[Pathological staging and response evaluation of rectal carcinoma].

The application of so-called neoadjuvant therapy may induce changes in tumor tissues that have to be determined concerning the degree of severity (regression grading) and which also influence pathological staging. The extent of morphological changes (response) to be evaluated ranges from carcinomas showing no damage at all to complete disappearance of carcinomas. More than ten different systems of regression grading have been published in order to assess the dimension of morphological changes in a semiquantitative manner.