[Regression grading of colorectal carcinoma after preoperative radiochemotherapy. An inventory]

The treatment of patients with colorectal cancer has changed over the last decades. More and more patients receive combined modality treatments including (preoperative) radiotherapy and chemotherapy. To assess the colorectal cancer specimen after neoadjuvant therapy, the pathologist has to be familiar with the histological features induced by radiochemotherapy. Performing a standardized pathological procedure, different grades of tumour regression can be observed and tumour staging should be standardized using valid and reproducible criteria. These criteria are recommended in the forthcoming TNM classification (6th edition, 2002). In the review, these classification rules will be discussed for rectal cancer.