Australia’s bowel cancer rates are world’s highest for under-50s. Scientists wonder if the gut microbiome is to blame

Rising rates of obesity, diabetes and increasingly sedentary lifestyles have been hypothesised to be contributing to the increase in early-onset bowel cancer. Photograph: Teodor Lazarev/Alamy

Australia’s rates of bowel cancer in people under 50 are the highest in the world, though the reason why remains unclear, experts say.

As incidences of what’s known as early-onset bowel cancer are increasing worldwide, a study of 50 countries – published recently in Lancet Oncology – revealed Australia was ranked worst.