Risk factors of female cancers in Ragusa population (Sicily). 2. Breast cancer.

A case-control study on breast, cervix and corpus uteri cancer cases registered in Ragusa between January 1, 1983 and June 30, 1985 has been conducted. Information on risk factors has been obtained by means of a structured questionnaire. Risk factors for breast cancer were: few pregnancies (1-2 vs greater than 4 OR 2.14, 95% CL 1.13-4.04), few children (for postmenopausal only, chi trend 4.84), previous breast disease (OR 1.97, 95% CL 1.20-3.23), family history (OR 3.57, 95% CL 1.92-6.63), alcohol (OR 1.68, 95% CL 1.12-2.53), high socioeconomical status (1 vs 4 OR 2.93, 95% CL 1.22-70.03). A protective role was evident for: early age at first birth (for premenopausal only, less than 20 vs greater than 20 OR 0.11, 95% CL 0.01-0.90), previous ovary disease (OR 0.26, 95% CL 0.08-0.88). Age at menarche, age at menopause, years of fertile life and breast feeding were not found to be related to breast cancer. A different distribution of risk factors among cases with and without family history has been suggested. A synoptic table shows the distribution of the most important risk factors of the three investigated female cancers in the Ragusa population, reported in the present and in an accompanying paper.