All about genetic testing for cancer

Genes play an essential role in determining your health. It is like a manual that tells your body how to function, develop and stay healthy. According to a report by the Organisation of Rare Diseases in India (ORDI), approximately 1 in 20 Indians are affected by a rare disorder. Many health conditions have genetic links which include rare diseases like inherited cancers, auto-immune deficiencies, and lysosomal storage disorders among others.

A genetic test thus can help you in understanding if you are at an increased risk for developing certain conditions that are present in your family and will allow you to take preventive measures in time.

While undergoing a genetic test people often have several questions in mind which include -

What is a genetic test?

A genetic test is a type of test that identifies the modifications in your chromosomes, genes or proteins. Dr. N Aditya Murali, Consultant - Medical & Haemato Oncology, Aster CMI Hospital, says, "Currently, there are more than 1,000 genetic tests that are available right now and are being developed. These tests are performed using a sample of blood, hair, skin, amniotic fluid (the fluid that surrounds a fetus during pregnancy), or other tissue. The clinicians may also perform a procedure called buccal smear that uses a small brush or cotton swab to collect a sample of cells from the inside surface of the cheek which is then sent to a laboratory where the technicians analyze any specific changes in chromosomes, DNA, or proteins, depending on the suspected disorder. The results can confirm or rule out if a person has a genetic condition or has a chance of developing or passing on a genetic disorder."

What information can a genetic test provide?

A genetic test can provide the following details -

• Provides clarity on the results, suggests therapy selection and monitoring and allows disease risk profiling

• Analyzes family health history and tells you which diseases run in your family

• Identifies risks associated with shared genes

• Shares insights on the lifestyle choices and the environmental factors that may affect you and your family and suggests changes to reduce your risk of developing a disease

How can one prepare themselves for genetic testing?

Even if a patient or their family members have been advised by a doctor to undergo genetic testing or if they have taken the decision by themselves, there are still several doubts that persist in one's mind while going for genetic testing. The test results are not always straightforward and patients may not be able to differentiate between a positive and a negative test.

A positive test result indicates that the laboratory has found a change in a specific gene, chromosome or protein. Based on the purpose of the test, this result may suggest a diagnosis and may indicate if a person is a carrier of a particular genetic mutation and identifies their risk of developing a disease like cancer in future. The positive result may also suggest further testing because your family members share the same genes; hence, they may have some implications in case you are diagnosed with a genetic disorder. It is important to note that a positive test result is only a predictive or pre-symptomatic genetic test and cannot determine the exact risk of developing a disorder. Healthcare professionals too cannot use a positive test result to predict the course or severity of a condition.

A negative test result on the other hand means that there were no changes in the genes, chromosomes, or protein and the person may not be affected by a disorder, is not a carrier of a specific genetic mutation and does not have an increased risk of a certain disease. In some cases, the test may miss a condition causing the genetic alteration because many tests cannot detect all genetic changes that can cause a particular disorder, therefore further testing is recommended to confirm a negative result.

Interpreting the results of genetic testing can be difficult and genetic counsellors can help you understand the exact impact of the disease on your body and can explain what the results of the genetic tests mean for you and your family. They are also trained in both medical genetics and counselling and they work closely with your doctor to provide you with both clinical and emotional advice. These counsellors will also guide you if you are having second thoughts while undergoing the test and will determine if you are a good fit or not for the test.

Can genetic testing provide overall well-being?

Genetic testing is not only limited to providing a preventive and proactive perspective but also provides personalized medicine and targeted gene therapy that can yield excellent results for the patients. If you are a cancer patient, then these tests can help your healthcare team in making more informed decisions on the treatments and surgical procedures that will benefit you.

For instance, certain cancers that are associated with genetic mutations respond better to some types of chemotherapy treatments. Genetic testing can also help you choose between a lumpectomy or a mastectomy when you are making surgical decisions about breast cancer. The results encourage early screening and allow you and your loved ones to make healthy decisions.