Health Topic: Cancer
Cancer involves the uncontrolled growth of abnormal cells that
have mutated from normal tissues. This growth can kill when these
cells prevent normal function of vital organs or spreadthroughout
the body, damaging essential systems.
Causes, Incidence, and Risk Factors
There are many different kinds of cancers. Cancer arises out of
normal cells in the body, and can develop in almost any organ or
such as the lung, colon, breast, skin, bones, or nerve tissue.
In general, cancer appears to be caused by abnormal regulation
of cell division. Cancers can occur when cells divide too rapidly
or when cells forget how to die.
There are multiple causes of cancers such as:
- Certain viruses
Certain poisonous mushrooms and aflatoxins (a poison produced by
organisms that can grow on peanut plants)
However, the cause of many cancers remains unknown.
The three most common cancers in men in the U.S. are prostate cancer,
lung cancer, and colon cancer. For women in the U.S., the three
most frequently occurring cancers are breast cancer, lung cancer,
and colon cancer.
The most common cause of cancer-related death is lung cancer.
Certain cancers are more common in particular geographic regions.
For example, in Japan, there are many cases of gastric cancer, while
in the U.S. this type of cancer is relatively rare. Dietary differences
may account for the variance.
Symptoms of cancer depend on the type and location of the tumor.
For example, lung cancer can cause coughing, shortness of breath,
or chest pain, while colon cancer often causes diarrhea, constipation,
and blood in the stool.
Some cancers may not have any symptoms at all. However, the following
symptoms are common with most cancers:
- Night sweats
- Weight loss
- Loss of appetite
Signs and tests
Like symptoms, the signs of cancer vary based on the type and location
of the tumor. Common tests include the following:
- CT scan
- Complete blood count (CBC)
- Blood chemistries
- Biopsy of the tumor
- Bone marrow biopsy (for lymphoma or leukemia)
- Chest x-ray
Most cancers are diagnosed by biopsy. Depending on the location
of the tumor, the biopsy may be a simple procedure or a serious
Most patients with cancer undergo CT scans to determine the exact
location of the tumor or tumors.
Treatment also varies based on the type of cancer and its stage.
The stage of a cancer refers to how much it has grown and whether
the tumor has spread from its original location.
If the cancer is confined to one location and has not spread, the
goal for treatment would be surgery and cure. This is often the
case with skin cancers.
If the tumor has spread to local lymph nodes only, sometimes these
can also be removed.
If all of the cancer cannot be removed with surgery, the options
for treatment include radiation, chemotherapy, or both. Some cancers
require a combination of surgery, radiation, and chemotherapy.
The diagnosis of cancer often causes a lot of anxiety and can affect
a person's entire life. There are numerous support groups for cancer
The outlook varies widely among different types of cancer. Even
among people with one particular type of cancer, the outcome varies
depending on the stage of the tumor at diagnosis. Some cancers can
be cured, some that are not curable can still be treated well, and
some patients can live for many years with the cancer. Other tumors
are rapidly fatal.
One complication is that the cancer may spread. Other complications
vary with the type and stage of the tumor.
One of the best ways to prevent cancer is to not smoke or chew tobacco.
Many cancers can be prevented by avoiding risk factors such as excessive
exposure to sunlight and heavy drinking.
Cancer screenings, such as mammography and breast examination for
breast cancer and colonoscopy for colon cancer, may help catch these
cancers at their early, most treatable stages. Some people at high
risk for developing certain cancers can take medication to reduce