Genetic testing is being used more frequently to screen people for the hereditary risk of cancer, according to MedCity News. While advancements have been made and research is ongoing, there are still problems that exist within this form of testing. The main issue is ambiguity. While doctors are able to screen patients who live with a high risk of cancer, it cannot always tell them the danger that their genes present.
The Issue With Genetic Testing
Since 2012, medical professionals have been improving multiple-gene panel testing to better screen for the risk of cancer. Current tests can screen for over 80 genes. This is a benefit to patients as they only have to undergo one test rather than multiple. It can save time, money, and stress.
While these new tests offer benefits, they also come at a price. Tests that scan for more than two genes are ten times more likely to report an inconclusive result than one that solely examines two genes. For example, screening for only the BRCA1 and BRCA2 genes – two genes that are heavily associated with breast cancer – is much more likely to give a definite result than screening for 80 genes.
The problem with an inconclusive result is that both doctors and patients are unable to assess the danger that the gene possesses. They cannot tell if it is harmless or linked to cancer. This type of result is defined as a variant of uncertain significance, or VUS. A study demonstrated that 20% to 40% of patients were told they have a VUS after undergoing a multiple-gene panel test.
Genetic Testing and Patients
Receiving inconclusive results and being told of a VUS can be a scary experience for many patients. For some, when they’re told about the possibility of inconclusive results, they decided to scale back the degree of their testing. Doctors should explain the process thoroughly to patients, and if they do decide to run a multiple-gene panel test, both parties should be prepared to handle a VUS.
Doctors should also be aware that racial minorities have a much higher chance of a VUS within their results, as the majority of genes are first sequenced from white people. A study showed that one-third of non-white patients saw a VUS included in their test results, which can be compared to the one-fourth of white people who saw the same.
Many patients may be asking, “what happens if my results show that I have a VUS?” The answer is nothing. Experts in genetics have decided that no medical decision should be made based off of a VUS, as more often than not, it is benign.
Unfortunately, this advice is not always followed. Evidence that was recently presented at the 2020 American Society of Clinical Oncology annual meeting showed that physicians may be recommending surgery based on the presence of a VUS, which is not the correct protocol to follow. The study went on to say that females are more likely to receive surgery after the discovery a VUS, demonstrating even further that many doctors are unable to properly read the tests.
As other doctors have issues with suggesting, administering, and reading the tests, it is best to see a geneticist or a genetic counselor if you want a test done.