Major pathologic response (MPR) and pathologic complete response (pCR) are increasingly being used in non-small cell lung carcinoma neoadjuvant clinical trials as an early endpoint of survival. MPR for all histologic types of lung cancer is ≤ 10% of viable tumor, while pCR requires no viable tumor. The International Association for the Study of Lung Cancer multidisciplinary recommendation for the assessment of response in surgically resected lung carcinomas after neoadjuvant therapy was the first attempt to standardize grossing processing and microscopic evaluation.