Clinical results of dynamic tumor tracking intensity-modulated radiotherapy with real-time monitoring for pancreatic cancers using a gimbal mounted linac.

Akira Nakamura,Yuzo Kodama,Hiroyoshi Isoda,Toshihiko Masui,Yoko Goto,Shigemi Matsumoto,Masashi Kanai,Mami Akimoto,Ryo Ashida,Nobutaka Mukumoto,Mitsuhiro Nakamura,Takashi Mizowaki,Masahiro Hiraoka,Kyoichi Takaori,Satoshi Itasaka,Keiko Shibuya

doi:10.18632/oncotarget.25310

Abstract

ObjectivesWe performed dynamic tumor-tracking IMRT (DTT-IMRT) in locally advanced pancreatic cancer (LAPC) patients using a gimbaled linac of Vero4DRT. The purpose of this study is to report the first clinical results.MethodsFrom June 2013 to June 2015, eleven LAPC patients enrolled in this study and DTT-IMRT was successfully performed. The locoregional progression free survival (LRPFS), distant metastasis free survival (DMFS), overall survival (OS), hematologic and gastrointestinal (GI) toxicities were evaluated. Oncologic outcomes were estimated using Kaplan-Meier analysis, and toxicities using CTCAE v4.0.ResultsThe median radiation dose was 48 Gy (range, 45-51) in 15 fractions. Concurrent chemoradiotherapy (CCRT) was performed using gemcitabine in 9 patients and S-1 in one, while one patient refused. With a median follow-up of 22.9 months, 1-year LRPFS, DMFS, and OS rates were 90.9%, 70.7%, and 100%, respectively. Median survival time was 23.6 months. Grade-3 leucopenia and neutropenia were observed in two (18%) and one patient (9%), respectively. Grade-2 acute GI toxicity occurred in 2 patients (18%) and late grade-3 in 1 patient (9%).ConclusionsPreliminarily application of DTT-IMRT using a gimbaled linac on CCRT in LAPC patients resulted in excellent locoregional control and OS without severe toxicity.

Highlights

Pancreatic cancer is one of the leading causes of cancer-related mortality [1]
Grade-2 acute GI toxicity occurred in 2 patients (18%) and late grade-3 in 1 patient (9%)
Preliminarily application of dynamic tumor-tracking (DTT)-Intensity-modulated radiotherapy (IMRT) using a gimbaled linac on Concurrent chemoradiotherapy (CCRT) in Locally advanced pancreatic cancer (LAPC) patients resulted in excellent locoregional control and overall survival (OS) without severe toxicity

Summary

Introduction

Pancreatic cancer is one of the leading causes of cancer-related mortality [1]. Locally advanced pancreatic cancer (LAPC) remains to be an oncologic challenge, as radical surgical resection is not applicable and the outcomes of chemotherapy with or without radiotherapy are still poor. The radiosensitive gastrointestinal (GI) organs limit the radiation dose to the tumors of pancreases. Previous attempts to increase radiation dose using conventional techniques were unsuccessful, resulting in a high morbidity and mortality [2]. Intensity-modulated radiotherapy (IMRT) can simultaneously reduce the dose to surrounding normal organs, while allowing an increase in target tumor dose. IMRT for LAPC is considered useful and is demonstrated to reduce GI toxicities [3]. Several recent reports have demonstrated that dose escalation by IMRT improved local control and overall survival in LAPC [4]. There are several ways of motion control including motion-encompassing methods, breath-hold techniques, forced shallow-breathing, respiratory-gated techniques, and dynamic-tumor tracking methods [6]. The dynamic-tumor tracking method is considered a favorable method due to patient compliance and throughput of the treatment system

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