Risk factors for breast cancer in nulliparous women.
The relation between hormonal and lifestyle factors and breast cancer risk in nulliparae was investigated using data from two case-control studies conducted in Italy between 1983 and 1994. The study included 1041 nulliparae with histologically confirmed incident breast cancer and 1002 nulliparous controls admitted to hospital for a wide range of acute, non-neoplastic, nonhormone-related diseases. In premenopausal nulliparae, there was an inverse relation with age at menarche [odds ratios (OR) 0.45; 95% confidence intervals (CI) 0.24-0.86 for > or = 15 years vs < 12], while no association emerged in postmenopausal. Breast cancer risk increased with age at menopause, the OR being 1.91 (95% CI 1.26-2.90) for nulliparae reporting age at menopause > or = 53 years compared with < 45. Abortion was not related to breast cancer risk, the OR being 0.92 for any spontaneous, 0.97 for any induced and 0.77 for > or = 2 total abortions compared to none. The OR was 1.75 (95% CI 1.03-2.97) for women reporting their first abortion at age > or = 30 years compared with < 30. Oral contraceptives and hormone replacement therapy in menopause were moderately related to risk. The OR was 2.71 (95% CI 1.85-3.95) in nulliparae with a family history of breast cancer and 1.60 (95% CI 1.20-2.14) in those with a history of benign breast disease. Compared with nulliparae reporting a low physical activity, the OR was 0.79 (95% CI 0.54-1.16) for those reporting intermediate/high activity. Breast cancer risk increased with total energy intake, the OR being 1.65 (95% CI 0.99-2.75) in the highest tertile; beta-carotene was inversely related to risk (OR 0.60, 95% CI 0.38-0.95) for the highest tertile. Thus, most risk factors for breast cancer in nulliparae were similar to those in women generally.
Fioretti
F
F
Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy.
Tavani
A
A
Bosetti
C
C
La Vecchia
C
C
Negri
E
E
Barbone
F
F
Talamini
R
R
Franceschi
S
S
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000209:etiology* / Q000503:physiopathology; D016022:Case-Control Studies; D005260:Female; D006728:Hormones / Q000502:physiology*; D006801:Humans; D008019:Life Style; D008875:Middle Aged; D016017:Odds Ratio; D010298:Parity; D017698:Postmenopause / Q000502:physiology; D017697:Premenopause / Q000502:physiology; D012098:Reproduction; D012307:Risk Factors
D006728:Hormones