According to the World Health Organization (WHO), breast cancer is the most common form of cancer, with more than 2.2 million cases in 2020. It is estimated that 1 in 12 women will develop breast cancer and it will be the primary cause of death among all other types of cancer in women. However, breast cancer survival has improved significantly since the 1980s due to increased early detection, screening programs, and improved treatment options.
What are Race and Ethnicity?
Among the identified risk factors of breast cancer, the WHO reports that half of the cases of breast cancer develop with no identifiable risk factor apart from being a female and being over the age of 40. Although these are the most common risk factors, race and ethnicity may also contribute to the development of breast cancer. Race is identified by the phenotype characteristics while ethnicity is identified as encompassing cultural factors, traditions, nationality, and language of a specified group. Researchers have now begun to examine how race and ethnicity may affect breast cancer diagnosis.
In Canada, the Ontario administrative health care data does not include ethnicity in their data collections. Independent researchers and some organizations are gathering this data through clinical studies. In countries like Canada, the United States, and the United Kingdom where there are many races and ethnicities within the population, there are limited studies available on breast cancer disparities within these communities. These limited studies are also restricted to Caucasian, Black and African American (BAA) or Asian and South Asian (ASA) participants, omitting other heterogeneous populations. It is also important to point out that in countries where race and ethnicity data is collected, many of the ethno-cultural populations are broadly grouped together which prevents crucial understanding of the differences in health, practices, and clinical outcomes.
What the Current Data Shows
More focus has begun on race and ethnicity correlations to breast cancer diagnosis, treatment options, and survivorship. Caucasian women and African-American women have the highest rates of breast cancer. Caucasian women are more likely to develop breast cancer compared to BAA, Hispanic and Asian women. The difference between Caucasian women and BAA women is not significant but this small difference may be explained by how breast cancer risk factors affect these women. The slight increase in Caucasian women developing breast cancer may be due to women having children at a later age, the number of children, and the use of hormonal therapy in menopause.
BAA women, while having a slightly lower breast cancer risk, experience poor breast cancer survival rates, are more likely diagnosed with advanced-stage breast cancer, and are diagnosed with aggressive hormone receptor-negative high-grade tumours. BAA women are also more likely to be diagnosed with aggressive triple-negative breast cancer. The link between race and ethnicity has not completely been understood but lifestyle choices may be a contributing factor. The age of onset of breast cancer among BAA women is at a younger age compared to Caucasian women with risk factors such as reproduction, lifestyle, and tumour biology as possible causes.
How do Race and Ethnicity Explain These Differences?
Keep in mind, data on ethnicity is very seldom collected in Canada. These data are applicable to the United States but significant parallels can be drawn. Some of the reasons may include, living in communities where BAA women face poverty levels well below the federal level according to US census data and where the rates of educational attainment are below high school level. This lack of education and lower socioeconomic status affects these women by limiting access to care, screening, follow-ups after a breast cancer diagnosis, the use of preventative services, and survivorship. This also affects BAA women in the United States who have insurance coverage to access mammograms and treatment uptake but due to the lack of awareness and education, they are limited in seeking other preventative options in clinical trials. Many times, BAA women are under-represented in clinical research studies especially in triple-negative breast cancer treatments due to these factors.
Among the different races and ethnicities, ASA women also experience an increased risk of a breast cancer diagnosis. This community of women also face lower socioeconomic status in addition to, ethno-cultural challenges in breast cancer screening uptake and treatment. ASA women face challenges that are influenced by cultural beliefs, values, and language which determines the amount of health care they receive. Ethno-cultural studies reveal that ASA women are diagnosed at a younger age but with advanced and aggressive types of breast cancer.
Clinical studies from Europe and North America show women from minority groups result in poor survival rates and are not likely to participate in cancer screening programs. This decreased participation and lack of awareness are due to the influence of societal cancer myths, stigma, and the taboos surrounding breast cancer in the ASA communities. This influence includes judgemental and negative comments from elders who are not educated in the disease process and treat cancer as a form of punishment. There is also cultural stigma and taboos surrounding women’s value and honour in the family. Pressure is placed on women to not discuss breast cancer illness in fear of compromising the family name or status and in turn, this confines the women from seeking health care for breast cancer.
In addition to sociocultural barriers, immigration may also be a factor in breast cancer survival due to assimilation to a different culture and healthcare systems. The low rates of cancer screening partly have to do with ASA women not being exposed to breast cancer health promotion and prevention from their country of origin. This consequentially relates to delayed breast cancer diagnosis.
The last group of women are at increased risk of breast cancer due to inherited genetic factors. Jewish women from Ashkenazi (Eastern Europe) also face an increased risk of breast cancer due to inheriting the BRCA1/2 gene mutation. Ashkenazi Jewish people account for about 80% of the Jewish population. It was in the mid-1990s where the BRCA1/2 gene mutations were discovered in the Ashkenazi Jewish community, where there is a 1 in 40 risk of being a BRCA1/2 gene mutation carrier; one of the highest risks in any population. The risk of breast cancer increases in this group of women when one of the BRCA1/2 genes mutates. BRCA1/2 mutated genes are inherited from either the mother or father and lead to a higher-than-average risk of breast cancer in addition to the other present risk factors.
The inherited genetic factor in Ashkenazi Jewish women stems from the Founder's Effect, whereby a group of founding people were carriers of mutated genes, and were geographically and culturally isolated within the same group. This isolation increased the number of people with genetic mutations within this closed group. Considering having a higher-than-average risk of developing an inherited gene, genetic testing to screen for mutated BRCA1/2 genes is not a standard of care in this population of women. Many Ashkenazi Jewish women discover they are carriers of a mutated BRCA1/2 gene only once they have been diagnosed with breast cancer and this may limit early preventative treatments.
The Future of Studies on Racial and Ethnic Risk Factors
More race and ethnicity-based clinical studies and data collections are required to assess the risk of breast cancer and to understand the health disparities of women in these groups. It is also evident more education and awareness among healthcare teams is needed to be able to recognize how race and ethnicity can affect various women. Race and ethnicity are not official non-modifiable risk factors for breast cancer, but there is clinical research demonstrating the benefit in breast cancer diagnosis. More health centers are now considering race and ethnicity as an influence in breast cancer in countries like the United Kingdom and the United States. It would be beneficial for other locations to follow suit. This would allow the general public to become aware and learn how women's race and ethnic backgrounds influence uptake in breast cancer diagnosis and treatment, and how socioeconomic, sociocultural, and education status can be driving factors.