Published in Cancer Detection and Prevention 1998; 22(6):485-494.

Sociodemographic Characteristics, Smoking, Medical and Family History, and Breast Cancer

Parviz Ghadirian, Ph.D.,a Andre Lacroix, M.D.,b Chantal Perret, D.E.A.,a Patrick Maisonneuve, Ph.D.,c and Peter Boyle, Ph.D.c

a Epidemiology Research Unit and b Laboratory of Nutrition and Cancer, Research Center, CHUM, Department of Nutrition, Faculty of Medicine, University of Montreal, Montreal, Quebec, Canada; and c Division of Epidemiology and Biostatistics, European Institute of Oncology, Milan, Italy

Address all correspondence and reprint requests to: Parviz Ghadirian, Ph.D., Epidemiology Research Unit, Research Center, CHUM, Hotel-Dieu Campus, University of Montreal, 3850 St. Urbain, Montreal, Quebec, H2W 1T5, Canada.

ABSTRACT: The relationship between sociodemographic characteristics, lifestyle, family history of cancer, medical history, and reproductive factors and breast cancer was investigated in a population-based case-control study of French Canadians in Montreal. In this study, a total of 414 French-Canadian cases and 429 age- and language-matched population controls were interviewed. Ever-married women showed significantly lower risk (OR: 0.64 [0.45-0.92]) for breast cancer, as did smokers (OR: 0.73 [0.55-0.98]), particularly of nonfilter cigarettes (OR: 0.36 [0.17-0.72]). Weight history, both for the year before the diagnosis of breast cancer and 10 years previously, was associated with risk for the disease. A strong inverse relationship was found between the number of full-term pregnancies (OR: 0.48 [0.28-0.82]) and the risk of breast cancer, while the p trend for late age at first pregnancy (p = 0.02) and menopause (p = 0.004) was statistically significant. A history of breast problems (OR: 1.87 [1.34-2.60]) and a history of breast cancer in relatives (OR: 2.95 [1.63-5.34]) were strongly associated with risk. This study confirms the risk factors of late age at first full-term pregnancy, nulliparity, late age at menopause, and positive family history of breast cancer in the etiology of this disease. Perhaps the protective effect of smoking against breast cancer could be due to its antiestrogenic influence.

KEY WORDS: breast cancer, family history, French Canadians, lifestyle, smoking, sociodemographics.

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