A Progress Report
year a report on cancer goes out to the nation, compiled by
experts at the National Cancer Institute, the Centers for Disease
Control and Prevention, and other agencies. This year's report,
like previous ones, had some good news. Apart from cancers caused
by tobacco, notably lung cancer, we are not in the middle of
a cancer epidemic. In fact, the rate of new cancer cases and
deaths from cancer in the U.S. declined in the 1990s. But it
pays to look closer. Cancer is, in fact, not one disease, but
they keep track of cancer
keeping track of cancer, scientists speak of incidence
(new cases diagnosed among a given number of people in a given
period) and mortality rate (deaths
among a given number of people in a given period). When incidence
goes up, it may be hard to tell why, but sometimes it's because
of some new method for detecting a particular cancer. Thus,
between 1988 and 1992, when PSA testing came into wide use,
the incidence of prostate cancer rosebut that was because
the new test found otherwise hidden disease. Of course, increased
or decreased incidence may also be caused by some change in
the environment or in people's habits. For example, the increase
in smoking is responsible for the huge upsurge in lung cancer
incidence and deaths during the past half century. On the other
hand, the mortality rate may fall because of a drop in incidence,
or because of some new medical advance: deaths from cervical
cancer declined dramatically because the Pap test came into
wide use, beginning in the 1940s. For the first time, doctors
could diagnose this cancer early and cure it.
of the new report
new report, covering through 1998 (the latest year for data),
shows that, as has been true for some time, the four cancers
that affect the most Americansand kill the mostare
lung, colorectal, breast, and prostate cancers: 56% of all cancers
diagnosed in 1998 were one of these four, and they accounted
for almost 53% of the cancer deaths that year. Looking at most
of these, you'll see a mix of good and bad news:
Lung cancer: This remains the biggest cancer killer
of both men and women (except Hispanic women, who died of
breast cancer more often than lung cancer). The incidence
of lung cancer in men is declining, as is the mortality rate.
And while the incidence in women has leveled off, the death
rate is still increasingbecause so many women started
smoking after the 1940s. To date there's no practical screening
test for lung cancer that has been shown to save lives.
Prostate cancer: Since
1994 the death rate has declined, possibly due to improved
treatments. It is difficult to evaluate the changing incidence
of prostate cancer because of the fluctuation in the use of
the PSA test for screening.
This is still the most common cancer among women, but more
women die each year from lung cancer. Breast cancer incidence
increased among women aged 50 to 74, probably because of wider
use of mammography, which detects hidden disease. But the
death rate among white women has declined steadily since 1989
and dramatically since 1995. The mortality rate remained stable
among black women in the 1990s.
The incidence declined between 1985 and 1995 and then stabilized.
The death rate has declined. The latter may be attributed
to better diagnosis and treatments.
news, however, is not good for every type of cancer. For example,
the incidence of melanoma, the most serious type of skin cancer,
increasedperhaps due to increased awareness and screening.
And the death rate from melanoma among white men also increased.
Also, the death rates for non-Hodgkin's lymphoma and esophageal
cancer rose between 1992 and 1998 (though the death rate from
esophageal cancer has decreased dramatically for black men and
women). Though these cancers do not contribute greatly to the
total number of cancer cases and deaths in this country, it
serves as a reminder that cancer comes in many varietiesand
that there is still much work to be done in understanding, preventing,
and treating cancer.
can you guard against cancer?
If nobody used tobacco, the total incidence and death rate
from cancer would fall by about one third. It is a tragedy
of our time that so little has been done to eliminate tobacco
A diet rich in fruits, vegetables, and grains is known to
help prevent cancer. Indeed, if a plant-based diet were the
norm, cancer incidence might fall by yet another third.
Maintaining a healthy weight is another good step: being obese
contributes to cancer risk, especially breast cancer. Nobody
knows why this is so, but the alarming increase in obesity
in the U.S. and other countries may well cause cancer incidence
Finally, get screened. If you're a woman 50 or older, have
a mammogram every year. Get Pap tests on a regular schedule.
Talk with your doctor about screening for colorectal cancerand
for prostate cancer if you're a man.
Reference Source 98