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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 cancccer 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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