Influence of menstrual and reproductive factors on ovarian cancer risk in women with and without family history of breast or ovarian cancer.

ABSTRACT

BACKGROUND: As women with a family history of ovarian and/or breast cancer possibly inherit genetic changes that alter their risk of ovarian cancer, other established risk factors for ovarian cancer may influence the risk differently in women with and without a family history of the disease. METHODS: Case-control study conducted between 1983 and 1991 in Northern Italy. Cases were 971 women, under 75 years, with incident, histologically confirmed epithelial ovarian cancer, and controls were 2758 women, under 75 years, admitted to hospitals for non-malignant, non-hormone-related conditions, who had not undergone bilateral oophorectomy. Of these, 93 cases and 139 controls had a family history of ovarian and/or breast cancer. RESULTS: The risk of ovarian cancer increased with irregular menstrual cycles, late age at menopause, natural menopause, nulliparity, never use of oral contraceptives and use of hormone replacement therapy. We computed an 'adult life risk score' (ALRS) considering the combined effect of these factors. Compared to women without a family history and a low ALRS, the OR was 1.7 for women without family history and high ALRS, 1.4 for women with a family history and low ALRS, and 3.5 for women with a family history and high ALRS. CONCLUSIONS: Intervention on selected hormonal risk factors for ovarian cancer might be important for women with a family history of the disease.