A population-based audit of ethnicity and breast cancer risk in one general practice catchment area in North London, UK: implications for practice

OBJECTIVES: To conduct a pilot population-based study within a general practice catchment area to determine whether the incidence of breast cancer was increased in the Ashkenazi population. DESIGN: Population-based cohort study. SETTING: A single general practice catchment area in North London. PARTICIPANTS: 1947 women over the age of 16 who responded to a questionnaire about ethnicity and breast cancer. MAIN OUTCOME MEASURES: Incidence of breast cancer, ethnicity. RESULTS: This study showed a 1.5-fold (95% CI 0.93–2.39) increase in breast cancer risk in the Ashkenazim compared with the non-Ashkenazi white population. The increased incidence was for both premenopausal and postmenopausal breast cancer (expected incidence pre:post is 1:4 whereas in the Ashkenazim it was 1:1; 51 and 52% of cases respectively). This increase was not shown in the Sephardim. Asians had a reduction in incidence (OR = 0.44; 95% CI 0.10–1.89). Results were adjusted for other risk factors for breast cancer. CONCLUSION: This study showed a 1.5-fold increase in breast cancer rates in Ashkenazim compared with the non-Jewish white population when adjusted for age (i.e. corrections were made to allow comparison of age groups) and this is not observed in the Sephardic population. The proportion of premenopausal breast cancer was just over double that of the general population. This is the first general practice population-based study in the UK to address this issue and has implications for general practitioners who care for patients from the Ashkenazi community.