University of Otago discovery could pave way for bowel cancer vaccine

Kiwi scientists believe they have identified a toxic bug that causes bowel cancer - a discovery that could lead to the development of a life-saving vaccine or early detection test.

The University of Otago researchers found a toxic form of bacteria, called Bacteroides fragilis, existed in the gut of almost 80 per cent of people with a cancerous lesion, known to be a precursor to the disease.

Bacteroides fragilis is a common bug in our gut, and for the most part, helps with digestion and the general health of the colon.

However, in some people it produces a toxin that disrupts the cells lining the gut and starts the process of cancer in the bowel.

Research head and bowel cancer surgeon, Professor Frank Frizelle, described the finding as a "game-changer".

"It gives us a clue as to what is actually driving the cancer, and in doing so, it gives us a possible means of being able to manage it," he said.

More than 1300 New Zealanders die of bowel cancer every year.

The disease is becoming increasingly common in people under the age of 50, which could be due to changes in our diet, the researchers said.

Diet has a direct influence on our gut health, and the micro organisms living there.

To make their findings, the researchers undertook a world first study tracking the progress of 150 people, who had undergone a colonoscopy.

They genetically analysed the DNA from bowel samples taken during the colonoscopies to see if Bacteroides fragilis was present.

Between 12 and 15 years after their initial colonoscopy, 79 per cent of patients with the toxic Bacteroides fragilis in their gut had developed low grade dysplasia, which is a type of pre-cancer.

With further time and money, the discovery could be used to screen for people with the bug, and it could be used to develop a lifesaving vaccine, the research team said.

Frizelle said his team wanted to further study the bug in the hope it can identify people with the highest risk of developing bowel cancer.

"The earlier you can catch a disease, the better the prognosis," he said.

"As a surgeon you can treat one person at a time, if we can prevent the cancer from beginning or treating people as early as possible, that's the goal."