The Associations of Ethnicity and Breast Cancer

Background Ethnic minority groups in England represent under-researched populations of breast cancer patients, with generally lower levels of engagement in healthcare research.

Limited data are available on breast cancer incidence and risk factor profiles, and we have previously shown that these groups have on average more advanced disease at presentation and more aggressive breast cancer tumour characteristics compared to white women, observations which require further examination.

Aims (1) To describe breast cancer incidence and risk factor profiles in Indian, Pakistani, Black Caribbean and Black African women. (2) To summarise the barriers and facilitators to the early diagnosis of breast cancer in ethnic minority women. (3) To assess the feasibility and acceptability of establishing a national multicentre study of incident breast cancer cases which is adequately powered to examine differences in tumour characteristics by ethnicity, and the extent to which these may be accounted for by differences in known risk factors and/or delays in diagnosis.

Methods Aim 1: Calculate (1) age standardised incidence rates in specific ethnic groups from 2011-2019 using National Cancer Registration and Analysis Service and the 2011 and 2021 Office for National Statistics census data and (2) breast cancer incidence rates and pooled estimates of the prevalence of key breast cancer risk factors by ethnicity, age and country of birth using data from the Million Women Study and UK Biobank cohorts.

Aim 2: Conduct a qualitative evidence synthesis of the barriers and enablers to the early diagnosis of breast cancer in ethnic minority groups following Cochrane methods.

Aim 3: Conduct a mixed methods pilot study, including 1000 participant surveys and 10 focus discussion groups, in ten NHS breast cancer centres in the West Midlands and Thames regions with PPI embedded throughout the research cycle.

Impact The generation of novel data on breast cancer incidence and risk factor profiles by ethnicity, age and country of birth, will inform hypotheses regarding the underlying associations of ethnicity with tumour characteristics, and help predict future trends in incidence among these ethnic groups.

Comprehensive information on the barriers to early diagnosis of breast cancer in ethnic minority groups, will directly inform breast cancer care policies and future qualitative and intervention studies.

The pilot study will provide a testbed for approaches to engagement and recruitment of an ethnically diverse population which, if appropriate, could then be used at scale in an adequately powered national case-case study of breast cancer in ethnic minority groups.