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Cancer
:
Early detection and better treatment have resulted in major improvements
in survival of patients with cancer. By 2000, 59 percent of people
diagnosed with cancer were alive five years later, compared with
only 25 percent in 1940. New drugs, surgical procedures, and ways
of treating cancer with X rays and radioactive isotope radiation
contributed to the improvement. In the 1990s, physicians used new
knowledge about the human immune system to develop immunotherapy
for some kinds of cancer, in which the immune system is stimulated
to produce antibodies against specific invaders. Another form of
immunotherapy is the use of monoclonal antibodies, genetically engineered
antibodies that target specific cancer cells.
Screening
tests for early detection of cancers of the cervix, prostate, breast,
and colon and rectum became widely available. Researchers also made
progress in identifying cancer genes that are associated with an
increased risk of the disease and developed screening tests for
some cancer genes. Advances in gene therapy also offered promise
for new cancer treatments.
Health
groups placed great emphasis in the second half of the century on
cancer prevention through avoiding smoking and eating a diet rich
in fresh fruits and vegetables. Despite these advances, the percentage
of deaths from cancer increased from about 2 percent in 1900 to
about 20 percent in 2000. Much of the rise, however, resulted from
an increased proportion of older people, who are more vulnerable
to cancer, and from cigarette smoking.
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