P-337 - Histologic analysis of anal sphincter after radiotherapy of rectal cancer

Date 04 July 2015
Event WorldGI 2015
Session Posters
Topics Rectal Cancer
Pathology/Molecular Biology
Surgery and/or Radiotherapy of Cancer
Presenter A. Beznosenko
Citation Annals of Oncology (2015) 26 (suppl_4): 1-100. 10.1093/annonc/mdv233
Authors A. Beznosenko, O. Kolesnik, D. Makhmudov, O. Lebedieva, O. Grabovoy
  • National Cancer Institute, Kiev/UA

Abstract

Introduction

Vast majority of evidence suggest negative impact of radiation therapy on anal sphincter function. On the other hand, morphologic changes, which lead to anal incontinence after applying different programs of neoadjuvant radiation therapy (NRT), remain unrevealed. The aim of this study was to assess histologic changes in the anal sphincter, occurring after applying different regimens of NRT in combined treatment of rectal malignancies.

Methods

Histologic changes in anal sphincter tissues were analyzed in 49 patients after NRT and abdomino-perineal resection. Twelve patients had been given a course of NRT with total dose of 20Gy by gross fractions, 14 patients – 30Gy by divided fractions, 30 patients – 50-60Gy by divided fractions. A control group consisted of 10 patients, who didn't undergo NRT.

Results

Grade I fibrosis was observed predominantly in groups of 20Gy and 30Gy – 75,1% and 64,3% respectively. Among groups of 50Gy and 60Gy grade II – III fibrosis was observed in 46,2% and 30,7% respectively. A tendency towards decreasing the number of nervous elements when increasing the dose of NRT was observed, but the difference appeared to be insignificant (р = 0,28).

Conclusion

Due to an alteration, caused by radiation therapy, degenerative and inflammatory changes occur in the anal sphincter tissue, which leads to substitution of muscular elements by fibrous tissue and turns out to be a morphological substance for further functional changes.