LAUSR

Micro‐Abstract The association of several factors with breast cancer is measured in this study on 526 case and 526 control participants. Hair coloring, stress and smoking as well as several other important risk factors were found to be associated with breast cancer. The results suggest that a wider range of factors affect the risk of breast cancer among women. Purpose: Epidemiologic characteristics of breast cancer in Iran are significantly different from those in the West and even other regional countries, but little is known about the related factors. Patients and Methods: A hospital‐based case‐control study was conducted on 1052 women (526 new cases and 526 controls). Logistic regression was performed to investigate associations of study factors with breast cancer risk. Results: This study introduced occupation (odds ratio [OR]employed/household, 1.77; 95% confidence interval [CI], 1.15‐2.69), marital age (OR24‐30 y/< 18 y, 2.13; 95% CI, 1.03‐4.40), age at first delivery (OR≥ 30 y/< 18 y, 3.53; 95% CI, 1.73‐7.18), parity (OR1‐2/Nulliparous or never married, 2.61; 95% CI, 1.13‐6.02), birth interval (OR30‐50 mos/< 18 mos, 2.38; 95% CI, 1.45‐3.89), lifetime breastfeeding (OR≥ 42 mos/< 6 mos, 0.37; 95% CI, 0.18‐0.77), and menarche age (year) (OR, 0.87; 95% CI, 0.79‐0.96) as significant associates of breast cancer. In addition, body mass index (OR, 1.07; 95% CI, 1.02‐1.11) and some health‐related behaviors including hair coloring on a regular basis (ORyes/no, 1.93; 95% CI, 1.41‐2.62), smoking (ORyes/no, 2.02; 95% CI, 1.22‐3.34), oral contraceptive usage (ORever/never. 1.46; 95% CI, 1.05‐2.04), physical inactivity (ORinactive/regular activity, 1.54; 95% CI, 1.39‐1.75), past life stress (ORoften stressful/often calm, 2.40; 95% CI, 1.62‐3.56), and regular bedtime (ORoften regular/no, 0.32; 95% CI, 0.19‐0.54) were related to a higher risk of breast cancer. Conclusion: This study revealed a significant number of factors that seem to contribute to the risk of breast cancer even more than the other previously introduced factors.