Systematic review of family studies of heritable breast cancer in Africa.

Abstract

e22508 Background: The incidence of breast cancer (BC) in Africa (40.4 per 100,000) is 49% that of Europe and North America (81.9 per 100,000) but the mortality rate is 42% higher (19.4 versus 13.7 per 100,000). The high mortality is due to lack of screening. However, more targeted screening based on genomic risks are also missed because of stigmatization, poor family history, and limited information on BC susceptibility gene mutations. Internationally based family members are influencing cultural attitudes to BC in Africa leading to reduced stigmatization, increased better family history and uptake of genomic screening. Family-based studies of BC in Africa would provide useful information on prevalence of mutations that can inform genomic screening panels. We conducted systemic review of all family-based studies of BC in Africa to document state of the art, identify barriers and facilitators of this research method and methods of advancing the science. Methods: Using a comprehensive research strategy, we reviewed articles indexed in PubMed and African Journals Online (AJOL) to identify studies of familial BC in Africa. Specifically, we searched for family-based, study design papers on BC in each country in Africa using the following keywords: breast cancer, family-studies, hereditary, genetic, gene, mutations, and Africa. We excluded case-control, and registry studies, and clinical trials. We extracted relevant information from each study using standardized criteria: number of first- and second-degree relatives affected by BC, mutations, genetic variations, and polymorphisms. Results: A total of 12 out of 727 studies met our inclusion criteria. 80% of these studies were published after the year 2010. There were 9 publications from North Africa evaluating 191 families in total. One study reported novel breast cancer candidate genes: MMS19, DNAH3, POLK and KATB6 and nine publications investigated the mutation spectrum of BRCA genes. One publication from West Africa and one publication from Southern Africa included 1 and 219 families, respectively. All the studies done in these two regions reported targeted genomic screening for only BRCA genes. No study was done in Central and East Africa. Conclusions: There is paucity of family-based studies of breast cancer in Africa. Given the high level of heterogeneity in African genomes, these types of studies may be needed to identify high penetrance, germline mutations to better understand hereditary BC risk and ultimately develop a multigene panel testing to for diagnosis of heritable BC in this population.