Although lung cancer is the leading cause of cancer death in the U.S. in both men and women, it is also one of the most preventable kinds of cancer. At least four out of five cases are associated with cigarette smoking, and the cause-and-effect relationship has been extensively documented. During the 1920s, large numbers of men began to smoke cigarettes, presumably in response to increased advertising. Twenty years later, the frequency of lung cancer in men climbed sharply. In the 1940s, significantly more women became smokers. Twenty years later, there was a similar dramatic increase in lung cancer among women.
Lung tumors almost always start in the spongy, pinkish gray walls of the bronchi -- the tubular, branching airways of the lungs. More than 20 types of cancerous tumors that originate in the lung itself -- primary lung cancer -- have been identified. The major types of lung cancer are small-cell lung cancer and non-small cell lung cancer. The more common non-small cell variety is further divided into squamous cell carcinoma, adenocarcinoma, large-cell carcinoma, and more. Mixed tumors may also occur.
Non-Small Cell Lung Cancer
Squamous cell carcinoma usually starts in cells of the central bronchi, the largest branches of the bronchial tree. It accounts for 30% of lung cancers, and occurs more commonly in men and in smokers. It's the easiest to detect early, since its distinctive cells are likely to show up in tests of mucus samples. It also tends to be most curable if found early because it spreads relatively slowly and often does not spread outside of the lung.
Adenocarcinoma is the most common type of lung cancer accounting for 40% of all cases with its incidence increasing. It is most commonly seen in women and nonsmokers. It tends to originate along the outer edges of the lungs in the smaller airways. Adenocarcinoma tends to spread to the lymph nodes and distant organs. It's commonly a mixed type of tumor and may cause no symptoms initially.
Large-cell carcinomas are a group of cancers with large, abnormal-looking cells that tend to originate along the outer edges of the lungs. They are the least common of the non-small cell lung cancers accounting for 10%-15% of all cases. However, this type of tumor has a high tendency to spread to nearby lymph nodes and distant sites.
Small Cell Lung Cancer
Small-cell lung cancer is the most aggressive form of lung cancer. This cancer usually originates in the large, central bronchi. It spreads quickly, usually within 90 days, often before symptoms appear, making it particularly threatening. In fact, in up to 75% of patients with this type of cancer, the disease has spread by the time it’s diagnosed. It frequently spreads (metastasizes) to the liver, bone, and brain. Although responsive to chemotherapy, small-cell lung cancer is rarely associated with long-term survival.
About 226,000 people in the U.S. will be diagnosed with lung cancer in 2012. It is the second most common cancer in both men and women. However, it is the leading cause of cancer deaths in both sexes -- killing over 160,000 people each year.
An individual cancer sufferer's prognosis will vary according to the type of lung cancer involved, the person's overall health, and the stge of the cancer at the time of initial diagnosis.
What Causes Lung Cancer?
About 85% of lung cancer is caused by smoking and, as with any cancer, each person's genetics. The fact that lung cancer runs in some families suggests that a predisposition can be inherited. Additionally, certain genetic traits have been identified that make some people more susceptible than others to cancer-causing substances like those found in tobacco smoke.
Nonetheless, anyone who smokes one pack of cigarettes daily is 20 times more likely than a nonsmoker to develop lung cancer. For people who smoke more than two packs a day, the risk more than triples. Breaking the smoking habit reduces risk significantly, yet former smokers are always slightly more susceptible than nonsmokers. Secondhand tobacco smoke can also cause lung cancer, giving nonsmokers who live or work with smokers a somewhat higher lung cancer risk than those in smoke-free environments. In fact, approximately 3,000 people die each year of lung cancer associated with second hand smoke exposure. And those living in a home with a smoker have a 30% higher risk of developing lung cancer than in a smoke-free home.
Cancer-causing substances other than those found in tobacco or tobacco smoke can also cause lung cancer if inhaled over time. However, experts disagree about how much exposure to specific cancer-causing substances is dangerous. Workers who are exposed on a daily basis to asbestos have a 90-fold increase of getting lung cancer when compared to non-exposed persons. Workers exposed to uranium dust or the radioactive gas radon are also much more likely than the average person to develop lung cancer, especially if they are smokers.
Lung tissue that has been scarred by disease or infection, such as scleroderma or tuberculosis, is more susceptible to tumor growth within the scar tissue (called a scar carcinoma). Because of a high frequency of lung cancer among people who eat large amounts of fat and cholesterol, some researchers speculate that diet may also influence lung cancer risk.
One fourth of all people with lung cancer have no symptoms when the cancer is diagnosed. These cancers are usually identified incidentally when a chest X-ray is performed for another reason. The other three fourths of people develop some symptoms. The symptoms are due to direct effects of the primary tumor; to effects of cancer spread to other parts of the body (metastases); or to disturbances of hormones, blood, or other systems.
Symptoms of lung cancer include cough, coughing up blood or rusty-colored phlegm, fatigue, unexplained weight loss, recurrent respiratory infections, hoarseness, new wheezing, and shortness of breath.
A new cough in a smoker or a former smoker should raise concern for lung cancer.
A cough that does not go away or gets worse over time should be evaluated by a health care provider.
Coughing up blood (hemoptysis) occurs in a significant number of people who have lung cancer. Any amount of coughed-up blood should be evaluated by a health care provider.
Pain in the chest area is a symptom in about one fourth of people with lung cancer. The pain is dull, aching, and persistent.
Shortness of breath usually results from a blockage in part of the lung, collection of fluid around the lung (pleural effusion), or the spread of tumor through the lungs
Wheezing or hoarseness may signal blockage or inflammation in the lungs that may go along with cancer.
Repeated respiratory infections, such as bronchitis or pneumonia, can be a sign of lung cancer.
Symptoms of metastatic cancer depend on the extent and location of the cancer spread. About 30-40% of people with lung cancer have some symptoms or signs of metastatic disease.
Lung cancer most often spreads to the liver, the bones, and the brain.
Metastatic lung cancer in the liver may cause yellowing of the skin and eyes (jaundice) but it may not cause any noticeable symptoms at the time of diagnosis.
Lung cancer that has metastasized to the bone causes bone pain, usually in the bones of the spine (vertebrae), the thigh bones, and the ribs.
Lung cancer that spreads to the brain can cause difficulties with vision, weakness on one side of the body, and/or seizures.
Paraneoplastic syndromes are the remote, indirect effects of cancer not related to direct invasion. Symptoms include the following:
New bone formation - particularly in the fingertips that can be painful
High levels of calcium in the blood
Low sodium levels in the blood
How Is Lung Cancer Diagnosed?
Your doctor may suspect lung cancer if a routine physical exam reveals:
swollen lymph nodes above the collarbone
a mass in the abdomen
abnormal sounds in the lungs
dullness when the chest is tapped
rounding of the fingernails
weakness in one arm
expanded veins in the arms, chest, or neck
swelling of the face
Some lung cancers produce abnormally high blood levels of certain hormones or substances such as calcium. If a person shows such evidence and no other cause is apparent, a doctor should consider lung cancer.
Lung cancer, which originates in the lungs, can also spread to other parts of the body, such as distant bones, the liver, adrenal glands, or the brain. It may be first discovered in a distant location, but is still called lung cancer if there is evidence it started there.
Once lung cancer begins to cause symptoms, it is usually visible on an X-ray. Occasionally, lung cancer that has not yet begun to cause symptoms is spotted on a chest X-ray taken for another purpose. A CT scan of the chest may be ordered for a more detailed exam.
Though exams of mucus or lung fluid may reveal fully developed cancer cells, diagnosis of lung cancer is usually confirmed through a lung biopsy. With the patient lightly anesthetized, the doctor guides a thin, lighted tube through the nose and down the air passages to the site of the tumor, where a tiny tissue sample can be removed. This is called a bronchoscopy and the scope is called a bronchoscope. This is useful for tumors near the center of the lung.
If the biopsy confirms lung cancer, other tests will determine the type of cancer and how far it has spread. Nearby lymph nodes can be tested for cancer cells with a procedure called a mediastinoscopy, while imaging techniques such as CT scans, PET scans, bone scans, and either an MRI or a CT scan of the brain can detect cancer elsewhere in the body.
If fluid is present in the lining of the lung, removal of the fluid with a needle (called a thoracentesis) may help diagnose cancer as well as improve breathing symptoms. If the fluid tests negative for cancer cells -- which occurs about 60% of the time -- then a procedure known as a video-assisted thoracoscopic surgery (or VATS) may be performed to examine the lining of the lung for tumors.
Because saliva, mucus, and chest X-rays have not proved particularly effective in detecting small tumors characteristic of early lung cancer, annual chest X-rays for lung cancer screening are not recommended by the American Cancer Society, the National Cancer Institute, or the American College of Radiology.
Screening CT scan clinical trials have been performed and some are completed. In one study, over 31,000 people were screened with CT scans and 484 -- or 1.5% -- were found to have lung cancer. Other studies, however, have shown no reduction in lung cancer deaths with CT scanning. Other clinical trials are ongoing.
One of the problems with CT scan screening is the increased risk of radiation exposure and subsequent development of radiation related cancers.
Surgery is the preferred treatment for patients with early stage NSCLC. Unfortunately, 60-80% of all patients who have advanced or metastatic disease are not suitable for surgery.
People who have NSCLC that has not spread can tolerate surgery provided they have adequate lung function.
A portion of a lobe, a full lobe, or an entire lung may be removed. The extent of removal depends on the size of the tumor, its location, and how far it has spread.
A technique called cryosurgery is sometimes used for NSCLC. In cryosurgery, the tumor is frozen, which destroys it. This treatment is mainly for relief of fatigue.
Cure rates for small peripheral cancers are around 80%.
Despite complete surgical removal, a large proportion of patients with early stage cancer have recurrence of cancer and die from it.
Surgery is not widely used in SCLC. Because SCLC spreads widely and rapidly through the body, removing it all by surgery is usually impossible.
An operation for lung cancer is major surgery. Many people experience pain, weakness, fatigue, and shortness of breath after surgery. Most have problems moving around, coughing, and breathing deeply. The recovery period can be several weeks or even months.
Lung Cancer - Medications
Chemotherapy uses powerful medicines to kill cancer cells. Chemotherapy is the most effective therapy for small cell lung cancer. It can help control the growth and spread of the cancer, but it cures lung cancer in only a small number of people. Chemotherapy also may be used to treat more advanced stages of non-small cell lung cancer.
Chemotherapy is called a systemic treatment because the medicines enter your bloodstream, travel through your body, and kill cancer cells both inside and outside the lung area. Some chemotherapy drugs are taken by mouth (orally), while others are injected into a vein (intravenous, or IV).
Recommended Related to Lung CancerLung Cancer Pain
Rating your pain and using a pain control diary can help your doctor figure out how to best relieve your cancer pain. Lung Cancer Pain Management
Extensive research and clinical trials have studied the different chemotherapy medicines used to treat lung cancer. Your oncologist will discuss and recommend chemotherapy treatment specific to your condition. Some of the more common chemotherapy medicines include the following:
Bevacizumab is an intravenous (IV) drug that helps prevent formation of blood vessels that supply the tumor with nutrients and help the cancer grow and multiply. Bevacizumab may be used with other chemotherapy drugs, such as carboplatin and paclitaxel, for treating non-small cell lung cancer.
What to Think About
Most chemotherapy causes some side effects. Your doctor may prescribe medicines to control nausea or vomiting.
Chemotherapy may be given before surgery (neoadjuvant) or after surgery (adjuvant therapy) to kill cancer cells.
If standard treatments are not effective or are causing more side effects than desired, you may want to consider being part of a clinical trial. Many clinical trials are studying the different combinations of chemotherapy medicines for the different stages of lung cancer. Ask your oncologist what trials are available for your lung cancer.