Information on Lung Cancer

Lung cancer usually develops within the wall or epithelium of the bronchial tree. Its most common types are epidermoid (squamous cell) carcinoma, small cell (oat cell) carcinoma, adenocarcinoma, and large cell (anaplastic) carcinoma.

Although the prognosis is usually poor, it varies with the extent of spread at the time of diagnosis and the growth rate of the specific cell type. Only about 13% of patients with lung cancer survive 5 years after diagnosis. Lung cancer is the most common cause of cancer death in men and is fast becoming the most common cause in women, even though it's largely preventable.

Prevention is critical because lung cancer usually isn't discovered until it's at an advanced stage when the outlook for recovery is poor. Although the survival rates for lung cancer have impro

Causes

Most experts agree that lung cancer is attributable to inhalation of carcinogenic pollutants by a susceptible host. Who is most susceptible? Any smoker over age 40, especially if he began to smoke before age 15, has smoked a whole pack or more per day for 20 years, or works with or near asbestos.

Pollutants in tobacco smoke cause progressive lung cell degeneration. Lung cancer is 10 times more common in smokers than in nonsmokers; indeed, 80% of lung cancer patients are or were smokers.

Cancer risk is determined by the number of cigarettes smoked daily, the depth of inhalation, how early in life smoking began, and the nicotine content of cigarettes. Two other factors also increase susceptibility: exposure to carcinogenic industrial and air pollutants (asbestos, uranium, arsenic, nickel, iron oxides, chromium, radioactive dust, and coal dust), and familial susceptibility.

Asbestos can cause a variety of lung diseases. It increases the risk of developing lung cancer. There is a synergistic effect between tobacco smoking and asbestos in the formation of lung cancer.

Asbestos can also cause cancer of the pleura, called mesothelioma (which is distinct from lung cancer).

Signs and symptoms

People often decide to visit the doctor only after they have been bothered by certain complaints over a period of time. Individuals who have lung cancer frequently experience symptoms such as:

• Cough
• Shortness of breath
• Wheezing
• Chest pain
• Hemoptysis (bloody, coughed-up sputum)
• Loss of appetite
• Weight loss
• Pneumonia (inflammation of the lungs)

• Weakness
• Chills
• Swallowing difficulties
• Speech difficulties or changes (e.g., hoarseness)
• Finger/nail abnormalities (e.g., "clubbing," or overgrowth of the fingertip tissue)
• Skin paleness or bluish discoloration
• Muscle contractions or atrophy (shrinkage)
• Joint pain or swelling
• Facial swelling or paralysis
• Eyelid drooping
• Bone pain/tenderness
• Breast development in men

Diagnosis

Your doctor will check your symptoms and ask questions about whether you smoke or have been exposed to any cancer-causing substances. He or she will also ask about your medical history, including any history of cancer in your family. This information will help your doctor decide how likely it is that you have lung cancer and whether tests are needed to be sure.

Performing a chest X-ray is the first step if a patient reports symptoms that may be suggestive of lung cancer. This may reveal an obvious mass, widening of the mediastinum (suggestive of spread to lymph nodes there), atelectasis (collapse), consolidation (infection) and pleural effusion. If there are no X-ray findings but the suspicion is high (e.g. a heavy smoker with blood-stained sputum), bronchoscopy and/or a CT scan may provide the necessary information. In any case, bronchoscopy or CT-guided biopsy is often necessary to identify the tumor type.

If investigations have confirmed lung cancer, scan results and often positron emission tomography (PET) are used to determine whether the disease is localised and amenable to surgery or whether it has spread to the point it cannot be cured surgically. PET is not useful as screening, as not all malignancies are positive on PET scan (such as bronchoalveolar carcinoma), and lung infections may be positive on PET Scan.

Blood tests and spirometry (lung function testing) are also necessary to assess whether the patient is well enough to be operated on. If spirometry reveals a very poor respiratory reserve, as may occur in chronic smokers, surgery may be contraindicated.

Treatment

Various combinations of surgery, radiation, and chemotherapy may improve the prognosis and prolong survival. Nevertheless, because treatment usually begins at an advanced stage, it's largely palliative

Surgery

Unless the tumor is nonresectable, or other conditions rule out surgery, excision is the primary treatment for stage I, stage II, or selected stage III squamous cell carcinoma, adenocarcinoma, and large cell carcinoma. Surgery may include partial removal of a lung (wedge resection, segmental resection, lobectomy, radical lobectomy) or total removal (pneumonectomy, radical pneumonectomy).

Radiation

Preoperative radiation therapy may reduce tumor bulk to allow for surgical resection. Preradiation chemotherapy helps improve response mtes. Radiation therapy is ordinarily recommended for stage I and stage II lesions, if surgery is contraindicated, and for stage III lesions when the disease is confined to the involved hemithorax and the ipsi lateral supraclavicular lymph nodes.

Generally, radiation therapy is delayed until 1 month after surgery, to allow the wound to heal, and is then directed to the part of the chest most likely to develop metastasis.High-dose radiation therapy or radiation implants may also be used.

Chemotherapy

Another treatment is chemotherapy including combinations of fluorouracil, vincristine, mitomycin, cisplatin, and vindesine, which produce a response rate of about 40% but have a minimal effect on overall survival. Promising combinations for treating small cell carcinomas include cyclophosphamide with doxorubicin and vincristine; cyclophosphamide with doxorubicin, vincristine, and etoposide; and etoposide with cisplatin, cyclophosphamide, and doxorubicin.radiation therapy or radiation implants may also be used.

Laser therapy

Still largely experimental, laser thempy involves direction of laser energy through a bronchoscope to destroy local tumors.

Prevention

If you smoke, stop smoking. Try to avoid second-hand smoke.

There is no evidence that screening for small cell lung cancer with chest x-rays, CT scans, or other means is beneficial for patients at high risk of developing non-small cell lung cancer. However, some recent studies have suggested that specialized scans called spiral CT scans may help improve cure rates by detecting lung cancer at an earlier stage. This is still under investigation, and such screening is not considered the standard of care.