Onm-4: Reproductive Factors Related to Cancerof the Breast, before and after Menopause;among Women Referring to Health Centers inTehran, 2005

Background: To find out those reproductive factors to incidence of breast cancer overall and by menopausal status. Materials and Methods: This was a case – control study, in which, the risk of menstrual, pregnancy- delivery and menopausal factors were determined in women with breast cancer (case) against those without (control). The risk factors stratified by menopausal status also. A total of 500 women, diagnosed with breast cancer, (250 in premenopausal and 250 in post menopausal status), were selected from shohada hospital and cancer institute in Tehran, and 500 women as controls visiting patients at the same time or living next door to cases. Results: The results showed that early menarche (OR=17.26, p=0.000), breast feeding less than 3 months in life (OR=2.73, p=0.000) are overall risk factors for breast cancer and both at pre (OR=15.61, p=0.000 and OR=1.77, p=0.000), and postmenopausal (OR=0.05, p=0.003 and OR=0.28, p=0.001). Menstrual interval less than 26 days, and irregular menstruation period was related to breast cancer (OR=0.30, p=0.000 and OR=2.39, p=0.026 respectively) and in premenopausal period (OR=0.25, p=0/000 and OR=2.71, p=0.017 respectively). On the other hand, irregular menstrual period in the age of 30, time interval more than 20 years betweenmenarche and first pregnancy were related to breast cancer (OR=18.66, p=0/000 and OR=0.45 , p=0.000 respectively). We also found that two mentioned variables were risk factors of breast cancer in post menopausal period (OR=0.02, p=0.000 and OR=2.85, p=0.000 respectively). This study showed that overall, cancer of the breast is statistically related to scantly menstrual bleeding (OR=1.72, p=0.000) and occurrence of first pregnancy after age of 20 (OR=2.40 , p=0.000 ) , history of post term delivery (OR=3.15 , p=0.038) ,history of 2 spontaneous abortion (OR=2.16 , P=0.043), history of induced abortion (OR=2.03, p=0.018), and the usage of oral contraceptive pill more than 5 years (OR=0.40, p=0.001) were only related to premenopausal breast cancer. It was also shown that, dysmenorrheal (OR=2.24, p=0.027), marital age after age of 30 (OR=3.79, p=0.011), hot flashes at menopause (OR=0.32, p=0.004) and occurrence of menopause after the age of 55 (OR=3.84, p=0.000) were only related to breast cancer of post menopausal status. Conclusion: Regarding our results the age in which the disease is diagnosed is a prominent point for sow factors. It can be assumed that the most important factors are irregular menstruation at the age of 30 for both pre and post menopause. Meanwhile, early menarche for premenopausal breast cancer and menopausal age for post menopausal breast cancer were considered to be the most important factors.