Feasibility of an adaptive strategy in preoperative radiochemotherapy for rectal cancer with image-guided tomotherapy: Boosting the dose to the shrinking tumor

Paolo Passoni, Claudio Fiorino, Najla Slim, Monica Ronzoni, Vincenzo Ricci, Saverio Di Palo, Paola De Nardi, Elena Orsenigo, Andrea Tamburini, Francesco De Cobelli, Claudio Losio, Nicola A. Iacovelli, Sara Broggi, Carlo Staudacher, Riccardo Calandrino, Nadia Di Muzio

Research output: Contribution to journalArticle

Abstract

Purpose: To investigate the feasibility of preoperative adaptive radiochemotherapy by delivering a concomitant boost to the residual tumor during the last 6 fractions of treatment. Methods and Materials: Twenty-five patients with T3/T4N0 or N+ rectal cancer were enrolled. Concomitant chemotherapy consisted of oxaliplatin 100 mg/m2 on days -14, 0, and +14, and 5-fluorouracil 200 mg/m2/d from day -14 to the end of radiation therapy (day 0 is the start of radiation therapy). Radiation therapy consisted of 41.4 Gy in 18 fractions (2.3 Gy per fraction) with Tomotherapy to the tumor and regional lymph nodes (planning target volume, PTV) defined on simulation CT and MRI. After 9 fractions simulation CT and MRI were repeated for the planning of the adaptive phase: PTVadapt was generated by adding a 5-mm margin to the residual tumor. In the last 6 fractions a boost of 3.0 Gy per fraction (in total 45.6 Gy in 18 fractions) was delivered to PTVadapt while concomitantly delivering 2.3 Gy per fraction to PTV outside PTVadapt. Results: Three patients experienced grade 3 gastrointestinal toxicity; 2 of 3 showed toxicity before the adaptive phase. Full dose of radiation therapy, oxaliplatin, and 5-fluorouracil was delivered in 96%, 96%, and 88% of patients, respectively. Two patients with clinical complete response (cCR) refused surgery and were still cCR at 17 and 29 months. For the remaining 23 resected patients, 15 of 23 (65%) showed tumor regression grade 3 response, and 7 of 23 (30%) had pathologic complete response; 8 (35%) and 12 (52%) tumor regression grade 3 patients had ≤5% and 10% residual viable cells, respectively. Conclusions: An adaptive boost strategy is feasible, with an acceptable grade 3 gastrointestinal toxicity rate and a very encouraging tumor response rate. The results suggest that there should still be room for further dose escalation of the residual tumor with the aim of increasing pathologic complete response and/or cCR rates.

Original languageEnglish
Pages (from-to)67-72
Number of pages6
JournalInternational Journal of Radiation Oncology Biology Physics
Volume87
Issue number1
DOIs
Publication statusPublished - Sep 1 2013

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ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Radiation
  • Cancer Research

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