Genetic tests allow us to find genetic predisposition to cancer and it was found that 5-10% of all cancer are caused by genetic mutations . It helps to identify those people who are at increased risk of developing cancer due to family inheritance. The defective genes can be inherited from either one of parent.
One of the most important genes that attribute to cancer is TP53 gene which is responsible for most of the mutated genes in all cancer. It produces a protein called p53 which acts as a tumour suppressor. It regulates cell division and prevents the cells from growing in an uncontrolled manner. If there is DNA damage, p53 will instruct other genes to fix the damage. If the DNA cannot be repaired, p53 will prevent the cells from dividing and let the cells to undergo apoptosis. Hence, the damaged cells can be prevented from dividing and reduce the risk of cancer development . The mutation of TP53 genes can cause the p53 not to function efficiently which can lead to DNA damage and damaged cells proliferation.
In breast cancer, BRCA1 and BRCA2 are two well-known genes that contribute to approximately 3-5% of breast cancers and 12-15% of ovarian cancer . In a previous study, it was suggested that genetic test should be performed among breast cancer patients either newly diagnosed or high risk due to family history. The test should include at least BRCA1, BRCA2 and PALB2 genes, with other related genes . On top of providing benefits to family members, it can also help the healthcare providers to provide risk reduction strategies and reduce the complications.
National Cancer Institute has provided a guideline on who should consider genetic testing for cancer risk. If you have a family history with cancer, you may consider doing the genetic tests because it is common for the cancer predisposition genes to run in the family members . In addition to that, it is suggested to do the genetic test if the medical history of a person or family may suggest a hereditary cancer syndrome include:
- Cancer was diagnosed at an unusually young age
- Several different types of cancer occurred in the same person
- Cancer in both organs in a set of paired organs, such as both kidneys or both breasts
- Several first-degree relatives (the parents, siblings, or children of an individual) have the same type of cancer (for example, a mother, daughter, and sisters with breast cancer); family members with breast or ovarian cancer; family members with colon cancer and endometrial cancer
- Unusual cases of a specific cancer type (for example, breast cancer in a man)
- The presence of birth defects that are known to be associated with inherited cancer syndromes, such as certain noncancerous (benign) skin growths and skeletal abnormalities associated with neurofibromatosis type 1.
- Being a member of a racial or ethnic group that is known to have an increased risk of having a certain inherited cancer susceptibility syndrome and having one or more of the above features as well
- Several family members with cancer
(Retrieved from National Cancer Institute)
However, not all people with family history with cancers will definitely develop cancer as there are many factors that can contribute to cancer such as lifestyle and environment factors including smoking, physical inactivity and eating unhealthy foods. If you are having a high risk of developing cancer, you are encouraged to consult your healthcare providers on cancer prevention.
- P. Anand et al., “Cancer is a Preventable Disease that Requires Major Lifestyle Changes,” doi: 10.1007/s11095-008-9661-9.
- “TP53 gene – Genetics Home Reference – NIH.” https://ghr.nlm.nih.gov/gene/TP53#conditions (accessed Sep. 07, 2020).
- Z. Kemp et al., “Evaluation of Cancer-Based Criteria for Use in Mainstream BRCA1 and BRCA2 Genetic Testing in Patients With Breast Cancer,” doi: 10.1001/jamanetworkopen.2019.4428.
- E. R. Manahan et al., “Consensus Guidelines on Genetic` Testing for Hereditary Breast Cancer from the American Society of Breast Surgeons,” Ann. Surg. Oncol., vol. 26, doi: 10.1245/s10434-019-07549-8.
- “Genetic Testing Fact Sheet – National Cancer Institute.” https://www.cancer.gov/about-cancer/causes-prevention/genetics/genetic-testing-fact-sheet#who-should-consider-genetic-testing-for-cancer-risk (accessed Sep. 14, 2020).