Genetic Testing - Why Should I Consider It?

23 Aug 2021

Learning you may carry a genetic mutation that places you at an increased risk of developing cancer can be a confronting and confusing time. Pink Hope reached out to Dr Hilda High from the Sydney Cancer Genetics clinic to help you understand why you should consider genetic testing and the process involved.

Who should consider genetic testing?
Dr High says testing is usually offered to someone if there is a 10% or higher chance of them being a carrier, especially if that person has had cancer, or if a germline mutation has already been detected in a blood relative. The likelihood is determined using calculators (quantitative algorithms) and guidelines such as the Australian national eviQ guidelines.

As a rough guide, a family that presents with three individuals diagnosed with same cancer, covering two generations, where one of those family members was diagnosed before the age of 50, would indicate a likelihood of being a carrier.

Dr High would also suggest that anyone with triple negative breast cancer, a personal or family history of ovarian cancer, or breast cancer who was diagnosed before the age of 40 seek genetic assessment +/- testing. With the increase of targeted treatments, testing may alter your treatment options so anyone with cancer should discuss their personal and family history with their doctor.

More specific referral guidelines can be found on the Sydney Cancer Genetics website and on the eviQ website.

What can genetic testing tell you?
Testing will tell you if there is a mistake in the gene or genes, that are tested.  What testing cannot tell you is if you will, or won’t, get cancer, a likely age of diagnosis, or the type of cancer you may develop. But, if a genetic mistake, such as a mutation or more scientifically a variant, is identified that increases cancer risk, you have the knowledge and power to take steps to reduce that risk.

Why do I need to have counselling before testing?
Dr High explains that counselling is a requirement to ensure that you can consider the implications of the test, whether a mutation is detected or not, for you and for your family.

These considerations include.

    • New or additional cancer risks (e.g. ovarian cancer risk) and what you can do about that risk.
    • The limitation of the test in regard to sensitivity, specificity and future research.
    • Understanding that “no mutation” does not equal “no risk” or even a “low risk” of cancer – your family history is still your family history!
    • The impact of testing on income or disability insurance for yourself and other family members.
    • Devising a plan for how you will tell relatives if they are also at risk.
    • Understanding how your DNA will be stored and whether the lab will use your DNA for research or even sell your DNA or data, which is a common issue with American laboratories.

How is the testing done?
Genetic testing requires DNA, which is located inside the nucleus of a cell, any cell with a nucleus can be tested. The easiest way for clinicians to gather cells for a germline test, looking for inherited mutations, is through a blood test but saliva or a buccal swab, which uses the cheek cells, work as well.  A cancer tumour can also be tested, but this is usually carried out when doctors are looking for mutations that occurred as the cancer developed and is called somatic testing. The results of somatic testing can guide a patient’s treatment options.

If testing is positive what will the next steps be and why would these be important?
Guidelines exist for hereditary cancer syndromes which include the management of risk through regular screening protocols, risk reducing surgery options and sometimes through the prescription of medications to reduce risk. These guidelines outline when regular screening should commence, what screenings should be done, how often screening should take place, and includes information on whether screening will be Medicare funded.

How might results affect my family?
A person who has tested positive to carrying a familial mutation, male or female, has a 50% chance of passing the mutation onto their children, both sons and daughters.  Dr High explains that testing will be offered to your parents, siblings, and offspring, as well as more distant blood relatives such as cousins.

If a blood relative is found to also carry the familial mutation, they can then take steps to reduce their risk. If testing reveals they don’t carry the mutation, they generally return to being considered at average risk of developing cancer and can follow population-based screening advice.

Knowing that you are a familial mutation carrier, also provides you with access to techniques such as preimplantation genetic diagnosis (PGD), through the setting of in vitro fertilisation (IVF). PGD allows those wishing to start a family the opportunity to prevent the familial mutation from being passed on to future offspring.

Who pays for genetic testing?
Dr High advises that if you meet the Medicare criteria, testing carried out through either a private clinic or at a public familial cancer clinic, may be covered by Medicare. If you meet the guidelines of 10% (using a “qualitative algorithm”) and have had breast or ovarian cancer, or if it’s a predictive test, the testing should be bulk billed, regardless of where you are seen.  It is important to note, however, that testing can not be ordered by a GP or a genetic counselor.

The eviQ guidelines criteria for risk assessment and consideration of testing are more generous and these guidelines only apply to patients seen at a public familial clinic.

Testing for patients that don't meet either of the guidelines, maybe self-funded with a cost from $200 to $800, dependent on how many genes are tested.

Can the test results lead to discrimination by an employer or insurance company?
Laws exist to protect individuals from all types of discrimination. In general, cancer or health diagnosis does tend to have a greater impact on eligibility for some insurances. For example, Dr High notes that if you have had breast cancer it may be difficult to obtain some types of insurance and if you have ever had depression or anxiety, it is not usually possible to get income protection insurance.

But Dr High stressed that meeting with a genetic oncologist to discuss the implications of your own, or family history, and genetic testing options does not affect insurance.

If you have specific concerns about insurance discrimination, you can find more information here.

This article was sponsored by Astra Zeneca and developed independently by the team at Pink Hope in consultation with medical experts.