How to work up pulmonary nodules in the new era (Review, AJRCCM)

It’s time to revise the traditional approach to the management of pulmonary nodules, abandon the concept of a “solitary pulmonary nodule,” and update our cognitive strategy incorporating the changes in practice and decision-making brought by the frequency of chest CT scanning and its vastly increased sensitivity over chest films of the old era. So say David Ost and Michael Gould, in their concise clinical review in the February 15 AJRCCM.

But as they acknowledge, for patients whose pulmonary nodule is at intermediate risk for lung cancer (i.e., most patients), the question of whether to resect or biopsy a pulmonary nodule, with or without a PET scan, has always been more art than science, and far from simplifying things, new technologies have broadened the range of appropriate, “artful” management even further.

In essence, Ost’s and Gould’s cognitive approach goes like this:

1. Estimate the pretest probability of cancer. They suggest using clinical judgment based on the patient’s risk factors, or using a risk modeler (such as this online calculator based on Swensen SJ, or the validated VA or Mayo models).
2. Consider the consequences of surgery: its potential benefits if a cancerous nodule is resected; its potential harms if complications result (whether the nodule is cancerous or not, but especially if it’s not).
3. Determine the “treatment threshold,” which must incorporate the patient’s surgical risk (cardiopulmonary reserve, comorbidities) and personal preferences. This is the part that’s art and always will be — it’s an intuitive judgment based on multiple imprecise and subjective inputs, both from the physician (educated guesses at to the risks of various options) and from the patient (understanding of the situation, trust in the physician, risk tolerance, spirituality, previous experience, etc).

They offer a decision-making algorithm that is no doubt exceptionally well-thought out, but at its core boils down to the following (Ost and Gould chose these arbitrary risk cut-off points, but in almost the same breath toss them aside, since patients’ personal preferences should help define the thresholds):

• In patients with a “very high” pretest probability of cancer (>60%), surgery is preferable.
• For nodules considered low probability for cancer (<5-10%), observation with 2 years of serial CT scans is recommended.
• For the those at intermediate risk for cancer (the large majority), they recommend CT-guided needle biopsy, or a PET scan possibly followed by CT-biopsy. (Conventional bronchoscopic biopsy, electromagnetic navigational bronchoscopy, and radial endoscopic ultrasound all are appropriate as well, depending on local availability and expertise.)

They emphasize strongly that “the difference in outcomes between strategies may not be large.” But have any of the decision making algorithms for pulmonary nodules been examined prospectively? I don’t think so — and even if they were, we’d be foolish to rely overly on such a study when treating our individual patient, thanks to the extreme heterogeneity inherent to this clinical problem. Even moreso than other conditions, each patient with one or more pulmonary nodules is a unique n of 1, a personalized and non-reproducible clinical trial of his very own.

In truth, it seems very little has changed since the previous state-of-the-art reviews by Ost (NEJM), Gould (Chest), Winer-Muram (Radiology) and others. New technologies have just offered new ways to biopsy intermediate-risk lesions, with a lower risk for pneumothorax compared to CT-guided FNA. But as much as ever, the decision of who’s a “surgical candidate” is a profoundly human one, dominated more by messy things like the patient-doctor relationship, the local surgeon and radiologist’s professional proclivities, and the patient’s trust, hopes, and fears, than by Bayes’s Theorem or any other impersonal probabilism. Intuition and experience still rules here, and often as not, the decision is made by the answer we give when the patient bewildered by our statistics looks us the eye and says, “But what do you think, Doc?”

Ost DE, Gould MK. Decision Making in Patients with Pulmonary Nodules. Am J Respir Crit Care Med 2012;185:363-372. 

Ost DE et al. The solitary pulmonary nodule. N Engl J Med 2003;348:2535-2542.

Gould MK et al. Evaluation of patients with pulmonary nodules: when is it lung cancer?: ACCP evidence-based clinical practice guidelines (2nd edition). Chest 2007;132(3 suppl):108S-130S.

Winer-Muram HT. The solitary pulmonary nodule. Radiology 2006;239:34-49.