Multidisciplinary Treatment of Colorectal Cancer by Gunnar Baatrup

Author:Gunnar Baatrup
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

Evaluation of Response After Preoperative (Chemo)radiotherapy

Since the response to preoperative therapy (5 × 5 Gy with a delay or prolonged CRT to 46–50.4 Gy) may influence prognosis [61–63] and thus subsequent therapy, both the extent of surgery and postoperative chemotherapy, attempts to clinically and pathologically restage the tumours have been made. There is an increasing experience in evaluating tumour response by repeat MRI or PET-CT. Using MRI, decrease in size can be seen as well as increase in fibrosis and mucous degeneration indicating response [64]. Using FDG-PET, decrease in uptake can be seen [65–68]. At present, the knowledge about the relevance of these changes is too uncertain to modify the extent of surgery.

Several systems for pathological tumour regression grading have been used (e.g. by [69–72]). The best (reproducibility, prognostic information, etc.) is not known. The tumours should at least be graded into three groups, complete response (pCR), some (potentially in the future good, moderate and poor) response and no response. The proportion of pCRs, meaning the absence of tumour cells after a given treatment for a certain substage, is influenced by intensity of dissection. A standardisation of the dissection is required if pCR rates should be used as a valid endpoint [73].

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