Bowel cancer has four distinct types

Bowel cancer consists of four distinct diseases, each with its own set of biological characteristics, say researchers, including one of Indian-origin. The research could allow doctors to treat each type of bowel cancer differently - and drive the design of distinct sets of targeted drugs for each type.

"Our study has identified four distinct types of bowel cancer, each with a definite set of genetic and biological characteristics, and some of which are more aggressive and more likely to be fatal than others,” said study co-leader Anguraj Sadanandam, team leader in precision cancer medicine at The Institute of Cancer Research, London.

"This could allow doctors to pick out those patients with more aggressive disease and treat them accordingly,” Sadanandam pointed out. The study combined data from 3,443 patients with bowel cancer from all over the world to form the largest collection of molecular and clinical data on the disease ever assembled - including genetic mutations, gene activity, immune system activation, cell metabolism, cancer cell type and ability to invade neighbouring tissues, the researchers said.

They aimed to group bowel cancers using mathematical algorithms that combined all these parameters, in order to improve on various existing attempts to classify types of the disease based on smaller datasets. The scientists found that 87 per cent of bowel cancers could be robustly assigned to one of the four groups.

Tumours within the four 'consensus molecular subtypes', or CMSs, each had a pattern of irregularities that could leave them vulnerable to a treatment strategy. Patients with one particular type of bowel tumour - CMS4 - were often diagnosed late (stage III and IV), had high levels of spread to other sites in the body, and had significantly worse survival rates than the other types.

Patients with another type, CMS2, had much better survival rates even if the cancer had relapsed. "Ultimately, it could lead to development of new molecular diagnostic tests to diagnose patients by their particular type of bowel cancer, and give them the most effective treatments for that type,” Sadanandam said. (The study was published in the journal Nature Medicine.)