Erfahrungen mit Einer Statistischen Entscheidungsunterstützung bei der Chirurgischen Behandlung des Rektumkarzinoms

Summary

For the treatment of patients with carcinoma of the mid rectum mainly three types of operations are available: rectum-saving methods, sphincter-saving methods and excisional surgery. The goal is the proper selection of patients and to realize surgery adapted to the individual situation. The treatment should be as limited as possible and as radical as necessary. In particular, the method should minimize the risk of local recurrence which is one of the chief causes of an unfavourable course of the disease.

To support the surgeon by a formal decision rule a statistical model has been developed in order to estimate the probability of local recurrence for each operation strategy given the individual status of disease. The approach takes into account the competing risk of dying without local recurrence. The rate of recurrence has been estimated separately for each operation by use of seven characteristics of disease status. The decision rule was based on a fixed difference between predicted recurrence rates.

While the rule was applied the need to further examine the precision of the predicted recurrence rates became apparent. The variability of the estimated probabilities and its implications on the decision rule is studied by means of model reduction, treating’ surgical method’ and its interactions with disease charactaristics as covariates, and by jackknife procedures.