Hormone Therapy and Factors Affecting Fertility of Women Under 50-Year-Old with Breast Cancer

BACKGROUND: Although the use of contraceptive hormones is a risk factor for development of breast cancer, level of risk is unknown; thus the current research was conducted to investigate the effect of factors related to fertility and hormone use on risk of breast cancer in women aged under 50 years old in the west of Iran. METHODS: In this case-control study, all incidence cases of breast cancer aged between 25–49 years old (n=212) were selected. Twice as many as the case group, the individuals referred to other outpatient sections of the same hospital at the time of study and up to 2 years after the follow-up not diagnosed with breast or other cancers were selected as a control group. The data were collected using healthy fertility program and middle-aged periodical care forms developed by Iran’s Ministry of Health (MOH). RESULTS: After controlling for confounding variables, history of hormonal use for contraception (OR=2.02, 95% CI=1.2–3.3) and hormone therapies (OR=1.9, 95% CI=1.2–3.04) were identified as factors increasing the risk of breast cancer. Dose-response relationships between breast cancer and the use of hormones for contraception and hormone therapy indicated that these factors increased the risk of breast cancer. The risk was found to be higher in women who had been under hormone therapy for more than 120 months. With an increase in the age of the first menstruation, risk of breast cancer increased linearly, but with an increase in the age of the first pregnancy, risk of breast cancer increased exponentially. After 20 years of age, the risk increased with a steeper slope. CONCLUSION: Considering the effect of hormone therapy and fertility factors on breast cancer and changeability of listed risk factors, the researchers suggest planning for sensitizing, increasing the awareness, and educating women and professionals regarding the influence of fertility and hormonal factors including pregnancy at lower ages, minimizing the use of hormones for contraception, and hormone therapy.