Tehran University of Medical Sciences Basic & Clinical Cancer Research 2228-6527 8 1&2 2016 08 03 4 17 EN Rahim Akrami Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Iran AND Department of Epidemiology & Biostatistics, School of Public Health, Tehran University of Medical Sciences, Iran Reza Ghiasvand Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Iran AND Department of Biostatistics, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway Akbar Fotouhi Department of Epidemiology & Biostatistics, School of Public Health, Tehran University of Medical Sciences, Iran Iraj Harirchi Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Iran Abbas Rezaianzadeh Research Center for Health Sciences, Department of Epidemiology, School of Health and Nutrition, Shiraz University of Medical Sciences, Shiraz, Iran Abdolrasoul Talei Breast diseases research group, Breast Cancer research Center , ACECR Asiie Olfatbakhsh Breast diseases research group, Breast Cancer research Center , ACECR Fatemeh Homaei Shandiz Associated professor of Radiation Oncology, Mashhad University of Medical Sciences, Mashhad, Iran Kazem Zendehdel Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran AND Cancer Biology Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran 2016 07 04 Background: The etiology of breast cancer and our understanding on the carcinogenicity of different risk factors is impotant for control programms. We investigated the expression of estrogen and progesterone receptors (ER, PR), and human epithelial receptor 2 (HER2) overexpression and its associations, with environmental risk factors among breast cancer patients. Methods: We classified the patients into four groups including; triple negative (ER–/ PR–/HER2–), HER2-overexpression (ER–/PR–/HER2+), luminal A (ER+ and/or PR+/HER2–) and luminal B (ER+ and/or PR+/HER2+). We used a case-only design and multinomial logistic regression analyses. Results: In premenopausal patients, those with high BMI had lower prevalence of luminal B tumors compared to luminal A groups (OR= 0.42, 95% CI= 0.23 to 0.74). However, in the postmenopausal groups, prevalence of the luminal B tumors was less than luminal A tumors oral contraceptive pill (OCP) users (OR= 0.64, 95% CI= 0.42 to 0.98). In addition, among those who had an older age at menarche had a higher risk of ER2-overexpression tumors compared to luminal A tumors (OR= 2.82, 95% CI= 1.29-6.19). Conclusion: Expression of HER2, ER, and PR, among breast cancer patients seems to be associated with OCP use, BMI, age at menarche and age at first pregnancy. https://bccr.tums.ac.ir/index.php/bccrj/article/view/197 https://bccr.tums.ac.ir/index.php/bccrj/article/download/197/07