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Press Release Date: January 23, 1997
The Agency for Health Care Policy and Research (AHCPR) today released the
first evidence report under its new Evidence-based Practice Initiative. The
report indicates that screening has been shown to be effective in
detecting
early-stage colorectal cancers and their precursors. Early
detection and
treatment are the primary means of preventing deaths from
colorectal cancer.
Colorectal cancer is the third most commonly diagnosed cancer
and the second
leading cause of cancer death in the United States. It is
estimated that in
1996, 133,500 new cases of colorectal cancer were diagnosed, and
that colorectal
cancer accounted for 54,900 deaths.
"This evidence report will improve the early detection
and treatment of
colorectal cancer by giving clinicians and others
state-of-the-art information
on screening and diagnostic tests to help them reduce the
mortality from this
deadly disease," said AHCPR Administrator Clifton R. Gaus.
"Our goal
is to make this information, and all the evidence reports
released in the
future, available in the public domain to the widest audience
possible."
AHCPR's Evidence-based Practice Initiative, established in
October 1996,
will provide medical societies, health care systems, purchasers,
health plans,
and others with a scientific foundation for developing and
implementing their
own clinical practice guidelines, performance measures, and other
quality
improvement tools. In December 1996, AHCPR issued a
Request for Proposals to fund
Evidence-based
Practice Centers to produce future evidence reports and also
published a notice
in the Federal Register inviting nominations for report topics.
The Colorectal Cancer Screening Evidence Report is based on a
systematic
review of 3,500 citations from the scientific literature
published between 1966
and 1994. The review found evidence that a reduction in deaths
from colorectal
cancer can be achieved through detection and treatment of
early-stage colorectal
cancers and the identification and removal of adenomatous
polyps—the
precursors of colorectal cancers. Other findings include:
- Colorectal cancer incidence rises with age, beginning
around age 40,
and is higher in men than in women (60.4 versus 40.9 per 100,000
per year).
- Survival from colorectal cancer is closely related to the
clinical and
pathological stage of the disease at diagnosis. Up to 90 percent
of patients
with cancer limited to the bowel wall will be alive five years
after diagnosis,
as compared with 35-60 percent of those with involvement of
the lymph
nodes, and less than 10 percent of patients with metastatic
disease.
- Racial differences in colorectal cancer survival have been
observed. The
1983-1989 five-year relative survival for colon cancer was
61 percent among
white men, 50 percent among white women, 48 percent among
African-American
men, and 49 percent among African-American women.
African-American men and
women with colorectal cancer have a 50 percent greater
probability of dying
of colon cancer than do white men and women.
- Well-established risk factors for colorectal cancer include
older age, male
sex, history of inflammatory bowel disease, certain
hereditary conditions,
and a family history of colorectal cancer. However, about
75 percent of
all colorectal cancer occurs in people with no known risk
factors.
- Most Americans are not screened for colorectal cancer. More
than
two-thirds of patients present with advanced disease.
Information from the
National Health Interview Survey (NHIS) indicates that in
1992, only 17.3
percent of people aged 50 and older had undergone fecal
occult blood
testing the previous year, and 9.4 percent had undergone
sigmoidoscopy in the
previous three years.
- Screening with fecal occult blood testing has been shown to
reduce
colorectal cancer mortality. Screening with flexible
sigmoidoscopy can reduce
colorectal cancer mortality risk but clinical trials have not
been performed
that directly assess mortality reduction. Double contrast barium
enema and
colonoscopy are proven methods of identifying polyps and
colorectal cancer
but have not been studied as screening tests. Further
research is needed
to demonstrate the effectiveness of colorectal cancer screening
tests and
determine proper intervals for such testing.
The information contained in AHCPR's evidence report is the
basis for a
clinical practice guideline by the American Gastroenterology
Association (AGA)
on colorectal cancer screening that will be published in the
February issue of
Gastroenterology. The AGA led a consortium that
directed an
AHCPR-sponsored clinical practice guideline panel on colorectal
cancer
screening. Work on the AHCPR-sponsored guideline was
discontinued when the
agency ended its clinical practice guideline program and began
developing
evidence reports. The AGA then decided to sponsor its own
science-based
guideline on colorectal cancer screening.
"AGA's use of this information on colorectal cancer
screening to
develop its guideline on colorectal cancer screening demonstrates
the importance
and potential impact of AHCPR's Evidence-based Practice
Initiative," noted
Dr. Gaus. "AHCPR is filling a need for comprehensively
reviewed, rigorously
analyzed science sought by public- and private-sector
organizations to use in
improving the quality of health care services they provide."
An executive summary of the Evidence Report on Colorectal
Cancer Screening
is available from AHCPR's Publications Clearinghouse at 800-358-9295. Select for Colorectal Cancer Screening: Summary. The complete evidence report will be available in the near future.
For additional information, contact AHCPR Public Affairs: Karen Carp, (301) 427-1858, or Salina Prasad, (301) 427-1864.