Background: Pathologic complete response (CR) to preoperative chemotherapy has been shown to be a strong prognostic factor in resected non-small cell lung cancer (NSCLC). This preoperative setting offers the opportunity to evaluate the clinical prediction of CR by investigators and an evaluation committee (EC) using the “gold standard” pathologic examination as the reference. The only published large randomized trial of preoperative chemotherapy (to our knowledge), the French neoadjuvant study, constitutes an interesting database to evaluate CT scan-based CR assessment.
Study objectives and design: The French trial compared mitomycin-ifosfamide-cisplatin followed by surgery with surgery alone in stage I (except T1N0) to IIIa resectable NSCLC. Response was prospectively assessed in all patients receiving preoperative chemotherapy by the investigator in charge of the patient and by an EC, and was compared with pathologic postoperative data.
Results: In the preoperative chemotherapy study, 167 patients were operated on. Nineteen patients were found to have a pathologic CR. Only seven patients were classified as having a CR by investigators and five patients by the EC. Evaluation of CR was correct in six of these seven cases and in three of these five cases, respectively. Sensitivity of the CR diagnosis was 31.6% for investigators and 15.8% for the EC. Specificities of the CR diagnosis were 99.4% and 98.8%, respectively. Positive predictive values were 85.7% and 60%, respectively. Negative predictive values were 91.9% and 90.1%, respectively. Accuracies were 91.6% and 89.2%, respectively.
Conclusion: Investigator assessment of CR was highly predictive of pathologic CR. However, this study showed that clinical CT scan-based assessment, whether performed by investigators or the EC, underestimated the frequency of CR after preoperative chemotherapy in resectable NSCLC.