Therapy-induced tumor regression and regression grading in lung cancer

After neoadjuvant therapy of non-small cell lung cancer, the extent of therapy-induced tumor regression in corresponding resection specimens of primary tumors and lymph nodes represents an independent prognostic factor. In the former tumor area, different sized target-like foci with central necrosis, adjoining narrow foam cell rim, peripheral vascular granulation tissue and transition into a marked scarry fibrosis can be found after neoadjuvant therapy. Morphological changes indicating therapy-induced tumor regression can be graded according to the Bochum regression grading system. Therapy-induced cytomorphological changes do not allow reliable conclusions on the success of the applied neoadjuvant therapy and should not form the basis of cytopathological grading.