Cases rising, but genomic testing offers hope
Nathan Borg was still dazed from anesthesia when his doctor told him he had bowel cancer.
The 29-year-old young man was three months away from his wedding date. His fiancée, Samantha, sat next to him, crying.
“I had just bought a house, had a mortgage, and was getting married,” Borg said. He assumed that a colonoscopy would confirm that the blood in his stool was from hemorrhoids.
“I never thought for a second that it was cancer.”
An increasing number of young Australians are being diagnosed with bowel cancer for reasons that are not well understood. The incidence in people in their 30s has increased by 137 percent since 2000.
But as one global leader in precision oncology notes, a subset of patients – about one in six – appear to have tumors with a genomic quirk that makes them “extremely sensitive” to immunotherapies.
Analysis of a group of cancer patients whose tumors were thought to be incurable or advanced found that a third of bowel cancer patients were under 50 years of age.
Analysis of Omico’s database found that almost 14 percent of bowel cancer patients were under 40 years of age. This is an initiative that facilitates genomic profiling for cancer patients with a poor prognosis and pairs them with next-generation treatments or clinical trials.
Two percent were under 30 years old (about 60 people). Fourteen patients were diagnosed with bowel cancer before they turned 25 years old.
“Being diagnosed at such a young age is absolutely devastating,” said David Thomas, Omico founder and chief scientist.
Bowel cancer is still very rare in young Australians (for example, the number of cases in 30 to 39-year-olds increased from 184 in 2000 to an estimated 772 in 2025) and survival rates are improving.
The vast majority of people with bowel cancer, also called colorectal cancer, are still diagnosed over the age of 50 (at this age Australians automatically receive a bowel cancer screening kit, but can also be requested from age 45).
But Thomas said cancer can no longer be considered a thing for older people.
“We need to understand why the cases of early-onset colorectal cancer are increasing. Is it environmental or microplastic? Diet? It’s not genetic alone, but there may be a genetic component,” he said.
Up to 15 percent of colorectal cancers have a genomic signature called microsatellite instability (MSI), which occurs when DNA mismatch repair proteins fail to correct errors in short stretches of DNA, Thomas said. Most occur spontaneously rather than being inherited.
“These tumors are extremely sensitive to immunotherapies,” Thomas said.
Borg’s cancer was one of them. He didn’t know then that he was embarking on a deeply confronting series of radiation and chemotherapy to shrink his six-centimeter-long tumor and surgery to remove a 30-centimeter section of his intestine, living with a stoma for six months.
“I lost my hair twice and had all the other fun symptoms of chemotherapy,” she said wryly.
Borg had just bought a house, had a mortgage to pay, and was about to get married. As a project manager for a commercial outfitting company, he couldn’t afford to take time off from work.
But when spots of cancer were found on his liver, his oncologist found the key to his survival.
Accordingly, Dr. Siobhan O’Neill was sitting in a session at the Australian Gastro-Intestinal Tumors conference when she opened Borg’s Omico test results. He was “MSI high”.
“I jumped in my seat. I thought, ‘Oh my God, this is great news. He can have immunotherapy,'” O’Neill said.
MSI testing is a routine part of the pathology process for newly diagnosed bowel cancer.
Borg’s specific gene mutation meant that it was not possible to detect the MSI signature of his tumor without genomic testing.
Further genomic testing revealed that Borg had Lynch syndrome, an inherited genetic disease that accounts for about 3 percent of colorectal cancers with MSI.
Borg had no trouble tolerating the PBS-funded immunotherapy drug pembrolizumab during its two-year course. He has been cancer-free since January.
“This was a game changer,” Borg said. He and Samantha are expecting their first child in August.
“I always knew I would win in the end,” he said.
Fast facts: Bowel cancer patients in Omico’s cohort
- Bowel cancer accounted for 11.5 percent of the 3,024 people referred for comprehensive genomic profiling and treatment matching.
- 34 percent of bowel cancer participants in Omico’s programs are under the age of 50; For all other cancers, this rate is 23.5 percent.
- Almost 80 per cent of bowel cancer patients received a matching treatment recommendation
- One in five people have enrolled in a clinical trial or accessed a treatment to which they were matched after genomic profiling
Cancer Australia chief executive Professor Dorothy Keefe said lowering the bowel cancer screening age would cost enormous amounts of money that could be better spent, harm people without cancer and delay cancer diagnosis by filling up waiting lists for colonoscopy.
Keefe urged young people to contact their GP if they notice blood in their stool, a change in bowel habits or any changes to their health that do not resolve, including pain, vomiting, unexplained weight loss, fatigue or low haemoglobin.
Cancer Australia has commissioned an evidence review into risk factors for early-onset cancer, while updated evidence-based guidelines reflect how young people get cancer and what research and referrals need to be made.
“As a medical profession, we need to reexamine our thinking on this issue as signs of cancer become more common in young people,” Keefe said.
Cancer Australia and the National Health and Medical Research Council announced on Monday $15 million to help fund seven research projects About early-onset cancer risk factors, tests and treatments. Three projects will focus on colorectal cancer.
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