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%.