Health experts are calling for younger Australians to be screened for bowel cancer after two new global studies reveal the disease is increasing in people under 50.

Bowel Cancer Australia says dropping the age of bowel cancer screening from 50 to 45 will help put a dent in the country's second deadliest cancer.

"Given the increasing rates of bowel cancer among younger Australians, we may need to review screening guidelines and consider lowering the starting age from 50 to 45 as the American Cancer Society now recommends," Julien Wiggins, Bowel Cancer Australia CEO said.

A study published in the medical journal Lancet found the number of people aged under 50 diagnosed with colon cancer increased significantly each year by 2.9 per cent in Australia and New Zealand, by 3.1 per cent in Denmark and by 1.8 per cent in the UK.

People aged 45 to 49 make up about 40 per cent of cases diagnosed under 50 which translates to hundreds of Australians each year. (Nine)

Mr Wiggins says nearly 1 in 10 bowel cancers are detected in people under the age of 50 and the rise is linked to diet and lifestyle.

"Certainly the research identified that obesity, type two diabetes, for example, were risk factors, high meat consumption particularly red meat, smoking, alcohol consumption," he said.

Mr Wiggins said people aged 45 to 49 make up about 40 per cent of cases diagnosed under 50 which translates to hundreds of Australians each year.

Darren Kwan, 34, is receiving gruelling treatment for his bowel cancer after being diagnosed two years ago.

He says extended screening and more awareness of the disease among younger Australians will help make a difference.

Cancer in the bowel can spread to other parts of the body if it's not detected and treated. (AP)

"If I could've nailed this early, I wouldn't have to go through all this sort of stuff," he said.

Mr Kwan has had major surgery and 18 rounds of chemotherapy after the cancer spread to his liver and lungs.

"A lower start-age for bowel cancer screening could be part of the solution, together with ways to reduce risk through diet and lifestyle changes, as well as improved symptom awareness among both patients and GPs," Graham Newstead, Colorectal Surgeon and Bowel Cancer Australia director said.