The facts about genetic testing
Cancer, and the gruelling treatment that comes with it, is hard enough for a patient to handle, yet many find themselves feeling guilty or scared their disease could be passed on to their children or grandchildren through their genes. Many patients will also often receive genetic testing to help determine the best treatment for their specific cancer.
With more than 44,000 Australians dying from cancer each year, genetic testing is one way thousands of Aussies are putting their minds at ease and preparing family members with preventative measures before a mutated gene turns deadly.
Icon doctor and medical director Dr Ian Irving says many cancer patients fear for their family members – even when they themselves are in care to treat their own cancer diagnosis.
“On top of everything a cancer patient goes through, many of them also wonder whether their cancer is hereditary. The fear that their children and grandchildren might be at risk is a constant concern. Giving them that access to genetic testing is an important part of their care and wellbeing. And having that conversation with them can provide reassurance to them and their families.”
– Dr Ian Irving
Genetic Oncologist Dr Hilda High from Sydney Cancer Genetics explains that genetic testing doesn’t detect cancer, but rather a mistake or mutation in a cancer-protection gene that has been there since birth.
“Genetic testing allows people to take precautions for themselves, their children and their grandchildren.” she explains. “We’re looking for a mutation in a gene that came across in the egg or in the sperm, and so is present in every cell in that person’s body.”
Testing doesn’t require oncologists to use invasive measures to pluck genes from the body, but rather assesses the DNA inside white cells found in the blood collected via a standard blood test.
While genetic testing has been available for many years, it hit headlines in 2013 when actress Angelina Jolie had both her breasts and her fallopian tubes and ovaries surgically removed after discovering she carried a BRCA1 gene mutation (a mutation is a spelling error in the DNA code of the gene).
Everyone, male and female, carries the BRCA genes. They protect women from breast and ovarian cancer and men from breast and prostate cancer. When damaged, the risk of these cancers goes up very significantly.
Some women decide to remove their breast tissue (a mastectomy) while others start annual breast screening including a breast MRI at age 30. As there is no effective screening for ovarian cancer, the ovaries and fallopian tubes should be removed at age 35 (BRCA1) or 45 (BRCA2) to reduce or eliminate the chances of cancer developing.
“Angelina is effectively saying that one of her BRCA1 cancer protection genes isn’t working properly,” Dr High says.
“We have two copies of our genes. One from our mum and one from our dad and so Angelina has a backup copy. That backup copy is still working fine and can make the ‘spellchecker’ that fixes the mistakes that build up in the DNA of our cells over time. If the backup copy gets damaged, that’s when the risk of cancer goes up a lot.”
Icon patient Rebecca Jeavons was diagnosed with an aggressive, triple negative breast cancer at the end of last year. Rebecca took the advice of her doctors and was tested for the BRCA 1 and BRCA 2 gene to provide reassurance and to effectively determine what would be the best treatment for her cancer.
“When I was told I had cancer, it felt like the earth had swallowed me up and I sat and cried for a long time. Then you go through the appointments and the scans and doctors explaining the treatment to you, which was pretty full on,” Rebecca said.
“My doctor then suggested I get genetically tested for the breast cancer gene because it looked aggressive. It dawned on me that I needed to know if I had the gene mutation as soon as possible. If I did, it would mean a double mastectomy, followed by the removal of my fallopian tubes and ovaries. The thought of losing both my breasts and undergoing a lot more surgery was daunting. So getting tested was necessary and would determine whether I needed to proceed with this. The test itself was simple, and results came back within a few weeks. Thankfully for me, they came back negative and I breathed a sigh of relief for myself and my children. With peace of mind, I was then able to continue with chemotherapy then a lumpectomy, followed by radiation therapy.”
Dr High explains that it’s relatively easy for health professionals to detect gene mutations and that while testing itself doesn’t save lives, the information it provides does.
“When you detect, for example, a BRCA mutation in a woman, her risk of breast cancer over her lifetime is 40 to 80 per cent and her lifetime risk of ovarian cancer is 20 to 60 per cent.
“If that woman has her ovaries and fallopian tubes removed and her breast tissue removed in a mastectomy, her lifetime risk drops to less than a 2 per cent. This compares to the average Australian woman who has between a 10 and 15 per cent lifetime chance of having breast cancer,” she says.
Most forms of cancer, including prostate, bowel and kidney, have particular genes that, when not working, are known to increase cancer risk. Dr High said that family history of cancer (as a guide: three relatives, two generations, one under 50) is usually the starting point for most people to consider testing.
“Not all families talk about cancer and doing so can be very important,” she says. “The risk is related to the age at which the cancer is diagnosed or the type – not the age that the person is now. Sometimes the person with the high-risk cancer has passed away, and then testing other family members can still be important.”
Dr Irving adds that testing and treatment can stir up an array of emotions in patients and it’s important for them to be aware and in control of their care.
“To improve outcomes, we need to bring cancer care closer to home, this is something Icon is actively committed to delivering. But we also strongly believe in arming patients with the knowledge they need in order to provide the best possible care. It’s more than supporting them through their treatment, it’s about answering questions they might have outside of our immediate care with them. Whether it’s finding help and providing advice about genetic testing, to knowing when to seek help emotionally or physically, delivering a holistic approach to care for each individual patient’s needs is our duty of care.”
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