Study is the first of its kind in Pakistan
Individuals who require testing for hereditary breast cancer should receive multi-gene testing, not just testing for pathogenic variants in the BRCA1 and BRCA2 genes, according to an AKU study that is the first of its kind in Pakistan. The study validated guidelines that recommend genetic testing for all individuals below the age of 50 who are diagnosed with breast cancer.
Hereditary breast cancer is mainly caused by pathogenic variants (that is, variants that cause disease) in genes inherited from one’s parents. In other cases, it may be present as a de novo variant (that is, only present in the patient as a new event). It accounts for 5-10 percent of cases but is understudied in lower-income countries. Knowing that an individual’s breast cancer is hereditary can help doctors to optimize patient management and help family members to understand their risk of cancer, enabling them to take better care of their health.
The study examined data on 284 individuals who had genetic testing done through the hereditary breast cancer clinic at the Aga Khan University Hospital over a three-year period. (The actual testing was outsourced to laboratories in the United States.) In total, 273 of the 284 patients had breast cancer, including four men. Researchers found that 45 percent of patients who tested positive for hereditary breast cancer had a pathogenic variant in a gene other than the BRCA1 and BRCA2 genes. If multi-gene testing had not been done, the fact that these patients had hereditary breast cancer would not have been detected, limiting doctors’ ability to treat them. Thus, multi-gene testing for those who require testing for hereditary breast cancer is advisable.
In total, 22 percent of those tested were found to have hereditary breast cancer, a result that is toward the higher end of the range of results reported in other countries. The median age of those who tested positive was 37.5 years. Twenty-five percent of patients who tested positive had no family history of breast or related cancers. Of the 44 patients below the age of 45 who tested positive for hereditary breast cancer, 11 had no family history of breast or related cancers.
The National Comprehensive Cancer Network 2023 guidelines recommend genetic testing for anyone under the age of 50 who develops breast cancer, regardless of whether they have a family history of cancer. The study’s authors note that some clinicians only refer breast cancer patients for genetic testing if they have a family history of cancer. Doing so can lead to hereditary breast cancer going undetected. The study, by Senior Instructor Fizza Akbar, Associate Professor Abida Sattar and Associate Professor and Chair of the Division of Women and Child Health Salman Kirmani, et al., was published in Hereditary Cancer in Clinical Practice.