BACKGROUND - The American College of Surgeons Oncology Group (ACOSOG) Z0050 trial demonstrated that positron emission tomography (PET) prevents nontherapeutic thoracotomies in a substantial fraction of patients with known or suspected non-small cell lung cancer (NSCLC). However, the benefit of PET in clinical stage IA patients has been questioned due to the lower prevalence of metastases and poor ability to discriminate benign from malignant lung lesions. This study evaluates whether PET prevents nontherapeutic pulmonary resections in clinical stage IA patients by finding advanced disease or by declaring a nodule as benign.
METHODS - We reanalyzed all patients with clinical stage IA NSCLC from ACOSOG Z0050. The clinical, PET, and pathologic stages were compared for this prospective cohort.
RESULTS - One hundred twenty-two clinical stage IA patients were evaluated and 78.7% (96 of 122; 95% confidence interval [CI], 70.4 to 85.6) were eventually shown to have cancer. PET correctly showed 7.4% (9 of 122; 95% CI, 3.4 to 13.5) of patients to have advanced disease (stages IIIA to IV). However, due to a high false positive rate, the positive predictive value for advanced disease was only 33.3% (9 of 27; 95% CI, 16.5 to 54.0). The negative predictive value of PET to predict benign lesions was only 57% (16 of 28; 95% CI, 37.2 to 75.5). Thus, 43% (12 of 28; 95% CI, 24.5 to 62.8) of patients with a PET negative primary lesion actually had cancer, and all of these had resectable disease (stages IA to IIB).
CONCLUSIONS - In clinical stage IA lung cancer patients, PET prevents nontherapeutic pulmonary resections less than 10% of the time. If a strategy of no surgery and serial computed tomographic scans is chosen for PET negative lesions, over 40% of patients with NSCLC will have surgery delayed. A prospective trial comparing PET versus resection for clinical stage IA lesions would clarify the value of PET for these patients.