Relationship between Reproductive Factor and Breast Cancer in Mazandaran Cohort: A Case-Control Study

BACKGROUND AND OBJECTIVE: Identification of cancer risk factors in the community and prevention planning in high-risk groups can be helpful in cancer prevention program. Hence, the aim of this study was to investigate the relationship between reproductive factors and breast cancer in the Tabari population-based cohort study in a case-control design. METHODS: This case-control study was performed on the enrolment phase of the Tabari population-based cohort. Patients with breast cancer were considered as case group (51) and non-cancerous individuals (204) as a control group. The two groups were matched based on age category and oral contraceptive pill (OCP) intake. The studied variables included breast cancer history, demographic and reproductive factors. FINDINGS: Mean age of first pregnancy (22.76±4.99 vs. 20.8±4.16, p=0.005), mean age at first birth (23.57±4.94 vs. 21.66±4.07, p=0.006) and age of marriage (22.24±5.75 vs. 19.54±4.92, p=0.001) in the case group were significantly higher than the control group and the number of pregnancies (3.76±2.22 vs. 4.67±2.76, p=0.032) and number of children (3.27±1.97 vs. 4.16±2.44, p=0.019) in the case group was significantly less than the control group. According to multivariate analysis, the odds of incidence of breast cancer in people with first pregnancy over 22 years was 2.76 times more than (p= 0.027) those with first pregnancy age below 22 years. CONCLUSION: “Age at first full-term pregnancy” is one of the major risk factors for breast cancer in the area.