DIAGNOSIS AND EVALUATION



A careful history and physical examination are crucial in patient evaluation, and availability of a previous chest x-ray is of tremendous value. Cer­tain generalizations regarding the relationship of the chest x-ray to the tissue type can be made: (1) A hilar mass as the only abnormal finding is most common in small cell carcinoma and almost never seen in adenocarcinoma. (2) A peripheral mass 4 cm or less in diameter is most likely an adeno­carcinoma, while one greater than 4 cm may be any of the cell types except small cell carcinoma. (3) Multiple masses are very rare in primary lung cancer. (4) Apical tumors are usually squamous cell carcinoma. (5) Atelectasis strongly suggests squamous cell carcinoma. (6) Consolidation is a rare finding in all cell types. (7) Cavitation is most common in squamous cell, is less common with large cell and adenocarcinoma, and is never seen in small cell carcinoma. (8) Mediastinal widening usually signifies spread from small cell carcinoma (after Fraser and Pare).

Routine laboratory studies are rarely helpful in the diagnosis of bronchogenic carcinoma but can be invaluable in evaluating extrathoracic spread of the disease, especially liver function studies and serum calcium and alkaline phosphatase, which screen for bone metastases.

Therapeutic decisions are based on a correct tis­sue diagnosis. Cytological examination of expec­torated sputum is the easiest and least invasive approach. False-positive results are rare, but false-negative results are relatively common (40 to 50 per cent), especially with peripheral lesions. When cytological examination of expectorated sputum is negative, bronchoscopy should be the next procedure in patients with central lesions, lung infiltrates, hoarseness, or hemoptysis. Posi­tive yield ranges from 90 per cent for central en-dobronchially visible tumors to 50 per cent for peripheral lesions. Small peripheral lung nodules should probably be approached by percutaneous needle aspiration performed under fluoroscopic guidance, which provides material for cytological examination. Diagnostic accuracy is greater than 80 per cent for malignant disease but is disturb­ingly less accurate with benign lesions.

Once bronchogenic carcinoma is diagnosed, therapeutic decisions depend on both physiolog­ical and anatomical considerations . Since successful surgery offers the only chance of cure, clinical evaluation is directed toward de­termining suitability for resection. Spirometric measurement of the forced expired volume in one second (FEVJ is sufficient for screening. As a rule of thumb, an FEVi of less than 2.0 liters preop­erative^ may result in an FEVj of 0.8 liter or less after pneumonectomy, a value generally consid­ered to preclude surgery. When the clinical eval­uation of the patient differs markedly from the findings on spirometry, a useful estimate of the relative contribution of each lung to overall func­tion can be obtained using a nuclear perfusion scan.

Determination of anatomical operability is the next step. Endobronchial lesions within 2 cm of the .carina on bronchoscopy are inoperable. Intra­thoracic spread to the lungs and to the hilar or mediastinal lymph nodes can often be determined from the plain radiograph, but computed tomog­raphy (CT) may be required. In situations of doubt, biopsy through the mediastinoscope (false negative rate of 20 per cent) or an anterior me-diastinotomy may be required.

Once intrathoracic spread is excluded, a nega­tive history and physical examination combined with a normal routine laboratory evaluation is usually adequate to exclude metastatic spread. Multiple imaging techniques in the absence of symptoms or signs suggesting specific organ in­volvement are costinefficient and are frequently misleading.