LOS ANGELES (AFP) - Colon cancer among people under 50 is on the rise, and tumours are often diagnosed at an advanced stage, according to research presented Tuesday (May 24).
The findings were based on a US study of more than a million people over the course of 10 years. They were presented during Digestive Disease Week, a medical conference in San Diego, California.
"While the healthcare system has done a great deal to address colorectal cancer in people over 50 - heightening patient awareness and increasing screenings - our findings show that much more needs to be done to fight this cancer in people under 50, a group not normally considered at risk," said lead author Elie Sutton, a research fellow at Mt. Sinai West Hospital in New York.
"Not only did we find that the rate of colorectal cancer in this group is rising, we also saw that within the group that was diagnosed at a younger age, a higher percentage were diagnosed at later stages of cancer (stage three or four), which is very concerning," she added.
Over the decade of research, the number of colon cancer cases in under-50s rose by 11.4 per cent, about 136 new cases every year.
This rise among young people comes even as overall colon cancer rates have been declining in recent years.
The study found colon cancer rates in those older than 50 fell by 2.5 per cent in the same time period.
Despite the rise among the young, doctors pointed out that the overwhelming majority of colon cancer cases still occur in people over 50.
Colon cancer often begins as a polyp, or a growth, inside the colon or rectum.
The main tool for prevention is a colonoscopy, which allows doctors to find and remove these polyps.
But often, symptoms only appear after the cancer has begun to grow, and these signs - such as rectal bleeding, constipation or diarrhoea that lasts more than a few days - can be mistaken for other ailments.
Colorectal cancer is the third most common cancer in the United States, with more than 132,000 new cases in 2015.
It was also the second-leading cause of cancer death, after lung cancer.
Sutton's study found that by the time of diagnosis, younger cancer patients tended to have more advanced cancers than older patients.
Nearly 31 per cent of younger patients were diagnosed at stage three, compared to 25.1 per cent of older patients.
One-quarter of patients under 50 were diagnosed at stage four, compared to 18.2 per cent of older patients.
Colon cancer in younger patients also occurred more frequently among non-white patients than in Caucasians.
The US National Cancer Database provided the data from 2004 to 2013, and it echoes a trend found in a previous study about five years ago.
"Between the time of the previous research and our study, we still have not adequately addressed the risk of colorectal cancer in people under the age of 50," Sutton said.
"It's critical that we reverse this trend so that we are able to reduce, and hopefully eliminate it in all populations, regardless of age."