Case-controlled study of the epidemiological risk factors for breast cancer in Nigeria

Background: The incidence of breast cancer is increasing worldwide, more rapidly in societies that hitherto enjoyed a low incidence of the disease, such as most African countries. Most of the epidemiological data on breast cancer from Africa have been retrospective studies with propensity for bias. Methods: This was a case-controlled study of 250 consecutive patients with breast cancer diagnosed between April 1992 and December 1995. An age- and sex-matched control group of patients with non-oncological and non-endocrine diseases was compared. Results: The peak age incidence of breast cancer in the sample studied was 43 years. There was a statistically significant difference in the height and weight of the patients compared with the controls. Patients also tended to be older at first pregnancy and at first lactation, and had a higher mean number of pregnancies. The patients also tended to be of an early birth order, to have lactated less often, to have used contraceptives and to have abused alcohol compared with the controls. Conclusion: The incidence of breast cancer in this environment is increasing. This is partly a result of the changing demographic profile, acquisition of 'western' lifestyle, and the changing socioeconomic profile of the country.