CT scan prior to radiotherapy in unresectable, locally advanced, non-small cell carcinoma of the lung: is it always necessary?

There is broad consensus regarding evaluating response to chemotherapy (CHT) by means of computerized tomography (CT) in patients with localized or locally advanced non-small cell lung carcinoma (NSCLC). We present a study comparing the usefulness of CT versus chest X-ray (XR) and clinical findings when indicating radiotherapy (RT) following CHT. Ninety-eight of 150 subjects with unresectable locally advanced NSCLC were blindly and independently evaluated by XR and CT, with pairs of chest XR and CT (before and after CHT). A null hypothesis (H0) was established of the conditioned probability of detecting progression by CT and not by XR of 10 % or more, with a statistical power of 80 %. Sensitivity, specificity, positive and negative predictive value of XR versus CT were 98, 89, 99, and 80 % respectively. A 4 % (p = 0.0451) probability of improvement of CT versus XR was calculated, enabling the H0 to be ruled out. The CT failed to prove to be significantly superior to the chest XR + clinical picture in indicating a change in treatment approach in patients with unresectable locally advanced NSCLC after CHT.