What’s your cancer risk – and what will you do about it?

The recently released Australian Cancer Plan has been designed to improve cancer outcomes across the country over the next 10 years. The Plan has six strategic objectives, the first of which is ‘maximising cancer prevention and early detection’.

As part of this objective, the Government has highlighted the importance of ‘evidence-based’ and ‘data-driven’ strategies that maximise early detection. This includes adopting targeted or personalised screening strategies using new technologies and the ‘assessment of genomic risk’.

Professor Jon Emery, Herman Professor of Primary Care Cancer Research at the University of Melbourne and the Victorian Comprehensive Cancer Centre Primary Care Research and Education Lead, is at the forefront of the focus on how best to evaluate genetic vulnerability to certain cancer types.

Professor Jon Emery.

In 2023, University of Melbourne researchers received $2.4 million from the Medical Research Future Fund (MRFF) to explore whether a new DNA test collected via a saliva swab at a GP clinic could be a cost-effective and efficient way to identify a person’s cancer risk.

The CASSOWARY (CAncer genomic riSk ScOres in primARY Care) trial is a multi-site study led by Professor Emery in partnership with Queen Mary University of London, Royal Melbourne Hospital, Royal Marsden NHS Foundation Trust and the Daffodil Centre using genomics-based tests developed by Genetic Technologies Limited.

The study will recruit almost 600 people from eight general practice sites across Victoria to assess the viability of using DNA testing to screen for risk for four common cancers — breast, colorectal, prostate and melanoma. During the four-year trial, participants will be followed up for one year to see what screening tests they do and then they will be followed up later to look at their long-term screening behaviour.

“The test looks at multiple common variants in your DNA that are associated with increased and lower risk of specific cancers. Using the sum of those multiple variants creates an individual risk score for each of the four cancers,” says Professor Emery.

“Existing screening guidelines recommend increased screening for those cancers at certain levels of risk that are mostly based on family history and age. The genomic test gives you a more precise risk estimate so a person can be given more effective screening recommendations. For example, if the genomic test suggests you are at increased risk of bowel cancer, we might recommend colonoscopy as your screening test rather than the faecal occult blood test. If you are at increased risk of breast cancer, we might bring forward the age at which you start having mammograms.”

While providing greater insights into appropriate screening for people identified as being at greater cancer risk, Professor Emery says the genomic saliva swab test can also reduce over-screening, too.

“We know there are people who are not at increased risk of bowel cancer having colonoscopies as a screening test. About 10 to 15 percent have colonoscopies when they don’t need them. This places them at potential harm and increases costs to the health system. The genomic test aims to tailor the right intensity of screening according to an individual’s level of risk,” he explains.

The accuracy of the saliva swab has already been established. Through the CASOWARY trial, Professor Emery is keen to see what measures individuals actually take when provided with information about their cancer risk and with a recommended screening program.

“If you give this information to individuals in general practice, does it lead to them performing the most risk-appropriate types of screening? What does the patient do when they have been given this information?” says Professor Emery.

“Currently, people are under-screened and over-screened and we want to get that balance right. If we offer this genomic information, we hope to get people who just need an FOB test to increase their uptake and we hope that those who don’t need colonoscopies will switch to the FOB test. We also expect the test will identify 5 to 10 percent of people who need colonoscopies who didn’t realise they needed this type of screening.”

Professor Emery says in the past decade countries around the world have recognised that standard population screening is inefficient and that precision screening delivers greater benefits by targeting people who are at higher risk of cancer. It also increases the cost effectiveness of screening programs and reduces overdiagnosis of slow-growing cancers that don’t cause harm.

“Once you know you have a cancer, it is difficult to then say ‘we are not going to treat it’. But there can be harm in the over-treatment of some slow-growing cancers that wouldn’t cause symptoms before a person dies anyway. Side effects of surgery or radiotherapy, quality of life impairments and the psychological harm of being told you have cancer are often not considered,” says Professor Emery.

“Precision screening aims to reduce over-diagnosis and over-treatment and provide a more targeted approach to identifying cancers that require treatment so people can benefit from that treatment. Many countries are switching to a more tailored approach to cancer screening and, in the future, we won’t all be offered the same screening tests based on our own personal risk of developing individual cancers.

“We are moving away from the one size fits all approach to cancer screening and this is a major step forward.”