Impact of lifestyle and psychological stress on the development of early onset breast cancer.

The present study aimed to investigate risk factors for early onset breast cancer that are related to lifestyle and psychological stress. A comparative case-control study was performed among patients from the Department of Breast Surgery in Shanghai Cancer Center of Fudan University. The information regarding risk factors associated with the development of early onset breast cancer was collected using a questionnaire in a face-to-face interview. The distribution of the risk factors associated with the development of early onset breast cancer between the patient group and the control group was analyzed with logistic regression. A total of 582 cases of young patients (≤40 years old) with breast cancer and 540 controls of young patients (≤40 years old) with benign breast disease were included in this study. The risk factors for breast cancer in young women include age at first birth (odds ratio [OR] = 0.93, 95% confidence interval [CI]: 0.88-0.98), history of breast cancer in an immediate family member (OR = 2.36, 95% CI: 1.14-4.89), history of genital surgery (OR = 2.11, 95% CI: 1.16-3.82), active and passive smoking in daily life or the environment (OR = 1.64, 95% CI: 1.19-2.25), weekly intake of soy products (OR = 1.24, 95% CI: 1.02-1.49), use of household cooking oil (OR = 2.04, 95% CI: 1.04-4.00), disharmonious marital status (OR = 1.16, 95% CI: 1.06-1.26), frequent depression (OR = 1.32, 95% CI: 1.00-1.75), and negative emotional experiences (OR = 1.15, 95% CI: 1.03-1.29). Our study could provide the basis for risk assessment and preventive interventions for early onset breast cancer.