The influence of lactation, occupational exposures and postmenopausal hormone use on the incidence of breast cancer

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:5569016

Yang, C P

A self-administered questionnaire was completely by 1,018 women diagnosed with breast cancer during 1988-1989 identified through the British Columbia Cancer Registry and by 1,025 controls selected at random from the Provincial Voters List. Data were collected on demographic characteristics, lifestyle factors, occupational and reproductive history as well as hormone use. Premenopausal women who ceased lactation within the first month had a relative risk of 3.0, adjusted for age and parity (95% C.I. = 1.6-5.4), compared to women who had breast fed two months or longer. Among women who nursed for at least two months, there was an indication of decreasing risk with increasing duration of nursing. Among post-menopausal women, no relation between lactation history and breast cancer risk was evident. Premenopausal women who reported ever having been a data processing operator (OR = 3.8), hairdresser (OR = 5.5), janitor/housekeeper (OR = 2.1), or having worked in the food processing (OR = 2.7) were found to have an excess risk of breast cancer. Among postmenopausal women, an excess risk was seen for nursing or medical workers (OR = 1.4) whereas a reduced risk was observed among waitresses/bartenders (OR = 0.5), textile workers (OR = 0.5) or defense industry personnel (OR = 0.4). The effect of menopausal hormone use was evaluated among 699 cases and 685 controls who were postmenopausal due to natural causes or to a hysterectomy. There was no overall increase in risk of breast cancer associated with ever use of unopposed estrogen (OR = 1.0, 95% CI = 0.8-1.3). For estrogen use of ten years or longer, the relative risk was 1.6 (95% CI = 1.1-2.5). The risk estimate for current users was somewhat elevated (OR = 1.4, 95% CI = 1.0-2.0). Compared to women who never used hormone preparations, women who had used estrogen plus progestogen had a relative risk of 1.2 (95% CI = 0.6-2.2).

• Research Organization: Washington Univ., Seattle, WA (United States)
• OSTI ID: 5569016
• Country of Publication: United States
• Language: English

Related Subjects

550100 -- Behavioral Biology
550900* -- Pathology
59 BASIC BIOLOGICAL SCIENCES
BODY
DISEASE INCIDENCE
DISEASES
ESTROGENS
GLANDS
HORMONES
LACTATION
MAMMARY GLANDS
NEOPLASMS
OCCUPATIONAL EXPOSURE
ORGANS
RESPONSE MODIFYING FACTORS
RISK ASSESSMENT
STEROID HORMONES