HUMAN BIOLOGY

434 Chapter 22

adjuvant therapy Cancer
therapy that combines sur-
gery with chemotherapy.

chemotherapy Use of
anticancer drugs to treat
cancer.

radiation therapy Irradiation
of relatively small, localized
cancer tumors. The radiation
comes from radioisotopes.

n When a person is diagnosed with cancer, a variety of

weapons are available to combat it. And anyone can adopt

an “anticancer lifestyle.”

n    Links to Monoclonal antibodies and immunotherapy 9.8,

Cell cycle 18.2

Patients understandably dread a

diagnosis of cancer, but today many

forms of cancer can be treated suc-

cessfully. Even if a complete cure

is not possible, modern treatment

approaches may prolong a patient’s

life and improve the quality of life

for years. The major weapons against

cancer are chemotherapy drugs,

radiation therapy, and surgery.

Surgery may even be a complete cure when a tumor is

fully accessible and has not spread.

Chemotherapy and radiation kill cancer cells

Chemotherapy uses drugs to kill cancer cells (Fig-

ure  22.15). Most anticancer drugs are designed to kill

dividing cells by disrupting some aspect of the normal

cell cycle. Unfortunately, chemotherapy drugs are also

toxic to rapidly dividing healthy cells such as hair cells,

stem cells in bone marrow, immune system lymphocytes,

and epithelial cells of the intestinal lining. This is why

chemotherapy patients may suffer side effects such as hair

loss, nausea, vomiting, and reduced immune responses.

A treatment option called adjuvant therapy (adjuvant

means “helping”) combines surgery and a less toxic dose

of chemo therapy. A cancer patient might receive enough

chemotherapy to shrink a tumor, for instance, then have

surgery to remove what’s left.

Drugs used in chemotherapy typically have been

matched to the organ in which a cancer occurs—this drug

for breast cancer, that one for lung cancer, and so on. A

promising new strategy instead matches chemotherapy

with the genetic characteristics of a patient’s cancer. This

approach recognizes that there are hundreds of genetically

different subgroups of cancer, and that some subgroups

have the same gene mutations—and chemical features—

regardless of where the cancer develops. For example, the

drug Gleevec works well against some types of leukemia

and also against some sarcomas.

Like surgery, radiation therapy may be used when

the cancer is small and has not spread (Figure 22.16).

The radiation comes from radioisotopes such as radium

226 and cobalt 60. Like traditional chemotherapy, it is

something of a “shotgun” approach to cancer treatment

Cancer treatment and prevention

Figure 22.16 Radiation therapy kills cells with a

targeted dose of lethal radiation.

Larry Mulvehill/Science Source

22.6

Figure 22.15 Chemotherapy uses cell-killing drugs. In some

cases, the drug is delivered through a tube that connects with a

port inserted into a vein, as shown here. Patients usually receive

chemotherapy over a period of weeks. Imaging tests are used to

determine whether the patient’s condition has improved.

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