Colon exam could 'massively' cut cancer rates:
study
Posted: 28 April 2010 1207 hrs
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A scanning electron micrograph of human colon cancer
cells
PARIS - A single exam of the rectum and lower colon
between the age of 55 and 64 slashes colon cancer mortality by more
than 40 percent, according to research published Wednesday.
The 16-year study of more than 170,000 people in Britain also found
that the one-time procedure cut incidence of the disease by a third
compared to a control group that did not undergo the
examination.
The relatively simple test "could massively reduce colorectal
cancer incidence and mortality," the British medical journal The
Lancet, which published the study, said in a press release.
The most effective and cost-efficient way to screen for various
cancers -- including of the breast, prostate and colon -- has been
hotly debated in recent years.
Colon cancer is the third most commonly diagnosed form of the
disease worldwide, accounting for more than one million cases and
600,000 deaths annually.
The large majority of colon cancers arise from adenomas, a type of
pre-malignant polyp that occurs in 20 to 30 percent of the
population. Most people who develop the disease will have adenomas
by the age of 60.
The new study provides the strongest evidence to date that a
procedure known as a sigmoidoscopy, when performed in late-middle
age, provides significant protection against the deadly
cancer.
Generally performed without anaesthesia, flexible signoidoscopy
allows a physician to examine the rectum and lower colon, called
the signoid. Two-thirds of colorectal cancers develop in this
region.
Growths, whether benign or cancerous, can be removed during the
procedure.
The examination is less invasive -- and less costly -- than a full
colonoscopy, in which the entire large intestine is looked at while
the patient is under anaesthesia.
Many health systems currently screen for colon cancer by testing
stool samples for the presence of blood, a procedure which has been
shown to reduce mortality by 15 percent.
In the study, 170,432 men and women recruited between 1994 and 1999
were divided into two groups.
Nearly 113,200 were assigned to the control group, and 57,237 to
the intervention group.
During the screening period and an 11-year follow up, 2,524
participants were diagnosed with colon cancer, 1,816 in the control
group and 706 in the intervention group.
Incidence of the disease in people who were screened was cut by 33
percent, and mortality by 43 percent.
When results were confined to the rectum and lower colon, incidence
was reduced by half.
"Flexible sigmoidoscopy is a safe and practical test and, when
offered only once to people between ages 55 and 64, confers a
substantial and long-lasting protection from colon cancer," the
authors concluded.
The exam, while far more expensive that checking for blood in the
stool, may also be cost effective "largely because of the avoided
costs of treatment resulting from the reduction in incidence", they
added.
The researchers, led by Wendy Atkin of Imperial College London,
speculate that the decrease in cancer rates and deaths in the test
group will become even greater over time.
"If incidence in the screened participants remains low during
further follow up, the magnitude of the reduction will continue to
increase," they said.
- AFP/rs