COMPUTERIZED-TOMOGRAPHY DOES NOT PREDICT N2 DISEASE IN PATIENTS WITH LUNG-CANCER

Background: Mediastinal node involvement in primary lung cancer determ ines the staging an prognosis of the patient, and as these nodes can b e seen on the computerised tomography (CT) scan of the chest it is a t emptation to diagnose malignant involvement if the nodes appear enlarg ed. However, initial experience with mediastinal node mapping at lung resection demonstrated this extrapolation to be unreliable and misinte rpretation of enlarged nodes on CT may lead to misdiagnosis and prejud ice the patient's management. Aim: To demonstrate that the sensitivity , specificity, and accuracy of the CT to detect malignant mediastinal nodes is too low to use size of node on CT as representative of malign ant involvement. Methods: One hundred and fifty-three sequential patie nts with resectable lung cancer were studied with preoperative CT. Two radiologists determined the preoperative T and N status from these st udies with nodes of 1.5 cm or larger diagnosed abnormal. These results were compared to the results of subsequent node mapping performed aft er lung resection. Results: Sensitivity was found to be 26%, specifici ty to be 81% and overall accuracy 69% - too low to justify the diagnos is of N2 disease on size of 1.5 cm or larger. CT is not a valid means of diagnosing malignant involvement of mediastinal nodes.