Smoking remains the greatest risk factor for lung cancer, accounting for
as many as 9 out of every 10 cases of the disease. Your risk increases
with the number of cigarettes you smoke each day and the number of years
you have smoked. Your risk is also greater if you start smoking early in
life even if you later quit. Smoking filtered, low-tar or low-nicotine
tobacco offers no additional protection because most people who smoke
these cigarettes inhale more deeply, which also increases the risk. The
good news is that it's never too late to quit smoking. Quitting at any
age can lower your risk of developing lung cancer.
Other risk factors include:
or former women smokers are at greater risk of lung cancer than are
men who have smoked an equal amount. Although the exact reasons for
this are unknown, some experts speculate that women may have a
greater susceptibility to the cancer-causing substances found in
tobacco. Others believe that estrogen may play a role. Women also
are known to inhale more than men do, and they are less likely to
Even if you don't
smoke yourself, you're at high risk of lung cancer if you're exposed
to the smoke of others. Daily exposure to secondhand smoke may
increase your chances of developing lung cancer by as much as 30
percent. The Environmental Protection Agency has determined that
secondhand smoke causes at least 3,000 lung cancer deaths a year.
Second only to smoking as a cause of lung cancer,
radon comes from the natural (radioactive) breakdown of uranium in
soil, rock and water that eventually becomes part of the air you
breathe. Although unsafe levels of radon can accumulate in any
building, the greatest exposure risk most people face is at home.
The Surgeon General and the Environmental Protection Agency
recommend that all homeowners check for the presence of radon. The
best tests are those that take 3 to 6 months.
asbestos and other chemicals.
to asbestos and other cancer-causing agents such as vinyl
chloride, nickel chromates and coal products also can increase
your risk of developing lung cancer, especially if you're a smoker.
cancer is much more prevalent among African Americans than it is
among whites. African American men are two to four times more likely
to develop lung cancer than are their white counterparts. They also
develop the disease at an earlier age and are less likely to
survive. Doctors don't think there's a genetic reason for this
disparity. Rather, it is more likely to be related to inequities in
health care and to environmental factors.
Screening and diagnosis
Screening for lung cancer is controversial. Some doctors believe that smokers, especially
those 50 years or older, should have an annual chest X-ray, although
having annual chest X-rays has never been shown to be of particular
standard chest X-ray can reveal an abnormal mass or nodule in your
lungs. And a CT scan may show very small lesions and whether cancer has
spread to other areas. But as with all types of cancer, lung cancer can
be definitively diagnosed only by looking at a tissue sample (biopsy)
under a microscope. The sample may be removed using one of the following
In this test, a flexible tube called a bronchoscope is passed into
your airway. The bronchoscope allows your doctor to look inside your
lungs as well as to take a tissue sample for examination in the
In this test, an instrument passed through a small incision at the
base of your neck allows your doctor to take a biopsy of lymph nodes
in your chest. This helps determine how far the cancer has spread
and whether surgery is a reasonable option for removing the tumor.
Using an X-ray or CT scan for guidance, your doctor takes a small
needle and places it into a mass in your lung, removing a small
piece for study.
If you have a cough and are producing sputum, looking at the sputum
under the microscope can sometimes reveal the presence of lung
If you have fluid in your chest cavity, your doctor can remove a
sample by inserting a thin needle into your chest between the ribs.
The fluid is then examined in the laboratory for presence of cancer
cells. When large amounts of fluid are present, thoracentesis can
improve your breathing.
In this procedure, your doctor inserts a tube (endoscope) through a
small incision between your ribs and partially collapses one of your
lungs. This creates a space through which a pen-sized instrument
with a video device is passed between the ribs and through your
chest wall. Your doctor then can perform biopsies of nodules or
masses while watching the procedure on a video screen. Your lung
will expand again after the procedure.
Staging is a system of classifying information about cancer, including
where and to what extent the cancer has spread. In many cases, Roman
numerals are used to describe stages, with 0 being the least advanced
and IV the most advanced. Your doctor uses this information to determine
what treatment you need and to evaluate how your cancer might progress.
Non-small cell lung cancer
Non-small cell lung cancer is staged according to the size of the tumor,
the level of lymph node involvement and the extent to which the cancer
has spread. Stages of non-small cell lung cancer include:
At this stage, cancer is limited to the lining of the air passages
and hasn't invaded lung tissue. Stage 0 cancers almost always are
found during bronchoscopy, which is likely to have been performed to
assess an abnormality on a chest X-ray. If found and treated
promptly, cancers at this stage usually can be eliminated.
Cancer at this stage has spread to layers of lung tissue but not to
the lymph nodes.
This stage cancer has invaded neighboring lymph nodes or spread to
the chest wall.
At this stage, cancer has spread from the lung to lymph nodes beyond
the lung area.
The cancer has spread locally to areas such as the heart, blood
vessels, trachea and esophagus all within the chest.
The cancer has spread to other parts of the body, such as the liver,
bones or brain.
Small cell lung cancer
Small cell lung cancer is staged differently from non-small cell types.
Rather than using numbers, it's classified as either limited or
Cancer is confined to one lung and to its neighboring lymph nodes.
Cancer has spread beyond one lung and nearby lymph nodes, and may
have invaded both lungs, more remote lymph nodes or other organs.
Your lungs are abundantly supplied with blood and lymph a fluid that
helps return water and proteins from your tissues to your blood. Lung
cancer spreads easily to other parts of your body through your
bloodstream and lymph system.
Small cell cancer, in particular, is a fast-growing tumor that quickly
spreads to other organs. At the time of diagnosis, this type of cancer
has already spread in more than two-thirds of people with the condition.
Without treatment, the tumor will continue to grow and may prove fatal
within a matter of months.
This kind of cancer responds very well to chemotherapy and radiation
therapy better than do non-small cell lung cancers. But even when
there is a positive response to treatment, relapses usually occur within
two years. Unfortunately, at that point the cancer usually isn't as
responsive to further therapy.
In addition, some non-small cell lung cancers even those identified at
any early stage may spread undetectably (micrometastasis) to lymph
nodes and other organs. As a result, cancer can reappear months and even
years after treatment.