lung cancer, a pulmonary malignancy attributable in the majority of cases to cigarette smoking. Other predisposing factors are exposure to acronitrile, arsenic, asbestos, beryllium, chloromethyl ether, chromium, coal products, ionizing radiation, iron oxide, mustard gas, nickel, petroleum, uranium, and vinyl chloride. Lung cancer develops most often in scarred or chronically diseased lungs. It is usually far advanced when detected because metastases may precede detection of the primary lesion in the lung. Symptoms of lung cancer include persistent cough, hoarseness, dyspnea, purulent or blood-streaked sputum, chest pain, and repeated attacks of bronchitis or pneumonia. Diagnostic measures include x-ray films, fluoroscopy, tomography, bronchography, angiography, cytological studies of sputum, bronchial washings or brushings, and needle biopsy. Epidermoid cancers and adenocarcinomas each account for approximately 30% of lung tumors; about 25% are small, or oat, cell carcinomas; and 15% are large cell anaplastic cancers. Small cell carcinomas frequently metastasize widely before diagnosis. Surgery is the most effective treatment, but only about 20% are resectable. Lung cancer is essentially incurable unless surgical resection can be accomplished. Thoracotomy is contraindicated if metastases are found in contralateral or scalene lymph nodes. Irradiation is used to treat localized lesions and unresectable intrathoracic tumors and as palliative therapy for metastatic lesions. Radiotherapy may also be administered after surgery to destroy remaining tumor cells and may be combined with chemotherapy. Targeted therapy with drugs such as paclitaxel, carboplatin, irinotecan, and erlotinib has also shown results. Chemotherapy is especially indicated for small cell carcinoma.
