Surgical excision not only is the most accurate method of evaluating a solitary pulmonary nodule, it is also the most cost effective, said Stephen C. Yang, md, Johns Hopkins assistant professor of surgery at the 1998 meeting of The American College of Chest Physicians. A solitary nodule is found in 1 chest x-ray per 1,000, and about 50% prove to be malignant (usually primary lung cancer). The dilemma is how to establish the benign nature of a nodule with enough confidence so as to avoid unnecessary testing and surgery.
Calculating Test Cost Per Correct Diagnosis
Dr. Yang outlined a diagnostic algorithm that would aid clinicians in working up patients who present with a nodule on chest x-ray or computed tomographic (CT) scan. While open lung biopsy would appear to be expensive, it actually offers the lowest cost per correct diagnosis of any of the diagnostic tests, he said. Sputum cytology, which costs only about $100 per test, proves in the algorithm to be the least cost-effective.
Using figures published by other investigators, Dr. Yang calculated that the total hospital cost of diagnosing a pulmonary nodule via open lung biopsy is approximately $12,888; bronchoscopy with transbronchial biopsy ran $16,615; fine-needle aspiration, $21,543; and sputum cytology, $63,000.
The reason for the high per diagnosis cost of sputum cytology, as well as the costs associated with the other diagnostic techniques, is that a negative result does not rule out a malignancy. A negative cytology still carries a 49% likelihood of malignancy; a negative result on bronchoscopy with transbronchial biopsy proves malignant 20% of the time; and a negative fine-needle aspiration biopsy has a 4% likelihood of being malignant.
Surgical resection, on the other hand, has a diagnostic yield of 100%, and with newer surgical techniques and better pain control, surgery carries much less risk of morbidity than it did in the past, said Dr. Yang.
With fine-needle aspiration, at the end of the pathway, 42% of patients are still without a diagnosis.
Computed tomography-guided fine-needle aspiration does not rule out malignancy entirely because malignant cells could be missed in the sampling. Furthermore, added Dr. Yang, it should not be used in patients with bleeding diathesis, severely compromised lung function, pulmonary hypertension, bulbus disease around the lesion or in the needles path, or contralateral pneumonectomy.
Bronchoscopy with transbronchial biopsy has a 20% to 80% diagnostic yield, especially in lesions less than 2 cm, and low sensitivity, he said. However, the procedure is indicated for patients for whom surgical resection is not an option.
Sputum cytology has only a 60% sensitivity at best; however, it can be useful in large, clinically unresectable lesions, in lesions over 5 cm, and in patients with hemoptysis. It has no role, Dr. Yang said, when the probability of malignancy is less than 5%.