16 October 2002
Statistics Show Increase, Not Decline, in Cancer Rates
Begley, Staff reporter
isn't winning the war on cancer after all.
to optimistic reports from the National Cancer Institute showing
the incidence of several devastating cancers has leveled off or
even declined in recent years, rates for at least some of those
cancers has been rising, according to a new analysis by NCI scientists.
indications of a decline reflected significant delays in reporting
cancer cases, the researchers report Wednesday in the Journal of
the National Cancer Institute. More accurate information about cancer
rates presents a grimmer picture.
we were a little too eager to declare the effectiveness of our intervention
and prevention programs," says Brenda Edwards, who is associate
director for the surveillance research program at NCI, of Bethesda,
Md., but wasn't among the authors of the new study.
revised estimates present a dispiriting picture of the nation's
progress in preventing cancer. Breast-cancer rates in white women
had been almost flat since 1987, according to the original NCI figures,
which the American Cancer Society also uses as the basis for the
popular "facts and figures" on its Web site.
reanalysis shows that breast-cancer rates actually have been rising
0.6% a year since 1987. That prompted the NCI scientists to call
for research "to explain the cause for the recent rise in breast
cancer in women also had been believed to be flat; the re-analysis
shows it has been rising 1.2% a year since 1996. Melanoma rates
in white males had reportedly been flat or even falling. The new
analysis finds it has been soaring 4.1% a year since 1981, suggesting
that prevention strategies that focus on staying out of the sun
are falling short. Prostate-cancer rates in white males, rather
than falling since 1995, have in fact been rising 2.2% a year. For
white men, 1998 prostate-cancer rates are actually 12% higher than
originally reported; for black men they are 14% higher.
cancer cases for both genders and all races are 3% higher than first
reported, suggesting that early-screening techniques (which focus
on discovering precancerous polyps through colonoscopies) aren't
as powerful or widely used as hoped. The rate of colorectal cancer
in white women, for instance, has been rising 2.8% annually since
1996, rather than the originally calculated 0.9%.
incidence data are based on reports from 10 registries in the SEER
(Surveillance, Epidemiology, and End Results) program at NCI, which
samples 14% of the U.S. population by collecting cancer reports
from hospitals, doctors and clinics. The registries have 19 months
to report cases to NCI.
had long suspected that the original numbers were skewed. "It
was well known that reports of new cancer cases dribbled in over
the years, long after the 19-month reporting deadline," says
Benjamin Hankey, the senior author of the study. So, researchers
wondered, just how sharply did late reporting affect the final cancer-rate
statistic for a specific year?
data from 1981 to 1998, scientists led by Mr. Hankey analyzed reporting
delays by counting how many additions nine registries made to their
original count over the years. Based on that, but allowing for improvement
in the timeliness and accuracy of the reports, NCI statistician
Limin Clegg estimated the under-reports from each registry for five
types of cancer. The delays are such that initial reports account
for only 88% to 97% of the actual cancer cases, depending on the
type, finds Dr. Clegg. That has left a "false impression of
a recent decline in cancer incidence," write the NCI scientists.
cancer-incidence rates are the basis for decisions by policy makers
and clinicians alike: The numbers are used to allocate research
and clinical resources, to give people a sense of their risk for
various cancers and to offer hints about environmental causes of
cancer ranging from use of sunblock to changes in diet and cumulative
exposure to toxic chemicals.
researchers feel a renewed urgency to study why the rates of several
cancers are still on the rise. "This tells us something we
didn't know about whether our intervention and prevention programs
are working," says Ahmedin Jemal, director of the surveillance
program for the American Cancer Society.