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The Leading Cause of Cancer Death ( courtecy;- medicineNet.com
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Lung cancer has emerged as the leading cancer killer. Learn
about lung cancer symptoms and treatments.
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Lung Cancer: The Leading
Cause of Cancer Death
Lung cancer has emerged
as the leading killer of men and women stricken with invasive cancer, affecting
husbands and wives, friends and neighbors, and causing suffering for many
families. In the United States, lung cancer overtook breast cancer as the leading
cause of cancer deaths in women in 1987. Lung cancer deaths account for a
quarter of all American cancer deaths, killing more people every year than
prostate, breast, and colon cancer combined. Over 157,000 Americans are
estimated to have died from lung cancer in 2015.
This disease is
difficult to detect in its early stages, and treatments for lung cancer in its
later stages provide a poor prognosis: Those with stage IV non-small cell lung
cancer—the most common type—have an estimated 1 percent survival rate five
years after diagnosis. The other type of lung cancer—small cell lung cancer—is
even more aggressive. According to the American Cancer Society, the overall
survival rate for lung cancer as of Jan. 1, 2014 stands at just 3%.
What Causes Lung Cancer?
The exact cause
of lung cancer is still being investigated. Certain risk factors have been
shown to play a part in causing cells to become cancerous. Risk factors for
lung cancer include smoking, exposure to air pollution, and genetics.
Does Smoking Cause Lung Cancer?
The major cause
of lung cancer in men and women is mainly due to cigarette smoking. In 1876, a
machine was invented to make rolled-up cigarettes and thus provided cheap
tobacco products to almost everyone. At that time, lung cancer was relatively
rare. Smoking dramatically increased and so did lung cancers following this
innovation. Currently about 90% of all lung cancers are related to smoking.
Radon gas, pollution, toxins, and other factors contribute to the remaining
10%.
Cigarettes and
cigarette smoke contains over 70 cancer-causing chemicals (carcinogens). Some
of the carcinogens found in cigarette smoke include:
·
Lead (a highly poisonous metal)
·
Arsenic (an insecticide)
·
Cadmium (a battery component)
·
Isoprene (used to make synthetic rubber)
·
Benzene (a gasoline additive)
Cigar smoke is
particularly heavy on tobacco-specific nitrosamines (TSNAs), which are
considered particularly cancerous.
Lung Cancer and Cilia
Cigarette smoke
damages and can kill hair-like projections on airway cells termed cilia. The
cilia normally sweep out toxins, carcinogens, viruses, and bacteria. When the
cilia are damaged or destroyed by smoke, all of these items may accumulate in
the lungs and may cause problems such as infections or lung cancer.
Lung Cancer Symptoms
Unfortunately,
lung cancers often have either no early symptoms or nonspecific early symptoms
that people often dismiss. About 25% of people with lung cancer and no symptoms
are diagnosed after having a chest X-ray or CT during a routine test or as a
procedure for other problems. Lung cancer symptoms that may be detected are
included below.
List of Lung Cancer Symptoms
·
Cough (chronic, recurrent)
·
Fatigue
·
Weight loss
·
Shortness of breath or wheezing
·
Coughing up phlegm that contains blood
·
Chest pain
Three Common Lung Cancer Screening Methods
Screening for
lung cancer is usually accomplished using three methods.
Physical Exam
A physical exam
will look for signs of wheezing, shortness of breath, cough, pain and other
possible signs of lung cancer. Depending on the advancement of the cancer,
other early signs of lung cancer symptoms may include a lack of sweating,
dilated neck veins, face swelling, excessively constricted pupils, and other
signs. The physical exam will also include the patient’s history of smoking and
a chest X-ray.
Sputum Cytology Exam
A sputum
cytology exam involves a microscopic examination of a patient’s mucus (sputum).
Spiral CT Exam
This method of
CT scanning builds a detailed image of the body’s internal workings. Inside a
spiral CT machine, detailed images are taken of the relevant parts of the
patient’s body. Those images are then linked to an X-ray machine to create 3D
images of the patient’s internal organs. These images may reveal potentially
cancerous tumors.
A study by
researchers suggested that people aged 55 to 74 years old who had smoked at
least one pack of cigarettes a day for 30 or more years may benefit from a
spiral CT study of the lungs. At best, the screening methods find about 30% of
lung cancers leaving the bulk (about 70%) cancers of lung undetected. In
addition, some test results are not clearly diagnostic which can lead to
patient concerns and possibly unnecessary biopsies or surgeries.
Lung Cancer Diagnosis
If the
screening tests suggest a person has lung cancer, definitive diagnostic tests
may be done by a pathologist. The pathologist will examine the patient’s lung
cells in sputum, phlegm, or from a biopsy sample to type and stage the lung
cancer.
Lung Cancer: Biopsy
As stated
previously, a tissue sample taken from the patient’s suspected cancer is
usually the best method to establish a definitive lung cancer diagnosis. In
general, lung biopsies are obtained by either needle biopsy, a lung
bronchoscopy technique, or by surgical removal of tissue. Many other tests may
be done to get more information about the cancer’s spread.
See the
following slides for types of lung cancer and lung cancer stages, including
stage IV lung cancer.
Types of Lung Cancer
There are only
two major types of lung cancers: small cell lung cancer and non-small cell lung
cancers. Less than 5% of lung cancer tumors will take the form of a carcinoid
tumor, while other cancerous tumors are even more rare, including adenoid
cystic carcinomas, lymphomas, and sarcomas. Although cancer from another part
of the body may spread to the lungs, these are not categorized as lung cancer.
Non-Small Cell Lung Cancer
Non-small cell
lung cancers are the most common type of lung cancer. These cancers account for
about 90% of all lung cancers and are less aggressive than small cell lung
cancers, meaning they spread to other tissues and organs more slowly.
Small Cell Lung Cancer
Small cell lung
cancer, also called oat cell lung cancer, accounts for about 10% of all lung
cancers. This form of cancer tends to spread quickly.
Lung Cancer Stages: Stage 0 Through Stage 4
After the type
of lung cancer is determined, the type is then assigned a lung cancer stage.
The stage indicates how much the cancer has spread in the body (for example, to
the lymph nodes or to distant organs like the brain). Stages for non-small cell
lung cancers are different from small cell lung cancers. The stages listed
below are taken from the National Cancer Institute’s lung cancer staging
information:
Small Cell Lung Cancer Stages
Limited stage:
In this form, small cell lung cancer is limited to one side of the chest,
typically in the lungs and lymph nodes. About one in three people with small
cell lung cancer have limited stage cancer upon the first diagnosis.
Extensive
stage: This refers to small cell lung cancer that has spread throughout one
lung, spread into both lungs, to lymph nodes on the other side of the chest or
to other body parts. About two in three people with small cell lung cancer have
extensive stage cancer upon first diagnosis.
Non-Small Cell Lung Cancer Stages
Occult (hidden)
stage: In this stage, cancer cells appear in a sputum cytology exam or other
test, though no tumor location can be found.
Stage 0
(carcinoma in situ): In this lung cancer stage, cancer cells are only found in
the top layer of cells lining air passages and has not crept deeper into the
lungs or spread beyond the air passages.
Stage I: A
small lung cancer tumor (less than 3 centimeters across) is discovered, but has
not spread to surrounding lung membranes, lymph nodes, or the main bronchial
branches of the lungs.
Stage II: There
are several ways that stage II lung cancer may be diagnosed. One is that the
lung cancer has spread to lymph nodes near the lungs.
·
Stage IIA: If the tumor is between 3 centimeters and 5
centimeters, the lung cancer is defined as stage IIA. Other factors can lead to
this classification as well.
·
Stage IIB: If the lung cancer tumor is between 5 centimeters and 7
centimeters, it is categorized as Stage IIB. Other factors can lead to this
classification as well.
Stage III: As
in stage II lung cancer, stage III has several definitions. One is that the
lung cancer is found in both the lung and lymph nodes in the middle of the
chest. Stage III lung cancer is divided into two subsets.
·
Stage IIIA: This defines a lung cancer that has spread on the same
side of the chest from where it started.
·
Stage IIIB: This defines a lung cancer in which the cancer has
spread to either the opposite side of the chest or above the collar bone.
Stage IV: This
is the most advanced stage of lung cancer. The cancer can be any size, but two
of these three things have happened:
·
The cancer has spread to the opposite lung from where it began.
·
Cancer cells have been discovered in the fluid surrounding the
lung.
·
Cancer cells have been discovered in the fluid surrounding the
heart.
Lung Cancer Survival Rates
The American
Cancer Society statistics are currently based on people diagnosed between 1998
and 2000 so the data may not reflect the effects of newer treatments. The data
indicates that survival rates of patients living 5 years after being diagnosed
with non-small cell lung cancers was dependent on the stage of the disease.
Stage I was
about 49% (with surgical removal, about 75%) while stage IV survival was about
1%. Small cell lung cancers are more aggressive and the data, like that for
non-small cell lung cancers, is not reflective of current survival rates.
However, even
some data collected as late as 2008 indicates slow progress in increasing
5-year survival rates. The overall rate of both limited-stage and
extensive-stage small cell lung cancer is about 6%. The overall rate of all
stages (I to IV combined) non-small cell lung cancer is about 15%.
cell lung cancers was dependent on the stage of the disease.
Stage I was
about 49% (with surgical removal, about 75%) while stage IV survival was about
1%. Small cell lung cancers are more aggressive and the data, like that for
non-small cell lung cancers, is not reflective of current survival rates.
However, even some
data collected as late as 2008 indicates slow progress in increasing 5-year
survival rates. The overall rate of both limited-stage and extensive-stage
small cell lung cancer is about 6%. The overall rate of all stages (I to IV
combined) non-small cell lung cancer is about 15%.
Early-Stage Lung Cancer Treatment: Surgery
Early stage
(stage 0 or even some stage I) cancer treatment of non-small cell lung cancer
may benefit from surgery. Part or all of a lung segment that contains the
cancer may be removed; in some individuals, this may result in a cure. However,
many patients still undergo chemotherapy, radiation therapy or both to kill any
cancer cells not removed by surgery. Because small cell lung cancers are almost
never diagnosed early, surgery (and other treatments) may prolong life but
rarely, if ever, result in a cure.
Advanced Lung Cancer Treatment
Most small cell
and non-small-cell lung cancers are treated with chemotherapy; they may also be
treated with radiation therapy and surgery. In many patients with advanced
disease, these methods may be used together, depending on the patient's
condition and recommendations by their cancer doctors
Targeted Lung Cancer Therapies
New therapeutic
treatments are being tried; for example, some therapies termed targeted
therapies are designed to prevent or stop lung cancer cells from growing by
targeting the new blood vessels that are needed to allow the cancer cells to
survive and grow; other treatments target growth and multiplication of lung
cancer cells by interfering with chemical signals required by growing or
multiplying cancer cells (illustrated in this slide).
Clinical Trials for Lung Cancer
In addition to
targeted therapies, there are a number of clinical trials that a person may
qualify for. Some may be available in your hometown. These clinical trials have
patients try the newest potentially helpful therapeutic methods and drugs to
combat lung cancers. The National Cancer Institute’s web site listed below
offers a list of current clinical trials; you and your doctor may find a
clinical trial that may help you with this disease.
Life After Lung Cancer Diagnosis
After a
diagnosis of lung cancer, it is not unusual to feel depressed and upset.
However, research is ongoing and it is possible to survive and extend your life
with treatment. Even with the diagnosis, there is evidence that people who
develop a healthy lifestyle and stop smoking do better than those who do not
change.
Lung Cancer and Secondhand Smoke
Tobacco smokers
put others at risk of developing lung cancer. A nonsmoker (wife, child,
significant other) who lives with a smoker has a 20% to 30% increase in risk of
developing lung cancer due to exposure to smoke concentrations in their local
environment.
Lung Cancer and Work Exposures
Although
smoking results in the highest risk of causing lung cancers, other
environmental exposures to certain compounds and chemicals increase the risk of
lung cancer. Such agents as asbestos, uranium, arsenic, benzene, and many
others increase the risk for developing lung cancers. Exposure to asbestos may
cause lung cancer (mesothelioma) many years after the initial exposure so
people may be at risk for lung disease for decades (10 to 40 years).
Lung Cancer and Radon Gas
Another
chemical, radon gas, is considered to be the second leading cause of lung
cancer. It occurs naturally but can seep into homes and collect in basements
and crawl spaces. It is colorless and odorless but can be detected with
relatively simple and inexpensive test kits. Smokers exposed to this gas have a
higher risk of developing lung cancer than nonsmokers.
Lung Cancer and Air Pollution
There are a
number of investigators that suggest air pollution contributes to the
development of lung cancers. Several studies present data that airborne
pollutants like diesel exhaust may cause some people to develop lung cancers.
Researchers estimate that about 5% of lung cancers are due to air pollutants.
Increased Risk Factors for Lung Cancer
Although much
is understood about lung cancers, there are still many things and situations
that are unclear. For example, it is unclear why some families have a history
of individuals with lung cancer and no clear risk factors. The same is true for
some patients who develop lung cancers with no clear risk factors. Another occurrence
such as drinking water that has high arsenic concentrations may increase lung
cancer risk but how the process happens is not clear. In addition, the reason
why adenocarcinoma in the lungs is more common in nonsmokers than smokers is
also not known.
Lung Cancer Prevention
For the
majority of lung cancers, prevention is possible if a person never smokes and
avoids second-hand smoke. For smokers who quit -- within 10 years -- the risk
of getting lung cancer drops to about the same risk as if they had never
smoked. Avoiding other risk factors (for example, certain chemicals or
compounds like benzene or asbestos or air pollution) may also prevent some
people from developing lung cancers.
Additional Information on Lung Cancer
For more
information about Lung Cancer, please consider the following:
·
Reviewed by Charles Patrick Davis, MD,
PhD on Friday, July 22, 2016
·
Lung Cancer
Symptoms, Stages, Treatment
·
·
Sources: 
·
This tool does not
provide medical advice.
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