What is lung cancer?
It can be devastating to find out
that you or someone close to you has lung cancer. It's a serious illness in
which some of the cells in your lungs have started to grow out of control,
invading and destroying other cells. In the weeks and months to follow, you
will probably have many different emotions, including anxiety about what lies
ahead.
Almost before you have had time to
take in what the doctors have told you, you will be offered a range of tests
and treatments that aim to get rid of your cancer or relieve your symptoms, or
both. The treatments you're offered will depend on the type of lung cancer you
have, how large it is, and whether it has spread. A lot will also depend on how
you feel about your illness and how you would like it to be treated.
If you are diagnosed with lung
cancer, you will need to make some important decisions about your treatment.
We hope our information will answer
your questions about lung cancer. It may also help you to talk with your doctor
about the best treatments for you.
Some
people want to know more about their cancer than others. Some will choose to have treatments that may help them
live longer but which could have unpleasant, sometimes harmful, side effects.
Other people prefer to enjoy as much of life as they can.
There's no
right or wrong way for you to deal with your cancer. The most important thing is for you to feel comfortable
with the decisions you make. It's also essential that your medical team and
those who care about you listen to what you say and respect your wishes.
- Lung cancer is the second most common type of cancer in both men and women (not counting skin cancer). It is the leading cause of death from cancer in the United States.
- By the time they are diagnosed, most people's lung cancer has spread outside of their lungs.
- You will be offered a range of treatments that aim to get rid of the cancer and improve your symptoms.
- Most treatments have side effects. These should be weighed against the benefits of the treatment.
- Cigarette smoking is the most common cause of lung cancer. The best way to prevent lung cancer is not to smoke.
You have two lungs. They sit in your
chest, inside your rib cage, one on each side of your heart. They are covered
by a layer of moist tissue called the pleura.
When you breathe in, your lungs fill
with air.
Your lungs are a little like two
spongy, elastic bags that fill up with air as you breathe in. They empty as you
breathe out. The right lung is divided into three sections. These sections are
called lobes. The left lung has two sections (or lobes).
Keeping your lungs healthy is
important. They take oxygen from the air you breathe, which your blood then
carries around your body. When you breathe out, they get rid of carbon dioxide,
which is a waste product made by your body.
Here's how air travels into your
lungs.
Your windpipe (trachea) is the air passage that leads
from your throat into your chest. In your chest, your windpipe divides into two
smaller airways (called bronchi).
Each airway leads into a lung.
Inside your lungs, the airways
divide into even smaller airways (called bronchioles). At the end of each of these smaller airways are
little air sacs (called alveoli).
When you breathe in, air travels
down your windpipe, through the airways, into your lungs and then into the
smaller airways and the air sacs.
The air sacs in your lungs are
connected to the network of blood vessels that surrounds your lungs. Oxygen
from the air you breathe in passes through the thin walls of the air sacs and
into these blood vessels. Then, the oxygen is carried back to your heart and
pumped around your body. At the same time, carbon dioxide (which is made as a
by-product of breathing) passes from your blood into the air sacs. The carbon
dioxide leaves your body when you breathe out.
This is an X-ray picture of normal
lungs. You can see the heart in the middle.
Also inside your chest, lying
between your lungs, are:
- Your heart
- The main blood vessels that carry blood to and from your heart and the rest of your body
- The tube that carries food from your mouth to your stomach. This tube is called the esophagus.
When your body's cells are healthy,
they divide, grow old, then die and are replaced in an orderly way. But when
you get cancer, your cells grow and multiply too quickly.
In lung cancer, abnormal cells group
together to form a lump called a tumor.
This means your cells don't have
time to develop into normal, healthy cells. They may be the wrong shape and may
not work properly. And they tend to lie on top of one another instead of in
neat rows. Lung cancer can start almost anywhere in your lungs, but it usually
starts in your airways. Abnormal cells tend to group together and form a lump,
which is called a tumor. This
slowly gets bigger.
Nearly all types of lung cancer can
spread to other parts of your body and form more tumors. These are called
secondary tumors. You may hear doctors talk about metastasis. This is the word doctors use to describe the way
cancer spreads.
Doctors divide lung cancer into two
main kinds, based on what the cancer cells look like when examined in the
laboratory.
The main types of lung cancer are:
Non-small-cell
lung cancer (NSCLC). This is the most common
kind. About 4 in 5 cases of lung cancer are this type. It can start in
different parts of the lung. There are three different types of non-small-cell
cancer.
- Adenocarcinoma: This kind of cancer grows in certain glands that produce mucus. It usually starts in the airways at the outer edges of the lungs. It is the most common type of non-small-cell lung cancer, making up about two-fifths of all cases of lung cancer.
- Squamous cell carcinoma: This is a slow-growing cancer that affects the airways. It makes up about one-third of all lung cancers.
- Large cell carcinoma: This type of cancer is made up of larger cells than other forms of lung cancer. About 15 percent of lung cancers are this type. 3
Small-cell
lung cancer (SCLC). About 1 in 5 cases of lung
cancer are this type. Doctors also call this sort of lung cancer oat cell cancer because it's made up
of small cells that look like oats. These cells grow and spread more quickly
than the cells in non-small-cell lung cancer.
Some things increase your chance of
getting lung cancer. Doctors call these things risk factors. Having a risk
factor doesn't mean you'll definitely get lung cancer. It just means you're
more likely to get it than someone who doesn't have the risk factor.
We've listed the main risk factors
for lung cancer below. The most important is smoking. But sometimes people who have never smoked still get lung
cancer.
If you think you have a high risk of
getting lung cancer, you may wonder if there is some way of being tested that
would catch lung cancer early, before it grows. This kind of test is called screening, but so far it hasn't been
very successful for finding lung cancer.
Smoking is responsible for 8 out of
10 deaths from lung cancer. Men who smoke are 22 times more likely to die from
the disease than those who don't smoke. Women who smoke have a 12-fold greater
risk of dying from lung cancer than nonsmokers.
Smoking leads to cancer because
cells in the lung become damaged by poisonous chemicals in cigarette smoke.
And, over time, these cells become cancerous.
How much you smoke is important,
too. If you smoke less than half a pack per day, you're 15 times more likely to
die from lung cancer than a nonsmoker. If you smoke one or two packs daily,
you're 42 times more likely to die from lung cancer than someone who doesn't
smoke.
Switching to a different brand with
less tar or less nicotine does not make any difference to your risk of getting
lung cancer. There's no such thing as a safer cigarette. The poisonous
chemicals in smoke that can cause lung cancer are also found in marijuana
cigarettes, so these are not a safe option.
Smoking cigars or a pipe also gives
you a higher chance of getting lung cancer, even if you don't inhale.
Living or working in a smoky
atmosphere makes it more likely you will get lung cancer, even if you don't
smoke. This is called passive smoking.
Living with a smoker increases your risk of lung cancer by one-third. 5
In 1990, the Environmental Protection Agency estimated that between 3,000 and
4,000 deaths from lung cancer were caused by passive smoking.
If you smoke or used to smoke, you
may feel that this has caused your lung cancer and you may feel guilty. You may
think other people blame you for getting lung cancer. You may even think that
your doctor doesn't have much sympathy. But you shouldn't blame yourself for
smoking. Nicotine is a highly addictive drug. And most people start smoking
when they are teenagers and get addicted when they're too young to know any
better. Also, some people with lung cancer have never smoked at all.
If you're African-American, you have
a higher chance of getting lung cancer than a white American. Researchers think
that this is because more African-Americans smoke, although there may also be a
difference in the way their bodies deal with tobacco smoke. Researchers also
think that African-Americans may, on average, have more fat in their diet. This
could have an effect on their risk of getting lung cancer. 7 If
you're African-American or native Hawaiian and smoke less than 30 cigarettes a
day, you are more likely to get lung cancer than other groups of Americans who
also smoke the same amount.
People who are Native American,
Hispanic, Asian-American, or Japanese-American all have less lung cancer than
average in the United States. These groups tend to smoke less, and the lower
levels of lung cancer may also be linked to differences in diet and their genes
(the inherited material in cells that controls how cells behave and grow).
These tables show how common cancer is in different ethnic groups in the United
States.
Ethnic group
|
Number of lung cancer cases per 100,000 men
|
Native American
|
14
|
Hispanics, Japanese, Chinese,
Filipinos, Koreans
|
42 to 53
|
Alaska Natives, Hawaiians, whites,
Vietnamese
|
71 to 89
|
African-Americans
|
117
|
Ethnic group
|
Number of lung cancer cases per 100,000 women
|
Japanese
|
15
|
Koreans, Filipinos, Hispanics,
Chinese
|
16 to 25
|
African-Americans, Vietnamese,
whites, Hawaiians
|
31 to 44
|
Alaska Natives
|
51
|
Lung cancer is more common in older
people, probably because they have been smoking longer. In the United States,
only around 2 in 100 people who have lung cancer are under age 45 when they get
the disease.
Young people who get lung cancer
tend to be heavy smokers who started smoking at a young age. They also tend to
have a family history of the disease. 7
If you work with certain materials
used in industry, you may have a higher chance of getting lung cancer. About 10
percent to 15 percent of lung cancer cases are probably due to working with
cancer-causing substances, the most common of which is asbestos.
All types of asbestos fibers cause
lung cancer, but long-term exposure to types of asbestos called crocidolite or amosite carries the highest risk. It can take many years for the
cancer to develop. The dangers of asbestos are now well-known, and there are
laws governing how it is used. So there should be fewer lung cancers due to
asbestos in the future.
Other chemicals that can cause lung
cancer include arsenic and chromium. Nickel and vinyl chloride
also carry a small risk. These substances are used in various industries, but
there are laws about their use.
Radon is an invisible, odorless, and
tasteless gas that is found naturally in soil and rocks. High levels of radon
are found in buildings built on land that contains a lot of radon. If you live
or work in one of these areas, you may have an increased chance of getting lung
cancer.
The average concentration of radon
in the home is 1.25 pCi/L, where pCi/L stands for picocuries (a measure of the
amount of radon) per liter of air. Radon levels more than 4 pCi/L are
considered unsafe. Although radon gas is thought to cause lung cancer,
researchers haven't proved whether there is a link.
Some studies have suggested there
might be a link between air pollution and lung cancer. Researchers are trying
to find out why this might be. If you breathe in certain particles from the
air, they may damage the cells in your lungs. These damaged cells may become
cancerous.
The main air pollutants are from
motor vehicles, and include carbon
monoxide, hydrocarbons, sulfur oxide, and nitrogen oxide. However, if pollution
does cause cancer, the risk is tiny compared to the risk from smoking. Studies
have shown that air pollution may cause less than 1 in 100 cases of lung
cancer.
If you have one or more other
persistent (chronic) lung diseases, such as tuberculosis, asthma, emphysema, or
chronic bronchitis, you are slightly more likely to get lung cancer than other
people.
If you smoke, you may have a
condition called chronic obstructive pulmonary disease (COPD). If you have
COPD, you are more likely to get lung cancer. 7 In COPD, not enough
air flows into or out of the lungs. COPD is nearly always caused by smoking.
If your parents, brothers, or
sisters have had lung cancer, you are slightly more likely to get the disease
than people with no family history.
The TNM system is used to classify your lung cancer. It looks at three
factors:
- T is for tumor
- N is for (lymph) nodes
- M is for metastasis. (Metastasis is when the cancer spreads to other parts of your body, such as your bones.)
Each factor is given a number.
Generally, lower numbers mean your cancer is smaller and has not spread far (if
at all).
- For T: The number tells you how big your cancer is and whether the cancer has spread outside the lung.
- For N: The number tells you whether your lung cancer has spread to your lymph nodes. Cancer cells can grow in the nodes and then travel from there to other parts of the body.
- For M: The number tells you whether your lung cancer has spread to other parts of your body.
The numbers are then sometimes
followed by letters. These tell the doctor how the cancer was found and they
give more detail about how far it has spread.
Here is an explanation of what each
letter and number says about your cancer.
TNM
|
What it means
|
|
T (tumor)
|
TX
|
Cancer cells have been found but
your doctor cannot find a tumor (lump).
|
T0
|
There is no sign of lung cancer.
|
|
Tis
|
Your tumor is only in the lining
of the airway (in the bronchus or bronchiole). Doctors call this carcinoma in
situ.
|
|
T1
|
The size of your tumor is 3
centimeters (cm) or less.
|
|
T2
|
Your tumor is more than 3 cm in
size and it has started to grow into the covering around your lungs (pleura).
But it is at least 2 cm from the point at which your windpipe (trachea)
divides into the left and right airways (bronchi).
|
|
T3
|
Your tumor has spread into the
covering around the lungs (pleura) or chest wall and is less than 2 cm from
the point at which the windpipe (trachea) divides into the left and right
airways (bronchi).
|
|
T4
|
Your tumor has spread to other
tissues in your chest, such as your heart, your main blood vessels, your
windpipe (trachea) or the tube that carries food to the stomach (esophagus).
Or it is growing on the covering around the lung (pleura). This causes fluid
containing cancer cells to build up around the lung.
|
|
N (nodes)
|
NX
|
Doctors can't tell if there's
cancer in your lymph nodes. (You may not have been able to undergo the
necessary tests.)
|
N0
|
Your lung cancer has not spread to
your lymph nodes.
|
|
N1
|
Your lung cancer has spread to
lymph nodes near your lung.
|
|
N2
|
Your lung cancer has spread to
lymph nodes in the middle of your chest.
|
|
N3
|
Your lung cancer has spread to
lymph nodes near your other lung or to lymph nodes above your collarbone.
|
|
M (metastasis)
|
MX
|
Doctors can't tell if your cancer
has spread. (You may not have been able to undergo the necessary tests.)
|
M0
|
Your lung cancer has not spread to
another part of your body.
|
|
M1
|
Your lung cancer has spread to
another lobe of your lung or to another part of your body.
|
Key:
2 cm = 8/10 of an inch
3 cm = 1.2 inches
If your lung cancer is described as
T1N1M0, it means that the tumor (lump) is 3 centimeters or smaller in size, has
spread only to lymph nodes nearby and has not spread to other parts of your
body.
If you have non-small-cell lung
cancer, doctors use the TNM system to stage your cancer on a scale of 0 through
4. Stage 0 is the least advanced stage of lung cancer (doctors call it
carcinoma in situ) and stage 4 is the most advanced. Doctors call stage 1 and
stage 2 lung cancer early disease.
Stage 3A is called locally advanced
disease, and stages 3B and 4 are advanced
disease. Most people with lung cancer have advanced disease by the time
they are diagnosed.
Here is an explanation of what
stages 1 to 4 mean.
- Stage 1: The cancer is only in the lung.
- Stage 2: The cancer is small but has spread to the lymph nodes closest to the affected lung (stage 2A) or into the chest wall, the outer covering of the lung, the diaphragm or the outer covering of the heart (stage 2B).
- Stage 3: The cancer has spread to the lymph nodes further away from the affected lung but is still on the same side of the chest (stage 3A) or to the lymph nodes on the other side of the chest or collar bone, or to other places in the chest (stage 3B). Stage 3B can also mean that there is more than one tumor in the lung or that fluid around the lung (also known as pleural fluid) contains cancer cells.
- Stage 4: The cancer has spread to another lobe of the lung from where it started, or to other parts of the body (for example, the liver, or brain).
By the time they are diagnosed:
- A quarter of non-small-cell lung cancer patients have cancer that hasn't spread
- A fifth have cancer that has spread to nearby lymph nodes
- More than half have cancer that has spread to other distant parts of the body.
If you have small-cell lung cancer,
your doctors won't describe the stage in such a complicated way as for
non-small-cell lung cancer. 16 They will describe the cancer as one
of two types.
- Limited stage disease: The cancer is on one side of the chest
- Extensive stage disease: The cancer has spread beyond one side of the chest.
About two-thirds of people with
small-cell lung cancer have extensive disease when they are diagnosed, and
about one-third have limited stage disease.