=======================Electronic Edition========================
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. RACHEL'S ENVIRONMENT & HEALTH WEEKLY #641 .
. ---March 11, 1999--- .
. HEADLINES: .
. THE CANCER WAR GRINDS ON .
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THE CANCER WAR GRINDS ON
In 1996 Donna Shalala, U.S. Secretary of Health and Human
Services, declared that the war on cancer was finally showing
results. "This looks like a turning point in the 25-year war on
cancer, and it should be cause for celebration by every
American," she said.[1] Shalala made her dramatic pronouncement
to underscore the fact that the death rate for all cancers
combined had declined 2.6% during the period 1991-1995. It was
the first sustained decline since the government started keeping
cancer statistics in the 1930s.
Cancer deaths declined for cancers of the lung and prostate in
men, breast and uterus in women, and colon/rectum in both sexes.
Since these are the most common cancers, they drove down the
overall death rate.
We suspect that these reported trends are questionable because
reputable studies indicate that many cancers remain undiagnosed
unless an autopsy is performed, and autopsy rates have declined
in recent years (see REHW #631).
However, for purposes of discussion, let's assume that the
government is right, that age-adjusted deaths from all cancers
combined really did decline 2.6% between 1991 and 1995.
Despite this bit of good news, the details of cancer in this
country are still awful. Cancer struck 1,228,000 Americans for
the first time in 1998, and 564,800 Americans died of cancer in
1998.[2] A man's chances of getting cancer during his lifetime are
now 48% (about 1 out of 2) and a woman's chances are now 38%
(about 4 out of 10). Clearly, we have a very long way to go
before we can claim that the "war on cancer" has been won.
Furthermore, the good news about cancer hides some terrible
injustices. For example, the largest declines in cancer death
rates between 1991 and 1995 occurred among African-Americans. The
death rate for all cancers combined declined 5.6% among blacks
between 1991 and 1995. The decline was especially great among
black men, whose cancer death rate decreased 8.1%, compared to
black women, who experienced a 2.5% decline during the same
period.
Despite this good news, the overall age-adjusted cancer death
rate is still 40% higher among black men compared to white men,
and 20% higher among black women compared to white women.[1]
Why do blacks die of cancer so much more than whites? The
Director of the National Cancer Institute, Richard Klausner,
phrases it delicately: "less access to care and less aggressive
treatment" play a role, he says.[1] Less aggressive treatment?
There is an extensive body of literature showing that many
physicians give second-class medical care to black patients.[3]
Perhaps this occurs because blacks tend to be poorer than whites,
but perhaps it also results from a widely-shared (and perhaps
subconscious) racist view that blacks deserve less than whites.
The "cancer establishment" has a ready explanation for the
declining death rates from all cancers combined. They say roughly
half the overall 2.6% improvement in cancer death statistics,
1991-1995, can be accounted for by improvements in "life style"
-- less smoking, better diet, more exercise. They say the other
half results from better diagnosis and treatment -- more people
are being kept alive by chemotherapy, radiation, and surgery.
But Richard Clapp at the Boston University School of Public
Health points out that heart disease is caused by these same
factors -- smoking, bad diet and insufficient exercise.[4]
Because of improvements in these factors, deaths from heart
disease have declined 49% during the past 25 years. If heart
disease and cancer are caused by the same factors, why has the
cancer death rate remained so high? It cannot be simply that
cancer is a disease of old age. Heart disease, too, is a disease
of old age. Is something else besides "life style" factors
causing cancer? It is a fair question.
We note that in a 1990 cancer prevention booklet titled
EVERYTHING DOESN'T CAUSE CANCER, the National Cancer Institute
(NCI) says, "Many cancers could be prevented by reducing our
exposure to carcinogens."[5] The NCI identifies 30 chemicals or
industrial processes that are known to cause cancer in humans.
Furthermore, NCI says, "Of the several hundred other chemicals
that cause cancer in animals, however, it is not known how many
are also human carcinogens. Nevertheless, materials that cause
cancer in one type of animal usually are found to cause cancer in
others.... For these and other reasons, we should expect animal
carcinogens to be capable of causing cancer in humans."
The NCI goes on to explain why weak cancer-causing chemicals
cannot be reliably identified among the 70,000 chemicals now in
industrial use. In a typical test of a chemical for
carcinogenicity, "groups of about 50 mice or rats of each sex are
exposed to the test substance at different dosages for about two
years." At the end of the experiment, the animals are killed and
examined for cancer.
NCI goes on: "In the human population, large numbers of people
are exposed to low doses of chemicals, but the total impact may
not be small at all. For example," NCI says, "a carcinogen might
cause one tumor in every 10,000 people exposed to it, which may
not seem great. But exposure of 230 million Americans would
result in 23,000 cancers -- a public health disaster."
NCI goes on: "We obviously could not identify a carcinogen that
causes one cancer in every 10,000 exposed mice by running the
test on only 50 mice. To detect such a low cancer rate, we would
need tens of thousands of mice. This would cost many millions of
dollars per test. Testing more than a few chemicals in such a
fashion would be too expensive and time-consuming," NCI says.
NCI also points out that it is difficult to identify which
carcinogens cause which cancers because "A chemical that causes
cancer of the liver in mice, for example, might cause cancer of
the breast in rats and cancer of the bladder in humans."
Is there a safe level of exposure to a cancer-causing chemical?
NCI says no: "There is no adequate evidence that there is a safe
level of exposure for any carcinogen." And "Low exposure that
might be safe for one person might cause cancer in another....
Unfortunately, scientists have not yet developed any way to
measure a person's individual risk. Exposure to a low level of a
carcinogen thus has to be considered a risk for everyone," NCI
says.
Here is the big picture of cancer: Table 1 shows that during the
last 45 years, the incidence of all cancers combined has risen
1.0% each year and the death rate for all cancers has increased
at the rate of 0.2% each year. If we exclude lung cancer, the
increase in the incidence of all other cancers is still 0.8% each
year for the past 45 years, but the death rate has declined at
the rate of 0.4% each year. A rising incidence and a dropping
death rate, taken together, mean more people are learning to live
with cancer.
==========
[1] Mary Jo Hoeksema and Catherine Law, "Cancer Mortality Rates
Fall: A Turning Point for the Nation," JOURNAL OF THE NATIONAL
CANCER INSTITUTE Vol. 88, No. 23 (December 4, 1996), pgs.
1706-1707.
[2] Lynn A.G. Ries and others, SEER CANCER STATISTICS REVIEW,
1973-1995 (Bethesda, Maryland: National Cancer Institute, 1998).
[3] For example, see the first 19 studies cited in Kevin A.
Schulman and others, "The Effect of Race and Sex on Physicians'
Recommendations for Cardiac Catheterization," NEW ENGLAND JOURNAL
OF MEDICINE Vol. 340, No. 8 (February 25, 1999), pgs. 618-626.
[4] Richard W. Clapp, "The Decline in U.S. Cancer Mortality from
1991 to 1995: What's Behind the Numbers?" INTERNATIONAL JOURNAL
OF HEALTH SERVICES Vol. 28, No. 4 (1998), pgs. 747-755.
[5] National Cancer Institute, EVERYTHING DOESN'T CAUSE CANCER
[NIH Publication No. 90-2039] (Bethesda, Maryland: National
Cancer Institute, March, 1990).
Search terms: cancer; carcinogens; heart disease; morbidity
statistics; mortality statistics; national cancer institute;
=================================================================
TABLE 1
U.S. Cancer Incidence and Deaths in 1995, and the Percent Change
in Age-Adjusted Rates of Incidence and Death per 100,000 U.S. .
Population, 1950-1995. .
. .
. -----ALL RACES------- ------WHITES---------
Cancer Incidence Deaths Percent Percent
type in 1995 in 1995 change in change in
. (estimated) incidence, deaths,
. 1950-1995 1950-1995
----------------------------------------------------------------
stomach 22,800 13,645 -76.6 -79.5
cervix 15,800 4,503 -79.3 -75.1
rectum 38,200 8,053 -26.8 -67.0
colon 100,000 49,591 +15.4 -19.1
larynx 11,600 3,871 +41.7 -13.1
testicles 7,100 314 +109.6 -72.3
bladder 50,500 11,083 +54.0 -34.8
Hodgkin's disease 7,800 1,431 +15.0 -73.0
childhood (0-14 yr) 8,300 1,584 +9.8 -66.5
leukemias 25,700 20,323 +8.9 -3.5
thyroid 13,900 1,122 +138.8 -49.9
ovaries 26,600 13,341 +2.4 +0.6
lung 169,900 151,099 +257.0 +261.2
skin melanomas 34,100 6,905 +426.0 +154.4
breast (female) 183,400 43,843 +56.1 -5.1
prostate 244,000 34,475 +204.0 +14.4
kidney 28,800 11,083 +128.9 +37.2
liver 18,500 11,191 +131.1 +30.9
non-Hodgkin's .
lymphomas 50,900 22,391 +199.3 +137.0
multiple myeloma 12,500 10,250 +199.5 +209.1
brain 17,200 12,062 +80.0 +46.3
pancreas 24,000 26,765 +10.8 +16.7
. .
All types ex- .
cluding lung 1,082,100 387,338 +42.1 -16.6
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Dennis Raphael, Ph.D.
Associate Professor and Associate Director,
Masters of Health Science Program in Health Promotion
Department of Public Health Sciences
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