HUMAN BIOLOGY

Genes and disease: CanCer 435

hoW is cancer treated?

• Surgery, chemotherapy, radiation, and other treatment
  strategies are used to fight cancer.


• The best defense against cancer is making lifestyle choices
  that promote good health.

taKe-Home messaGe

Four-dimensional computed tomography—4D CT, a

type of CT scanning—is an advanced medical imaging

technology used to precisely locate cancerous tumors

prior to radiation treatments. Visit the website of

the University of Pittsburgh Cancer Institute at

http://www.upmccancercenters.com. How might using

4D CT improve the treatment of a cancer patient

slated to receive radiation therapy?

THiNk OuTSidE THE BOOk

because it kills both cancer cells and healthy cells in the
irradiated area.
Because chemotherapy and radiation both damage or
kill healthy body cells, cancer researchers have looked for
more precise cancer treatments. Section 9.8 described how
monoclonal antibodies can be used to deliver lethal doses
of anticancer drugs to tumor cells while sparing healthy
cells. The antibodies target cell surface markers (antigens)
on various types of tumors. The idea is to link monoclo-
nal antibodies that bind to tumor cell markers with lethal
doses of cytotoxic (cell-killing) drugs. Experiments have
shown promising results in some patients with one form
of leukemia, one type of breast cancer, and certain gliomas
(cancers that arise in glia in the brain).
Interferons also can activate cytotoxic T cells and NK
cells, which then may recognize and kill some types of
cancer cells. So far, interferon therapy has been useful only
against some rare forms of cancer.

Good lifestyle choices can limit cancer risk

None of us can control factors in our heredity or biology
that might lead one day to cancer, but we can all make life-
style decisions that promote health (Figure 22.17). Accord-
ing to the National Cancer Institute, 40 percent of cancers
are related to lifestyle factors, such as smoking, suntan-
ning, and obesity that is due to improper diet and seden-
tary habits. The American Cancer Society recommends the
following strat egies for limiting cancer risk:

1. Avoid tobacco in any form, including secondary smoke
   from others.


2. Maintain a desirable weight. Being more than 40 percent
   overweight increases the risk of several cancers.


3. Eat a low-fat diet that includes plenty of vegetables
   and fruits. These foods contain anti oxidants, such as
   vitamin E, that may help prevent some kinds of cancer.


4. Drink alcohol in moderation. Heavy alcohol use,
   especially in combination with smoking, increases risk
   for cancers of the mouth, larynx, esophagus, and liver.


5. Learn whether your job or residence exposes you
   to such industrial agents as nickel, chromate, vinyl
   chloride, benzene, asbestos, and agricultural pesticides,
   which are associated with various cancers.


6. Protect your skin from excessive sunlight.

Photos.com/Jupiterimages

Figure 22.17 Lifestyle choices have a major impact on cancer

risk. Eating a healthy diet and choosing not to smoke are just two

ways everyone can improve their chances of avoiding cancer.

© Samuel Borges Photography/Shutterstock.com

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