Link between age and different subtypes of bowel cancer
A study by QIMR Berghofer Medical Research Institute has for the first time identified that bowel cancer has five distinct subtypes that are closely related to a patient’s age.
Senior author from QIMR Berghofer’s Conjoint Gastroenterology Laboratory, Associate Professor Vicki Whitehall, said the new way of classifying bowel cancers may have implications for the kinds of treatments patients are offered.
About 17,000 people are diagnosed with bowel cancer annually in Australia and more than 4,000 die from the disease each year, according to the Australian Institute of Health and Welfare.
Associate Professor Whitehall said the study found bowel cancer could be classified according to methylation of the genes – or simply put, how the genes turned on or off.
“Our study found those changes in methylation of bowel cancers closely track with a patient’s age. This may indicate that bowel cancers occurring in younger and older patients may have different underlying causes,” Associate Professor Whitehall said.
“DNA methylation is a way a cell can turn its own genes on or off, but in cancer this process gets hijacked and it turns on genes that favour growth and turns off genes that are meant to suppress it.
“This study suggests we should now focus on how methylation – the switching on or off of genes – causes these five different subtypes of bowel cancer and look for treatments that reduce DNA methylation to reduce the cancer risk.”
Lead researcher Lochlan Fennell said bowel cancer was generally a disease that struck later in life.
“Previous studies have linked DNA methylation to ageing and bowel cancer but ours is the first study to identify five different subtypes of bowel cancer based on this process,” Mr Fennell said.
“We were interested in finding out which genes were being switched on and off in tumours and that’s how we found the different subgroups.
“Our study indicates that the different genetic changes that cause cancer happen at different ages and that might have implications for different treatments, because we know some types respond better to immunotherapy and other targeted therapies while other types are resistant to these therapies.”
The three-year study involved samples from 216 patients at the Royal Brisbane and Women’s Hospital.
The findings have been published in the journal Cellular and Molecular Gastroenterology and Hepatology.
The study was funded by the National Health and Medical Research Council, Pathology Queensland and the US National Institute of Health.
See also the Australian Government National Bowel Cancer Screening Program at http://www.cancerscreening.gov.au/internet/screening/publishing.nsf/Content/bowel-screening-1
28 April 2019.