Non-Small Cell Lung Cancer

Accounting for 85 to 90 percent of all lung cancer cases, non-small cell lung cancer (NSCLC) is the most common classification of lung cancer. While early stages of the disease may not cause any symptoms, a worsening cough, chest pains and shortness of breath are signs that need to be taken seriously, especially by anyone who has a history of smoking or those who know they were exposed to asbestos.

Cigarette smoking is the leading cause of lung cancer, and smokers exposed to other known risk factors like asbestos have an elevated risk. NSCLC is less aggressive than small cell lung cancer (SCLC), usually growing and spreading at a much slower rate. There are three primary types of NSCLC distinguishable by the appearance and chemical makeup of their cells:

• Squamous cell (epidermoid) carcinoma – The most common variety of NSCLC, these cancers form in flat cells that line the inside airways of the lungs. About 25 to 30 percent of all lung cancers are squamous, and this is the most prevalent type of NSCLC among men.
• Adenocarcinoma – This type of cancer forms in mucus-producing glandular tissues that line the outer parts of the lungs. It is more common in women than men and the predominant type of cancer among non-smokers.
• Large cell (undifferentiated) carcinoma – Appearing in any part of the lung, this type of cancer grows and spreads more rapidly than the other varieties of NSCLC. Accounting for 10 to 15 percent of lung cancers, large cell carcinoma appears to be decreasing in occurrence due to advances in diagnostic techniques.

Risk Factors

Research has proven that people with certain risk factors, or anything that elevates the chance of getting a disease, have an increased likelihood of developing lung cancer. However, risk factors are not always definitive. For example, some patients develop lung cancer without having any risk factors at all. Likewise, exposure to multiple risk factors may not always result in the disease for some people. The most common risk factors for NSCLC are smoking cigarettes and exposure to asbestos.

Smoking

Cigarette smoking is responsible for lung cancer in 78 percent of men and 90 percent of women. Although women tend to be more susceptible to adenocarcinoma, they usually exhibit an increased survival rate at each stage of the disease.

The development of NSCLC directly corresponds to the number of cigarettes smoked, the length of smoking history and the quantity of tar and nicotine inhaled. The American Cancer Society asserts that if you quit smoking before cancer develops, damaged lung tissue will repair itself gradually. Regardless of your age or smoking history, quitting immediately can greatly lower risks of cancer while improving your lifespan. Because not every smoker develops lung cancer and some of those diagnosed are non-smokers, other factors such as secondhand smoke, genetics and environmental carcinogens (cancer causing substances) play a causative role as well.

Asbestos

Workplace exposure to asbestos is a well-documented risk factor for many types of lung disease, including NSCLC. Knowledge of asbestos-related dangers can be traced back as far as ancient Rome, where various historians noted that slaves working in asbestos mines were less healthy than others and often died young. Today, asbestos is classified as a known human carcinogen by the U.S. Department of Health and Human Services, the U.S. Environmental Protection Agency (EPA) and the International Agency for Research on Cancer.

When products containing asbestos are disturbed, microscopic asbestos fibers are released into the air. If inhaled, these fibers become trapped in the lungs and can accumulate over time causing inflammation and scarring. The National Cancer Institute states that people who inhale asbestos fibers have an elevated risk of developing lung cancer as well as a variety of nonmalignant lung disorders. Furthermore, the risk factor involved is significantly multiplied when asbestos workers also smoke cigarettes.

For smokers and non-smokers alike, asbestos exposure increases the chance of developing mesothelioma, a rare cancer that starts in the soft lining that surrounds the lungs and abdomen. Of all cancers associated with asbestos, mesothelioma is the most common. Although mesothelioma can be difficult to treat, an early diagnosis and aggressive treatment can greatly improve the patient's outlook. For more information about mesothelioma, treatment options and referrals to top doctors, click here to receive a complimentary information packet from the Mesothelioma Center.

Primary Symptoms

In most cases, lung cancers are not diagnosed until they start to present symptoms. Unfortunately, however, NSCLC tends to be asymptomatic until the disease is well-advanced and has already spread. For example, between 7 and 10 percent of lung cancer patients are diagnosed via chest X-ray while presenting no symptoms at all. Early recognition of cancer symptoms can increase treatment options and overall outcome. Consult a doctor if you experience any of these primary symptoms of non-small cell lung cancer:

• Worsening cough
• Breathlessness
• Chest pain
• Hoarseness
• Blood in spit or phlegm
• Recurring lung infections (pneumonia and bronchitis)
• Weight loss or change in appetite

If the cancer has spread from the lungs to distant organs, it may cause:

• Bone pain
• Headaches
• Numbing of limbs
• Dizziness
• Jaundice
• Lumps near the surface of the body

Experiencing any combination of these symptoms is not a definitive sign of lung cancer. In fact, it is more likely that less-serious conditions are the underlying cause. To be certain, you should consult a doctor immediately to determine the problem and begin treatment if needed.

Associated Syndromes

When medical conditions cause a specific group of symptoms they are often referred to as syndromes. Between 10 and 20 percent of patients will experience syndromes in response to a cancerous tumor. For example, SCLC and NSCLC located in the upper portion of the lungs can damage a nerve that passes from the upper chest into the neck. This results in Horner syndrome, which can lead to severe shoulder pain, a drooping eyelid, a smaller pupil and reduced sweating on one side of the face. Other common syndromes associated with non-small cell lung cancer include:

• Syndrome of Inappropriate Anti-Diuretic Hormone (SIADH): This condition occurs when cancer cells produce a hormone which causes the kidneys to retain water. Salt levels in the blood are reduced causing symptoms like restlessness, fatigue, nausea and muscle weakness.
• Ectopic Cushing Syndrome: Cancer cells sometimes produce a hormone that causes the adrenal glands to secrete cortisol. In turn, symptoms such as weight gain, drowsiness and high blood pressure often arise.
• Bamberger-Marie disease: This condition affects the bones of the extremities and can cause pain, inflammation and clubbing.
• Hypercalcemia: NSCLC can cause elevated calcium levels in the blood. This often leads to frequent urination, constipation, nausea, weakness and several other nervous system problems.
• Gynecomastia: The cancer can upset normal hormone balances causing excess breast growth in men.
  

Staging and Prognosis

Staging is a formal system doctors use to identify the extent to which the cancer has spread. Patients diagnosed with non-small cell lung cancer are typically assigned a stage based on the TNM system, which classifies cancer based on the tumor (T), lymph node involvement (N) and metastasis, or spreading (M). Doctors use numbers and letters after T, N and M to further describe the state of the cancer. Numbers increase from zero to four as the disease progresses, and the letter X is used when there is a lack of sufficient information for a numerical assessment.

For example, a Stage II lung cancer patient may receive a TNM classification of T1N1M0. That classification would indicate early state cancer. Treatment options depend primarily on the stage of the disease. In general, the lower the stage, the better the chances of curing the cancer. NSCLC is divided into five stages:

• Stage 0: The cancer has not spread beyond the inner lining of the lung
• Stage I: The cancer is small and has not spread to the lymph nodes
• Stage II: The cancer has spread to lymph nodes near the original tumor
• Stage III: The cancer has spread to nearby tissue or distant lymph nodes
• Stage IV: The cancer has spread to organs such as the other lung, brain or liver

NSCLC tends to grow slowly and cause few or no symptoms during initial stages. During stages I and II, cancer can be cured with surgery around 50 percent of the time. Stage III cancer can only be cured in some cases. Stage IV disease or cases where the cancer has returned are almost never cured. Instead, the goals of therapy are to extend and improve the quality of the patient's life.