral contraceptive use, age at first pregnancy, menopausal status, and age at menopause, breastfeeding, stress, abortion, alcohol use and smoking, hormone therapy and physical activity was collected by a questionnaire. The analysis of collected data was performed by using odds ratio and logistic regression model and SPSS software, version 16 (SPSS, Inc., Chicago, IL, USA). The statistical significance was set at a two-sided p-value of %5.

Results: The results of this study showed that, women with the family history [OR: 6.78 (95% CI: 2.15-21.41)] and women with the stress history [OR: 4.86 (95% CI: 2.46-9.59)] had higher risk of breast canser, while women with the history of having physical activity at least once a week [OR: 0.29 (95% CI: 0.13-0.65)] and women with the history breast feeding for 3 to 4 years [OR: 0.36 (95% CI: 0.16-0.81)] had lower risk of breast cancer.

Conclusion: It is recommended that the mentioned risk factors and protective factors be considered in first and second level (screening) of preventive programs.