Cancer is a genetic disease in the sense that all cancers arise as a result of some changes in the genetic makeup of a cell in the body. Usually, it takes multiple mutations over a lifetime to cause cancer and this is why cancer occurs more often in older people.
Not all cancers are inherited; only approximately 5-10 percent of cancers are attributable to a hereditary risk, even though cancer can sometimes appear to “run in the family” if the members share the same environmental risk factor, for example, tobacco usage.
Identifying those patients with cancer who have a truly inherited genetic risk has significant benefits both to the patient and to his relatives. With the current level of understanding of molecular targets in oncology, patients’ short- and long-term treatment can be personalized based on their genetic status. Knowing an individual’s risk for a hereditary cancer also helps in adopting specific screening and preventive measures including surgeries that can significantly reduce the risk of development of cancer and improve survival.
The most well-known among all hereditary cancers is the BRCA cancer-gene-associated breast-ovarian cancer syndrome. Some well-known personalities have undergone bilateral mastectomies and oophorectomies after being diagnosed as a carrier of the gene. These risk reduction interventions have been proven to reduce the risk of cancer in a carrier of this gene from as high as 85 percent to nearly 0 percent as a result of these interventions.
Family history is key to the identification of those individuals who have an inherited predisposition to cancer. The chances of hereditary cancer risk increase with the number of cancer cases among your first and second degree relatives, especially if there is a clustering of the same type of cancer.
It also increases if the cancer has been diagnosed at a younger age and if multiple cancers have been diagnosed in the same individual.
In addition, there are certain cancers for which genetic counselling and testing should be considered, even in absence of family history. The American Society of Clinical Oncology has long confirmed that the recognition and management of individuals with an inherited risk to cancer are core elements of oncology care and periodically releases policy updates on genetic and genomic testing for cancer risk.
More than 2,000 genetic tests analyzing genes, proteins and chromosomes are presently available for many different diseases, including breast, ovarian, colon, thyroid, and other cancers. It is essential that individuals undergo pre- and post–test counselling in order to help them understand the risks, benefits and limitations pertaining to these tests in their particular situation.
The current key issues with genetic risk assessment pertain to access to cancer genetic services, quality assurance in genetic testing, interpretation of the results of comprehensive panel testing and education of oncology professionals leading to appropriate and timely referral for testing.
Dr. Vineetha Binoy, resident oncologist, heads the new Department of Medical Oncology at Health City Cayman Islands. She is one of the speakers at this week’s Conquering Cancer event.