Stereotactic body radiotherapy and gemcitabine for locally advanced pancreatic cancer. Int J Radiat Oncol Biol Phys. 2010;78:735-742. [PMID: 20171803 DOI: 10.1016/j.ijrobp.2009.08.046]

Stereotactic Body Radiation Therapy for Locally Advanced Pancreatic Cancer

Introduction

For patients with locally advanced pancreatic cancer (LAPC), who are candidates for radiation therapy, dose-escalated radiation therapy (RT) offers unique benefits over traditional radiation techniques. In this review, we present a historical perspective of dose-escalated RT for LAPC. We also outline advances in SBRT delivery, one form of dose escalation and a framework for selecting patients for treatment with SBRT.

Results

Techniques for delivering SBRT to patients with LAPC have evolved considerably, now allowing for dose-escalation and superior respiratory motion management. At the same time, advancements in systemic therapy, particularly the use of induction multiagent chemotherapy, have called into question which patients would benefit most from radiation therapy. Multidisciplinary assessment of patients with LAPC is critical to guide management and select patients for local therapy. Results from ongoing trials will establish if there is a role of dose-escalated SBRT after induction chemotherapy for carefully selected patients.

Conclusion

Patients with LAPC have more therapeutic options than ever before. Careful selection for SBRT may enhance patient outcomes, pending the maturation of pivotal clinical trials.

Stereotactic body radiotherapy in pancreatic adenocarcinoma

BACKGROUND

Stereotactic body radiotherapy (SBRT) in pancreatic cancer allows high delivery of radiation doses on tumors without affecting surrounding tissue. This review aimed at the SBRT application in the treatment of pancreatic cancer.

DATA SOURCES

We retrieved articles published in MEDLINE/PubMed from January 2017 to December 2022. Keywords used in the search included: "pancreatic adenocarcinoma" OR "pancreatic cancer" AND "stereotactic ablative radiotherapy (SABR)" OR "stereotactic body radiotherapy (SBRT)" OR "chemoradiotherapy (CRT)". English language articles with information on technical characteristics, doses and fractionation, indications, recurrence patterns, local control and toxicities of SBRT in pancreatic tumors were included. All articles were assessed for validity and relevant content.

RESULTS

Optimal doses and fractionation have not yet been defined. However, SBRT could be the standard treatment in patients with pancreatic adenocarcinoma in addition to CRT. Furthermore, the combination of SBRT with chemotherapy may have additive or synergic effect on pancreatic adenocarcinoma.

CONCLUSIONS

SBRT is an effective modality for patients with pancreatic cancer, supported by clinical practice guidelines as it has demonstrated good tolerance and good disease control. SBRT opens a possibility of improving outcomes for these patients, both in neoadjuvant treatment and with radical intent.

A phantom to simulate organ motion and its effect on dose distribution in carbon ion therapy for pancreatic cancer

Objective. Carbon ion radiotherapy is a promising radiation technique for malignancies like pancreatic cancer. However, organs' motion imposes challenges for achieving homogeneous dose delivery. In this study, an anthropomorphicPancreasPhantom forIon-beamTherapy (PPIeT) was developed to simulate breathing and gastrointestinal motion during radiotherapy.Approach. The developed phantom contains a pancreas, two kidneys, a duodenum, a spine and a spinal cord. The shell of the organs was 3D printed and filled with agarose-based mixtures. Hounsfield Units (HU) of PPIeTs' organs were measured by CT. The pancreas motion amplitude in cranial-caudal (CC) direction was evaluated from patients' 4D CT data. Motions within the obtained range were simulated and analyzed in PPIeT using MRI. Additionally, GI motion was mimicked by changing the volume of the duodenum and quantified by MRI. A patient-like treatment plan was calculated for carbon ions, and the phantom was irradiated in a static and moving condition. Dose measurements in the organs were performed using an ionization chamber and dosimetric films.Main results. PPIeT presented tissue equivalent HU and reproducible breathing-induced CC displacements of the pancreas between (3.98 ± 0.36) mm and a maximum of (18.19 ± 0.44) mm. The observed maximum change in distance of (14.28 ± 0.12) mm between pancreas and duodenum was consistent with findings in patients. Carbon ion irradiation revealed homogenous coverage of the virtual tumor at the pancreas in static condition with a 1% deviation from the treatment plan. Instead, the dose delivery during motion with the maximum amplitude yielded an underdosage of 21% at the target and an increased uncertainty by two orders of magnitude.Significance. A dedicated phantom was designed and developed for breathing motion assessment of dose deposition during carbon ion radiotherapy. PPIeT is a unique tool for dose verification in the pancreas and its organs at risk during end-to-end tests.

Radiotherapy for Locally Advanced Pancreatic Adenocarcinoma-A Critical Review of Randomised Trials

Pancreatic cancer is rising as one of the leading causes of cancer-related death worldwide. Patients often present with advanced disease, limiting curative treatment options and therefore making management of the disease difficult. Systemic chemotherapy has been an established part of the standard treatment in patients with both locally advanced and metastatic pancreatic cancer. In contrast, the use of radiotherapy has no clear defined role in the treatment of these patients. With the evolving imaging and radiation techniques, radiation could become a plausible intervention. In this review, we give an overview over the available data regarding radiotherapy, chemoradiation, and stereotactic body radiation therapy. We performed a systematic search of Embase and the PubMed database, focusing on studies involving locally advanced pancreatic cancer (or non-resectable pancreatic cancer) and radiotherapy without any limitation for the time of publication. We included randomised controlled trials involving patients with locally advanced pancreatic cancer, including radiotherapy, chemoradiation, or stereotactic body radiation therapy. The included articles represented mainly small patient groups and had a high heterogeneity regarding radiation delivery and modality. This review presents conflicting results concerning the addition of radiation and modality in the treatment regimen. Further research is needed to improve outcomes and define the role of radiation therapy in pancreatic cancer.

High Intensity Focused Ultrasound Ablation for Patients With Locally Advanced Pancreatic Adenocarcinoma: A Propensity Score-Matching Analysis

OBJECTIVES

This retrospective study was conducted to assess the efficacy and safety of high intensity focused ultrasound (HIFU) in combination with chemotherapy compared with chemotherapy alone in treating patients with unresectable locally advanced pancreatic cancer (LAPC).

METHODS

The data of unresectable LAPC patients who received chemotherapy with or without HIFU ablation were retrieved retrospectively. The overall survival (OS), objective response rate (ORR), cancer antigen 19-9 response rate, and safety were compared between these two groups before and after propensity score matching (PSM).

RESULTS

Overall, 254 patients with LAPC were included, of whom 92 underwent HIFU ablation. After PSM to control for potential biases, HIFU was associated with improved OS (12.8 versus 12.2 months, log-rank P = .046), as compared to patients without HIFU ablation. Patients with numeric rating scale (NRS) less than 4, and receiving HIFU ablation were significantly associated with improved OS (adjusted hazard ratio [aHR] = 0.365 [95% confidence interval (CI) = 0.148-0.655], P = .002; aHR = 0.490 [95% CI = 0.250-0.961], P = .038; respectively) by multivariate analyses with the adjustment of age, NRS, and tumor size. ORR was also observed to be higher in HIFU group of 30.0% than in the chemotherapy group of 13.3% (P = .039). No severe adverse events of special interest or HIFU-caused deaths were observed.

CONCLUSIONS

Patients with unresectable LAPC who received gemcitabine-based chemotherapy might benefit from additional HIFU ablation.

Feasibility of delivered dose reconstruction for MR-guided SBRT of pancreatic tumors with fast, real-time 3D cine MRI

BACKGROUND AND PURPOSE

In MR-guided SBRT of pancreatic cancer, intrafraction motion is typically monitored with (interleaved) 2D cine MRI. However, tumor surroundings are often not fully captured in these images, and motion might be distorted by through-plane movement. In this study, the feasibility of highly accelerated 3D cine MRI to reconstruct the delivered dose during MR-guided SBRT was assessed.

MATERIALS AND METHODS

A 3D cine MRI sequence was developed for fast, time-resolved 4D imaging, featuring a low spatial resolution that allows for rapid volumetric imaging at 430 ms. The 3D cines were acquired during the entire beam-on time of 23 fractions of online adaptive MR-guided SBRT for pancreatic tumors on a 1.5 T MR-Linac. A 3D deformation vector field (DVF) was extracted for every cine dynamic using deformable image registration. Next, these DVFs were used to warp the partial dose delivered in the time interval between consecutive cine acquisitions. The warped dose plans were summed to obtain a total delivered dose. The delivered dose was also calculated under various motion correction strategies. Key DVH parameters of the GTV, duodenum, small bowel and stomach were extracted from the delivered dose and compared to the planned dose. The uncertainty of the calculated DVFs was determined with the inverse consistency error (ICE) in the high-dose regions.

RESULTS

The mean (SD) relative (ratio delivered/planned) D_99% of the GTV was 0.94 (0.06), and the mean (SD) relative D_0.5cc of the duodenum, small bowel, and stomach were respectively 0.98 (0.04), 1.00 (0.07), and 0.98 (0.06). In the fractions with the lowest delivered tumor coverage, it was found that significant lateral drifts had occurred. The DVFs used for dose warping had a low uncertainty with a mean (SD) ICE of 0.65 (0.07) mm.

CONCLUSION

We employed a fast, real-time 3D cine MRI sequence for dose reconstruction in the upper abdomen, and demonstrated that accurate DVFs, acquired directly from these images, can be used for dose warping. The reconstructed delivered dose showed only a modest degradation of tumor coverage, mostly attainable to baseline drifts. This emphasizes the need for motion monitoring and development of intrafraction treatment adaptation solutions, such as baseline drift corrections.

Induction FOLFIRINOX followed by stereotactic body radiation therapy in locally advanced pancreatic cancer

Introduction

FOLFIRINOX (the combination of 5-fluorouracil, leucovorin, irinotecan, and oxaliplatin) is the preferred systemic regimen for locally advanced pancreatic cancer (LAPC). Furthermore, stereotactic body radiation therapy (SBRT) is a promising treatment option for achieving local control in these patients. However, clinical outcomes in patients with LAPC treated using FOLFIRINOX followed by SBRT have not been clarified. Therefore, we aimed to evaluate clinical outcomes of induction FOLFIRINOX treatment followed by SBRT in patients with LAPC.

Methods

To this end, we retrospectively reviewed the medical records of patients with LAPC treated with induction FOLFIRINOX followed by SBRT in a single tertiary hospital. We evaluated overall survival (OS), progression-free survival (PFS), resection rate, SBRT-related adverse events, and prognostic factors affecting survival.

Results

Fifty patients were treated with induction FOLFIRINOX for a median of 8 cycles (range: 3-28), which was followed by SBRT. The median OS and PFS were 26.4 (95% confidence interval [CI]: 22.4-30.3) and 16.7 months (95% CI: 13.0-20.3), respectively. Nine patients underwent conversion surgery (eight achieved R0) and showed better OS than those who did not (not reached vs. 24.1 months, p = 0.022). During a follow-up period of 23.6 months, three cases of grade 3 gastrointestinal bleeding at the pseudoaneurysm site were noted, which were managed successfully. Analysis of the factors affecting clinical outcomes revealed that a high radiation dose (≥ 35 Gy) resulted in a higher rate of conversion surgery (25% [8/32] vs. 5.6% [1/18], respectively) and was an independent favorable prognostic factor for OS in the adjusted analysis (hazard ratio: 2.024, 95% CI: 1.042-3.930, p = 0.037).

Conclusion

Our findings suggest that induction FOLFIRINOX followed by SBRT in patients with LAPC results in better survival with manageable toxicities. A high total SBRT dose was associated with a high rate of conversion surgery and could afford better survival.

Stereotactic Body Radiotherapy (SBRT) of Pancreatic Cancer-A Critical Review and Practical Consideration

Pancreatic cancer is the third leading cause of cancer death in the developed world and is predicted to become the second by 2030. A cure may be achieved only with surgical resection of an early diagnosed disease. Surgery for more advanced disease is challenging and can be contraindicated for many reasons. Neoadjuvant therapy may improve the probability of achieving R0 resection. It consists of systemic treatment followed by radiation therapy applied concurrently or sequentially with cytostatics. A novel approach to irradiation, stereotactic body radiotherapy (SBRT), has the potential to improve treatment results. SBRT can deliver higher doses of radiation to the tumor in only a few treatment fractions. It has attracted significant interest for pancreatic cancer patients, as it is completed quickly, requires less time away from full-dose chemotherapy, and is well-tolerated than conventional radiotherapy. In this review, we aim to provide the reader with a basic overview of current evidence for SBRT indications in the treatment of pancreatic tumors. In the second part of the review, we focus on practical information with respect to SBRT treatment plan preparation the performance of such therapy. Finally, we discuss future directions related to the use of magnetic resonance linear accelerators.

A phantom-based analysis for tracking intra-fraction pancreatic tumor motion by ultrasound imaging during radiation therapy

Purpose

In this study, we aim to further evaluate the accuracy of ultrasound tracking for intra-fraction pancreatic tumor motion during radiotherapy by a phantom-based study.

Methods

Twelve patients with pancreatic cancer who were treated with stereotactic body radiation therapy were enrolled in this study. The displacement points of the respiratory cycle were acquired from 4DCT and transferred to a motion platform to mimic realistic breathing movements in our phantom study. An ultrasound abdominal phantom was placed and fixed in the motion platform. The ground truth of phantom movement was recorded by tracking an optical tracker attached to this phantom. One tumor inside the phantom was the tracking target. In the evaluation of the results, the monitoring results from the ultrasound system were compared with the phantom motion results from the infrared camera. Differences between infrared monitoring motion and ultrasound tracking motion were analyzed by calculating the root-mean-square error.

Results

The 82.2% ultrasound tracking motion was within a 0.5 mm difference value between ultrasound tracking displacement and infrared monitoring motion. 0.7% ultrasound tracking failed to track accurately (a difference value > 2.5 mm). These differences between ultrasound tracking motion and infrared monitored motion do not correlate with respiratory displacements, respiratory velocity, or respiratory acceleration by linear regression analysis.

Conclusions

The highly accurate monitoring results of this phantom study prove that the ultrasound tracking system may be a potential method for real-time monitoring targets, allowing more accurate delivery of radiation doses.

Dosimetric impact of intrafraction motion under abdominal compression during MR-guided SBRT for (Peri-) pancreatic tumors

Objective. Intrafraction motion is a major concern for the safety and effectiveness of high dose stereotactic body radiotherapy (SBRT) in the upper abdomen. In this study, the impact of the intrafraction motion on the delivered dose was assessed in a patient group that underwent MR-guided radiotherapy for upper abdominal malignancies with an abdominal corset. Approach. Fast online 2D cine MRI was used to extract tumor motion during beam-on time. These tumor motion profiles were combined with linac log files to reconstruct the delivered dose in 89 fractions of MR-guided SBRT in twenty patients. Aside the measured tumor motion, motion profiles were also simulated for a wide range of respiratory amplitudes and drifts, and their subsequent dosimetric impact was calculated in every fraction. Main results. The average (SD) D 99% of the gross tumor volume (GTV), relative to the planned D 99%, was 0.98 (0.03). The average (SD) relative D 0.5cc of the duodenum, small bowel and stomach was 0.99 (0.03), 1.00 (0.03), and 0.97 (0.05), respectively. No correlation of respiratory amplitude with dosimetric impact was observed. Fractions with larger baseline drifts generally led to a larger uncertainty of dosimetric impact on the GTV and organs at risk (OAR). The simulations yielded that the delivered dose is highly dependent on the direction of on baseline drift. Especially in anatomies where the OARs are closely abutting the GTV, even modest LR or AP drifts can lead to substantial deviations from the planned dose. Significance. The vast majority of the fractions was only modestly impacted by intrafraction motion, increasing our confidence that MR-guided SBRT with abdominal compression can be safely executed for patients with abdominal tumors, without the use of gating or tracking strategies.

Evolution of Radiation Therapy in Pancreas Cancer Management toward MRI-Guided Adaptive Radiation Therapy

Pancreas cancer has a poor prognosis despite aggressive treatment and is the fourth leading cause of cancer death in the United States. At diagnosis, most patients have either metastatic or locally advanced disease. In this article, we review the evolution of treatments in locally advanced pancreas cancer (LAPC) and discuss the various radiation therapy fractionation schemes. Furthermore, we examine the data supporting dose escalation and the delivery of ablative biologically effective doses in the setting of LAPC. Finally, we review the role of MRI-guided radiation therapy in escalating dose while sparing organs at risk in the era of stereotactic magnetic resonance-guided adaptive radiation therapy.

Stereotactic MR-Guided Radiotherapy for Pancreatic Tumors: Dosimetric Benefit of Adaptation and First Clinical Results in a Prospective Registry Study

Introduction

Stereotactic MR-guided adaptive radiotherapy (SMART) is an attractive modality of radiotherapy for pancreatic tumors. The objectives of this prospective registry study were to report the dosimetric benefits of daily adaptation of SMART and the first clinical results in pancreatic tumors.

Materials and Methods

All patients treated in our center with SMART for a pancreatic tumor were included. Patients were planned for five daily-adapted fractions on consecutive days. Endpoints were acute toxicities, late toxicities, impact of adaptive treatment on target volume coverage and organs at risk (OAR) sparing, local control (LC) rate, distant metastasis-free survival (DMFS), and overall survival (OS).

Results

Thirty consecutive patients were included between October 2019 and April 2021. The median dose prescription was 50 Gy. No patient presented grade > 2 acute toxicities. The most frequent grade 1–2 toxicities were asthenia (40%), abdominal pain (40%), and nausea (43%). Daily adaptation significantly improved planning target volume (PTV) and gross tumor volume (GTV) coverage and OAR sparing. With a median follow-up of 9.7 months, the median OS, 6-month OS, and 1-year OS were 14.1 months, 89% (95% CI: 70%–96%), and 75% (95% CI: 51%–88%), respectively, from SMART completion. LC at 6 months and 1 year was respectively 97% (95% CI: 79–99.5%) and 86% (95% CI: 61%–95%). There were no grade > 2 late toxicities. With a median follow-up of 10.64 months, locally advanced pancreatic cancer (LAPC) and borderline resectable pancreatic cancer (BRPC) patients (22 patients) had a median OS, 6-month OS, and 1-year OS from SMART completion of 14.1 months, 76% (95% CI: 51%–89%), and 70% (95% CI: 45%–85%), respectively. Nine patients underwent surgical resection (42.1% of patients with initial LAPC and 33.3% of patients with BRPC), with negative margins (R0). Resected patients had a significantly better OS as compared to unresected patients (p = 0.0219, hazard ratio (HR) = 5.78 (95% CI: 1.29–25.9)).

Conclusion

SMART for pancreatic tumors is feasible without limiting toxicities. Daily adaptation demonstrated a benefit for tumor coverage and OAR sparing. The severity of observed acute and late toxicities was low. OS and LC rates were promising. SMART achieved a high secondary resection rate in LAPC patients. Surgery after SMART seemed to be feasible and might increase OS in these patients.

A non-surgical COMBO-therapy approach for locally advanced unresectable pancreatic adenocarcinoma: preliminary results of a prospective study

In this short report we present a series of thirteen patients with locally advanced, unresectable, pancreatic cancer treated with a COMBO-Therapy consisting of: STEP-1: induction chemotherapy; STEP-2: concomitant chemoradiotherapy; STEP-3: stereotactic body radiotherapy boost. After four weeks from the end of each step all patients had a re-staging and a surgical re-evaluation. All patients completed STEP-1 and STEP-2. STEP-3 has been successfully delivered to 8/13 patients with a median dose of 12 Gy (range 10-21 Gy) in 1-3 fractions. The median LC was 20 months (range 10-32) with a 2-year LC of 72.9%, and none of the patients developed G3 acute or late toxicities. The median OS was 21.5 months (range 12-34), and the 2-year OS was 53.9%; the median PFS was 17.5 months (range 10-27). Our non-surgical COMBO-Therapy has demonstrated a feasible profile with good tolerance. Further prospective protocols are needed to confirm our preliminary results.

Intrafraction pancreatic tumor motion patterns during ungated magnetic resonance guided radiotherapy with an abdominal corset

Background

Stereotactic body radiotherapy (SBRT) has been shown to be a promising therapy for unresectable pancreatic tumors. However, intrafraction motion, caused by respiratory motion and organ drift, is one of the main concerns for efficient dose delivery in ungated upper abdominal radiotherapy. The aim of this study was to analyze the intrafraction gross tumor volume (GTV) motion in a clinical cohort.

Materials and methods

We included 13 patients that underwent online adaptive magnetic resonance (MR)-guided SBRT for malignancies in the pancreatic region (5 × 8 Gy). An abdominal corset was fitted in order to reduce the abdominal respiratory motion. Coronal and sagittal cine magnetic resonance images of the tumor region were made at 2 Hz during the entire beam-on time of each fraction. We used deformable image registration to obtain GTV motion profiles in all three directions, which were subsequently high-pass and low-pass filtered to isolate the motion caused by respiratory motion and baseline drift, respectively.

Results

The mean (SD) respiratory amplitudes were 4.2 (1.9) mm cranio-caudal (CC), 2.3 (1.1) mm ventral-dorsal (AP) and 1.4 (0.6) mm left–right (LR), with low variability within patients. The mean (SD) maximum baseline drifts were 1.2 (1.1) mm CC, 0.5 (0.4) mm AP and 0.5 (0.3) mm LR. The mean (SD) minimum baseline drifts were −0.7 (0.5) mm CC, −0.6 (0.5) mm AP and −0.5 (0.4) mm LR.

Conclusion

Overall tumor motion during treatment was small and interfractionally stable. These findings show that high-precision ungated MR-guided SBRT is feasible with an abdominal corset.

Online adaptive MR-guided stereotactic radiotherapy for unresectable malignancies in the upper abdomen using a 1.5T MR-linac

BACKGROUND

Introduction of online adaptive MR-guided radiotherapy enables stereotactic body radiation therapy (SBRT) of upper abdominal tumors. This study aimed to evaluate the feasibility of MR-guided SBRT on a 1.5 T MR-linac in patients with unresectable upper abdominal malignancies.

MATERIAL AND METHODS

Patients treated at the UMC Utrecht (April 2019 to December 2020) were identified in the prospective 'Multi-OutcoMe EvaluatioN of radiation Therapy Using the MR-linac' (MOMENTUM) study. Feasibility of treatment was arbitrarily defined as an on-table time interval of ≤60 min for >75% of delivered fractions and completion of >95% of fractions as scheduled, reflecting patient tolerability. Acute treatment-related toxicity was assessed at 3 months of follow-up and graded according to the National Cancer Institute Common Terminology Criteria of Adverse Events version 5.0.

RESULTS

Twenty-five consecutive patients with a median follow-up time of 8 (range 4-23) months were treated with 35 Gray (n = 4) and 40 Gray (n = 21) in five fractions over 2 weeks. For all fractions, contours were adapted based on the daily anatomy and delivered within 47 min/fraction (range 30-74). In 98/117 fractions (84%), adapted treatment was completed within 1 h. All patients received the scheduled irradiation dose as planned. No acute grade 3 toxicity or higher was reported. Treatment resulted in pain alleviation in 11/13 patients.

DISCUSSION

Online adaptive MR-guided SBRT on a 1.5 T MR-linac is feasible and well-tolerated in patients with unresectable upper abdominal malignancies. Dose escalation studies, followed by comparative studies, are needed to determine the optimal radiation dose for irradiation of upper abdominal malignancies.

Impact of neoadjuvant chemotherapy and stereotactic body radiation therapy (SBRT) on R0 resection rate for borderline resectable and locally advanced pancreatic cancer

BACKGROUND

The role of neoadjuvant stereotactic body radiation therapy (SBRT) in patients with borderline resectable pancreas cancer (BRPC) and locally advanced pancreas cancer (LAPC) remains controversial.

METHODS

We retrospectively evaluated BRPC and LAPC patients treated at our institution who underwent 2-3 months of chemotherapy followed by SBRT to a dose of 30-33 Gy. Overall survival (OS) and recurrence-free survival (RFS) were estimated and compared by Kaplan-Meier and log-rank methods.

RESULTS

We identified 103 (85 BRPC and 18 LAPC) patients treated per our neoadjuvant paradigm between 2011 and 2018, with resectability based on NCCN definitions. Median follow up was 25 months. Of patients completing neoadjuvant therapy, 73 (71%) underwent definitive resection. Seventy-one (97%) patients with definitively resected tumors had R0 resection and 5 (7%) had a complete pathologic response CR to neoadjuvant therapy. The median overall survival (OS) of the cohort was 24 months. Those with a complete or marked pathologic response had significantly better OS than those with a moderate response (41 vs 24 months, p < 0.02) and patients unable to undergo definitive surgery (17 months, p < 0.0003). Six resected patients experienced grade ≥3 surgical complications.

CONCLUSIONS

Neoadjuvant chemotherapy and SBRT are associated with promising pathologic response rates and R0 resection rates, with acceptable perioperative morbidity.

Survival outcome after stereotactic body radiotherapy for locally advanced and borderline resectable pancreatic cancer: A systematic review and meta-analysis

•

For LAPC, median OS was 14.1 months; pooled 1/2/3-year OS rates were 57%, 19% and 10%.

•

The median PFS was 10 months; pooled 1/2/3-year PFS rates were 36%, 12% and 4%.

•

Pooled rates of acute GI, acute hematologic and late GI toxicities were 2%, 4% and 8%.

•

For BRPC, median OS was 17.5 months; pooled 1/2-year OS rates were 75% and 29%.

•

The median PFS was 12.2 months; pooled 1/2-year PFS rates were 48% and 18%.

Background

Some studies reported stereotactic body radiotherapy (SBRT) has demonstrated superior therapeutic results than conventional radiotherapy. Nevertheless, this statement is controversial and the trial attempting to prove this is underway. We conducted this systemic review and meta-analysis aiming to combine the latest and most complete information about the survival outcomes and toxicities following SBRT for locally advanced pancreatic cancer (LAPC) and borderline resectable pancreatic cancer (BRPC).

Methods

Items involving SBRT and pancreatic cancer were searched in PubMed, EMBASE, Cochrane Library, SCOPUS and Web of Science. Median overall survival (OS), 1/2/3-year OS, median progression-free survival (PFS), 1/2/3-year PFS and incidence of grade 3–5 toxicities were the endpoints of interest in this meta-analysis. These endpoint proportions were pooled and analyzed using R.

Results

For the LAPC series, the median OS was 14.1 months; pooled 1/2/3-year OS rates were 57%, 19% and 10%, respectively; the median PFS was 10 months; pooled 1/2/3-year PFS rates were 36%, 12% and 4%; pooled incidence rates of acute gastrointestinal (GI), acute hematologic and late GI toxicity (grade≥3) were 2%, 4% and 8%. For the BRPC series, the median OS was 17.5 months; pooled 1/2-year OS rates were 75% and 29%; the median PFS was 12.2 months; pooled 1/2-year PFS rates were 48% and 18%; the incidence rates of toxicity (grade ≥ 3) were all 0%.

Conclusions

Our meta-analysis based on published results of OS, PFS and incidence rates of toxicity demonstrated that SBRT does not show desirable therapeutic result than the standard therapies for LAPC and BRPC.

Reducing the Toxicity of Radiotherapy for Pancreatic Cancer With Magnetic Resonance-guided Radiotherapy

Pancreatic cancer is a highly fatal malignancy for which surgery is currently considered to be the only curative treatment. However, less than a quarter of patients have disease amenable to definitive surgical resection. Local treatment with radiation therapy is a promising alternative to surgery for those patients with unresectable disease. However, conventional radiation techniques with computed tomography (CT)-guided therapy have yielded disappointing results due to the inability to deliver ablative doses of ionizing radiation, while sparing the radiosensitive adjacent organs at risk. Magnetic resonance-guided radiotherapy (MRgRT) has emerged as an alternative to CT-guided radiation treatment which allows for the delivery of higher doses of radiation with low toxicity to surrounding structures. Further study into the use of MRgRT and dose escalation for locally advanced unresectable pancreatic cancer is needed.

Controversies in radiotherapy for pancreas cancer

The management of pancreatic adenocarcinoma remains an area of controversy and ongoing discovery. Despite advances in surgical and radiation techniques, as well as chemotherapeutic agents, outcomes of patients diagnosed with this devastating malignancy remain poor. This article aims to review the available literature evaluating the efficacy of adjuvant, neoadjuvant, and definitive radiation therapy. We will also highlight areas of ongoing research efforts being carried out to improve outcomes in this patient population.

[Stereotactic body radiotherapy for locally advanced pancreatic cancer: A systemic review]

Stereotactic body radiation therapy (SBRT) for locally advanced pancreatic cancer (LAPC) is an emerging treatment option. Most studies showed local control of approximately 75% with no evidence of improved overall survival. Gastrointestinal toxicities could be significant, ranging up to 22% for acute toxicities≥grade 3+ and 44% for late toxicities≥grade 3+. Currently, no standardized guidelines for treatment and management scheme. We conducted a systemic review of published prospective and retrospective trials to evaluate the efficacy, safety, technical data, and discuss future directions.

Delta Radiomics Analysis for Local Control Prediction in Pancreatic Cancer Patients Treated Using Magnetic Resonance Guided Radiotherapy

The aim of this study is to investigate the role of Delta Radiomics analysis in the prediction of one-year local control (1yLC) in patients affected by locally advanced pancreatic cancer (LAPC) and treated using Magnetic Resonance guided Radiotherapy (MRgRT). A total of 35 patients from two institutions were enrolled: A 0.35 Tesla T2*/T1 MR image was acquired for each case during simulation and on each treatment fraction. Physical dose was converted in biologically effective dose (BED) to compensate for different radiotherapy schemes. Delta Radiomics analysis was performed considering the gross tumour volume (GTV) delineated on MR images acquired at BED of 20, 40, and 60 Gy. The performance of the delta features in predicting 1yLC was investigated in terms of Wilcoxon Mann-Whitney test and area under receiver operating characteristic (ROC) curve (AUC). The most significant feature in predicting 1yLC was the variation of cluster shade calculated at BED = 40 Gy, with a p-value of 0.005 and an AUC of 0.78 (0.61-0.94). Delta Radiomics analysis on low-field MR images might play a promising role in 1yLC prediction for LAPC patients: further studies including an external validation dataset and a larger cohort of patients are recommended to confirm the validity of this preliminary experience.

Accuracy and efficiency of respiratory gating comparable to deep inspiration breath hold for pancreatic cancer treatment

Purpose

Deep inspiration breath hold (DIBH) and respiratory gating (RG) are widely used to reduce movement of target and healthy organs caused by breathing during irradiation. We hypothesized that accuracy and efficiency comparable to DIBH can be achieved with RG for pancreas treatment.

Methods and Materials

Twenty consecutive patients with pancreatic cancer treated with DIBH (eight) or RG (twelve) volumetric modulated arc therapy during 2017–2019 were included in this study, with radiopaque markers implanted near or in the targets. Seventeen patients received 25 fractions, while the other three received 15 fractions. Only patients who could not tolerate DIBH received RG treatment. While both techniques relied on respiratory signals from external markers, internal target motions were monitored with kV X‐ray imaging during treatment. A 3‐mm external gating window was used for DIBH treatment; RG treatment was centered on end‐expiration with a duty cycle of 40%, corresponding to an external gating window of 2–3 mm. During dose delivery, kV images were automatically taken every 20^◦ or 40^◦ gantry rotation, from which internal markers were identified. The marker displacement from their initial positions and the residual motion amplitudes were calculated. For the analysis of treatment efficiency, the treatment time of every session was calculated from the motion management waveform files recorded at the treatment console.

Results

Within one fraction, the displacement was 0–5 mm for DIBH and 0–6 mm for RG. The average magnitude of displacement for each patient during the entire course of treatment ranged 0–3 mm for both techniques. No statistically significant difference in displacement or residual motion was observed between the two techniques. The average treatment time was 15 min for DIBH and 17 min for RG, with no statistical significance.

Conclusions

The accuracy and efficiency were comparable between RG and DIBH treatment for pancreas irradiation. RG is a feasible alternative strategy to DIBH.

Maximizing Tumor Control and Limiting Complications With Stereotactic Body Radiation Therapy for Pancreatic Cancer

PURPOSE

Stereotactic body radiation therapy (SBRT) and stereotactic ablative body radiation therapy is being increasingly used for pancreatic cancer (PCa), particularly in patients with locally advanced and borderline resectable disease. A wide variety of dose fractionation schemes have been reported in the literature. This HyTEC review uses tumor control probability models to evaluate the comparative effectiveness of the various SBRT treatment regimens used in the treatment of patients with localized PCa.

METHODS AND MATERIALS

A PubMed search was performed to review the published literature on the use of hypofractionated SBRT (usually in 1-5 fractions) for PCa in various clinical scenarios (eg, preoperative [neoadjuvant], borderline resectable, and locally advanced PCa). The linear quadratic model with α/β= 10 Gy was used to address differences in fractionation. Logistic tumor control probability models were generated using maximum likelihood parameter fitting.

RESULTS

After converting to 3-fraction equivalent doses, the pooled reported data and associated models suggests that 1-year local control (LC) without surgery is ≈79% to 86% after the equivalent of 30 to 36 Gy in 3 fractions, showing a dose response in the range of 25 to 36 Gy, and decreasing to less than 70% 1-year LC at doses below 24 Gy in 3 fractions. The 33 Gy in 5 fraction regimen (Alliance A021501) corresponds to 28.2 Gy in 3 fractions, for which the HyTEC pooled model had 77% 1-year LC without surgery. Above an equivalent dose of 28 Gy in 3 fractions, with margin-negative resection the 1-year LC exceeded 90%.

CONCLUSIONS

Pooled analyses of reported tumor control probabilities for commonly used SBRT dose-fractionation schedules for PCa suggests a dose response. These findings should be viewed with caution given the challenges and limitations of this review. Additional data are needed to better understand the dose or fractionation-response of SBRT for PCa.

Failure patterns and outcomes of dose escalation of stereotactic body radiotherapy for locally advanced pancreatic cancer: a multicenter cohort study

Objective

This study aims to compare recurrence patterns and outcomes of biologically effective dose (BED₁₀, α/β = 10) of 60-70 Gy with those of a BED₁₀ >70 Gy for locally advanced pancreatic cancer (LAPC).

Methods

Patients from three centers with a biopsy and a radiographically proven LAPC were retrospectively included and data were prospectively collected from June 2012 to June 2019. Radiotherapy was delivered by stereotactic body radiation therapy. Recurrences were categorized as in-field, marginal, and outside-the-field recurrence. Patients in two groups were required to receive abdominal enhanced contrast CT or MRI every 2-3 months and CA19-9 examinations every month during follow-up. Treatment-related toxicities were evaluated every month. Overall survival (OS) and progression-free survival (PFS) were estimated using the Kaplan-Meier method.

Results

After propensity score matching, there were 486 patients in each group. The median prescription dose of the two groups was 37 Gy/5-8 f (range: 36-40.8 Gy/5-8 f) and 42 Gy/5-8 f (range: 40-49.6 Gy/5-8 f), respectively. The median OS of patients with a BED₁₀ >70 Gy and a BED₁₀ 60-70 Gy was 20.3 months (95% CI: 19.1-21.5 months) and 18.2 months (95% CI: 17.8-18.6 months) respectively (p < 0.001). The median PFS of the two cohorts was 15.4 months (95% CI: 14.2-16.6 months) and 13.3 months (95% CI: 12.9-13.7 months) respectively (p < 0.001). A higher incidence of in-field and marginal recurrence was found in patients with BED₁₀ of 60-70 Gy (in-field: 97/486 versus 72/486, p = 0.034; marginal: 109/486 versus 84/486, p = 0.044). However, more patients with BED₁₀ >70 Gy had grade 2 or 3 acute (87/486 versus 64/486, p = 0.042) and late gastrointestinal toxicities (77/486 versus 55/486, p = 0.039) than those with BED₁₀ of 60-70 Gy.

Conclusion

BED₁₀ >70 Gy was found to have the best survival benefits along with a higher incidence of acute and late gastrointestinal toxicities. Therefore, a higher dose may be required in the case of patients' good tolerance.

Hypofractionated sequential radiotherapy boost: a promising strategy in inoperable locally advanced pancreatic cancer patients

PURPOSE

To investigate the potential benefits of a hypofractionated radiotherapy boost (HRB) after chemotherapy (CT) and concomitant chemoradiotherapy (CRT) in locally advanced pancreatic cancer (LAPC) patients. Primary endpoints were early and late toxicity, local control (LC) and pain-free progression (PFP) assessment. Two-years overall survival (OS), metastasis-free survival (MFS) and disease-free survival (DFS) were secondary endpoints.

MATERIALS AND METHODS

Patients (pts) affected by unresectable non-metastatic LAPC, previously treated with CT and CRT in upfront or sandwich setting, were selected for sequential HRB. Total prescribed dose was 30 Gy in 5 fractions (fr) to pancreatic primary lesion. Dose de-escalation was allowed in case of failure in respecting organs at risk constraints. Early and late toxicity were assessed according to CTCAE v.4.0 classification. The Kersh-Hazra scale was used for pain assessment. Local Control, PFP, MFS and DFS were calculated from the date of HRB to the date of relapse or the date of the last follow-up.

RESULTS

Thirty-one pts affected by unresectable, non-metastatic LAPC were consecutively enrolled from November 2004 to October 2019. All pts completed the planned HRB. Total delivered dose varied according to duodenal dose constraint: 20 Gy in 5 fr (N: 6; 19.4%), 20 Gy in 4 fr (N: 5; 16.2%), 25 Gy in 5 fr (N: 18; 58.0%) and 30 Gy in 6 fr (N: 2; 6.4%). Early and late toxicity were assessed in all pts: no Grade 3 or 4 acute gastrointestinal toxicity and no late gastrointestinal complications occurred. Median LC was 19 months (range 1-156) and 1- and 2-year PFP were 85% and 62.7%, respectively (median 28 months; range 2-139). According to the Kersh-Hazra scale, four pts had a Grade 3 and four pts had a Grade 1 abdominal pain before HRB. At the last follow-up only 3/31 pts had residual Grade 1 abdominal pain.Median MFS was 18 months (range 1-139). The 2-year OS after HRB was 57.4%, while 2-year OS from diagnosis was 77.3%.

CONCLUSION

Treatment intensification with hypofractionated radiotherapy boost is well tolerated in pts affected by unresectable LAPC previously treated with CT/CRT. Its rates of local and pain control are encouraging, supporting its introduction in clinical practice. Timing, schedule and dose of HRB need to be further investigated to personalize therapy and optimize clinical advantages.

Stereotactic Radiotherapy for Pancreatic Cancer: A Single-Institution Experience

Introduction

Despite treatment advances, the prognosis of locally advanced pancreatic cancer is poor. Treatment remains varied and includes systemic and radiotherapy (RT). Stereotactic body radiotherapy (SBRT), highly conformal high-dose RT per fraction, is an emerging treatment option.

Materials and methods

We performed a single-institution retrospective review of patients with pancreatic adenocarcinoma treated with SBRT from 2015-2017. The median dose was 27 Gy (range: 21-36 Gy) in three fractions. Endpoints included local progression (RECIST 1.1; Response Evaluation Criteria in Solid Tumors 1.1), distant metastasis, overall survival, and toxicity.

Results

Forty-one patients were treated, with a median follow-up of eight months. Patients who received SBRT had unresectable (49%), metastatic (17%), or borderline resectable (7%) disease, declined surgery (17%), medically inoperable (7%), or developed local recurrence following the Whipple procedure (2%). The six-month and one-year rates of local progression-free survival, distant metastasis-free survival, and overall survival were 62% and 55%, 44% and 32%, and 70% and 49%, respectively. Five patients (12%) experienced seven late gastrointestinal (GI) grade 3 events.

Conclusion 

SBRT may be considered a treatment option to achieve local control of pancreatic cancer and is associated with a modest risk of severe late GI toxicities. Systemic therapies remain important, given the proportion of patients who develop distant metastases.

Ablative 5-Fraction Stereotactic Magnetic Resonance-Guided Radiation Therapy With On-Table Adaptive Replanning and Elective Nodal Irradiation for Inoperable Pancreas Cancer

PURPOSE

Radiation therapy dose escalation using stereotactic body radiation therapy may significantly improve both local control (LC) and overall survival (OS) for patients with inoperable pancreas cancer. However, ablative dose cannot be routinely offered because of the risk of causing severe injury to adjacent normal organs. Stereotactic magnetic resonance (MR)-guided adaptive radiation therapy (SMART) represents a novel technique that may achieve safe delivery of ablative dose and improve long-term outcomes.

METHODS AND MATERIALS

We performed a single institution retrospective analysis of 35 consecutive pancreatic cancer patients treated with SMART in mid-inspiration breath hold on an MR-linear accelerator. Most had locally advanced disease (80%) and received induction chemotherapy (91.4%) for a median 3.9 months before stereotactic body radiation therapy. All were prescribed 5 fractions delivered in consecutive days to a median total dose of 50 Gy (BED₁₀ 100 Gy₁₀), typically with a 120% to 130% hotspot. Elective nodal irradiation was delivered to 20 (57.1%) patients. No patient had fiducial markers placed and all were treated with continuous intrafraction MR visualization and automatic beam triggering.

RESULTS

With median follow-up of 10.3 months from SMART, acute (2.9%) and late (2.9%) grade 3 toxicities were uncommon. One-year LC, distant metastasis-free survival, progression-free survival, cause-specific survival, and OS were 87.8%, 63.1%, 52.4%, 77.6%, and 58.9%, respectively.

CONCLUSIONS

To our knowledge, this is the first report of 5-fraction pancreas SMART delivered on an MR-linear accelerator. We observed minimal severe treatment-related toxicity and encouraging early LC. Prospective confirmation of feasibility and long-term clinical outcomes of dose intensified SMART is warranted.

Role of endoscopic ultrasonography guided fiducial marker placement in gastrointestinal cancer

PURPOSE OF REVIEW

Dose escalation radiation therapy such as those delivered by stereotactic body radiation therapy (SBRT) has shown to improve local disease control in multiple types of malignancies. This requires fiducial placement to improve accuracy of treatment and avoid adverse events to adjacent radiosensitive organs during respiration phases. The purpose of this review is to provide updates of recent high-quality articles related to endoscopic ultrasonography (EUS)-guided fiducial placement for gastrointestinal malignancies, particularly in pancreatic cancer, which is expected to be the second leading cause of cancer-related deaths in the USA within this decade.

RECENT FINDINGS

A recent systematic review and meta-analysis has shown that EUS-guided fiducial placement for gastrointestinal malignancies has excellent technical success and safety profile. Comparative studies of most commercially available fiducial types via a 22-gauge needle system showed that a 0.035 mm diameter and 10 mm long gold fiducial with coiled configuration, hollow core and external helical design might be favoured due to its most balanced performance of visibility, artifact and migration.

SUMMARY

A fine balance of performance characteristics of fiducials should be discussed with radiation oncologists to select a suitable and preferred type of fiducials. The comparative studies of other newly developed platinum fiducials and liquid fiducial are pending.

Patterns of Failure After Adjuvant Stereotactic Body Radiation Therapy for Pancreatic Cancer With Close or Positive Margins

Purpose

There is no consensus on treatment volumes for adjuvant stereotactic body radiation therapy (SBRT) for pancreatic cancer. Herein, we report patterns of failure after pancreatic SBRT for close/positive margins, which may inform target volume design.

Methods and Materials

An institutional review board-approved retrospective review of patients with pancreatic adenocarcinoma treated with adjuvant SBRT for close/positive margins from 2009 to 2018 was conducted. Patterns of failure were defined as local (LF) within the tumor bed, regional (RF) within lymph nodes or anastomoses, or distant (DF). The cumulative incidence of locoregional failure was calculated using the cumulative incidence function accounting for the competing risk of death. LFs were mapped to the planning target volume (PTV) and classified as in-field (completely within the PTV), marginal (partially within the PTV), or out-of-field (completely outside the PTV). The location of LFs was compared with the Radiation Therapy Oncology Group 0848 contouring atlas to determine whether standard postoperative radiation therapy volumes would have included the LF.

Results

Seventy-six patients were treated with adjuvant SBRT for close (51.3%) or positive (48.7%) margins. Most (81.6%) received 36 Gy in 3 fractions, with a median PTV volume of 17.8 cc (interquartile range, 12.1-25.6). With a median follow-up of 17.0 months (interquartile range, 7.3-28.4), crude rates of first isolated LF, isolated RF, and DF +/- LF or RF were 9.2%, 6.6%, and 56.6%, respectively. Two-year cumulative incidences of LF, RF, locoregional failure, and DF were 34.9%, 30.8%, 49.2%, and 60.4%, respectively. Of 28 reviewable LFs, 21.4% were in-field while the remainder were completely outside (60.7%) or partially outside (17.9%) the PTV. Most LFs (92.9%) would have been encompassed by the Radiation Therapy Oncology Group consensus target volumes.

Conclusions

After adjuvant pancreatic SBRT for close/positive margins, the majority of LFs were outside the PTV but within contemporary target volumes for conventional radiation therapy.

Intensified systemic therapy and stereotactic ablative radiotherapy dose for patients with unresectable pancreatic adenocarcinoma

PURPOSE

We aimed to report the long-term impact of modern chemotherapy and SABR dose regimens on oncologic outcomes of unresectable pancreatic adenocarcinoma (PA).

MATERIALS AND METHODS

We reviewed the treatment characteristics and outcomes of all patients who received multi-fraction SABR for unresectable PA between February 2007 and August 2018 at our institution. Time-to-events were calculated from date of diagnosis treating death as a competing risk.

RESULTS

A total of 149 patients were identified. Median follow-up was 15 months (range: 5-47). Median SABR dose was 33 Gy (range: 20-45) delivered in 5 fractions in 143 patients, and 3 or 6 fractions in 6 patients. 107 patients (72%) received gemcitabine-based chemotherapy while 31 (21%) received modified FOLFIRINOX (mFFX). Median OS was 16 months (95% CI, 14-17), with a 1-year cumulative incidence of LF of 14%. The combination of SABR doses ≥40 Gy and mFFX (n = 21) showed a superior PFS and OS to the use of GEM-based chemotherapy with <40 Gy SABR doses (median PFS: 14 vs. 10 months, HR: 0.46, 95% CI: 0.29-0.71, P = 0.003; median OS: 24 vs. 14 months, HR: 0.36, 95% CI: 0.22-0.59, P = 0.002), with 1-year PFS and OS of 67% and 90% compared to 35% and 59% for those who received GEM-based chemotherapy with <40 Gy SABR doses, respectively.

CONCLUSIONS

The use of mFFX and a SABR dose ≥40 Gy in 5 fractions may be superior compared to regimens that utilize gemcitabine-based chemotherapy or SABR doses <40 Gy.

Hypofractionated Stereotactic Body Radiation Therapy With Simultaneous Integrated Boost and Simultaneous Integrated Protection in Pancreatic Ductal Adenocarcinoma

AIMS

To evaluate the safety and feasibility of stereotactic body radiation therapy (SBRT) with simultaneous integrated boost (SIB) and simultaneous integrated protection (SIP) in borderline resectable and locally advanced pancreatic ductal adenocarcinoma.

MATERIALS AND METHODS

Patients receiving SBRT following induction chemotherapy from January 2017 to December 2018 were included in this observational analysis. SBRT was delivered in five consecutive daily fractions by administering 30 Gy to the planning target volume while simultaneously delivering a 50 Gy SIB to the tumour-vessel interface. SIP was created by lowering the dose to 25 Gy on the overlap area between the planning target volume and the planning organ at risk volume. The primary end point was acute and late gastrointestinal grade ≥3 toxicity. Secondary end points were freedom from local progression, overall survival and progression-free survival (PFS).

RESULTS

Fifty-nine consecutive patients (27 borderline resectable and 32 locally advanced) were included. Fifty-eight patients (98.3%) completed the SBRT planned treatment and 35 patients (59.4%) received surgical resection following SBRT. No acute or late grade ≥3 SBRT-related adverse events were observed. The median follow-up time was 15.1 months in the overall cohort and 18.1 months in censored patients. One- and 2-year freedom from local progression rates were 85% and 80% versus 79.7% and 60.6% in resected and unresected patients, respectively (P = 0.33). The median overall survival and PFS were 30.2 months and 19 months from diagnosis and 19.1 months and 10.7 months from SBRT in the entire cohort. Resected patients had improved 2-year overall survival rates (72.5% versus 49%, P = 0.012) and median PFS (13 months versus 5 months; P < 0.001) relative to unresected patients. There was no survival difference between borderline resectable and locally advanced patients.

CONCLUSIONS

SBRT with SIB/SIP had an excellent toxicity profile and could be administered safely on pancreatic ductal adenocarcinoma patients, even in a total neoadjuvant setting.

On-line adaptive MR guided radiotherapy for locally advanced pancreatic cancer: Clinical and dosimetric considerations

Introduction

Magnetic Resonance-guided Radiation Therapy (MRgRT) allows online adaptations (OA) of the treatment plan to optimize daily dose distribution based on patient's anatomy, just before fraction delivery. The aim of this study is to evaluate feasibility and the dosimetric improvement of the OA workflow implemented in our institution for locally advanced pancreatic cancer (LAPC) patients, in terms of target coverage and organs at risk (OARs) sparing.

Methods

We retrospectively analysed 8 LAPC patients treated with MRgRT in combination with the OA approach, using video-assisted inspiratory breath-hold for a total of 38 fractions with a dose ranging from 30 Gy to 40 Gy in 5 fractions.Dose distribution of the baseline plan was first calculated based on daily anatomy, obtaining a "predicted" plan to assess the dosimetric improvement. If the dose distribution did not meet the constraints set in the planning phase, PTV, GTV and OARs were re-contoured within a distance of 3 cm from the PTV external edge and a new online "adaptive" plan was generated. Other clinical and planning parameters were also evaluated to assess the feasibility and the dosimetic benefit of the online adaptive workflow.

Results

Out of 38 total fractions, 26 (68.4%) were adapted online and 12 (31.6%) were delivered using the baseline plan. The use of the adaptive workflow resulted to be feasible in our clinical practice and advantageous in all the patients: mean PTV V95% increased by 10.8% (5.7-20.8) while mean CTV V98% of 12.6% (7.3-17.7). Also OARs V33 and V25 showed a positive trend avoiding unnecessary irradiation.

Conclusion

OA workflow improves the dosimetric benefit of MRgRT, preventing the occurrence of high-doses to OARs and increasing the safety of stereotactic treatment for LAPC, without any drawback for our daily clinical practice routine.

A Novel Scaffold-Based Hybrid Multicellular Model for Pancreatic Ductal Adenocarcinoma-Toward a Better Mimicry of the in vivo Tumor Microenvironment

With a very low survival rate, pancreatic ductal adenocarcinoma (PDAC) is a deadly disease. This has been primarily attributed to (i) its late diagnosis and (ii) its high resistance to current treatment methods. The latter specifically requires the development of robust, realistic in vitro models of PDAC, capable of accurately mimicking the in vivo tumor niche. Advancements in the field of tissue engineering (TE) have helped the development of such models for PDAC. Herein, we report for the first time a novel hybrid, polyurethane (PU) scaffold-based, long-term, multicellular (tri-culture) model of pancreatic cancer involving cancer cells, endothelial cells, and stellate cells. Recognizing the importance of ECM proteins for optimal growth of different cell types, the model consists of two different zones/compartments: an inner tumor compartment consisting of cancer cells [fibronectin (FN)-coated] and a surrounding stromal compartment consisting of stellate and endothelial cells [collagen I (COL)-coated]. Our developed novel hybrid, tri-culture model supports the proliferation of all different cell types for 35 days (5 weeks), which is the longest reported timeframe in vitro. Furthermore, the hybrid model showed extensive COL production by the cells, mimicking desmoplasia, one of PDAC's hallmark features. Fibril alignment of the stellate cells was observed, which attested to their activated state. All three cell types expressed various cell-specific markers within the scaffolds, throughout the culture period and showed cellular migration between the two zones of the hybrid scaffold. Our novel model has great potential as a low-cost tool for in vitro studies of PDAC, as well as for treatment screening.

Conventionally fractionated radiation therapy versus stereotactic body radiation therapy for locally advanced pancreatic cancer (CRiSP): An international systematic review and meta-analysis

BACKGROUND

The goal of this study was to characterize the efficacy and safety of stereotactic body radiation therapy (SBRT) versus conventionally fractionated radiation therapy with concurrent chemotherapy (CFRT) for the definitive treatment of locally advanced pancreatic cancer. The primary outcome measure was efficacy, defined by 2-year overall survival (OS). Secondary outcomes were incidence of any grade 3/4 toxicity and 1-year OS.

METHODS

A PICOS/PRISMA/MOOSE selection protocol was used to identify eligible studies. Inclusion criteria were: 1) patients diagnosed with locally advanced N0-1 M0 pancreatic cancer; 2) CFRT 1.8 to 2.0 Gy/fraction with chemotherapy per protocol or SBRT ≥5 Gy/fraction in ≤5 fractions; 3) either no control group or another definitive chemotherapy or radiation therapy arm; 4) at least 1 of the outcome measures reported; and 5) single or multi-arm phase 2/3 prospective study for CFRT and/or phase 1/2 or retrospective study for SBRT. Neoadjuvant and/or adjuvant chemotherapy was prescribed per protocol specifications. Weighted random effects meta-analyses were conducted using the DerSimonian and Laird method to characterize summary effect sizes for each outcome.

RESULTS

A total of 470 studies were initially screened; of these, 9 studies assessed SBRT and 11 studies assessed CFRT. For SBRT, the median dose was 30 Gy, and the most common regimen was 30 Gy/5 fractions. For CFRT, doses ranged from 45 to 54 Gy in 1.8- to 2.0-Gy fractions, with the majority of studies delivering 50.4 Gy in 28 fractions with concurrent gemcitabine. The random effects estimate for 2-year OS was 26.9% (95% CI, 20.6%-33.6%) for SBRT versus 13.7% (95% CI, 8.9%-19.3%) for CFRT and was statistically significant in favor of SBRT. The random effects estimate for 1-year OS was 53.7% (95% CI, 39.3%-67.9%) for SBRT versus 49.3% (95% CI, 39.3%-59.4%) for CFRT, and was not statistically significant. The random effects estimate for acute grade 3/4 toxicity was 5.6% (95% CI, 0.0%-20.0%) for SBRT versus 37.7% (95% CI, 24.0%-52.5%) for CFRT and was statistically significant in favor of SBRT. The random effects estimate for late grade 3/4 toxicity was 9.0% for SBRT (95% CI, 3.3%-17.1%) versus 10.1% (95% CI, 1.8%-23.8%) for CFRT, which was not statistically significant.

CONCLUSION

These results suggest that SBRT for LAPC may result in a modest improvement in 2-year OS with decreased rates of acute grade 3/4 toxicity and no change in 1-year-OS or late toxicity. Further study into the use of stereotactic body radiation therapy for these patients is needed.

Clinical Limitations of Photon, Proton and Carbon Ion Therapy for Pancreatic Cancer

Introduction: Despite improvements in radiation therapy, chemotherapy and surgical procedures over the last 30 years, pancreatic cancer 5-year survival rate remains at 9%. Reduced stroma permeability and heterogeneous blood supply to the tumour prevent chemoradiation from making a meaningful impact on overall survival. Hypoxia-activated prodrugs are the latest strategy to reintroduce oxygenation to radioresistant cells harbouring in pancreatic cancer. This paper reviews the current status of photon and particle radiation therapy for pancreatic cancer in combination with systemic therapies and hypoxia activators. Methods: The current effectiveness of management of pancreatic cancer was systematically evaluated from MEDLINE^® database search in April 2019. Results: Limited published data suggest pancreatic cancer patients undergoing carbon ion therapy and proton therapy achieve a comparable median survival time (25.1 months and 25.6 months, respectively) and 1-year overall survival rate (84% and 77.8%). Inconsistencies in methodology, recording parameters and protocols have prevented the safety and technical aspects of particle therapy to be fully defined yet. Conclusion: There is an increasing requirement to tackle unmet clinical demands of pancreatic cancer, particularly the lack of synergistic therapies in the advancing space of radiation oncology.

The role of seed implantation in patients with unresectable pancreatic carcinoma after relief of obstructive jaundice using ERCP

PURPOSE

The purpose of the study was to investigate the role of iodine-125 seed implantation, guided by endoscopic ultrasound (EUS) and/or percutanous ultrasound, in patients with unresectable pancreatic carcinoma after relief of obstructive jaundice using endoscopic retrograde cholangiopancreatography (ERCP).

METHODS AND MATERIALS

A total of 101 patients with obstructive jaundice due to unresectable pancreatic carcinoma were enrolled between January 2010 and December 2017 in this retrospective study. Of these patients, 50 underwent implantation of iodine-125 seeds under EUS and/or percutaneous ultrasound guidance after receiving a stent via ERCP (treatment group), and 51 received a stent via ERCP without undergoing seed implantation (control group). The clinical data and therapeutic outcomes of these patients were analyzed.

RESULTS

Compared with the control group, the treatment group obtained significant relief of abdominal pain at the 1-week, 1-month, and 3-month followup (p < 0.05), with a significantly lower visual analog scale pain score (p < 0.05). The treatment group obtained a longer median survival (8.8 vs. 6.5 months, p = 0.02), longer median duration of stent patency (10.8 ± 1.4 vs. 6.9 ± 0.8 months, p = 0.02), and prolonged average time to gastric outlet obstruction (6.8 ± 1.6 vs. 5.3 ± 1.3 months, p = 0.02). Differences between liver function and appetite for the two groups were not significant (p > 0.05 and p = 0.59, respectively).

CONCLUSIONS

Iodine-125 seed implantation after relief of obstructive jaundice via ERCP prolongs survival, biliary stent patency, and time to gastric outlet obstruction and improves patient quality of life by relieving pancreatic pain in patients with unresectable pancreatic carcinoma.

[Stereotactic body radiotherapy: Passing fad or revolution?]

Stereotactic body radiotherapy (SBRT) is a young technology that can deliver a high dose of radiation to the target, utilizing either a single dose or a small number of fractions with a high degree of precision within the body. Various technical solutions co-exist nowadays, with particular features, possibilities and limitations. Health care authorities have currently validated SBRT in a very limited number of locations, but many indications are still under investigation. It is therefore challenging to accurately appreciate the SBRT therapeutic index, its place and its role within the anticancer therapeutic arsenal. The aim of the present review is to provide SBRT definitions, current indications, and summarize the future ways of research. There are three validated indications for SBRT: un-resecable T1-T2 non small cell lung cancer, <3 slow-growing pulmonary metastases secondary to a stabilized primary, and the tumours located close to the medulla. In other situations, the benefit of SBRT is still to be demonstrated. One of the most promising way of research is the ablative treatment of oligo metastatic cancers, with recent studies suggesting a survival benefit. Furthermore, the most recent data suggest that SBRT is safe. Finally, the SBRT combined with immune therapies is promising, since it could theoretically trigger the adaptative anticancer response.

Influence of dose-averaged linear energy transfer on tumour control after carbon-ion radiation therapy for pancreatic cancer

•

High LET and high RBE of carbon ion made it a promising tool for treating pancreatic cancers.

•

Dose averaged LET minimum within the GTV is significantly associated with local control.

•

Outcome of CIRT in pancreatic cancers can be improved by modulating dose averaged LET within the GTV.

Background and purpose

High linear energy transfer (LET) radiation carbon-ion radiotherapy (C-ion RT) is one of the most promising modalities for treating unresectable primary pancreatic cancers. However, how LET contributes to a therapeutic effect is not clear. To assess whether there is an enhanced effect of high LET radiation on tumour control, we aimed to determine the impact of dose-averaged LET on local control (LC) of primary pancreatic tumours.

Materials and methods

A retrospective analysis of 18 patients with primary pancreatic carcinomas treated with definitive C-ion RT with concurrent chemotherapy in 2013 was conducted. The dose of irradiation was 55.2 Gy (RBE). The relationship between dose-averaged LET and LC of primary tumours was evaluated.

Results

All patients had histologically confirmed adenocarcinoma. The median follow-up duration was 22 months. The actuarial LC and overall survival (OS) at 18 months were 62.5% and 70.1%, respectively. There were no cases of grade ≥3 late toxicities observed. Local recurrences developed in four patients (22%), all of which were infield central recurrences. Although there were no significant differences in gross tumour volume (GTV) dose coverage, patients with higher minimum dose-averaged LET (LETmin) values within the GTV had better LC (dose-averaged LETmin ≥44 keV/microm; 18-months LC 100.0% vs 34.3%; p = 0.0366).

Conclusion

Dose-averaged LETmin within the GTV was significantly associated with LC of primary pancreatic cancers. Our data suggest that outcomes for patients with unresectable primary pancreatic cancers receiving C-ion RT can be improved by modulating the dose-averaged LET within the GTV.

Dose Escalation in Stereotactic Body Radiation Therapy for Pancreatic Cancer: A Meta-Analysis

OBJECTIVE

To determine whether increasing biologically effective dose (BED) with stereotactic body radiation therapy (SBRT) is associated with improved local control (LC) or toxicities in patients with locally advanced pancreatic cancer.

METHODS

A PICOS/PRISMA/MOOSE selection protocol was used to identify 15 studies across 12 institutions in 5 countries where patients received definitive SBRT for nonmetastatic disease. Biologically equivalent doses were calculated with an α/β of 10 (ie, BED10) for LC and acute toxicity and 3 (ie, BED3) for late toxicity. Fixed and random effects models were used to characterize LC and grade 3/4 toxicities by BED.

RESULTS

There were 508 patients included with a median follow-up time of 9.1 months. The median dose was 30 Gy, and the most common regimen was 30 Gy/5 fractions. There was no significant difference in LC rates at 1 year between the BED10<70 Gy versus ≥70 Gy groups, with an estimate of 0.60 (95% confidence interval [CI], 0.36-0.81) versus 0.83 (95% CI, 0.63-0.97), respectively. There was no significant difference in acute toxicity rates between the BED10<70 Gy versus ≥70 Gy groups, with an estimate of 0.02 (95% CI, 0.00-0.08) versus 0.05 (95% CI, 0.00-0.22), respectively. Given the dose distribution across studies, 3 intervals were used to characterize BED3. There were no significant differences in late toxicity among those receiving BED3<100, 100 to 200, or >200 Gy.

CONCLUSIONS

SBRT for pancreatic cancer results in LC rates of 60% to 83% and clinically significant toxicity of <7%. Increasing BED10 beyond 70 Gy was not associated with increased rates of 1-year LC or acute toxicity. Increasing BED3 beyond 100 Gy was not associated with increased rates of late toxicity.

The Evolving Field of Stereotactic Body Radiation Therapy in Pancreatic Cancer

Pancreatic cancer remains a devastating disease with dismal outcomes despite the development of novel chemotherapeutic regimens and radiation techniques. Stereotactic body radiation therapy (SBRT) offers an advantage both in image guidance and radiation dose delivery to direct ablative doses to tumors with acceptable toxicity compared to conventional techniques. Recent literature is clustered with data pertaining to SBRT in patients with resectable, borderline resectable and locally advanced pancreatic tumors. We here present a summary of the current data and highlight the limitations and potential for future growth. Further clinical study in the form of multi-institutional trials is warranted to establish the role of SBRT in combination with new chemo- therapeutic agents as well as a non-invasive alternative to surgery.

Hypofractionated intensity-modulated radiotherapy in locally advanced unresectable pancreatic cancer: A pilot study

PURPOSE

To test feasibility and safety of hypofractionated intensity modulated radiotherapy (H-IMRT) in pancreatic adenocarcinoma (PAC) treatment.

METHODS

Patients with unresectable nonmetastatic PAC were prospectively enrolled on a pilot study. Patients received H-IMRT to gross tumor volume to a total dose of 52 Gy (4 Gy/fraction). Toxicity rates, duodenal dosimetric parameters, and clinical outcomes were evaluated.

RESULTS

Ten patients received H-IMRT regimen. Objective tumor response was recorded in all patients but one. Gastrointestinal toxicity was the most common acute side effect and its severity moderately correlated with duodenal maximum dose (ρ = 0.46) and percentage of duodenal volume exposed to 5 Gy (ρ = 0.46). The 1-year overall and disease-free survival were 83.3% and 68.6%, respectively.

CONCLUSION

H-IMRT seems to guarantee a high local control rate without severe toxicity. Its use in unresectable nonmetastatic PAC needs to be further investigated.

Stereotactic body radiation therapy for locally advanced pancreatic cancer

PURPOSE

Stereotactic body radiation therapy (SBRT) is a promising treatment modality for locally advanced pancreatic cancer (LAPC). We evaluated the clinical outcomes of SBRT in patients with LAPC.

PATIENTS AND METHODS

We retrospectively analyzed the medical records of patients with LAPC who underwent SBRT at our institution between April 2011 and July 2016. Fiducial markers were implanted using endoscopic ultrasound guidance one week prior to 4-dimensional computed tomography (CT) simulation and daily cone beam CT was used for image guidance. Patients received volumetric modulated arc therapy or intensity modulated radiotherapy using respiratory gating technique. A median dose of 28 Gy (range, 24-36 Gy) was given over four consecutive fractions delivered within one week. Survival outcomes including freedom from local disease progression (FFLP), progression-free survival (PFS), and overall survival (OS) were analyzed. Acute and late toxicities related to SBRT were assessed.

RESULTS

A total of 95 patients with LAPC were analyzed, 52 of which (54.7%) had pancreatic head cancers. Most (94.7%) had received gemcitabine-based chemotherapy. The 1-year FFLP rate was 80.1%. Median OS and PFS were 16.7 months and 10.2 months, respectively; the 1-year OS and PFS rates were 67.4% and 42.9%, respectively. Among 79 patients who experienced failure, the sites of first failures were isolated local progressions in 12 patients (15.2%), distant metastasis in 55 patients (69.6%), and both in 12 patients (15.2%). Seven patients (7.4%) were able to undergo surgical resection after SBRT and four had margin-negative resections. Three patients (3.2%) had grade 3 nausea/vomiting during SBRT, and late grade 3 toxicity was observed in another three patients.

CONCLUSIONS

LAPC patients who received chemotherapy and SBRT had favorable FFLP and OS with minimal treatment-related toxicity. The most common pattern of failure was distant metastasis, which warrants further studies on the optimal scheme of chemotherapy and SBRT.

Intrafraction tumor motion during deep inspiration breath hold pancreatic cancer treatment

Purpose

Beam gating with deep inspiration breath hold (DIBH) has been widely used for motion management in radiotherapy. Normally it relies on some external surrogate for estimating the internal target motion, while the exact internal motion is unknown. In this study, we used the intrafraction motion review (IMR) application to directly track an internal target and characterized the residual motion during DIBH treatment for pancreatic cancer patients through their full treatment courses.

Methods and Materials

Eight patients with pancreatic cancer treated with DIBH volumetric modulated arc therapy in 2017 and 2018 were selected for this study, each with some radiopaque markers (fiducial or surgical clips) implanted near or inside the target. The Varian Real‐time Position Management (RPM) system was used to monitor the breath hold, represented by the anterior‐posterior displacement of an external surrogate, namely reflective markers mounted on a plastic block placed on the patient's abdomen. Before each treatment, a cone beam computed tomography (CBCT) scan under DIBH was acquired for patient setup. For scan and treatment, the breath hold reported by RPM had to lie within a 3 mm window. IMR kV images were taken every 20° or 40° gantry rotation during dose delivery, resulting in over 5000 images for the cohort. The internal markers were manually identified in the IMR images. The residual motion amplitudes of the markers as well as the displacement from their initial positions located in the setup CBCT images were analyzed.

Results

Even though the external markers indicated that the respiratory motion was within 3 mm in DIBH treatment, significant residual internal target motion was observed for some patients. The range of average motion was from 3.4 to 7.9 mm, with standard deviation ranging from 1.2 to 3.5 mm. For all patients, the target residual motions seemed to be random with mean positions around their initial setup positions. Therefore, the absolute target displacement relative to the initial position was small during DIBH treatment, with the mean and the standard deviation 0.6 and 2.9 mm, respectively.

Conclusions

Internal target motion may differ from external surrogate motion in DIBH treatment. Radiographic verification of target position at the beginning and during each fraction is necessary for precise RT delivery. IMR can serve as a useful tool to directly monitor the internal target motion.

Application of stereotactic body radiotherapy in advanced pancreatic cancers in Australia

INTRODUCTION

The majority of pancreatic cancers present locally advanced and carry a high mortality rate. Treatment is challenging, with mixed data suggesting use of chemotherapy alone or in combination with radiotherapy. The use of radiotherapy has previously been limited due to lack of ability to deliver radiation to the tumour mass without causing significant toxicity to surrounding organs. Stereotactic body radiotherapy (SBRT) allows delivery of higher biologically equivalent dose in a shorter treatment duration. We sought to investigate the safety and application of this technique in our centre.

METHOD

We enrolled 27 patients from 2015, identified as locally advanced unresectable with histologically confirmed, non-metastatic, pancreatic adenocarcinoma. All patients had endoscopically inserted fiducial markers and where possible concurrent chemotherapy was administered. Dose schedules ranged from 25 to 42 Gy in 5 or 3 fractions.

RESULTS

With an overall median follow up of 9 months (range, 3-32.7), the median survival was 11.6 months. Of those alive at 1 year, the local control rate was 67%. Six patients had Grade 3 toxicity, and other six had Grade 2 toxicity. None had Grade 4 or above toxicity. The most common symptom recorded was fatigue.

CONCLUSION

SBRT for locally advanced pancreatic cancer is technically complex but feasible in a high volume centre. SBRT is unique, allowing safe delivery of high radiation dose resulting in good local control and decreases treatment time making it an attractive option for patients with unresectable pancreatic cancer.

Chemoradiotherapy screening in a novel biomimetic polymer based pancreatic cancer model

Pancreatic Ductal Adenocarcinoma (PDAC) is a deadly and aggressive disease with a very low survival rate. This is partly due to the resistance of the disease to currently available treatment options. Herein, we report for the first time the use of a novel polyurethane scaffold based PDAC model for screening the short and relatively long term (1 and 17 days post-treatment) responses of chemotherapy, radiotherapy and their combination. We show a dose dependent cell viability reduction and apoptosis induction for both chemotherapy and radiotherapy. Furthermore, we observe a change in the impact of the treatment depending on the time-frame, especially for radiation for which the PDAC scaffolds showed resistance after 1 day but responded more 17 days post-treatment. This is the first study to report a viable PDAC culture in a scaffold for more than 2 months and the first to perform long-term (17 days) post-treatment observations in vitro. This is particularly important as a longer time-frame is much closer to animal studies and to patient treatment regimes, highlighting that our scaffold system has great potential to be used as an animal free model for screening of PDAC.

Poly-urethane scaffold based 3D pancreatic cancer model enables realistic long term chemotherapy and radiotherapy screening. This model can be used for personalised treatment screening.

Technical Assessment of an Automated Treatment Planning on Dose Escalation of Pancreas Stereotactic Body Radiotherapy

BACKGROUND

Stereotactic body radiotherapy has been suggested to provide high rates of local control for locally advanced pancreatic cancer. However, the close proximity of highly radiosensitive normal tissues usually causes the labor-intensive planning process and may impede further escalation of the prescription dose.

PURPOSE

The present study aims to evaluate the consistency and efficiency of Pinnacle Auto-Planning for pancreas stereotactic body radiotherapy with original prescription and escalated prescription.

METHODS

Twenty-four patients with pancreatic cancer treated with stereotactic body radiotherapy were studied retrospectively. The prescription is 40 Gy over 5 consecutive fractions. Most of patients (n = 21) also had 3 other different dose-level targets (6 Gy/fraction, 5 Gy/fraction, and 4 Gy/fraction). Two types of plans were generated by Pinnacle Auto-Planning with the original prescription (8 Gy/fraction, 6 Gy/fraction, 5 Gy/fraction, and 4 Gy/fraction) and escalated prescription (9 Gy/fraction, 7 Gy/fraction, 6 Gy/fraction, and 5 Gy/fraction), respectively. The same Auto-Planning template, including beam geometry, intensity-modulated radiotherapy objectives and intensity-modulated radiotherapy optimization parameters, were utilized for all the auto-plans in each prescription group. The intensity-modulated radiotherapy objectives do not include any manually created structures. Dosimetric parameters including percentage volume of PTV receiving 100% of the prescription dose, percentage volume of PTV receiving 93% of the prescription dose, and consistency of the dose-volume histograms of the target volumes were assessed. Dmax and D1 cc of highly radiosensitive organs were also evaluated.

RESULTS

For all the pancreas stereotactic body radiotherapy plans with the original or escalated prescriptions, auto-plans met institutional dose constraints for critical organs, such as the duodenum, small intestine, and stomach. Furthermore, auto-plans resulted in acceptable planning target volume coverage for all targets with different prescription levels. All the plans were generated in a one-attempt manner, and very little human intervention is necessary to achieve such plan quality.

CONCLUSIONS

Pinnacle3 Auto-Planning consistently and efficiently generate acceptable treatment plans for multitarget pancreas stereotactic body radiotherapy with or without dose escalation and may play a more important role in treatment planning in the future.

Review and current state of radiation therapy for locally advanced pancreatic adenocarcinoma

Pancreatic cancer is characterized by a high rate of metastatic spread and overall poor prognosis. Yet 30% of patients have progressive local disease at the time of death, and local progression can cause significant morbidity. Approximately 30-40% of patients present with locally advanced pancreatic cancer (LAPC) that is not surgically resectable, and the optimal treatment for these patients continues to evolve. The role of radiation in the management of LAPC is an area of controversy, and the recent LAP07 randomized trial reported no survival benefit of radiation following gemcitabine plus or minus erlotinib. However, the efficacy of modern systemic regimens has improved since the design of the LAP07 study, and radiation therapy may be of greater benefit in the context of more effective systemic therapy. Advances in radiation delivery including the increasing use of stereotactic body radiation therapy (SBRT) have the potential to improve outcomes through dose escalation and better treatment tolerability. In addition, the combination of radiation therapy and immune therapy is an area of promising research. These advances suggest that radiation therapy will continue to play an integral role in the management of LAPC.