Hyperfractionated abdominal reirradiation for gastrointestinal malignancies

Abstract

BackgroundWe sought to determine the role of abdominal reirradiation for patients presenting with recurrent or new primary gastrointestinal (GI) malignancies. At our institution, we have established a hyperfractionated, accelerated reirradiation regimen consisting of 39 Gray (Gy) in 26 twice-daily fractions. Although this regimen is used frequently in the pelvis, we sought to determine its toxicity and efficacy for abdominal tumors.MethodsTwenty-four patients who received abdominal reirradiation with a hyperfractionated, accelerated approach from 2000 to 2017 were identified. Overall survival (OS) and local progression-free survival (LPFS) were calculated using the Kaplan-Meier method. Several patient, tumor and treatment characteristics were evaluated on univariate analyses for association with OS and LPFS using a Cox proportional hazards model.ResultsOf the twenty-four patients identified, the majority (n = 11, 46%) had pancreatic adenocarcinoma as their primary disease but also included upper GI adenocarcinoma (n = 4), colon adenocarcinoma (n = 3), hepatobiliary cancers (n = 4) and other malignancies (n = 2). The majority of patients received 45–50.4Gy in 1.8Gy fractions as their initial abdominal radiation course. The median reirradiation dose was 39Gy in 26 twice-daily fractions with a minimum six hour interval. The median [interquartile range (IQR)] interval between the courses of radiotherapy was 28 [18.6–38.9] months. Only palliative reirradiation intent was associated with decreased OS. While colon adenocarcinoma primary was significantly associated with increased LPFS, the sample size was small (n = 3). The 1-yr rate of LPFS was 38%. The median [IQR] duration of freedom from local progression was 8 [3.8–19.2] months. The 1-year OS was 50% and the median (IQR) OS was 14 [6.3–19.6] months. Thirteen patients (54%) had acute side effects with one patient experiencing G3 nausea and one experiencing a G4 bleed; the remaining patients experienced G1-G2 symptoms.ConclusionHyperfractionated, accelerated reirradiation to the abdomen was relatively well-tolerated but provided limited local control to recurrent or second primary abdominal malignancies. Reirradiation could play a role in treating these patients with palliative or curative intent, but alternative strategies for delivering increased biologically effective dose should be further explored.

Dose-Escalated Magnetic Resonance Image–Guided Abdominopelvic Reirradiation With Continuous Intrafraction Visualization, Soft Tissue Tracking, and Automatic Beam Gating

“…Because of the exceptional OAR sparing uniquely achieved with an MR-Linac we used a dose escalation strategy for most patients; nearly all were prescribed >40 Gy EDQ2 10 and nearly half >50 Gy EDQ2 10. Our use of higher prescription doses was motivated by data suggesting that this can improve long-term treatment efficacy (4,5,17,18). Koom et al reported significantly higher LC among locally recurrent rectal cancer patients prescribed >50 Gy EQD2 10 who did not have subsequent surgery (5).…”

“…Historically, reRT has been prescribed to 30 to 40 Gy EQD2 10 to minimize the risk of severe toxic effects, although these modest doses are not associated with durable LC, especially in patients who do not proceed to surgery. 4 Owing to the exceptional OAR sparing uniquely achieved with an MR-Linac, we used a dose escalation strategy for most patients; nearly all were prescribed ≥40 Gy EDQ2 10 , and nearly half were prescribed ≥50 Gy EDQ2 10. Our use of higher prescription doses was motivated by data suggesting that this can improve long-term treatment efficacy.…”

“…As such, reRT is a complex undertaking in which an appropriate balance must be realized between delivering an effectively high target dose while simultaneously achieving appropriately low OAR doses. ReRT prescription doses are typically modest out of necessity to prioritize patient safety (3,4). However, safely achieving prescription dose intensification may improve long-term local control (LC), and also overall survival (OS) (4)(5)(6).…”

“…Prescription doses for ReRT are typically modest out of necessity to prioritize patient safety. 3 , 4 However, safely achieving prescription dose intensification may improve long-term local control (LC) and also overall survival (OS). 4 , 5 , 6 …”

“… 3 , 4 However, safely achieving prescription dose intensification may improve long-term local control (LC) and also overall survival (OS). 4 , 5 , 6 …”