Breast cancer incidence and determinants of cancer stage in the Western Cape

Objective. To describe the overall and age-specific incidence rates for bre ast cancer and determinants of the stage of breast cancer at the time of di agnosis in the Western Cape, South Africa. Methods. Data were derived from a case-control study of the association bet ween injectable progestagen contraceptives and breast cancer conducted over a 4-year period from January 1994 to December 1997. In all, 485 cases were drawn from a study population consisting of coloured and black women under the age of 55 years, who presented with a first occurrence of invasive bre ast cancer at two tertiary hospitals in Cape Town. A questionnaire was admi nistered and information on a large number of variables was recorded. Results. The 249 cases who were interviewed during the first 2 years of the study constituted the numerator for estimates of incidence rates. The over all incidence rate was 23.1 per 100 000 women per year The incidence rate f or coloured women was 25.6 per 100 000, almost twice that for black women ( 14.7 per 100 000). The incidence rate in urban areas was 26.6 per 100 000, almost twice that in the rural areas (16.3 per 100 000). Stages 1 and 2 acc ounted for 57.8% of the cases. Early stage at diagnosis was significantly a ssociated with a higher educational level, membership of a medical aid, res idence in an urban area and a positive family history. Conclusion. The data suggest that there is scope for improvement in the det ection of the disease through education and access to diagnostic measures, particularly in rural and disadvantaged populations.