Pancreatic cancer adjuvant radiotherapy target volume design: based on the postoperative local recurrence spatial location

Phase 1 Study of Hypofractionated Proton Beam Radiation Therapy in Adjuvant Pancreatic Cancer (PROTON-PANC)

PURPOSE

Despite improvement in systemic therapy, patients with pancreatic ductal adenocarcinoma (PDAC) frequently experience local recurrence. We sought to determine the safety of hypofractionated proton beam radiation therapy (PBT) during adjuvant chemotherapy.

METHODS AND MATERIALS

Nine patients were enrolled in a single-institution phase 1 trial (NCT03885284) between 2019 and 2022. Patients had PDAC of the pancreatic head and underwent R0 or R1 resection and adjuvant modified FOLFIRINOX (mFFX) chemotherapy. The primary endpoint was to determine the dosing schedule of adjuvant PBT (5 Gy × 5 fractions) using limited treatment volumes given between cycles 6 and 7 of mFFX. Patients received PBT on days 15 to 19 in a 28-day cycle before starting cycle 7 (dose level 1, DL1) or on days 8 to 12 in a 21-day cycle before starting cycle 7 (DL2).

RESULTS

The median patient age was 66 years (range, 52-78), and the follow-up time from mFFX initiation was 12.5 months (range, 6.2-37.4 months). No patients received preoperative therapy. Four had R1 resections and 5 had node-positive disease. Three patients were enrolled on DL1 and 6 patients on DL2. One dose-limiting toxicity (DLT) occurred at DL2 (prolonged grade 3 neutropenia resulting in discontinuation of mFFX after cycle 7). No other DLTs were observed. Four patients completed 12 cycles of mFFX (range, 7-12; median, 11). No patients have had local recurrence. Five of 9 patients had recurrence: 3 in the liver, 1 in the peritoneum, and 1 in the bone. Six patients are still alive, 4 of whom are recurrence-free. The median time to recurrence was 12 months (95% CI, 4 to not reached [NR]), and median overall survival was NR (95% CI, 6 to NR; 2-year survival rate, 57%).

CONCLUSIONS

PBT integrated within adjuvant mFFX was well tolerated, and no local recurrence was observed. These findings warrant further exploration in a phase 2 trial.

Involved-Field Radiation Therapy for Patients With Unresectable Pancreatic Adenocarcinomas: Failure Pattern Analysis

Introduction Unresectable pancreatic tumors are frequently diagnosed. Initial treatment is carried out with chemotherapy. Eventually, in selected cases, radiotherapy may be used to improve local control rates and relieve the symptoms. The volume of radiotherapy treatment fields is the subject of controversy in the literature. The use of involved fields with the gross tumor volume encompassing the primary tumor and lymph nodes considered clinically positive is associated with a lower rate of side effects, but can lead to a higher rate of regional loco failures, especially in regional lymph nodes. The purpose of this article is to analyze the failure pattern of chemotherapy and involved-field radiation therapy (IFRT) for treating patients with unresectable pancreatic adenocarcinomas. Methods Clinical records of thirty consecutive patients treated from March 2016 to June 2020 for unresectable pancreatic adenocarcinoma were analyzed. The patients were treated with initial systemic chemotherapy (median: 6 cycles) with regimens based on gemcitabine or oxaliplatin-irinotecan (folfirinox/folfox) followed by radiotherapy (total dose of 50-54 Gy/with fractionation of 2 Gy/day). The patients were treated with IFRT. Local failure (LF) was defined as an increase in radiographic abnormality within the planning target volume (PTV). Elective nodal failure (ENF) was defined as recurrence in any lymph node region outside the PTV. Any other failure was defined as distant failure (DF). Results The median age of the patients was 68 years (range: 44-80 years); 20 patients (66.7%) were men, and 11 (36.6%) and 19 (63.4%) patients presented with tumors of stage II and III, respectively. Most patients (63.3%) had tumors in the pancreatic head. The median survival was 17.2 months. Tumor recurrences were classified as LF, DF, LF and DF in 7 (23.3%), 17 (56.7%), and 5 (16.7%) patients, respectively. Only one patient (3.3%) had both LF and ENF. No severe side effects related to radiotherapy were reported. Conclusion The use of IFRT did not cause a significant amount of ENF, besides presenting low morbidity, which is of special importance for patients with locally advanced tumors or low performance status. The predominant failure pattern was distant metastases.

Patterns of Recurrence After Primary Local Therapy for Pancreatic Ductal Adenocarcinoma - A Critical Review of Rationale and Target Delineation for (Neo)Adjuvant Radiation Therapy

PURPOSE

The purpose of this work was to describe pancreatic ductal adenocarcinoma (PDAC) patterns of locoregional spread and recurrence to help guide clinicians on (neo)adjuvant radiation therapy (RT) planning strategies and target volume delineation.

METHODS AND MATERIALS

A comprehensive review of clinical data was performed to describe PDAC patterns of locoregional spread, including extrapancreatic tumor extension, perineural invasion, regional lymph node involvement, and patterns of disease recurrence as influenced by (neo)adjuvant treatment strategy.

RESULTS

This review describes PDAC patterns of spread, disease progression, and evolving treatment techniques. Based upon this data, we advocate for inclusion of elective at-risk regions of extrapancreatic extension, perineural invasion, and lymphatic spread for patients receiving neoadjuvant RT.

CONCLUSIONS

This review provides a nuanced description of PDAC patterns of spread and recurrence to guide clinicians on target volume delineation and planning strategies to maximize the effectiveness of neo(adjuvant) RT delivery for patients with PDAC. Further prospective studies are needed to better define the optimal RT dose, fractionation regimens, and target volumes to be used in the (neo)adjuvant setting.

Adjuvant therapy with gemcitabine and stereotactic body radiation therapy versus gemcitabine alone for resected stage II pancreatic cancer: a prospective, randomized, open-label, single center trial

Background

The role of adjuvant radiation in pancreatic adenocarcinoma (PDAC) remains unclear. We aimed to investigate the efficacy of gemcitabine combined with stereotactic body radiation therapy (SBRT) as adjuvant therapy for resected stage II PDAC.

Methods

In this single-center randomized controlled trial, patients with stage II PDAC that underwent margin-negative resection were randomly assigned to gemcitabine-alone adjuvant chemotherapy or adjuvant SBRT followed by gemcitabine chemotherapy. The primary endpoint was recurrence-free survival (RFS). Secondary endpoints included locoregional recurrence-free survival (LRFS), overall survival (OS), and incidence of adverse events.

Results

Forty patients were randomly assigned to treatment between Sep 1, 2015 and Mar 31, 2018. Of these, 38 were included in the intention-to-treat analysis (20 in gemcitabine arm and 18 in gemcitabine plus SBRT arm). The median RFS and OS were 9.70, 28.0 months in the gemcitabine arm and 5.30, 15.0 months in the gemcitabine plus SBRT arm (RFS, P = 0.53; OS, P = 0.20), respectively. The median LRFS in both arms was unreached (P = 0.81). Grade 3 or 4 adverse events were all comparable between the two arms. Evaluation of data from the enrolled patients indicated that the addition of adjuvant SBRT was not associated with either better local disease control or recurrence-free survival.

Conclusions

Adjuvant SBRT neither provided a survival benefit nor improved local disease control in resected stage II PDAC.

Trial registration

ClinicalTrials.gov, NCT02461836. Registered 03/06/2015

Patterns of Regional Failure after Pancreaticoduodenectomy in Patients with Distal Extrahepatic Cholangiocarcinoma: Suggestion of the Clinical Target Volume for Elective Nodal Irradiation

AIMS

To evaluate the pattern of locoregional recurrence (LRR) after pancreaticoduodenectomy in patients with distal extrahepatic cholangiocarcinoma (DEHC) and to identify an optimal target volume for elective nodal irradiation.

MATERIALS AND METHODS

We analysed the medical records of DEHC patients who underwent pancreaticoduodenectomy and had LRR between 1991 and 2015. Among these patients, 30 received adjuvant chemotherapy alone, 14 underwent radiotherapy with or without chemotherapy and 28 received no treatment. After reviewing computed tomography or magnetic resonance imaging scans, the sites of LRR were identified and mapped to the corresponding locations on the representative computed tomography images.

RESULTS

In total, 136 LRRs were identified in 72 patients from four institutions. Local recurrences were observed at 44 sites (32.4%): tumour bed in 15, choledochojejunostomy in 25 and pancreaticojejunostomy in four. Regional recurrences were observed at 92 sites (67.6%); the most common site was the portal vein area (n = 18), followed by the para-aortic area (n = 17). Based on the mapped plots of regional recurrence, a clinical target volume covering 90% of regional recurrences was generated using the appropriate margin for the vascular structures of the portal vein, celiac axis, superior mesenteric artery, left gastric artery and aorta.

CONCLUSIONS

Given the pattern of LRR, we showed that the nodal clinical target volume based on vascular structures could appropriately cover high-risk regions of nodal involvement. These findings may help physicians construct a target volume in postoperative radiotherapy for DEHC patients undergoing pancreaticoduodenectomy.

Definition of Local Recurrence Site in Resected Pancreatic Adenocarcinoma: A Multicenter Study (DOLORES-1)

Simple Summary

Pancreatic cancer remains a disease with a dismal outlook for patients, with high relapse rates after surgery and adjuvant treatments. Thanks to the high conformality achievable with advanced radiotherapy techniques, a more robust definition of clinical target volume (CTV) margins is mandatory. Moreover, a precise CTV definition may affect local control, minimizing radiation-related toxicity and allowing dose escalation. Contrary to two recent studies, RTOG contouring guidelines are not based on a pattern of failure analysis. We provided a local failure risk map in resected pancreatic cancer, validating the results of previous studies. Moreover, according to a new probabilistic approach, we provided new CTV contouring guidelines for the postoperative radiotherapy of pancreatic cancer, modeling targets’ margins on a combination of our validated local failure map (30% of local failures) and RTOG guidelines (70% of local failures).

Abstract

The study aimed to generate a local failure (LF) risk map in resected pancreatic cancer (PC) and validate the results of previous studies, proposing new guidelines for PC postoperative radiotherapy clinical target volume (CTV) delineation. Follow-up computer tomography (CT) of resected PC was retrospectively reviewed by two radiologists identifying LFs and plotting them on a representative patient CT scan. The percentages of LF points randomly extracted based on CTV following the RTOG guidelines and based on the LF database were 70% and 30%, respectively. According to the Kernel density estimation, an LF 3D distribution map was generated and compared with the results of previous studies using a Dice index. Among the 64 resected patients, 59.4% underwent adjuvant treatment. LFs closer to the root of the celiac axis (CA) or the superior mesenteric artery (SMA) were reported in 32.8% and 67.2% cases, respectively. The mean (± standard deviation) distances of LF points to CA and SMA were 21.5 ± 17.9 mm and 21.6 ± 12.1 mm, respectively. The Dice values comparing our iso-level risk maps corresponding to 80% and 90% of the LF probabilistic density and the CTVs-80 and CTVs-90 of previous publications were 0.45–0.53 and 0.58–0.60, respectively. According to the Kernel density approach, a validated LF map was proposed, modeling a new adjuvant CTV based on a PC pattern of failure.

Adjuvant therapeutic strategies for resectable pancreatic adenocarcinoma

Of all patients diagnosed with pancreatic adenocarcinoma, only 15-20% present with resectable disease. Despite curative-intent resection, the prognosis remains poor with the majority of patients recurring, prompting the need for adjuvant therapy. Historical data support the use of adjuvant 5-fluorouracil (5-FU) or gemcitabine, but recent data suggest either gemcitabine plus capecitabine or modified FOLFIRINOX can improve overall survival when compared to gemcitabine alone. The use of adjuvant chemoradiation therapy remains controversial, primarily due to limitations in study design and mixed results of historical trials. The ongoing Radiation Therapy Oncology Group (RTOG)-0848 trial hopes to further define the role of adjuvant chemoradiation therapy. Intraoperative radiation therapy (IORT) and adjuvant immunotherapy represent additional possibilities to improve outcomes, but evidence supporting their use is limited. This article reviews adjuvant therapeutic strategies for resectable pancreatic adenocarcinoma, including chemotherapy, chemoradiation therapy, IORT and immunotherapy.