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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. |
