- What Is Cancer?
- Screening and Early Detection
- Symptoms of Cancer
- Side Effects of CancerTreatment
What Is Cancer?
Cancer is a group of more than 100 different diseases. Cancer
occurs when cells become abnormal and keep dividing and forming
more cells without control or order.
All organs of the body are made of cells. Normally, cells
divide to produce more cells only when the body needs them.
This orderly process helps keeps us healthy.
If cells keep dividing when new cells are not needed, a mass
of tissue forms. This mass of extra tissue, called a growth
or tumor, can be benign or malignant.
Most cancers are named for the type of cell or the organ in
which they begin. When cancer spreads, the new tumor has the
same kind of abnormal cells and the same name as the primary
tumor. For example, if lung cancer spreads to the liver, the
cancer cells in the liver are lung cancer cells. The disease
is called metastatic lung cancer (it is not liver cancer).
- Benign tumors are not cancer. They can usually be removed
and, in most cases, they do not come back. Most important,
cells from benign tumors do not spread to other parts of
the body. Benign tumors are rarely a threat to life.
- Malignant tumors are cancer. Cancer cells can invade and
damage nearby tissues and organs. Also, cancer cells can
break away from a malignant tumor and enter the bloodstream
or the lymphatic system. This is how cancer spreads from
the original (primary) tumor to form new tumors in other
parts of the body. The spread of cancer is called metastasis.
Screening and Early Detection
Sometimes, cancer can be found before the disease causes
symptoms. Checking for cancer (or for conditions that may
lead to cancer) in a person who does not have any symptoms
of the disease is called screening.
Screening may involve a physical exam, lab tests, and/or
procedures to look at internal organs, either directly or
indirectly. During a physical exam, the doctor looks for anything
unusual and feels for any lumps or growths. Examples of lab
tests include blood and urine tests, the Pap test (microscopic
examination of cells collected from the cervix), and the fecal
occult blood test (to check for hidden blood in stool). Internal
organs can be seen directly through a thin, lighted tube (such
as a sigmoidoscope, which lets the doctor see the rectum and
the lower part of the colon) or indirectly with x-ray images
(such as mammograms to check the breasts).
Doctors consider many factors before recommending a screening
test. They weigh factors related to the individual, the test,
and the cancer that the test is intended to detect. For example,
doctors take into account the person's age, medical history
and general health, family history, and lifestyle. In addition,
they assess the accuracy and the risks of the screening test
and any followup tests that may be necessary. Doctors also
consider the effectiveness and side effects of the treatment
that will be needed if cancer is found. People may want to
discuss any concerns or questions they have with their doctors,
so they can weigh the pros and cons and make an informed decision
about whether to have a screening test.
Symptoms of Cancer
You should see your doctor for regular checkups and not wait
for problems to occur. But you should also know that the following
symptoms may be associated with cancer: changes in bowel or
bladder habits, a sore that does not heal, unusual bleeding
or discharge, thickening or lump in the breast or any other
part of the body, indigestion or difficulty swallowing, obvious
change in a wart or mole, or nagging cough or hoarseness.
These symptoms are not always a sign of cancer. They can also
be caused by less serious conditions. Only a doctor can make
a diagnosis. It is important to see a doctor if you have any
of these symptoms. Don't wait to feel pain: Early cancer usually
does not cause pain.
If you have a sign or symptom that might mean cancer, the
doctor will do a physical exam and ask about your medical
history. In addition, the doctor usually orders various tests
and exams. These may include imaging procedures, which produce
pictures of areas inside the body; endoscopy, which allows
the doctor to look directly inside certain organs; and laboratory
tests. In most cases, the doctor also orders a biopsy, a procedure
in which a sample of tissue is removed. A pathologist examines
the tissue under a microscope to check for cancer cells.
Images of areas inside the body help the doctor tell whether
a tumor is present. These images can be made in several ways.
In many cases, the doctor uses a special dye so that certain
organs show up better on film. The dye may be swallowed or
put into the body through a needle or a tube.
X-rays are the most common way doctors make pictures of the
inside of the body. In a special kind of x-ray imaging, a
CT or CAT scan uses a computer linked to an x-ray machine
to make a series of detailed pictures.
In radionuclide scanning, the patient swallows or is given
an injection of a mildly radioactive substance. A machine
(scanner) measures radioactivity levels in certain organs
and prints a picture on paper or film. By looking at the amount
of radioactivity in the organs, the doctor can find abnormal
Ultrasonography is another procedure for viewing the inside
of the body. High-frequency sound waves that cannot be heard
by humans enter the body and bounce back. Their echoes produce
a picture called a sonogram. These pictures are shown on a
monitor like a TV screen and can be printed on paper.
In MRI, a powerful magnet linked to a computer is used to
make detailed pictures of areas in the body. These pictures
are viewed on a monitor and can also be printed.
Endoscopy allows the doctor to look into the body through
a thin, lighted tube called an endoscope. The exam is named
for the organ involved (for example, colonoscopy to look inside
the colon). During the exam, the doctor may collect tissue
or cells for closer examination.
Although no single test can be used to diagnose cancer, laboratory
tests such as blood and urine tests give the doctor important
information. If cancer is present, lab work may show the effects
of the disease on the body. In some cases, special tests are
used to measure the amount of certain substances in the blood,
urine, other body fluids, or tumor tissue. The levels of these
substances may become abnormal when certain kinds of cancer
The physical exam, imaging, endoscopy, and lab tests can
show that something abnormal is present, but a biopsy is the
only sure way to know whether the problem is cancer. In a
biopsy, the doctor removes a sample of tissue from the abnormal
area or may remove the whole tumor. A pathologist examines
the tissue under a microscope. If cancer is present, the pathologist
can usually tell what kind of cancer it is and may be able
to judge whether the cells are likely to grow slowly or quickly.
When cancer is found, the patient's doctor needs to know
the stage, or extent, of the disease to plan the best treatment.
The doctor may order various tests and exams to find out whether
the cancer has spread and, if so, what parts of the body are
affected. In some cases, lymph nodes near the tumor are removed
and checked for cancer cells. If cancer cells are found in
the lymph nodes, it may mean that the cancer has spread to
Cancer is treated with surgery, radiation therapy, chemotherapy,
hormone therapy, or biological therapy. Patients with cancer
are often treated by a team of specialists, which may include
a medical oncologist (specialist in cancer treatment), a surgeon,
a radiation oncologist (specialist in radiation therapy),
and others. The doctors may decide to use one treatment method
or a combination of methods. The choice of treatment depends
on the type and location of the cancer, the stage of the disease,
the patient's age and general health, and other factors.
Some cancer patients take part in a clinical trial (research
study) using new treatment methods. Such studies are designed
to improve cancer treatment.
Methods of Treatment
Surgery--Surgery is local therapy to remove the tumor.
Tissues around the tumor and nearby lymph nodes may also be
removed during the operation.
Radiation Therapy--In radiation therapy (also called
radiotherapy), high-energy rays are used to damage cancer
cells and stop them from growing and dividing. Like surgery,
radiation therapy is local therapy; it can affect cancer cells
only in the treated area. Radiation may come from a machine
(external radiation). It also may come from an implant (a
small container of radioactive material) placed directly into
or near the tumor (internal radiation). Some patients get
both kinds of radiation therapy.
External radiation therapy is usually given on an outpatient
basis in a hospital or clinic 5 days a week for several weeks.
Patients are not radioactive during or after the treatment.
For internal radiation therapy, the patient stays in the
hospital for a few days. The implant may be temporary or permanent.
Because the level of radiation is highest during the hospital
stay, patients may not be able to have visitors or may have
visitors only for a short time. Once an implant is removed,
there is no radioactivity in the body. The amount of radiation
in a permanent implant goes down to a safe level before the
patient leaves the hospital.
Chemotherapy--Treatment with drugs to kill cancer
cells is called chemotherapy. Most anticancer drugs are injected
into a vein (IV) or a muscle; some are given by mouth. Chemotherapy
is systemic treatment, meaning that the drugs flow through
the bloodstream to nearly every part of the body.
Often, patients who need many doses of chemotherapy receive
the drugs through a catheter (a thin flexible tube). One end
of the catheter is placed in a large vein in the chest. The
other end is outside the body or attached to a small device
just under the skin. Anticancer drugs are given through the
catheter. This can make chemotherapy more comfortable for
the patient. Patients and their families are shown how to
care for the catheter and keep it clean. For some types of
cancer, doctors are studying whether it helps to put anticancer
drugs directly into the affected area.
Chemotherapy is generally given in cycles: A treatment period
is followed by a recovery period, then another treatment period,
and so on. Usually a patient has chemotherapy as an outpatient--at
the hospital, at the doctor's office, or at home. However,
depending on which drugs are given and the patient's general
health, the patient may need to stay in the hospital for a
Hormone Therapy--Some types of cancer, including most
breast and prostate cancers, depend on hormones to grow. For
this reason, doctors may recommend therapy that prevents cancer
cells from getting or using the hormones they need. Sometimes,
the patient has surgery to remove organs (such as the ovaries
or testicles) that make the hormones; in other cases, the
doctor uses drugs to stop hormone production or change the
way hormones work. Like chemotherapy, hormone therapy is systemic
treatment; it affects cells throughout the body.
Biological Therapy--Biological therapy (also called
immunotherapy) is a form of treatment that uses the body's
natural ability (immune system) to fight infection and disease
or to protect the body from some of the side effects of treatment.
Monoclonal antibodies, interferon, interleukin-2 (IL-2), and
several types of colony-stimulating factors (CSF, GM-CSF,
G-CSF) are forms of biological therapy.
Side Effects of Cancer Treatment
It is hard to limit the effects of treatment so that only
cancer cells are removed or destroyed. Because treatment also
damages healthy cells and tissues, it often causes unpleasant
The side effects of cancer treatment vary. They depend mainly
on the type and extent of the treatment. Also, each person
reacts differently. Doctors try to plan the patient's therapy
to keep side effects to a minimum and they can help with any
problems that occur.
Surgery--The side effects of surgery
depend on the location of the tumor, the type of operation,
the patient's general health, and other factors. Although
patients are often uncomfortable during the first few days
after surgery, this pain can be controlled with medicine.
Patients should feel free to discuss pain relief with the
doctor or nurse. It is also common for patients to feel tired
or weak for a while. The length of time it takes to recover
from an operation varies for each patient.
Radiation Therapy--With radiation
therapy, the side effects depend on the treatment dose and
the part of the body that is treated. The most common side
effects are tiredness, skin reactions (such as a rash or redness)
in the treated areas, and loss of appetite. Radiation therapy
also may cause a decrease in the number of white blood cells,
cells that help protect the body against infection. Although
the side effects of radiation therapy can be unpleasant, the
doctor can usually treat or control them. It also helps to
know that, in most cases, they are not permanent.
Chemotherapy--The side effects
of chemotherapy depend mainly on the drugs and the doses the
patient receives. Generally, anticancer drugs affect cells
that divide rapidly. These include blood cells, which fight
infection, help the blood to clot, or carry oxygen to all
parts of the body. When blood cells are affected by anticancer
drugs, patients are more likely to get infections, may bruise
or bleed easily, and may have less energy. Cells that line
the digestive tract also divide rapidly. As a result of chemotherapy,
patients may have side effects, such as loss of appetite,
nausea and vomiting, hair loss, or mouth sores. For some patients,
the doctor may prescribe medicine to help with side effects,
especially with nausea and vomiting. Usually, these side effects
gradually go away during the recovery period or after treatment
Hair loss, another side effect of chemotherapy, is a major
concern for many patients. Some chemotherapy drugs only cause
the hair to thin out, while others may result in the loss
of all body hair. Patients may feel better if they decide
how to handle hair loss before starting treatment.
In some men and women, chemotherapy drugs cause changes that
may result in a loss of fertility (the ability to have children).
Loss of fertility may be temporary or permanent depending
on the drugs used and the patient's age. For men, sperm banking
before treatment may be a choice. Women's menstrual periods
may stop, and they may have hot flashes and vaginal dryness.
Periods are more likely to return in young women.
In some cases, bone marrow transplantation and peripheral
stem cell support are used to replace tissue that forms blood
cells when that tissue has been destroyed by the effects of
chemotherapy or radiation therapy.
Hormone Therapy--Hormone therapy
can cause a number of side effects. Patients may have nausea
and vomiting, swelling or weight gain, and, in some cases,
hot flashes. In women, hormone therapy also may cause interrupted
menstrual periods, vaginal dryness, and, sometimes, loss of
fertility. Hormone therapy in men may cause impotence, loss
of sexual desire, or loss of fertility. These changes may
be temporary, long lasting, or permanent.
Biological Therapy--The side effects
of biological therapy depend on the type of treatment. Often,
these treatments cause flu-like symptoms such as chills, fever,
muscle aches, weakness, loss of appetite, nausea, vomiting,
and diarrhea. Some patients get a rash, and some bleed or
bruise easily. In addition, interleukin therapy can cause
swelling. Depending on how severe these problems are, patients
may need to stay in the hospital during treatment. These side
effects are usually short-term; they gradually go away after