A simple and quick test could reduce the number of colon cancer deaths by more than 40 per cent, report British researchers in a landmark study.
The test is called a sigmoidoscopy. It's similar to a colonoscopy in which a thin flexible tube equipped with a tiny video camera is inserted into the colon to check for and remove polyps that can become cancerous.
The sigmoidoscopy differs from a colonoscopy in that the scope examines only the lower colon, where about two-thirds of colorectal cancers occur.
The test can be completed in five to 10 minutes and usually doesn't require sedatives.
Now, British researchers have completed the he first, large randomized trial of sigmoidoscopy to prove the test can save lives. It's been released online in advance of publication in The Lancet.
Experts say the results suggest that the screening might be an even more effective tool for spotting colon cancer than mammography is for spotting breast cancer.
"We don't often use the word ‘breakthrough,' but this is one of those rare occasions when I am going to use that word," Harpal Kumar, chief executive of Cancer Research UK, said in a news conference.
"It is extremely rare to see the results of a clinical trial which are quite as compelling as this one."
Lead researcher Dr. Wendy Atkin, a professor of surgery and cancer at Imperial College London, said the results showed that people would only need one test in a lifetime.
"The results from our trial show that flexible sigmoidoscopy is a safe and practical test and, when offered only once to people between ages 55 and 64 years, confers a substantial and long-lasting protection from colorectal cancer," she and her co-authors wrote.
For the study, Atkin and her researchers followed more than 170,000 people aged between 55 and 64 for about 11 years. Around 57,000 participants were randomly assigned in an intervention group in which they were offered sigmoidoscopy screening. Of those volunteers, 40,674 underwent the test.
During the follow-up, 1,818 volunteers who didn't undergo screening were diagnosed with colorectal cancer, compared to 706 in the intervention group. There were also 538 colorectal cancer deaths in the control group, but just 189 in the intervention group.
The researchers concluded that the screening test reduced peoples' chances of getting colon cancer by 33 per cent and cut their chances of dying by 43 per cent.
Cancer Research UK, which helped fund the study, called on the government to add sigmoidoscopy to the existing national bowel screening program. The Department of Health reacted by saying that an independent bowel cancer screening committee will discuss the proposal.
They noted though, that the fecal blood test would still be necessary, since it can spot cancers higher up in the colon.
Dr. David Ransohoff, of the departments of medicine and epidemiology at the University of North Carolina at Chapel Hill, North Carolina, wrote an accompanying commentary in the Lancet and said the study's findings might make doctors rethink whether sigmoidoscopy plus fecal blood test could be superior to a colonoscopy.
He said the finding the sigmoidoscopy needed to be performed only once in a person's lifetime was "striking" and said further follow-up was necessary to see how long the protective effect lasts.
Colorectal cancer is the second leading cause of death from cancer in Canadian men and women combined. In 2009, an estimated 22,000 Canadians will be diagnosed with the cancer and 9,100 will die of it.
In the U.K., government-funded colon cancer screening doesn't start until age 60, when men and women are tested every other year using the fecal blood test.
In Canada, men and women are urged to have the fecal blood test every two year starting from age 50.
