Outcomes for patients with locally advanced pancreatic adenocarcinoma treated with stereotactic body radiation therapy versus conventionally fractionated radiation

Total Neoadjuvant Therapy in Localized Pancreatic Cancer: Is More Better?

Pancreatic ductal adenocarcinoma (PDAC) poses a significant challenge in oncology due to its advanced stage upon diagnosis and limited treatment options. Surgical resection, the primary curative approach, often results in poor long-term survival rates, leading to the exploration of alternative strategies like neoadjuvant therapy (NAT) and total neoadjuvant therapy (TNT). While NAT aims to enhance resectability and overall survival, there appears to be potential for improvement, prompting consideration of alternative neoadjuvant strategies integrating full-dose chemotherapy (CT) and radiotherapy (RT) in TNT approaches. TNT integrates chemotherapy and radiotherapy prior to surgery, potentially improving margin-negative resection rates and enabling curative resection for locally advanced cases. The lingering question: is more always better? This article categorizes TNT strategies into six main groups based on radiotherapy (RT) techniques: (1) conventional chemoradiotherapy (CRT), (2) the Dutch PREOPANC approach, (3) hypofractionated ablative intensity-modulated radiotherapy (HFA-IMRT), and stereotactic body radiotherapy (SBRT) techniques, which further divide into (4) non-ablative SBRT, (5) nearly ablative SBRT, and (6) adaptive ablative SBRT. A comprehensive analysis of the literature on TNT is provided for both borderline resectable pancreatic cancer (BRPC) and locally advanced pancreatic cancer (LAPC), with detailed sections for each.

Prediction of Isolated Local Recurrence After Resection of Pancreatic Ductal Adenocarcinoma: A Nationwide Study

BACKGROUND

Distinguishing postoperative fibrosis from isolated local recurrence (ILR) after resection of pancreatic ductal adenocarcinoma (PDAC) is challenging. A prognostic model that helps to identify patients at risk of ILR can assist clinicians when evaluating patients' postoperative imaging. This nationwide study aimed to develop a clinically applicable prognostic model for ILR after PDAC resection.

PATIENTS AND METHODS

An observational cohort study was performed, including all patients who underwent PDAC resection in the Netherlands (2014-2019; NCT04605237). On the basis of recurrence location (ILR, systemic, or both), multivariable cause-specific Cox-proportional hazard analysis was conducted to identify predictors for ILR and presented as hazard ratios (HRs) with 95% confidence intervals (CIs). A predictive model was developed using Akaike's Information Criterion, and bootstrapped discrimination and calibration indices were assessed.

RESULTS

Among 1194/1693 patients (71%) with recurrence, 252 patients (21%) developed ILR. Independent predictors for ILR were resectability status (borderline versus resectable, HR 1.42; 95% CI 1.03-1.96; P = 0.03, and locally advanced versus resectable, HR 1.11; 95% CI 0.68-1.82; P = 0.66), tumor location (head versus body/tail, HR 1.50; 95% CI 1.00-2.25; P = 0.05), vascular resection (HR 1.86; 95% CI 1.41-2.45; P < 0.001), perineural invasion (HR 1.47; 95% CI 1.01-2.13; P = 0.02), number of positive lymph nodes (HR 1.04; 95% CI 1.01-1.08; P = 0.02), and resection margin status (R1 < 1 mm versus R0 ≥ 1 mm, HR 1.64; 95% CI 1.25-2.14; P < 0.001). Moderate performance (concordance index 0.66) with adequate calibration (slope 0.99) was achieved.

CONCLUSIONS

This nationwide study identified factors predictive of ILR after PDAC resection. Our prognostic model, available through www.pancreascalculator.com , can be utilized to identify patients with a higher a priori risk of developing ILR, providing important information in patient evaluation and prognostication.

Prospective study on stereotactic body radiotherapy for small pancreatic neuroendocrine tumors: tolerance and effectiveness analysis

INTRODUCTION

Surgery is the standard treatment for pancreatic neuroendocrine tumors (pNETs), obtaining favorable results but associating high morbidity and mortality rates. This study assesses stereotactic body radiation therapy (SBRT) as a radical approach for small (< 2 cm) nonfunctioning pNETs.

MATERIALS AND METHODS

From January 2017 to June 2023, 20 patients with small pNETs underwent SBRT in an IRB-approved study. Endpoints included local control, tolerance, progression-free survival, and overall survival (OS). Diagnostic assessments comprised endoscopy, CT scans, OctreScan or PET-Dotatoc, abdominal MRI, and histological confirmatory samples.

RESULTS

In a 30-month follow-up of 20 patients (median age 55.5 years), SBRT was well-tolerated with no grade > 2 toxicity. 40% showed morphological response, 55% remained stable. Metabolically, 50% achieved significant improvement. With a median OS of 41.5 months, all patients were alive without local or distant progression or need for surgical resection.

CONCLUSION

SBRT is a feasible and well-tolerated approach for small neuroendocrine pancreatic tumors, demonstrating effective local control. Further investigations are vital for validation and extension of these findings.

Stereotactic body radiotherapy plus rucosopasem in locally advanced or borderline resectable pancreatic cancer: GRECO-2 phase II study design

Ablative doses of stereotactic body radiotherapy (SBRT) may improve pancreatic cancer outcomes but may carry greater potential for gastrointestinal toxicity. Rucosopasem, an investigational selective dismutase mimetic that converts superoxide to hydrogen peroxide, can potentially increase tumor control of SBRT without compromising safety. GRECO-2 is a phase II, multicenter, randomized, double-blind, placebo-controlled trial of rucosopasem in combination with SBRT in locally advanced or borderline resectable pancreatic cancer. Patients will be randomized to rucosopasem 100 mg or placebo via intravenous infusion over 15 min, before each SBRT fraction (5 × 10 Gy). The primary end point is overall survival. Secondary end points include progression-free survival, locoregional control, time to metastasis, surgical resection rate, best overall response, in-field local response and acute and long-term toxicity.

Stereotactic body radiotherapy for pancreatic cancer - A systematic review of prospective data

Purpose

This systematic review aims to comprehensively summarize the current prospective evidence regarding Stereotactic Body Radiotherapy (SBRT) in various clinical contexts for pancreatic cancer including its use as neoadjuvant therapy for borderline resectable pancreatic cancer (BRPC), induction therapy for locally advanced pancreatic cancer (LAPC), salvage therapy for isolated local recurrence (ILR), adjuvant therapy after radical resection, and as a palliative treatment. Special attention is given to the application of magnetic resonance-guided radiotherapy (MRgRT).

Methods

Following PRISMA guidelines, a systematic review of the Medline database via PubMed was conducted focusing on prospective studies published within the past decade. Data were extracted concerning study characteristics, outcome measures, toxicity profiles, SBRT dosage and fractionation regimens, as well as additional systemic therapies.

Results and conclusion

31 studies with in total 1,571 patients were included in this review encompassing 14 studies for LAPC, 9 for neoadjuvant treatment, 2 for adjuvant treatment, 2 for ILR, with an additional 4 studies evaluating MRgRT. In LAPC, SBRT demonstrates encouraging results, characterized by favorable local control rates. Several studies even report conversion to resectable disease with substantial resection rates reaching 39%. The adoption of MRgRT may provide a solution to the challenge to deliver ablative doses while minimizing severe toxicities. In BRPC, select prospective studies combining preoperative ablative-dose SBRT with modern induction systemic therapies have achieved remarkable resection rates of up to 80%. MRgRT also holds potential in this context. Adjuvant SBRT does not appear to confer relevant advantages over chemotherapy. While prospective data for SBRT in ILR and for palliative pain relief are limited, they corroborate positive findings from retrospective studies.

Neoadjuvant radioimmunotherapy in pancreatic cancer enhances effector T cell infiltration and shortens their distances to tumor cells

Radiotherapy is hypothesized to have an immune-modulating effect on the tumor microenvironment (TME) of pancreatic ductal adenocarcinoma (PDAC) to sensitize it to anti-PD-1 antibody (a-PD-1) treatment. We collected paired pre- and posttreatment specimens from a clinical trial evaluating combination treatment with GVAX vaccine, a-PD-1, and stereotactic body radiation (SBRT) following chemotherapy for locally advanced PDACs (LAPC). With resected PDACs following different neoadjuvant therapies as comparisons, effector cells in PDACs were found to skew toward a more exhausted status in LAPCs following chemotherapy. The combination of GVAX/a-PD-1/SBRT drives TME to favor antitumor immune response including increased densities of GZMB+CD8+ T cells, TH1, and TH17, which are associated with longer survival, however increases immunosuppressive M2-like tumor-associated macrophages (TAMs). Adding SBRT to GVAX/a-PD-1 shortens the distances from PD-1+CD8+ T cells to tumor cells and to PD-L1+ myeloid cells, which portends prolonged survival. These findings have guided the design of next radioimmunotherapy studies by targeting M2-like TAM in PDACs.

Initial Observation of Contrast Profiles for 2-Dimensional and 3-Dimensional Magnetic Resonance Imaging Sequences in Magnetic Resonance-Guided Radiation Therapy for Locally Advanced Pancreatic Cancer

Purpose

In our experience treating locally advanced pancreatic cancer with magnetic resonance-guided radiation therapy (MRgRT), the true-fast imaging with steady-state free precession sequences used to generate both the real-time 2-dimensional (2D) magnetic resonance images (MRI; 2D cine) and the pretreatment high-resolution 3-dimensional (3D) MRI impart differing intensities for relevant structures between the 2 scans. Since these variations can confound target tracking selection, we propose that an understanding of the differing contrast profiles could improve selection of tracking structures.

Methods and Materials

We retrospectively reviewed both 2D cine and 3D MRI images for 20 patients with pancreatic cancer treated with MRgRT. At simulation, an appropriate tracking target was identified and contoured on a single 3-mm sagittal slice of the 3D MRI. This sagittal slice was directly compared with the coregistered 7-mm 2D cine to identify structures with notable discrepancies in signal intensity. The 3D MRI was then explored in additional planes to confirm structure identities. For quantitative verification of the clinically observed differences, the pixel intensity distributions of 2D cine and 3D MRI digital imaging and communications in medicine data sets were statistically compared.

Results

In all patients reviewed, arteries (aorta, celiac, superior mesenteric artery, hepatic artery) appeared mildly hyperintense on both scans. However, veins (portal vein, superior mesenteric vein) appeared hyperintense on 2D cine but isointense on 3D MRI. Biliary structures appeared mildly hyperintense on 2D cine but starkly hyperintense on 3D MRI. The pixel intensity distributions extracted from 2D cine and 3D MRI images were confirmed to differ significantly (2 sample Kolmogorov-Smirnov test; test statistic, 0.40; P < .001).

Conclusions

There are significant variations in image intensity between the immediate pretreatment 2D cine compared with the initial planning 3D MRI. Understanding variations of image intensity between the different MRI sequences used in MRgRT is valuable to radiation oncologists and may lead to improved target tracking and optimized treatment delivery.

Single-Fraction Stereotactic Ablative Body Radiotherapy for Primary and Extracranial Oligometastatic Cancers

Stereotactic ablative body radiotherapy (SABR) consists of delivering high doses of ionising radiation, typically across three to eight fractions with high precision and conformity. SABR has become increasingly commonplace throughout the last quarter of a century and is offered for the treatment of various primary and metastatic tumour types. Delivering SABR in a single fraction has arisen as an appealing possibility for several reasons. These include fewer hospital visits, greater patient convenience, improved sustainability and lower costs. However, these factors must be balanced against considerations such as toxicity, side-effects and, most importantly, progression-free and overall survival. In this review we seek to analyse the results of studies looking at the efficacy of single-fraction SABR for lung, prostate, renal and pancreas primary tumours, as well as oligometastases. The tumour type to be most widely treated with single-fraction SABR is lung, but its remit continues to expand. We also look at the biological rationale underpinning SABR and how this can be extended to single-fraction regimens. Finally, we turn our attention towards the future directions of SABR and specifically single-fraction regimens. These include the possibility of combining SABR with immunotherapy and technological advances in the field, which could serve to expand the scope of SABR. We conclude by summarising the current clinical studies of single-fraction SABR.

Phase 1 Dose Escalation Study of SBRT Using 3 Fractions for Locally Advanced Pancreatic Cancer

PURPOSE

The optimal dose and fractionation of stereotactic body radiation therapy (SBRT) for locally advanced pancreatic cancer (LAPC) have not been defined. Single-fraction SBRT was associated with more gastrointestinal toxicity, so 5-fraction regimens have become more commonly employed. We aimed to determine the safety and maximally tolerated dose of 3-fraction SBRT for LAPC.

METHODS AND MATERIALS

Two parallel phase 1 dose escalation trials were conducted from 2016 to 2019 at Memorial Sloan Kettering Cancer Center and University of Colorado. Patients with histologically confirmed LAPC without distant progression after at least 2 months of induction chemotherapy were eligible. Patients received 3-fraction linear accelerator-based SBRT at 3 dose levels, 27, 30, and 33 Gy, following a modified 3+3 design. Dose-limiting toxicity, defined as grade ≥3 gastrointestinal toxicity within 90 days, was scored by National Cancer Institute Common Terminology Criteria for Adverse Events, version 4. The secondary endpoints included cumulative incidence of local failure (LF) and distant metastasis (DM), as well as progression-free and overall survival PFS and OS, respectively, toxicity, and quality of life (QoL) using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (QLQ-C30) and the pancreatic cancer-specific QLQ-PAN26 questionnaire.

RESULTS

Twenty-four consecutive patients were enrolled (27 Gy: 9, 30 Gy: 8, 33 Gy: 7). The median (range) age was 67 (52-79) years, and 12 (50%) had a head/uncinate tumor location, with a median tumor size of 3.8 (1.1-11) cm and CA19-9 of 60 (1-4880) U/mL. All received chemotherapy for a median of 4 (1.4-10) months. There were no grade ≥3 toxicities. Two-year rates (95% confidence interval) of LF, DM, PFS, and OS were 31.7% (8.6%-54.8%), 70.2% (49.7%-90.8%), 20.8% (4.6%-37.1%), and 29.2% (11.0%-47.4%), respectively. Three- and 6-month QoL assessment showed no detriment.

CONCLUSIONS

For select patients with LAPC, dose escalation to 33 Gy in 3 fractions resulted in no dose-limiting toxicities, no detriments to QoL, and disease outcomes comparable with conventional RT. Further exploration of SBRT schemes to maximize tumor control while enabling efficient integration with systemic therapy is warranted.

Radiotherapy in Pancreatic Cancer: To Whom, When, and How?

The diagnosis rate of pancreatic cancer is steadily increasing. The average age of onset is close to 70 years. In most cases, the disease is diagnosed at an advanced stage. The indications for and techniques of radiotherapy are changing over time. The aim of this thesis is to present the role and possibilities of radiotherapy from the perspective of radiation oncologist. The most common cause of treatment failure in pancreatic cancer remains generalisation. The implementation of new systemic treatment regimens contributes to improved treatment outcomes regardless of the stage of the disease. With improved treatment outcomes in terms of the incidence of distant metastases, the impact of local curability on the length and quality of life of patients increases. Modern radiotherapy offers the opportunity to achieve high local cure rates. Postoperative radiotherapy in combination with chemotherapy seems justified in the group of postoperative pancreatic cancer patients with pT3 and pN+ features. In the group of patients with borderline resectable pancreatic cancer, the impact of radiotherapy in combination with the latest chemotherapy regimens is difficult to define clearly. In the setting of a diagnosis of advanced pancreatic cancer, radiotherapy, especially stereotactic radiotherapy, in combination with chemotherapy, contributes to improved local curability and allows to achieve a significantly reduced level of pain.

Comparative Effectiveness of Chemotherapy Alone Versus Radiotherapy-Based Regimens in Locally Advanced Pancreatic Cancer: A Real-World Multicenter Analysis (PAULA-1)

Different options for locally advanced pancreatic cancer (LAPC) are available based on international guidelines: chemotherapy (CHT), chemoradiation (CRT), and stereotactic body radiotherapy (SBRT). However, the role of radiotherapy is debated in LAPC. We retrospectively compared CHT, CRT, and SBRT ± CHT in a real-world setting in terms of overall survival (OS), local control (LC), and distant metastasis-free survival (DMFS). LAPC patients from a multicentric retrospective database were included (2005-2018). Survival curves were calculated using the Kaplan-Meier method. Multivariable Cox analysis was performed to identify predictors of LC, OS, and DMFS. Of the 419 patients included, 71.1% were treated with CRT, 15.5% with CHT, and 13.4% with SBRT. Multivariable analysis showed higher LC rates for CRT (HR: 0.56, _95%CI 0.34-0.92, p = 0.022) or SBRT (HR: 0.27, _95%CI 0.13-0.54, p < 0.001), compared to CHT. CRT (HR: 0.44, _95%CI 0.28-0.70, p < 0.001) and SBRT (HR: 0.40, _95%CI 0.22-0.74, p = 0.003) were predictors of prolonged OS with respect to CHT. No significant differences were recorded in terms of DMFS. In selected patients, the addition of radiotherapy to CHT is still an option to be considered. In patients referred for radiotherapy, CRT can be replaced by SBRT considering its duration, higher LC rate, and OS rate, which are at least comparable to that of CRT.

Ablative vs. Non-Ablative Radiotherapy in Palliating Locally Advanced Pancreatic Cancer: A Single Institution Experience and a Systematic Review of the Literature

We studied the dose-local control (LC) relationship in ablative vs. non-ablative radiotherapy in a non-radical treatment setting of "locally advanced pancreatic cancer (LAPC)" by comparing our patients (n = 89) treated with SBRT on the CyberKnife unit vs. conventional radiation between January 2005 and January 2021, and by reviewing the literature. A systematic search was performed leveraging Medline for references on SBRT use in pancreatic cancer without date terms or language restrictions. A total of 3702 references were identified and the search was then repeated in Embase and the Cochrane database. Ultimately, 12 studies were eligible for inclusion, which either compared SBRT to conventional radiation, or SBRT use in dose escalation for primary LAPC in a non-neoadjuvant setting. Our cohort's median overall survival was 152 days (CI 95%, 118-185); including 371 days (CI 95%, 230-511) vs. 126 days (CI 95%, 90-161) favoring SBRT, p = 0.004. The median time to local progression was 170 days (48-923) for SBRT vs. 107 days (27-489) for the non-ablative group. In our SBRT patients, no local progressions were seen with BED₁₀ > 60 Gy. Even when palliating LAPC, SBRT should be considered as an alternative to conventional radiation, especially in patients with a low disease burden. BED₁₀ ≥ 60-70 Gy offers better local control without increasing toxicity rates. Less local progression may provide a better quality of life to those patients who already have a short life expectancy.

Impact of chemoradiotherapy on the survival of unresectable locally advanced pancreatic cancer: a retrospective cohort analysis

BACKGROUND

The role of chemoradiotherapy in unresectable locally advanced pancreatic cancer is still unclear.

METHODS

Data from patients with unresectable locally advanced pancreatic cancer were extracted from the Surveillance, Epidemiology, and End Results Program database. Univariate and multivariate Cox regression analyses were conducted to identify the independent prognostic factors of survival. Propensity score matching was carried out to minimize the interference of confounding factors. Subgroup analysis was performed to screen the characteristics of patients who would benefit from chemoradiotherapy.

RESULTS

A total of 5002 patients with unresectable locally advanced pancreatic cancer were included. Among them, 2423 (48.4%) received chemotherapy, and 2579 (51.6%) received chemoradiotherapy. The median overall survival of all patients was 11 months. Multivariate Cox analysis showed that age (p < 0.001), marital status (p < 0.001), tumor size (p = 0.001), N stage (p = 0.015) and radiotherapy (p < 0.001) were independent prognostic factors of survival. Both before (HR, 0.817; 95% CI, 0.769-0.868; p < 0.001) and after (HR, 0.904; 95% CI, 0.876-0.933; p < 0.001) propensity score matching, chemoradiotherapy significantly improved the median overall survival of patients from 10 to 12 months. Subgroup analysis showed that chemoradiotherapy was significantly associated with improved survival regardless of sex, primary site or N stage. In addition, the following subgroups all significantly benefited from chemoradiotherapy: age ≥ 50 years, not divorced, grade 2-4, tumor size > 2 cm, adenocarcinoma, mucinous adenocarcinoma and white race.

CONCLUSIONS

Chemoradiotherapy is highly recommended for patients with unresectable locally advanced pancreatic cancer.

Stereotactic Body Radiotherapy as an Effective Treatment for Pancreatic Cancer

Background Stereotactic body radiotherapy (SBRT) allows the delivery of an ablative radiation dose to the tumor with minimal toxicity. Although magnetic resonance imaging (MRI)-guided SBRT appears to be a promising approach in the modern era, X-ray image-guided SBRT is still used worldwide for pancreatic cancer. This study aims to evaluate the results of X-ray image-guided SBRT in patients with locally advanced pancreatic cancer (LAPC). Methodology Medical records of 24 patients with unresectable LAPC who underwent X-ray image-guided SBRT between 2009 and 2022 were retrospectively evaluated. SPSS version 23.0 (IBM Corp., Armonk, NY, USA) was utilized for all analyses. Results The median age was 64 years (range = 42-81 years), and the median tumor size was 3.5 cm (range = 2.7-4 cm). The median total dose of SBRT was 35 Gy (range = 33-50 Gy) in five fractions. After SBRT, 30% of patients showed complete and 41% showed partial response, whereas 20% had stable disease and 9% had progression. Median follow-up was 15 months (range = 6-58 months). During follow-up, four (16%) patients had local recurrence, one (4%) had a regional recurrence, and 17 (70%) had distant metastasis (DM). The two-year local control (LC), local recurrence-free survival (LRFS), overall survival (OS), and DM-free survival (DMFS) rate was 87%, 36%, 37%, and 29%, respectively. In univariate analysis, a larger tumor size (>3.5 cm) and higher cancer antigen 19-9 level (>106.5 kU/L) significantly decreased the OS, LRFS, and DMFS rates. No severe acute toxicity was observed. However, two patients had severe late toxicity as intestinal bleeding. Conclusions X-ray image-guided SBRT provides a good LC rate with minimal toxicity for unresectable LAPC. However, despite modern systemic treatments, the rate of DM remains high which plays a major role in survival.

The Current Role of Radiation in Pancreatic Cancer and Future Directions

Survival outcomes for localized pancreatic adenocarcinoma remains poor. Multimodality therapeutic regimens are critical to maximizing survival outcomes for these patients, which includes the use of systemic therapy, surgery, and radiation. In this review, the evolution of radiation techniques are discussed with a focus on modern techniques such as intensity modulated radiation and stereotactic body radiation therapy. However, the current role of radiation within the most common clinical scenarios for pancreatic cancer in the neoadjuvant, definitive, and adjuvant settings continues to be highly debated. The role of radiation in these settings is reviewed in the context of historical and modern clinical studies. In addition, emerging concepts including dose-escalated radiation, magnetic resonance-guided radiation therapy, and particle therapy are discussed to promote an understanding of how such concepts may change the role of radiation in the future.

Impact of conversion surgery on survival in locally advanced pancreatic cancer patients treated with FOLFIRINOX chemotherapy

BACKGROUND

Locally advanced (unresectable) pancreatic cancer (LAPC) is surgically unresectable and often treated with chemotherapy. Most previous studies, that have evaluated conversion surgery after chemotherapy, included heterogeneous patients and chemotherapy regimens, making it challenging to determine the impact of FOLFIRINOX. The present study evaluated the survival benefit of conversion surgery in patients with LAPC who received FOLFIRINOX chemotherapy, and analyzed the prognostic factors.

METHODS

Patients with LAPC who received FOLFIRINOX as first-line therapy for at least four cycles were included. During chemotherapy, surgical eligibility was determined based on radiologic and metabolic response to the treatment. Clinicopathologic characteristics were compared between the curative-intent surgery and non-resection groups, and the prognostic factors were analyzed.

RESULTS

A total of 279 patients were included. The rates of partial response (PR) and stable disease (SD) were 34.1% and 51.4%, respectively, and 16.8% patients underwent curative-intent surgery. The median survival was significantly longer in the resection group than in the non-resection group (56 vs 21 months, P < .001). In a multivariate analysis, curative-intent surgery (HR 0.260; P < .001) was the most important factor.

CONCLUSIONS

Conversion surgery after FOLFIRINOX chemotherapy effectively rescues patients with LAPC. Patients without progression after FOLFIRINOX could be considered as potential candidates for conversion surgery.

Multiagent Chemotherapy and Stereotactic Body Radiation Therapy in Patients with Unresectable Pancreatic Adenocarcinoma: A Prospective Nonrandomized Controlled Trial

PURPOSE

In a prospective multicenter study, gemcitabine monotherapy followed by stereotactic body radiation therapy (SBRT) was well tolerated with outcomes comparable to chemoradiation for locally advanced pancreatic cancer (LAPC). Recent trials have reported improved survival with multiagent chemotherapy (MA-CTX) alone. This prospective trial explored whether SBRT could be safely delivered after MA-CTX. Herein, we report the long-term outcomes of adding SBRT after MA-CTX in LAPC patients and evaluate whether genetic profiles of specimens obtained before SBRT influence outcomes.

METHODS AND MATERIALS

This prospective nonrandomized controlled phase 2 trial enrolled 44 LAPC and 4 locally recurrent patients after multidisciplinary evaluation between 2012 and 2015 at a high-volume pancreatic cancer center. For induction CTX, most received modified FOLFIRINOX (mFFX), or gemcitabine and nab-paclitaxel (GnP) followed by 5-fraction SBRT for all. During fiducial placement, biopsies were obtained with DNA extracted for targeted sequencing using the Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets platform.

RESULTS

Median induction CTX duration was ≥4 months, and 31 patients received mFFX (65%). Among 44 LAPC patients, 17 (39%) were surgically explored, and 12 of 16 (75%) achieved a R0 resection. Median overall survival (mOS) was 20.2 and 14.6 months from diagnosis and SBRT, respectively. One- and 2-year OS from SBRT was 58% and 28%. The mOS after resection was 28.6 and 22.4 months from diagnosis and SBRT, respectively. Median local progression-free survival was 23.9 and 15.8 months from diagnosis and SBRT, respectively. The mOS for pre-SBRT CA 19-9 ≤180 U/mL versus >180 was 23.1 and 11.3 months, respectively (hazard ratio, 0.53; P = .04). Only 1 patient (2.1%) had late grade ≥2 gastrointestinal toxic effects attributable to SBRT. Despite significant pretreatment with chemotherapy, 88% of tumor specimens were effectively sequenced; survival outcomes were not significantly associated with specific mutational patterns. Quality of life was prospectively collected pre- and post-SBRT with the EORTC QLQ-C30 and PAN26 questionnaires showing no significant change.

CONCLUSIONS

SBRT was safely administered with MA-CTX with minimal toxicity. A high proportion of LAPC patients underwent R0 resection with favorable survival outcomes.

A nationwide randomized controlled trial on additional treatment for isolated local pancreatic cancer recurrence using stereotactic body radiation therapy (ARCADE)

BACKGROUND

Disease recurrence is the main cause of mortality after resection of pancreatic ductal adenocarcinoma (PDAC). In 20-30% of resected patients, isolated local PDAC recurrence occurs. Retrospective studies have suggested that stereotactic body radiation therapy (SBRT) might lead to improved local control in these patients, potentially having a beneficial effect on both survival and quality of life. The "nationwide randomized controlled trial on additional treatment for isolated local pancreatic cancer recurrence using stereotactic body radiation therapy" (ARCADE) will investigate the value of SBRT in addition to standard of care in patients with isolated local PDAC recurrence compared to standard of care alone, regarding both survival and quality of life outcomes.

METHODS

The ARCADE trial is nested within a prospective cohort (Dutch Pancreatic Cancer Project; PACAP) according to the 'Trials within Cohorts' design. All PACAP participants with isolated local PDAC recurrence after primary resection who provided informed consent for being randomized in future studies are eligible. Patients will be randomized for local therapy (5 fractions of 8 Gy SBRT) in addition to standard of care or standard of care alone. In total, 174 patients will be included. The main study endpoint is survival after recurrence. The most important secondary endpoint is quality of life.

DISCUSSION

It is hypothesized that additional SBRT, compared to standard of care alone, improves survival and quality of life in patients with isolated local recurrence after PDAC resection.

TRIAL REGISTRATION

ClinicalTrials.gov registration NCT04881487 . Registered on May 11, 2021.

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.

Brachytherapy via a depot of biopolymer-bound 131I synergizes with nanoparticle paclitaxel in therapy-resistant pancreatic tumours

Locally advanced pancreatic tumours are highly resistant to conventional radiochemotherapy. Here we show that such resistance can be surmounted by an injectable depot of thermally responsive elastin-like polypeptide (ELP) conjugated with iodine-131 radionuclides (131I-ELP) when combined with systemically delivered nanoparticle albumin-bound paclitaxel. This combination therapy induced complete tumour regressions in diverse subcutaneous and orthotopic mouse models of locoregional pancreatic tumours. 131I-ELP brachytherapy was effective independently of the paclitaxel formulation and dose, but external beam radiotherapy (EBRT) only achieved tumour-growth inhibition when co-administered with nanoparticle paclitaxel. Histological analyses revealed that 131I-ELP brachytherapy led to changes in the expression of intercellular collagen and junctional proteins within the tumour microenvironment. These changes, which differed from those of EBRT-treated tumours, correlated with the improved delivery and accumulation of paclitaxel nanoparticles within the tumour. Our findings support the further translational development of 131I-ELP depots for the synergistic treatment of localized pancreatic cancer.

Association of survival with stereotactic body radiation therapy following induction chemotherapy for unresected locally advanced pancreatic cancer

Aim:

Induction chemotherapy (iC) followed by concurrent chemoradiation has been shown to improve overall survival (OS) for locally advanced pancreatic cancer (LAPC). However, the survival benefit of stereotactic body radiation therapy (SBRT) versus conventionally fractionated radiation therapy (CFRT) following iC remains unclear.

Materials and methods:

The National Cancer Database (NCDB) was queried for primary stage III, cT4N0-1M0 LAPC (2004–15). Kaplan–Meier analysis, Cox proportional hazards method and propensity score matching were used.

Results:

Among 872 patients, 738 patients underwent CFRT and 134 patients received SBRT. Median follow-up was 24·3 and 22·9 months for the CFRT and SBRT cohorts, respectively. The use of SBRT showed improved survival in both the multivariate analysis (hazards ratio 0·78, p = 0·025) and 120 propensity-matched pairs (median OS 18·1 versus 15·9 months, p = 0·004) compared to the CFRT.

Findings:

This NCDB analysis suggests survival benefit with the use of SBRT versus CFRT following iC for the LAPC.

Efficacy of stereotactic body radiation therapy for locoregional recurrent pancreatic cancer after radical resection

Objective

This study aimed to analyze the efficacy and toxicity of stereotactic body radiotherapy (SBRT) for locoregional recurrent pancreatic cancer after radical resection.

Methods

Patients with locoregional recurrent pancreatic cancer after surgery treated with SBRT in our institution were retrospectively investigated from January 2010 to January 2020. Absolute neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) recorded at pretreatment were analyzed. Endpoints included overall survival (OS), progression-free survival (PFS) and cumulative incidences of local failure (LF) and metastatic failure (MF).

Results

A total of 22 patients received SBRT with a median prescribed dose of 40 Gy (range of 30-50 Gy)/4 to 7 fractions. The median OS of all patients was 13.6 months (95% CI, 9.6-17.5 months). 0-1 performance status (HR 12.10, 95% CI 2.04-71.81, P=0.006) and ≤2.1 pre-SBRT NLR (HR 4.05, 95% CI 1.21-13.59, P=0.023) were significant predictors of higher OS on multivariable analysis. The median progression-free survival (PFS) of the cohort was 7.5 months (95% CI, 6.5-8.5 months). The median time to LF and MF were 15.6 months and 6.4 months, respectively. The rate of MF as a first event was higher than that of first event LF. Pain relief was observed in all patients (100%) 6 weeks after SBRT. In terms of acute toxicity, grade 1 including fatigue (6, 27.3%), anorexia (6, 27.3%), nausea (4, 18.2%) and leukopenia (4, 18.2%) was often observed. No acute toxicity of grade 4 or 5 was observed. In terms of late toxicity, no treatment-related toxicity was found during follow-up.

Conclusion

This study showed that SBRT can significantly reduce pain, effectively control local tumor progression, and have acceptable toxicity for patients with locoregional recurrence after radical resection of primary pancreatic cancer. Good performance status and lower pre-SBRT NLR were associated with improved overall survival.

Neoadjuvant Radiotherapy After (m)FOLFIRINOX for Borderline Resectable Pancreatic Adenocarcinoma: A TAPS Consortium Study

BACKGROUND

The value of neoadjuvant radiotherapy (RT) after 5-fluorouracil with leucovorin, oxaliplatin, and irinotecan, with or without dose modifications [(m)FOLFIRINOX], for patients with borderline resectable (BR) pancreatic ductal adenocarcinoma (PDAC) is uncertain.

METHODS

We conducted an international retrospective cohort study including consecutive patients with BR PDAC who received (m)FOLFIRINOX as initial treatment (2012-2019) from the Trans-Atlantic Pancreatic Surgery Consortium. Because the decision to administer RT is made after chemotherapy, patients with metastases or deterioration after (m)FOLFIRINOX or a performance score ≥2 were excluded. Patients who received RT after (m)FOLFIRINOX were matched 1:1 by nearest neighbor propensity scores with patients who did not receive RT. Propensity scores were calculated using sex, age (≤70 vs >70 years), WHO performance score (0 vs 1), tumor size (0-20 vs 21-40 vs >40 mm), tumor location (head/uncinate vs body/tail), number of cycles (1-4 vs 5-8 vs >8), and baseline CA 19-9 level (≤500 vs >500 U/mL). Primary outcome was overall survival (OS) from diagnosis.

RESULTS

Of 531 patients who received neoadjuvant (m)FOLFIRINOX for BR PDAC, 424 met inclusion criteria and 300 (70.8%) were propensity score-matched. After matching, median OS was 26.2 months (95% CI, 24.0-38.4) with RT versus 32.8 months (95% CI, 25.3-42.0) without RT (P=.71). RT was associated with a lower resection rate (55.3% vs 72.7%; P=.002). In patients who underwent a resection, RT was associated with a comparable margin-negative resection rate (>1 mm) (70.6% vs 64.8%; P=.51), more node-negative disease (57.3% vs 37.6%; P=.01), and more major pathologic response with <5% tumor viability (24.7% vs 8.3%; P=.006). The OS associated with conventional and stereotactic body RT approaches was similar (median OS, 25.7 vs 26.0 months; P=.92).

CONCLUSIONS

In patients with BR PDAC, neoadjuvant RT following (m)FOLFIRINOX was associated with more node-negative disease and better pathologic response in patients who underwent resection, yet no difference in OS was found. Routine use of RT cannot be recommended based on these data.

Stereotactic Ablative Radiotherapy Using CALYPSO® Extracranial Tracking for Intrafractional Tumor Motion Management-A New Potential Local Treatment for Unresectable Locally Advanced Pancreatic Cancer? Results from a Retrospective Study

(1) Background: The aim of this study was to evaluate the efficacy and safety of SABR for LAPC using Calypso® Extracranial Tracking for intrafractional, fiducial-based motion management, to present this motion management technique, as there are yet no published data on usage of Calypso® during SABR for LAPC, and to report on our clinical outcomes. (2) Methods: Fifty-four patients were treated with SABR in one, three, or five fractions, receiving median BED10 = 112.5 Gy. Thirty-eight patients received systemic treatment. End points were OS, FFLP, PFS, and toxicity. Actuarial survival analysis and univariate analysis were investigated. (3) Results: Median follow-up was 20 months. Median OS was 24 months. One-year FFLP and one-year OS were 100% and 90.7%, respectively. Median PFS was 18 months, and one-year PFS was 72.2%. Twenty-five patients (46.3%) were alive at the time of analysis, and both median FU and OS for this subgroup were 26 months. No acute/late toxicity > G2 was reported. (4) Conclusions: SABR for LAPC using Calypso® presented as an effective and safe treatment and could be a promising local therapeutic option with very acceptable toxicity, either as a single treatment or in a multimodality regimen. Dose escalation to the tumor combined with systemic treatment could yield better clinical outcomes.

Pain Relief after Stereotactic Radiotherapy of Pancreatic Adenocarcinoma: An Updated Systematic Review

Severe pain is frequent in patients with locally advanced pancreatic ductal adenocarcinoma (PDCA). Stereotactic body radiotherapy (SBRT) provides high local control rates in these patients. The aim of this review was to systematically analyze the available evidence on pain relief in patients with PDCA. We updated our previous systematic review through a search on PubMed of papers published from 1 January 2018 to 30 June 2021. Studies with full available text, published in English, and reporting pain relief after SBRT on PDCA were included in this analysis. Statistical analysis was carried out using the MEDCALC statistical software. All tests were two-sided. The I2 statistic was used to quantify statistical heterogeneity (high heterogeneity level: >50%). Nineteen papers were included in this updated literature review. None of them specifically aimed at assessing pain and/or quality of life. The rate of analgesics reduction or suspension ranged between 40.0 and 100.0% (median: 60.3%) in six studies. The pooled rate was 71.5% (95% CI, 61.6−80.0%), with high heterogeneity between studies (Q2 test: p < 0.0001; I2 = 83.8%). The rate of complete response of pain after SBRT ranged between 30.0 and 81.3% (median: 48.4%) in three studies. The pooled rate was 51.9% (95% CI, 39.3−64.3%), with high heterogeneity (Q2 test: p < 0.008; I2 = 79.1%). The rate of partial plus complete pain response ranged between 44.4 and 100% (median: 78.6%) in nine studies. The pooled rate was 78.3% (95% CI, 71.0−84.5%), with high heterogeneity (Q2 test: p < 0.0001; I2 = 79.4%). A linear regression with sensitivity analysis showed significantly improved overall pain response as the EQD2α/β:10 increases (p: 0.005). Eight papers did not report any side effect during and after SBRT. In three studies only transient acute effects were recorded. The results of the included studies showed high heterogeneity. However, SBRT of PDCA resulted reasonably effective in producing pain relief in these patients. Further studies are needed to assess the impact of SBRT in this setting based on Patient-Reported Outcomes.

Stereotactic Body Radiation Therapy versus Concurrent Chemoradiotherapy for Locally Advanced Pancreatic Cancer: A Propensity Score-Matched Analysis

In locally advanced pancreatic cancer (LAPC), stereotactic body radiation therapy (SBRT) has been applied as an alternative to concurrent chemoradiotherapy (CCRT); however, direct comparative evidence between these two modalities is scarce. The aim of this study was to compare the clinical outcomes of SBRT with CCRT for LAPC. We retrospectively reviewed the medical records of patients with LAPC who received SBRT (n = 95) or CCRT (n = 66) with a concurrent 5-FU-based regimen between January 2008 and July 2016. The clinical outcomes of freedom from local progression (FFLP), progression-free survival (PFS), overall survival (OS), and toxicities were analyzed before and after propensity score (PS) matching. After a median follow-up duration of 15.5 months (range, 2.3-64.5), the median OS, PFS, and FFLP of the unmatched patients were 17.3 months, 11 months, and 19.6 months, respectively. After PS matching, there were no significant differences between the SBRT and CCRT groups in terms of the 1-year rates of OS (66.7% vs. 80%, p = 0.455), PFS (40.0% vs. 54.2%, p = 0.123), and FFLP (77.2% and 87.1%, p = 0.691). Our results suggest SBRT could be a feasible alternative to CCRT in treating patients with LAPC.

Stereotactic radiotherapy and the potential role of magnetic resonance-guided adaptive techniques for pancreatic cancer

BACKGROUND

Pancreatic cancer is a malignancy with one of the poorest prognoses amongst all cancers. Patients with unresectable tumours either receive palliative care or undergo various chemoradiotherapy regimens. Conventional techniques are often associated with acute gastrointestinal toxicities, as adjacent critical structures such as the duodenum ultimately limits delivered doses. Stereotactic body radiotherapy (SBRT) is an advanced radiation technique that delivers highly ablative radiation split into several fractions, with a steep dose fall-off outside target volumes.

AIM

To discuss the latest data on SBRT and whether there is a role for magnetic resonance-guided techniques in multimodal management of locally advanced, unresectable pancreatic cancer.

METHODS

We conducted a search on multiple large databases to collate the latest records on radiotherapy techniques used to treat pancreatic cancer. Out of 1229 total records retrieved from our search, 36 studies were included in this review.

RESULTS

Studies indicate that SBRT is associated with improved clinical efficacy and toxicity profiles compared to conventional radiotherapy techniques. Further dose escalation to the tumour with SBRT is limited by the poor soft-tissue visualisation of computed tomography imaging during radiation planning and treatment delivery. Magnetic resonance-guided techniques have been introduced to improve imaging quality, enabling treatment plan adaptation and re-optimisation before delivering each fraction.

CONCLUSION

Therefore, SBRT may lead to improved survival outcomes and safer toxicity profiles compared to conventional techniques, and the addition of magnetic resonance-guided techniques potentially allows dose escalation and conversion of unresectable tumours to operable cases.

Modern Radiation Oncology: From IMRT to Particle Therapy—Present Status and the Days to Come

There has been tremendous technological development in the field of radiation oncology, mainly during the last few decades. Parallel advancements in imaging and accelerator technologies have contributed significantly to the same. Present-day radiation therapy is aimed at precision, in terms of physical accuracy of both its planning and delivery. This has been made possible by improvements in defining the target (use of various radiological and functional imaging modalities), advanced radiotherapy planning methods (intensity-modulated radiation therapy and recent emergence of particle therapy), and robust verification techniques (image-guided radiation therapy). These developments have enabled delivery of adequate tumoricidal doses conforming to the target, thereby improving disease control with reduced normal tissue toxicity in a wide range of malignancies. Elucidation of molecular pathways determining radioresistance or systemic effects of radiotherapy and strategies for therapeutic manipulation of the same are also being explored. Overall, we look forward to ensuring basic radiotherapy access to all patients, and precision radiation therapy to appropriate candidates (triaged by disease anatomy or biology and associated cost-effectiveness).

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.

Evolving pancreatic cancer treatment: From diagnosis to healthcare management

The prognosis of pancreatic ductal adenocarcinoma is still the worst among solid tumors. In this review, a panel of experts addressed the main unanswered questions about the clinical management of this disease, with the aim of providing practical decision support for physicians. On the basis of the evidence available from the literature, the main topics concerning pancreatic cancer are discussed: the diagnosis, as the need for a pathological characterization and the role for germ-line and somatic molecular profiling; the therapeutic management of resectable disease, as the role of upfront surgery or neoadjuvant chemotherapy, the post-operative restaging and the optimal timing foradjuvant chemotherapy, the management of the borderline resectable and locally advanced disease; the metastatic disease and the role of surgery for the management of patients with isolated metastasis and the use of biomarkers of metastatic potential; the role of supportive care and the healthcare management of pancreatic ductal adenocarcinoma.

Current status of non-surgical treatment of locally advanced pancreatic cancer

Pancreatic cancer is the 7th leading cause of death due to cancer in industrialized countries and the 11th most common cancer globally, with 458918 new cases (2.5% of all cancers) and 432242 deaths (4.5% of all cancer deaths) in 2018. Unfortunately, 80% to 90% of the patients present with unresectable disease, and the reported 5-year survival rate range between 10% and 25%, even after successful resection with tumor-free margins. Systemic chemotherapy, radiotherapy, and minimally invasive image-guided procedures that have emerged over the past years, are used for the management of non-operable PC. This review focuses on currently available non-surgical options of locally advanced pancreatic cancer.

Modulation of the Human Pancreatic Ductal Adenocarcinoma Immune Microenvironment by Stereotactic Body Radiotherapy

PURPOSE

Stereotactic body radiotherapy (SBRT) is an emerging treatment modality for pancreatic ductal adenocarcinoma (PDAC), which can effectively prime cytotoxic T cells by inducing immunogenic tumor cell death in preclinical models. SBRT effects on human PDAC have yet to be thoroughly investigated; therefore, this study aimed to characterize immunomodulation in the human PDAC tumor microenvironment following therapy.

EXPERIMENTAL DESIGN

Tumor samples were obtained from patients with resectable PDAC. Radiotherapy was delivered a median of 7 days prior to surgical resection, and sections were analyzed by multiplex IHC (mIHC), RNA sequencing, and T-cell receptor sequencing (TCR-seq).

RESULTS

Analysis of SBRT-treated tumor tissue indicated reduced tumor cell density and increased immunogenic cell death relative to untreated controls. Radiotherapy promoted collagen deposition; however, vasculature was unaffected and spatial analyses lacked evidence of T-cell sequestration. Conversely, SBRT resulted in fewer tertiary lymphoid structures and failed to lessen or reprogram abundant immune suppressor populations. Higher percentages of PD-1⁺ T cells were observed following SBRT, and a subset of tumors displayed more clonal T-cell repertoires.

CONCLUSIONS

These findings suggest that SBRT augmentation of antitumor immunogenicity may be dampened by an overabundance of refractory immunosuppressive populations, and support the continued development of SBRT/immunotherapy combination for human PDAC.

Local Control and Survival After Induction Chemotherapy and Ablative Radiation Versus Resection for Pancreatic Ductal Adenocarcinoma With Vascular Involvement

OBJECTIVE

We sought to compare overall survival (OS) and disease control for patients with localized pancreatic ductal adenocarcinoma (PDAC) treated with ablative dose radiotherapy (A-RT) versus resection.

SUMMARY BACKGROUND DATA

Locoregional treatment for PDAC includes resection when possible or palliative RT. A-RT may offer durable tumor control and encouraging survival.

METHODS

This was a single-institution retrospective analysis of patients with PDAC treated with induction chemotherapy followed by A-RT [≥98 Gy biologically effective dose (BED) using 15-25 fractions in 3-4.5 Gy/fraction] or pancreatectomy.

RESULTS

One hundred and four patients received A-RT (49.8%) and 105 (50.2%) underwent resection. Patients receiving A-RT had larger median tumor size after induction chemotherapy [3.2 cm (undetectable-10.9) vs 2.6 cm (undetectable-10.7), P < 0.001], and were more likely to have celiac or hepatic artery encasement (48.1% vs 11.4%, P <0.001), or superior mesenteric artery encasement (43.3% vs 9.5%, P < 0.001); however, there was no difference in the degree of SMV/PV involvement (P = 0.123). There was no difference in locoregional recurrence/progression at 18-months between A-RT and resection; cumulative incidence was 16% [(95% confidence interval (CI) 10%-24%] versus 21% (95% CI 14%-30%), respectively (P= 0.252). However, patients receiving A-RT had a 19% higher 18-month cumulative incidence of distant recurrence/progression [58% (95% CI 48%-67%) vs 30% (95% CI 30%-49%), P= 0.004]. Median OS from completion of chemotherapy was 20.1 months for A-RT patients (95% CI 16.4-23.1 months) versus 32.9 months (95% CI 29.7-42.3 months) for resected patients (P < 0.001).

CONCLUSION

Ablative radiation is a promising new treatment option for PDAC, offering locoregional disease control similar to that associated with resection and encouraging survival.

Treatment optimization of locally advanced and metastatic pancreatic cancer (Review)

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignant tumor types, being the sixth leading cause of mortality worldwide and the fourth in Europe. Globally, it has a mortality/incidence ratio of 98%, and the 5‑year survival rate in Europe is only 3%. Although risk factors, such as obesity, diabetes mellitus, smoking, alcohol consumption and genetic factors, have been identified, the causes of PDAC remain elusive. Additionally, the only curative treatment for PDAC is surgery with negative margins. However, upon diagnosis, ~30% of the patients already present with locally advanced disease. In these cases, a multidisciplinary approach is required to improve disease‑related symptoms and prolong patient survival. In the present article, a comprehensive review of PDAC epidemiology, physiology and treatment is provided. Moreover, guidelines on patient treatment are suggested. Among the different available therapeutic options for the treatment of advanced PDAC, results are modest, most likely due to the complexity of the disease, and so the prognostic remains poor. Molecular approaches based on multi‑omics research are promising and will contribute to groundbreaking personalized medicine. Thus, economic investment that promotes research of pancreatic cancer will be critical to the development of more efficient diagnostic and treatment strategies.

Isotoxic high-dose stereotactic body radiotherapy integrated in a total multimodal neoadjuvant strategy for the treatment of localized pancreatic ductal adenocarcinoma

Background

Our aim was to evaluate the feasibility and safety of isotoxic high-dose (iHD) stereotactic body radiation therapy (SBRT) in a total neoadjuvant sequence for the treatment of localized pancreatic adenocarcinoma.

Materials and methods

Biopsy-proven borderline resectable/locally advanced pancreatic cancer (BR/LAPC) patients were included in this observational prospective analysis from August 2017 to April 2020 without excluding tumours showing a radiological direct gastrointestinal (GI) invasion. An induction chemotherapy by modified fluorouracil, irinotecan and oxaliplatin was performed for a median of six cycles. In case of non-progression, an isotoxic high-dose stereotactic body radiotherapy (iHD-SBRT) was delivered in 5 fractions followed by a surgical exploration. The primary endpoint was acute/late gastrointestinal grade ⩾3 toxicity. Secondary endpoints were overall survival (OS), progression-free survival (PFS) and local control (LC).

Results

A total of 39 consecutive patients (21 BR and 18 LAPC) were included: 34 patients (87.2%, 18 BR and 16 LAPC) completed the planned neoadjuvant sequence. After iHD-SBRT, 19 patients [55.9% overall, 13/18 BR (72.2%) and 6/16 LAPC (37.5%)] underwent an oncological resection among the 25 patients surgically explored (73.5%). The median follow up was 18.2 months. The rates of acute and late GI grade 3 toxicity were, respectively, 2.9% and 4.2%. The median OS and PFS from diagnosis were, respectively, 24.5 and 15.6 months. The resected patients had improved median OS and PFS in comparison with the non-resected patients (OS: 32.3 versus 18.2 months, p = 0.02; PFS: 24.1 versus 7.1 months, p < 0.001). There was no survival difference between the BR and LAPC patients. The 1-year LC from SBRT was 74.1% and the median locoregional PFS was not reached for both BR and LAPC patients.

Conclusions

iHD-SBRT displays an excellent toxicity profile, also for potentially high-risk patients with radiological direct GI invasion at diagnosis and can be easily integrated in a total neoadjuvant strategy. The oncological outcomes are promising and emphasise the need for further exploration of iHD-SBRT in phase II/III trials.

Investigate the Dosimetric and Potential Clinical Benefits Utilizing Stereotactic Body Radiation Therapy With Simultaneous Integrated Boost Technique for Locally Advanced Pancreatic Cancer: A Comparison Between Photon and Proton Beam Therapy

Purpose

To investigate the potential clinical benefits of using stereotactic body radiation therapy (SBRT) with simultaneous integrated boost (SIB) technique for locally advanced pancreatic cancer (LAPC) among different treatment modalities and planning strategies, including photon and proton.

Method

A total of 19 patients were retrospectively selected in this study: 13 cases with the tumor located in the head of the pancreas and 6 cases with the tumor in the body of the pancreas. SBRT-SIB plans were generated using volumetric modulated arc therapy (VMAT), two-field Intensity Modulated Proton Therapy (IMPT), and three-field IMPT. The IMPT used the robust optimization parameters of ± 3.5% range and 5-mm setup uncertainties. Root-mean-square deviation dose (RMSD) volume histograms were used to evaluate the target coverage robustness quantitatively. Dosimetric metrics based on the dose-volume histogram (DVH), homogeneity index (HI), and normal tissue complication probability (NTCP) were analyzed to evaluate the potential clinical benefits among different planning groups.

Results

With a similar CTV and SIB coverage, two-field IMPT provided a lower maximum dose for the stomach (median: 18.6GyE, p<0.05) and duodenum (median: 32.62GyE, p<0.05) when the target was located in the head of the pancreas compared to VMAT and three-field IMPT. The risks of gastric bleed (3.42%) and grade ≥ 3 GI toxicity (4.55%) were also decreased. However, for the target in the body of the pancreas, VMAT showed a lower maximum dose for the stomach (median 30.93GyE, p<0.05) and toxicity of gastric bleed (median: 8.67%, p<0.05) compared to two-field IMPT and three-field IMPT, while other maximum doses and NTCPs were similar. The RMSD volume histogram (RVH) analysis shows that three-field IMPT provided better robustness for targets but not for OARs. Instead, three-field IMPT increased the Dmean of organs such as the stomach, duodenum, and intestine.

Conclusion

The results indicated that the tumor locations could play a critical role in determining clinical benefits among different treatment modalities. Two-field IMPT could be a better option for LAPC patients whose tumors are located in the head of the pancreas. It provides lower severe toxicity for the stomach and duodenum. Nevertheless, VMAT is preferred for the body with better protection for the possibility of gastric bleed.

Korean clinical practice guideline for pancreatic cancer 2021: A summary of evidence-based, multi-disciplinary diagnostic and therapeutic approaches

Pancreatic cancer is the eighth most common cancer and the fifth most common cause of cancer-related death in Korea. To enable standardization of management and facilitate improvements in outcome, a total of 53 multi-disciplinary experts in gastroenterology, surgery, medical oncology, radiation oncology, radiology, nuclear medicine, and pathology in Korea developed new recommendations that integrate the most up-to-date, evidence-based research findings and expert opinions. Recommendations were made on imaging diagnosis, endoscopic management, surgery, radiotherapy, palliative chemotherapy, and specific management procedures, including neoadjuvant treatment or adjuvant treatment for patients with resectable, borderline resectable, and locally advanced unresectable pancreatic cancer. This is the English version of the Korean clinical practice guideline for pancreatic cancer 2021. This guideline includes 20 clinical questions and 32 statements. This guideline represents the most standard guideline for the diagnosis and treatment of patients with pancreatic ductal adenocarcinoma in adults at this time in Korea. The authors believe that this guideline will provide useful and informative advice.

An Investigation of Non-Coplanar Volumetric Modulated Radiation Therapy for Locally Advanced Unresectable Pancreatic Cancer Using a Trajectory Optimization Method

PURPOSE

This study was conducted in order to develop a trajectory optimization algorithm for non-coplanar volumetric modulated arc therapy (VMAT) and investigate the potential of organs at risk (OARs) sparing in locally advanced pancreatic cancer patients using non-coplanar VMAT.

METHODS AND MATERIALS

Firstly, a cost map that represents the ray-OAR voxel intersections at each source position was generated using a ray-tracing algorithm. A graph search algorithm was then used to determine the least-cost path from the cost map. Lastly, full arcs or partial arcs were selected based on the least-cost path to generate the non-coplanar VMAT (ncVMAT) trajectories. Clinical coplanar VMAT (coVMAT) plans for 11 patients diagnosed with locally advanced unresectable pancreatic cancer (LAPC) receiving 45 to 70 Gy in 25 fractions were replanned using non-coplanar VMAT trajectories. Both coplanar and non-coplanar plans were normalized to cover 95% of the PTV45 Gy volume with a prescription dose of 45 Gy. The conformity index (CI), homogeneity index (HI), PTV coverage, and dose to the OARs were compared between coVMAT and ncVMAT plans.

RESULTS

With ncVMAT, the mean coverage of PTV50 Gy, PTV54 Gy, PTV60 Gy, and PTV70 Gy increased significantly. The mean conformity index of PTV45 Gy, PTV54 Gy, and PTV70 Gy was also improved in the ncVMAT plans. Compared with coVMAT plans, the ncVMAT plans resulted in significantly lower doses to the spinal cord, bilateral kidneys, stomach, and duodenum. The maximum dose to the spinal cord decreased by 6.11%. The mean dose to the left and right kidneys decreased by an average of 5.52% and 11.71%, respectively. The D max, D mean, and D 15% of the stomach were reduced by an average of 7.45%, 15.82%, and 16.79%, separately. The D 15% and D mean of the duodenum decreased 6.38% and 5.64%, respectively.

CONCLUSION

A trajectory optimization algorithm was developed for non-coplanar VMAT. Compared with conventional coplanar VMAT, non-coplanar VMAT resulted in improved coverage and conformity to the targets. The sparing of OARs was significantly improved in non-coplanar VMAT compared with coVMAT plans for locally advanced pancreatic cancer.

Multimodal Treatment with GEMOX Plus Helical Tomotherapy in Unresectable Locally Advanced Pancreatic Cancer: A Pooled Analysis of Two Phase 2 Studies

In locally advanced pancreatic cancer (LAPC), the combination of chemotherapy and radiotherapy is a widely used treatment option. We performed a pooled analysis, including an exploratory analysis for prognostic and predictive factors, of two phase 2 trials including 73 patients with LAPC, treated with gemcitabine and oxaliplatin (GEMOX) and hypofractionated tomotherapy. With a median follow-up of 36 months (range 1–65), median progression-free (PFS) and overall survival (OS) were 10.2 (95% confidence interval [CI] 7.8–13.2) and 14.3 (95% CI 12.0–18.1) months, respectively. The overall resectability rate was 23.3% (95% CI 13.6–33.0), and the R0 resection rate was 13.7% (95% CI 5.8–21.6). In the multivariate analysis, ECOG performance status (PS) 0 and low levels of CA 19–9 were associated with improved OS and PFS. Concerning OS, log(CA19–9) resulted in a hazard ratio (HR) of 1.20 (95% CI 1.02–1.42), p = 0.027. For ECOG PS 0, HR was 1.00; for PS 1, HR was 2.69 (95% CI 1.46–4.96); for PS 2, HR was 4.18 (95% CI 0.90–19.46); p = 0.003. Low CA19–9 levels were also predictive for resection, with an odds ratio of 0.71 (95% CI 0.52–0.97), p = 0.034. In conclusion, GEMOX and hypofractionated radiotherapy is a treatment option in LAPC. Further studies are needed to identify differences in tumor biology, which may help to predict resectability and prognosis.

Phase I Trial of Stereotactic Body Radiation Therapy Dose Escalation in Pancreatic Cancer

PURPOSE

Stereotactic body radiation therapy (SBRT) has demonstrated encouraging local tumor control rates in the treatment of pancreatic cancer, yet we lack prospective clinical trials evaluating dose-escalation strategies among patients treated with 5-fraction SBRT. This phase 1 dose-escalation trial was conducted to determine the maximum tolerated dose of SBRT in patients with pancreatic cancer.

METHODS AND MATERIALS

Thirty patients with pancreatic cancer were enrolled and treated with 40, 45, or 50 Gy SBRT in 5 fractions with doses determined using a time-to-event continual reassessment method trial design. Systemic therapy was permitted before and after SBRT, but not mandated by the study protocol. Toxicity was the primary study endpoint, and any grade ≥3 acute or late toxicity potentially attributable to SBRT was considered a dose-limiting toxicity. Secondary endpoints included local progression, distant progression, and overall survival.

RESULTS

The median follow up from SBRT was 8.9 months (range, 1.7-62.6 months). Nineteen patients (63%) had locally advanced disease, 3 patients (10%) had metastatic disease, and 8 patients (27%) had medically unresectable disease. Three patients (10%) received 40 Gy, 16 patients (53%) received 45 Gy, and 11 patients (37%) received 50 Gy. Seven patients (23%) experienced grade ≤2 acute toxicity, and 2 patients (6.7%) experienced grade 4 to 5 late toxicity, both of which occurred in the 45 Gy group. Median survival time was 17.1 months from the time of diagnosis and 9.8 months from SBRT. The 1-year cumulative incidence of local progression was 14.2% (95% confidence interval, 4.2%-30%).

CONCLUSIONS

This dose-escalation trial evaluated high-dose SBRT delivered in 5 fractions, and overall demonstrated favorable local control and survival, but was associated with nontrivial rates of severe late gastrointestinal toxicity potentially attributable to radiation. Further prospective studies are needed to define the safety and efficacy of high-dose SBRT in patients with pancreatic cancer.

Diffusion-Weighted and Dynamic Contrast-Enhanced MRI Derived Imaging Metrics for Stereotactic Body Radiotherapy of Pancreatic Ductal Adenocarcinoma: Preliminary Findings

We aimed to assess longitudinal changes in quantitative imaging metric values obtained from diffusion-weighted (DW-) and dynamic contrast-enhanced magnetic resonance imaging (DCE)-MRI at pre-treatment (TX[0]), immediately after the first fraction of stereotactic body radiotherapy (D1-TX[1]), and 6 weeks post-TX (Post-TX[2]) in patients with pancreatic ductal adenocarcinoma. Ten enrolled patients (n = 10) underwent DW- and DCE-MRI examinations on a 3.0 T scanner. The apparent diffusion coefficient, ADC (mm²/s), was derived from DW imaging data using a monoexponential model. The tissue relaxation rate, R _1t, time-course data were fitted with a shutter-speed model, which provides estimates of the volume transfer constant, K ^trans (min^-1), extravascular extracellular volume fraction, v_e , and mean lifetime of intracellular water protons, τ _i (seconds). Wilcoxon rank-sum test compared the mean values, standard deviation, skewness, kurtosis, and relative percentage (r, %) changes (Δ) in ADC, K ^trans, v_e , and τ _i values between the magnetic resonance examinations. rADC_Δ2-0 values were significantly greater than rADC_Δ1-0 values (P = .009). rK ^trans _Δ2-0 values were significantly lower than rK ^trans _Δ1-0 values (P = .048). rv_{e Δ2-1} and rv_eΔ2-0 values were significantly different (P = .016). rτ _{i Δ2-1} values were significantly lower than rτ _{i Δ2-0} values (P = .008). For group comparison, the pre-TX mean and kurtosis of ADC (P = .18 and P = .14), skewness and kurtosis of K ^trans values (P = .14 for both) showed a leaning toward significant difference between patients who experienced local control (n = 2) and failed early (n = 4). DW- and DCE-MRI-derived quantitative metrics could be useful biomarkers to evaluate longitudinal changes to stereotactic body radiotherapy in patients with pancreatic ductal adenocarcinoma.

Added Value of Radiotherapy Following Neoadjuvant FOLFIRINOX for Resectable and Borderline Resectable Pancreatic Cancer: A Systematic Review and Meta-Analysis

Background

The added value of radiotherapy following neoadjuvant FOLFIRINOX chemotherapy in patients with resectable or borderline resectable pancreatic cancer ((B)RPC) is unclear. The objective of this meta-analysis was to compare outcomes of patients who received neoadjuvant FOLFIRINOX alone or combined with radiotherapy.

Methods

A systematic literature search was performed in Embase, Medline (ovidSP), Web of Science, Scopus, Cochrane, and Google Scholar. The primary endpoint was pooled median overall survival (OS). Secondary endpoints included resection rate, R0 resection rate, and other pathologic outcomes.

Results

We included 512 patients with (B)RPC from 15 studies, of which 7 were prospective nonrandomized studies. In total, 351 patients (68.6%) were treated with FOLFIRINOX alone (8 studies) and 161 patients (31.4%) were treated with FOLFIRINOX and radiotherapy (7 studies). The pooled estimated median OS was 21.6 months (range 18.4–34.0 months) for FOLFIRINOX alone and 22.4 months (range 11.0–37.7 months) for FOLFIRINOX with radiotherapy. The pooled resection rate was similar (71.9% vs. 63.1%, p = 0.43) and the pooled R0 resection rate was higher for FOLFIRINOX with radiotherapy (88.0% vs. 97.6%, p = 0.045). Other pathological outcomes (ypN0, pathologic complete response, perineural invasion) were comparable.

Conclusions

In this meta-analysis, radiotherapy following neoadjuvant FOLFIRINOX was associated with an improved R0 resection rate as compared with neoadjuvant FOLFIRINOX alone, but a difference in survival could not be demonstrated. Randomized trials are needed to determine the added value of radiotherapy following neoadjuvant FOLFIRINOX in patients with (B)PRC.

Supplementary Information

The online version contains supplementary material available at 10.1245/s10434-021-10276-8.

Risk Adapted Ablative Radiotherapy After Intensive Chemotherapy for Locally Advanced Pancreatic Cancer

Background and Objective

To assess the efficacy of a Risk-Adapted Ablative Radiotherapy (RAdAR) approach, after intensive induction chemotherapy, in patients with locally advanced pancreatic cancer (LAPC).

Material and Methods

Patients with LAPC who received RAdAR following induction chemotherapy from January 2017 to December 2019 were included in this observational study. The RAdAR approach consisted of an anatomy- and simultaneous integrated boost (SIB)-based dose prescription strategy. RAdAR was delivered with stereotactic ablative radiation therapy (SAbR), administering 30 Gy in 5 fractions to the tumor volume (PTV_t) and 50 Gy SIB (BED₁₀ 100 Gy) to the vascular involvement, or with (hypo-)fractionated ablative radiotherapy (HART) prescribing 50.4 Gy in 28 fractions to the PTV_t, with a vascular SIB of 78.4 Gy (BED₁₀ 100 Gy). Primary end points were freedom from local progression (FFLP), overall survival (OS), and progression-free survival (PFS).

Results

Sixty-four LAPC patients were included. Induction chemotherapy consisted of gemcitabine/nab-paclitaxel in 60.9% and FOLFIRINOX in 39.1% of cases. SAbR was used in 52 (81.2%) patients, and HART in 12 (18.8%). After RAdAR, surgery was performed in 17 (26.6%) patients. Median follow-up was 16.1 months. Overall local control (LC) rate was 78.1%, with no difference between resected and non-resected patients (2-year FFLP 75.3% vs 56.4%; p = 0.112). Median OS and PFS were 29.7 months and 8.7 months, respectively, for the entire cohort. Resected patients had a better median OS (not reached versus 26.1 months; p = 0.0001) and PFS (19 versus 5.6 months; p < 0.0001) compared to non-resected patients. In non-resected patients, no significant difference was found between SAbR and HART for median FFLP (28.1 versus 18.5 months; p = 0.614), OS (27.4 versus 25.3 months; p = 0.624), and PFS (5.7 versus 4.3 months; p = 0.486). One patient (1.6%) experienced acute grade 4 gastro-intestinal bleeding. No other acute or late grade ≥ 3 toxicities were observed.

Conclusions

The RAdAR approach, following intensive induction chemotherapy, is an effective radiation treatment strategy for selected LAPC patients, representing a promising therapeutic option in a multimodality treatment regimen.

Adjuvant chemotherapy versus observation following neoadjuvant therapy and surgery for resectable stages I–II pancreatic cancer

Aim:

This National Cancer Database (NCDB) analysis was performed to evaluate the outcomes of adjuvant chemotherapy (AC) versus observation for resected pancreatic adenocarcinoma treated with neoadjuvant therapy (NT).

Materials and methods:

The NCDB was queried for primary stages I–II cT1-3N0-1M0 resected pancreatic adenocarcinoma treated with NT (2004–2015). Baseline patient, tumour and treatment characteristics were extracted. The primary end point was overall survival (OS). With a 6-month conditional landmark, Kaplan–Meier analysis, multivariable Cox proportional hazards method and 1:1 propensity score matching was used to analyse the data.

Results:

A total of 1,737 eligible patients were identified, of which 1,247 underwent post-operative observation compared to 490 with AC. The overall median follow-up was 34·7 months. The addition of AC showed improved survival on the multivariate analysis (HR 0·78, p < 0·001). AC remained statistically significant for improved OS, with a median OS of 26·3 months versus 22·3 months and 2-year OS of 63·9% versus 52·9% for the observation cohort (p < 0·001). Treatment interaction analysis showed OS benefit of AC for patients with smaller tumours.

Findings:

Our findings suggest a survival benefit for AC compared to observation following NT and surgery for resectable pancreatic adenocarcinoma, especially in patients with smaller tumours.

New Potential Options for SBRT in Pancreatic Cancer

Stereotactic body radiotherapy (SBRT) is an emerging treatment option for patients with pancreatic cancer, as it can provide a therapeutic benefit with significant advantages for patients' quality of life over standard conventional chemoradiation (CRT). The objective of this review is to present alternative clinical settings in which SBRT may benefit patients with pancreatic cancer. These include palliation of pain, elderly patients who are not surgical candidates, local therapy in oligometastatic cases and salvaging local failures after surgery or external beam radiation. We will review these individually and provide supporting literature for each.

Radiotherapy for locally advanced pancreatic ductal adenocarcinoma

Locally advanced, unresectable pancreatic ductal adenocarcinoma has a poor prognosis with a median overall survival of 10-16 months. It is defined by tumor involvement of neighboring blood vessels that precludes resection. Standard doses of conventionally fractionated radiation have had little effect on overall survival in this setting, although they are associated with improved progression-free survival and time off chemotherapy. Evolving radiotherapy techniques have allowed for higher, ablative doses of radiotherapy to target tumor while also respecting normal tissue constraints of neighboring radiosensitive structures in the gastrointestinal tract. Moreover, advancements in image guidance, organ motion management, and the use of adaptive planning have enabled safe delivery of higher, ablative doses of radiation. This has resulted in improved survival. This review will summarize the expanding role of radiotherapy in the management of locally advanced, unresectable pancreatic cancer.

The Role of Radiation Therapy in the Older Patient

PURPOSE OF REVIEW

Older patients represent a unique subgroup of the cancer patient population for which the role of radiation therapy (RT) requires special consideration. This review will discuss many of these considerations as well as various radiation treatment techniques in the context of a variety of disease sites.

RECENT FINDINGS

Several recent studies give insight into the management of older cancer patients considering their age, performance status, comorbid conditions, quality of life, genetics, cost, and individual goals. RT plays an evolving and pivotal role in providing optimal care for this population. Recent advances in RT technique allow for more precise treatment delivery and reduced toxicity. Studies evaluating the use of radiation therapy in breast, brain, lung, prostate, rectal, pancreatic, esophageal, and oligometastatic cancer are summarized and discussed in the context of treating the older patient population. Individual age, performance and functional status, comorbid conditions, and patients' objectives and goals should all be considered when presenting treatment options for older patients and age alone should not disqualify patients from curative intent treatments. When possible, hypofractionated courses should be utilized as outcomes are often equivalent and toxicities are reduced. In many cases, RT may be preferable to other treatment options due to decreased toxicity profile and acceptable disease control.

Dosimetric Feasibility Study of Dose Escalated Stereotactic Body Radiation Therapy (SBRT) in Locally Advanced Pancreatic Cancer (LAPC) Patients: It Is Time to Raise the Bar

Background and Objective

To assess the dosimetric feasibility of a stereotactic body radiotherapy (SBRT) dose escalated protocol, with a simultaneous integrated boost (SIB) and a simultaneous integrated protection (SIP) approach, in patients with locally advanced pancreatic cancer (LAPC).

Material and Methods

Twenty LAPC lesions, previously treated with SBRT at our Institution, were re-planned. The original prescribed and administered dose was 50/30/25 Gy in five fractions to PTV_sib (tumor-vessel interface [TVI])/PTV_t (tumor volume)/PTV_sip (overlap area between PTV_t and planning organs at risk volume [PRV_oars]), respectively. At re-planning, the prescribed dose was escalated up to 60/40/33 Gy in five fractions to PTV_sib/PTV_t/PTV_sip, respectively. All plans were performed using an inspiration breath hold (IBH) technique and generated with volumetric modulated arc therapy (VMAT). Well-established and accepted OAR dose constraints were used (D_0.5cc < 33 Gy for luminal OARs and D_0.5cc < 38 Gy for corresponding PRV_oars). The primary end-point was to achieve a median dose equal to the prescription dose for the PTV_sib with D₉₈≥ 95% (95% of prescription dose is the minimum dose), and a coverage for PTV_t and PTV_sip of D₉₅≥95%, with minor deviations in OAR dose constraints in < 10% of the plans.

Results

PTV_sib median (± SD) dose/D₉₅/conformity index (CI) were 60.54 (± 0.85) Gy/58.96 (± 0.86) Gy/0.99 (± 0.01), respectively; whilst PTV_t median (± SD) dose/D₉₅ were 44.51 (± 2.69) Gy/38.44 (± 0.82) Gy, and PTV_sip median (± SD) dose/D₉₅ were 35.18 (± 1.42) Gy/33.01 (± 0.84) Gy, respectively. With regard to OARs, median (± SD) maximum dose (D_0.5cc) to duodenum/stomach/bowel was 29.31 (± 5.72) Gy/25.29 (± 6.90) Gy/27.03 (± 5.67) Gy, respectively. A minor acceptable deviation was found for a single plan (bowel and duodenum D_0.5cc=34.8 Gy). V38 < 0.5 cc was achieved for all PRV luminal OARs.

Conclusions

In LAPC patients SBRT, with a SIB/SIP dose escalation approach up to 60/40/33 Gy in five fractions to PTV_sib/PTV_t/PTV_sip, respectively, is dosimetrically feasible with adequate PTVs coverage and respect for OAR dose constraints.