P-339 - Total Mesorectal (Chemo) Radiation (TMRT) with integrated Mesorectal boost followed by TME for preoperative therapy for locally advanced rectal canc...

Date 04 July 2015
Event WorldGI 2015
Session Posters
Topics Anti-Cancer Agents & Biologic Therapy
Rectal Cancer
Surgery and/or Radiotherapy of Cancer
Presenter N. Thawani
Citation Annals of Oncology (2015) 26 (suppl_4): 1-100. 10.1093/annonc/mdv233
Authors N. Thawani, S. Thomas, S. Vyas, E. Rahila, H. Papaconstantinou, L. Wong, D. Niloyjyoti, S. Mutyala, J. Fleshman
  • Temple/US

Abstract

Introduction

Intensity Modulated radiation therapy (IMRT) is underutilized in pelvic radiation for rectal cancer secondary to concerns of geographical misses. It can potentially reduce toxicity similar to other pelvic sites where it is widely accepted and used. TMRT was devised at our institution utilizing IMRT targeted as described in methods section below. This study was conducted to analyze early outcomes of TMRT followed by TME for locally advanced rectal cancers.

Methods

50 consecutive patients from 07/2010 to 12/2014 treated with neoadjuvant chemoradiation for rectal cancers on an IRB approved institutional protocol. All patients received 45 Gy in 25 fractions to the pelvic nodes and the entire mesorectum along with a simultaneous integrated boost to a dose of 50 Gy in 25 fractions to mesorectum at the level of gross disease. IMRT planning was done with dose constraints for bladder, small bowel, bone marrow and femoral heads. All patients received 5-flourouracil based chemotherapy concurrently with radiation. Evaluation of toxicity was based on RTOG scoring.

Results

All patients completed their prescribed course of radiation. Patient characteristics are described in Table 1.Median followup was 25 months (range 4-55 months). Partial to complete response was noted in all patients except 2. 18% (9/50) patients had pathological complete response and 66% (33/50) had down staging of the locoregional disease. All acute toxicities were tolerable and subsided within 3 weeks of treatment completion. The incidence of > Grade 2 toxicity was: GI 38% (19/50), GU 18% (9/50), skin 14% (7/50) and myelotoxicity 42% (21/50). 66% (33/50) patients achieved sphincter preservation at the initial surgery. 5 patients needed modification for chemotherapy dose.

Conclusion

TMRT followed by TME has decreased toxicity with comparable pathological outcomes and shortened duration to traditionally used 3DCRT. This is the largest published series so far for rectal cancer treatment with this technique. The current results are promising and will possibly allow dose escalation in the future along with addition of targeted agents.

Table: P-339. Patient Characteristics