What Is Cancer?
Cancer is a group of diseases characterized by uncontrolled
growth and spread of abnormal cells. If the spread
is not controlled, it can result in death. Cancer is caused
by both external factors (tobacco, infectious organisms,
chemicals, and radiation) and internal factors (inherited
mutations, hormones, immune conditions, and mutations
that occur from metabolism). These causal factors may
act together or in sequence to initiate or promote carcinogenesis.
Ten or more years often pass between exposure to
external factors and detectable cancer. Cancer is treated
with surgery, radiation, chemotherapy, hormone therapy,
biological therapy, and targeted therapy.
Can Cancer Be Prevented?
All cancers caused by cigarette smoking and heavy use
of alcohol could be prevented completely. The American
Cancer Society estimates that in 2009 about 169,000
cancer deaths are expected to be caused by tobacco use.
Scientific evidence suggests that about one-third of the
562,340 cancer deaths expected to occur in 2009 will be
related to overweight or obesity, physical inactivity, and
poor nutrition and thus could also be prevented. Certain
cancers are related to infectious agents, such as hepatitis
B virus (HBV), human papillomavirus (HPV), human
immunodeficiency virus (HIV), Helicobacter pylori (H.
pylori), and others, and could be prevented through behavioral
changes, vaccines, or antibiotics. In addition, many
of the more than 1 million skin cancers that are expected
to be diagnosed in 2009 could be prevented by protection
from the sun’s rays and avoiding indoor tanning.
Regular screening examinations by a health care professional
can result in the detection and removal of
precancerous growths, as well as the diagnosis of cancers
at an early stage, when they are most treatable. Cancers
that can be prevented by removal of precancerous tissue
include cancers of the cervix, colon, and rectum. Cancers
that can be diagnosed early through screening include
cancers of the breast, colon, rectum, cervix, prostate, oral
cavity, and skin. For cancers of the breast, colon, rectum,
and cervix, early detection has been proven to reduce
mortality. A heightened awareness of breast changes
or skin changes may also result in detection of these
tumors at earlier stages. Cancers that can be prevented
or detected earlier by screening account for at least half
of all new
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