The
lungs are two sponge like organs found in the chest. The right lung
has three sections, called lobes. The left lung has two lobes. The left
lung is smaller because the heart takes up more room on that side of the
body. The lungs bring air in and out of the body, taking in oxygen and
getting rid of carbon dioxide gas, a waste product.
The lining around the lungs, called the pleura, helps to protect the
lungs and allows them to move during breathing. The windpipe (trachea)
brings air down into the lungs. It divides into tubes called bronchi
(singular, bronchus) which divide into smaller branches called
bronchioles. At the end of these small branches are tiny air sacs known
as alveoli.
Most lung cancer starts in the lining of the bronchi, although it can also start in other parts of the lung.
Lung cancer often takes many years to develop. First, there may be
areas of pre-cancerous changes in the lung. These changes are not a mass
or tumor. They can’t be seen on an x-ray and they don’t cause symptoms.
But these changes can be found by special tests of cells in the lining
of the airways of lungs damaged by smoke.
As these pre-cancerous areas go on to become true cancer, they may
make chemicals that cause new blood vessels to form nearby. These new
blood vessels nourish the cancer cells and allow a tumor to form.
Finally, the tumor becomes large enough to show up on an x-ray.
Once lung cancer occurs, cancer cells can break away and spread to
other parts of the body in a process called metastasis. Lung cancer is a
life-threatening disease because it often spreads in this way before it
is found.
 |
Non-small cell cancer
|
 |
Small cell cancer
|
Types of Lung Cancer
There are
two main types of lung cancer and they are treated differently:
- Non-small cell lung cancer (NSCLC)
- Small cell lung cancer (SCLC)
If the cancer has features of both types, it is called
mixed small cell/large cell cancer. Other types of tumors can grow in the lungs as well. Some of these are not cancer and others are cancerous.
Carcinoid tumors, for example, are slow-growing and usually cured by surgery.
Non-Small Cell Lung Cancer (NSCLC)
About 85% of all lung cancers are of the non-small cell type. There
are 3 sub-types of NSCLC. The cells in these sub-types differ in size,
shape, and chemical make-up.
- Squamous cell carcinoma: about 25% to 30% of all lung cancers are of this kind. They are linked to smoking and tend to be found near the bronchus.
- Adenocarcinoma: this type accounts for about 40% of lung cancers. It is usually found in the outer part of the lung
- Large-cell undifferentiated carcinoma: about 10% to 15% of lung cancers are this type. It can start in any part of the lung. It tends to grow and spread quickly.
How many people get non-small cell lung cancer?
Lung
cancer is the leading cause of cancer death for both men and women.
More people die of lung cancer than of colon, breast, and prostate
cancers combined. Lung cancer is fairly rare in people under the age of
40.
In 2008, there will be about 215,020 new cases of lung cancer (both
small cell and non-small cell) in the United States and about 161,840
people will die from it. The average lifetime chance that a man will
develop lung cancer is 1 in 13. For a woman it is 1 in 16.
About 4 out of 10 people with lung cancer will still be living one year after finding out they have lung cancer.
What causes non-small cell lung cancer?
Different
cancers have different risk factors. Some risk factors, such as
smoking, can be controlled. Others, like a person's age or family
history, can't be changed. Several factors can increase the risk of lung
cancer.
- Smoking is by far the leading risk factor for lung
cancer. Tobacco smoke causes more than 8 out of 10 cases of lung cancer.
The longer a person has been smoking and the more packs per day sm
oked,
the greater the risk. If a person stops smoking before lung cancer
develops, the lung tissue slowly returns to normal. Stopping smoking at
any age lowers the risk of lung cancer.
- Cigar and pipe smoking are almost as likely to
cause lung cancer as is cigarette smoking. There is no evidence that
smoking low tar cigarettes reduces the risk of lung cancer.
- Second hand smoke: People who don’t smoke but who
breathe the smoke of others also have a higher risk of lung cancer.
Non-smoking spouses of smokers, for example, have a 30% greater risk of
developing lung cancer than do spouses of nonsmokers. Workers exposed to
tobacco smoke in the workplace are also more likely to get lung cancer.
- Hookah smoking has become popular among young
people. Although there is less tobacco in the product used for hookahs,
it is still dangerous and addictive.
- Arsenic, if found in high levels in drinking water, may increase the risk of lung cancer. The effect is even greater for smokers.
- Asbestos is another risk factor for lung cancer.
People who work with asbestos have a higher risk of getting lung cancer.
If they smoke as well, the risk is greatly increased. Although asbestos
was used for many years, the government has now nearly stopped its use
in the workplace and in home products. While it is still present in many
buildings, it is not thought to be harmful as long as it is not
released into the air. (Another type of cancer linked to asbestos (mesothelioma) can start in the lining of the lung.)
- Radon is a radioactive gas made by the natural
breakdown of uranium, which is found at higher than normal levels in the
soil in some parts of the United States. Radon can’t be seen, tasted,
or smelled. Radon can become concentrated indoors and create a possible
risk for cancer. Smokers are especially sensitive to the effects of
radon. State and local offices of the EPA (Environmental Protection
Agency) can provide information about how to test for radon in the home
- Cancer-causing agents in the workplace include the following:
- Uranium
- Beryllium
- Vinyl chloride
- Nickel chromates
- Coal products
- Mustard gas
- Chloromethyl ethers
- Gasoline
- Diesel exhaust
- Marijuana cigarettes have more tar than regular
cigarettes. Many of the cancer-causing substances in tobacco are also
found in marijuana. Marijuana is also inhaled very deeply and the smoke
is held in the lungs for a long time.
Medical reports suggest that marijuana could cause cancers of the mouth
and throat. But because marijuana is an illegal substance it is not
easy to gather information about its effects on the body.
- Radiation treatment to the lung: People who have
had radiation to the chest to treat cancer are at higher risk for lung
cancer, especially if they smoke. But non-smoking women who have
radiation to the breast after surgery for breast cancer do not have a
higher risk of lung cancer.
- Diseases such as silicosis and berylliosis (caused by breathing in certain minerals) also increase the risk of lung cancer.
- Personal and family history: If you have had lung
cancer, you have a higher risk of getting another lung cancer. Brothers,
sisters, and children of people who have had lung cancer may have a
slightly higher risk themselves.
- Diet: Some reports suggest that a diet low in
fruits and vegetables might increase the risk of lung cancer in people
who are exposed to tobacco smoke. It may turn out that fruits and
vegetables help protect against lung cancer.
- Air pollution: In some cities, air pollution may
slightly increase the risk of lung cancer. But the risk is still far
less than that caused by smoking.
During the past few years, scientists have made great progress in
understanding how risk factors produce certain changes in the DNA of
lung cells, causing the cells to become cancerous. DNA is the genetic
material that carries the instructions for nearly everything our cells
do.
Current research in this field is aimed at developing tests that can
find lung cancers at an early stage by spotting DNA changes. But these
tests are not yet ready for routine use. Therefore, doctors stress
avoiding tobacco smoke and the other risk factors listed above.
Can non-small cell lung cancer be prevented?
The best way to prevent lung cancer is
not to smoke
and to avoid people who do. If you already smoke, you should try to
quit. You should also avoid breathing in other people's smoke.
A good diet with lots of fruits and vegetables may also help prevent lung cancer.
Some people who get lung cancer do not have any known risk factors, so it is not possible to prevent all cases of lung cancer
How is non-small cell lung cancer found?
Because
most people with early lung cancer do not have any symptoms, only a
small number of lung cancers are found at an early stage. When lung
cancer is found early, it is often because of tests that were being done
for something else.
Screenings Tests for Lung Cancer
Screening is the use of tests or exams to find a disease (such as
cancer) in people who don’t have any symptoms. Because lung cancer often
spreads beyond the lungs before it causes symptoms, a good screening
test to find lung cancer early could save many lives.
- Chest x-rays and checking sputum (spit) under a
microscope to look for cancer cells have been studied for several years.
These studies have shown that this kind of screening does not find many
lung cancers early enough to improve a person’s chance for a cure. For
this reason, lung cancer screening is not usually advised even for
people at higher risk, such as those who smoke.
- Spiral CT scanning has shown some promise in
finding early lung cancer in smokers and former smokers. But it has not
yet known if this test will lower the chances of dying from lung cancer.
One major problem is that it finds a lot of things that turn out not to
be cancer. This leads to unnecessary tests and even surgery.
Common Signs and Symptoms of Lung Cancer
Although most lung cancers do not cause symptoms until they have
spread, you should report any of the following to your doctor right
away. Often these problems are caused by something other than cancer.
But if lung cancer is found, getting treatment right away could help you
live longer and relieve symptoms.
The most common symptoms are:
- A cough that does not go away
- Chest pain, often made worse by deep breathing
- Hoarseness
- Weight loss and loss of appetite
- Bloody or rust-colored sputum (spit or phlegm)
- Shortness of breath
- Infections such as bronchitis and pneumonia that keep coming back
- New onset of wheezing
When lung cancer spreads to distant organs, it may cause:
- Bone pain
- Weakness or numbness of the arms or legs
- Dizziness or seizure
- Yellow coloring of the skin and eyes (jaundice)
- Masses near the surface of the body, caused by cancer spreading to
the skin or to lymph nodes in the neck or above the collarbone
If you have any of these problems, you should see a doctor right away.
How is non-small cell lung cancer treated?
If
you have lung cancer, your treatment choices are surgery, radiation
therapy, and chemotherapy. More than one kind of treatment may be used,
depending on the stage of your cancer.
Your doctor will talk to you about treatment choices. The most
important factors to take into account include the stage of the cancer,
your overall health, the likely side effects of the treatment, and the
chance of curing the cancer or extending your life. Age alone should not
be a barrier to treatment. Older people can benefit from treatment as
much as younger people as long as their general health is good.
Types of Treatment for Non-Small Cell Lung Cancer Surgery
Surgery may be used to remove the cancer along with some of the lung tissue around it.
- Removing only part of a lobe (section) of the lung is called a wedge resection.
- If a whole lobe of the lung is removed, the surgery is called a lobectomy.
- If the entire lung is removed, the surgery is called a pneumonectomy.
- Lymph nodes are also removed so the doctor can see if the cancer has spread.
These operations are done with the patient asleep. A hospital stay of
1 or 2 weeks is usually needed. There will be some pain after the
surgery because the surgeon has to cut through the ribs to get to the
lungs. Other possible problems include bleeding, wound infections, and
pneumonia.
There is a new kind of surgery for people with early stage lung cancer. It is called
video-assisted chest surgery .
- A tiny camera can be placed through a small hole in the chest to help the surgeon see the tumor.
- Only small incisions are needed, so there is less pain after surgery.
- This approach is most often used for tumors smaller than about one and a half inches.
- The cure rate seems to be the same as for standard surgery.
- The doctor who does this surgery should have experience since it requires a lot of skill.
People whose lungs are in good condition (other than the cancer) can
often return to normal activities after a lobe or even an entire lung is
removed. But if they also have problems such as emphysema or chronic
bronchitis (common among heavy smokers), they may have long-term
shortness of breath.
For people who can't have the usual surgery because of lung disease
or other medical problems, or because the cancer is widespread, other
types of surgery (for example, laser surgery) can be done to relieve
symptoms.
Sometimes fluid collects in the chest and interferes with breathing.
This fluid can be removed through a small tube placed in the chest. Then
either talc or some type of drug is placed into the chest. This will
start a reaction that will help seal the space and prevent future fluid
buildup.
Radiation Therapy for Non-Small Cell Lung Cancer
Radiation therapy is treatment with high-energy rays (such as x-rays)
to kill or shrink cancer cells. The radiation may come from outside the
body (
external radiation). External radiation is the
type most often used to treat lung cancer. Also, radioactive materials
can be placed into or next to the tumor (
brachytherapy).
Radiation is sometimes used as the main treatment of lung cancer. It
might be used for people who are not healthy enough to have surgery. For
other patients, radiation might be used after surgery to kill small
areas of cancer that can't be seen and removed during surgery. Or it
could be used on the brain to try to prevent the spread of cancer there.
Radiation can also be used to relieve symptoms such as pain, bleeding,
trouble swallowing, or problems caused by the cancer spreading to the
brain.
Side effects of radiation could include:
- Mild skin problems
- Nausea
- Vomiting
- Tiredness
- Chest radiation may cause lung damage and trouble breathing or swallowing
Radiation therapy to the brain usually becomes most serious
1 or 2 years after treatment. These side effects could include memory
loss, headaches, trouble with thinking, and less sexual desire. These
side effects, though, are minor compared to those caused by a brain
tumor.
A special kind of radiation (called the
gamma knife)
can be used instead of surgery if the cancer spreads to the brain in
only 1 spot. In this method, several beams of radiation are focused on
the tumor over the span of a few minutes to hours. The head is held in
place with a rigid frame.
Chemotherapy for Non-Small Cell Lung Cancer
Chemotherapy is treatment with anticancer drugs given into a vein or
by mouth. These drugs enter the bloodstream and reach throughout the
body, making this treatment useful for cancer that has spread
(metastasized) to organs beyond the lung. Several drugs may be given at
the same time.
Chemotherapy drugs kill cancer cells but they also damage some normal
cells, causing side effects. These side effects depend on the type of
drugs used, the amount given, and the length of treatment.
You could have some of these short-term side effects:
- Loss of appetite
- Hair loss (temporary)
- Mouth sores
- Loose stools (diarrhea)
- A higher risk of infection caused by a shortage of white blood cells
- Bruising or bleeding after minor cuts caused by a shortage of blood platelets
- Fatigue or shortness of breath caused by low red blood cell counts
Some chemotherapy drugs can damage nerves. This can cause numbness in
the fingers and toes, and sometimes the arms and legs may feel weak.
Most of these side effects go away when treatment is over. If you
have any problems with side effects, be sure to tell your doctor or
nurse, as there are often ways to help.
There is a new drug (
erlotinib ) that works by
keeping cancer cells from growing. It is given, as a pill, to some
patients for whom chemotherapy is not working. Side effects can include
diarrhea, rashes, eye problems, vomiting, loss of appetite, and
tiredness.
For cancer cells to grow, they must form new blood vessels to “feed” the tumor. There is a drug (
Avastin)
which can keep new blood vessels from forming. It has been shown to
help people with advanced lung cancer live longer when it was given
along with chemotherapy. But it causes bleeding, so it can’t be used for
patients who are coughing up blood or whose cancer has spread to the
brain.
Non-Small Cell Lung Cancer Survival by Stage
Stage 5-year Survival Rate
I
|
47%
|
II
|
26%
|
III
|
8%
|
IV
|
2%
|
The 5-year survival rate refers
to the percentage of patients who live at least 5 years after their
cancer is found. Of course, some patients live much longer than 5 years.
Five-year relative survival rates means that people who die of other
causes are not included, and the rate only includes people who die from
lung cancer.
While these numbers provide an overall picture, keep in
mind that every person’s situation is unique and the statistics
can’t predict exactly what will happen in your case. Talk with your
cancer care team if you have questions about your own chances of a cure,
or how long you might survive your cancer. They know your situation
best.
Staging
Staging is the
process of determining how far the cancer has spread. This process is
very important because your treatment and the outlook for your recovery
depend on the stage of your cancer. The tests described above are also
used to stage lung cancer. There are different staging systems for small
cell and non-small cell lung cancer.
Staging of Non-Small Cell Lung Cancer
The system used to stage non-small cell lung cancer is the AJCC
system. Stages are described using Roman numerals from 0 to IV (0 to 4).
Some stages are further divided into A and B. In general, the lower the
number, the less the cancer has spread. A higher number, such as stage
IV (4), means a more serious cancer.
