Approximately 178,000 new cases of lung cancer were diagnosed leading to more than 160 deaths. Lung cancer is now the most common cause of cancer mortality in both sexes. In females, it exceeded breast cancer as the most common cause of mortality in mid 1980's. The dramatic increase in lung cancer mortality in both sexes has been related to increased smoking.
Small cell lung cancer accounts for roughly 20% of all lung cancers. Non-small cell lung cancer accounts for roughly 80% of all lung cancers. Adenocarcinoma is the most common non-small cell lung cancer. Squamous cell carcinoma is next most common followed by large cell carcinoma.
Smoking is the greatest risk factor for both small cell and non-small cell lung cancer. Passive smoking is also important. About 40% of lung cancer deaths in non-smokers are thought to be caused by passive smoking. With cessation of smoking, the incidence of lung cancer begins to decline and approaches that of non-smoking population after 10-15 years of abstinence. Radon gas exposure, uranium, asbestos, arsenic, beryllium, chloromethyl ethers, hydrocarbons, mustard gas and nickel can also cause lung cancer. Some of the other risk factors are prior therapeutic irradiation to lung as in cases of breast cancer, Hodgkin's disease and non-Hodgkin's lymphoma, diets deficient in vitamin A, beta-carotene and selenium and diets high in saturated fats.
Lung cancer commonly presents as fatigue, weight loss, cough, shortness of breath, chest pain, sputum production, hemoptysis, bone pain, fever, clubbing and lymph node enlargement. Paraneoplastic syndromes are commonly seen in both small cell and non-small cell lung cancer.
The diagnosis is made by imaging modalities like chest x-ray, CT scan of the chest or MRI. The diagnosis is confirmed by sputum cytology, broncoscopy or CT guided tissue biopsy. Sometimes in difficult cases, thoracotomy is required. Small cell and non-small cell lung cancer are treated differently. The treatment also depends on extent of the disease. Small cell lung cancer can be separated into limited stage and advanced stage disease. Non-small cell lung cancer can be classified into four stages. The advanced the disease is, less are the chances of cure and long term survival.
Limited stage small cell lung cancer is treated by chemotherapy and radiation therapy. Prophylactic radiation treatment to brain is also an important component of treatment. Advanced stage disease is treated with less aggressive chemotherapy or palliation because of poor survival. Metastatic disease to brain is treated with cranial irradiation.
Stage 1 and stage 2 non-small cell lung cancer is treated with curative intent with surgical resection in patients with good performance status. Those who cannot withstand surgery get radiation treatment with curative intent. Stage 3 disease is treated with chemotherapy and radiation. Stage 4 disease patients receive chemotherapy for paliation.
Second primary tumors are common in long term survivors of lung cancer. These patients deserve life long follow up and every effort should be made to encourage smoking cessation. Screening for lung cancer has not shown to decrease survival. Based on these results, mass screening for lung cancer is generally not recommended. However, certain molecular probes in high risk population holds some promise.
Beta-carotene dietary supplements should not be used in smokers as chemopreventive agents. Two trials have shown that dietary intake of beta-carotene in smokers was in fact associated with higher risk of lung cancer.