A Phase 1 Study of Stereotactic Body Radiation Therapy Dose Escalation for Borderline Resectable Pancreatic Cancer After Modified FOLFIRINOX (NCT01446458)

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.

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.

Comprehensive multimodal management of borderline resectable pancreatic cancer: Current status and progress

Borderline resectable pancreatic cancer (BRPC) is a complex clinical entity with specific biological features. Criteria for resectability need to be assessed in combination with tumor anatomy and oncology. Neoadjuvant therapy (NAT) for BRPC patients is associated with additional survival benefits. Research is currently focused on exploring the optimal NAT regimen and more reliable ways of assessing response to NAT. More attention to management standards during NAT, including biliary drainage and nutritional support, is needed. Surgery remains the cornerstone of BRPC treatment and multidisciplinary teams can help to evaluate whether patients are suitable for surgery and provide individualized management during the perioperative period, including NAT responsiveness and the selection of surgical timing.

Simulated computed tomography-guided stereotactic adaptive radiotherapy (CT-STAR) for the treatment of locally advanced pancreatic cancer

BACKGROUND AND PURPOSE

We conducted a prospective, in silico imaging clinical trial to evaluate the feasibility and potential dosimetric benefits of computed tomography-guided stereotactic adaptive radiotherapy (CT-STAR) for the treatment of locally advanced pancreatic cancer (LAPC).

MATERIALS AND METHODS

Eight patients with LAPC received five additional CBCTs on the ETHOS system before or after their standard of care radiotherapy treatment. Initial plans were created based on their initial simulation anatomy (P_I) and emulated adaptive plans were created based on their anatomy-of-the-day (P_A). The prescription was 50 Gy/5 fractions. Plans were created under a strict isotoxicity approach, in which organ-at-risk (OAR) constraints were prioritized over planning target volume coverage. The P_I was evaluated on the patient's anatomy-of-the-day, compared to the daily P_A, and the superior plan was selected. Feasibility was defined as successful completion of the workflow in compliance with strict OAR constraints in ≥80% of fractions.

RESULTS

CT-STAR was feasible in silico for LAPC and improved OAR and/or target dosimetry in 100% of fractions. Use of the P_I based on the patient's anatomy-of-the-day would have yielded a total of 94 OAR constraint violations and ≥1 hard constraint violation in 40/40 fractions. In contrast, 39/40 P_A met all OAR constraints. In one fraction, the P_A minimally exceeded the large bowel constraint, although dosimetrically improved compared to the P_I. Total workflow time per fraction was 36.28 minutes (27.57-55.86).

CONCLUSION

CT-STAR for the treatment of LAPC cancer proved feasible and was dosimetrically superior to non-adapted CT-stereotactic body radiotherapy.

Neoadjuvant treatment of pancreatic adenocarcinoma: Chemoradiation or stereotactic body radiation therapy?

Despite recent advances, the prognosis of pancreatic adenocarcinomas remains poor, even for patients with resectable tumors. For these latter, new approaches based on neoadjuvant treatment have been developed. Two components are used: chemotherapy and radiation therapy (RT). Indeed, pre-operative RT has many advantages in terms of efficacy and tolerance. It increases notably the chances of subsequent complete tumor resection. Several prospective trials are currently ongoing to clarify its place in the therapeutic arsenal. Another crucial question is to know which is the best RT technique: conventional normofractionated chemoradiotherapy or hypofrationated stereotactic body RT?

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.

Toll-like receptor 7/8 agonist R848 alters the immune tumor microenvironment and enhances SBRT-induced antitumor efficacy in murine models of pancreatic cancer

BACKGROUND

Stereotactic body radiotherapy (SBRT) has been increasingly used as adjuvant therapy in pancreatic ductal adenocarcinoma (PDAC), and induces immunogenic cell death, which leads to the release of tumor antigen and damage-associated molecular patterns. However, this induction often fails to generate sufficient response to overcome pre-existing tumor microenvironment (TME) immunosuppression. Toll-like receptor (TLR) 7/8 ligands, such as R848, can amplify the effect of tumor vaccines, with recent evidence showing its antitumor effect in pancreatic cancer by modulating the immunosuppressive TME. Therefore, we hypothesized that the combination of R848 and SBRT would improve local and systemic antitumor immune responses by potentiating the antitumor effects of SBRT and reversing the immunosuppressive nature of the PDAC TME.

METHODS

Using murine models of orthotopic PDAC, we assessed the combination of intravenous TLR7/8 agonist R848 and local SBRT on tumor growth and immune response in primary pancreatic tumors. Additionally, we employed a hepatic metastatic model to investigate if the combination of SBRT targeting only the primary pancreatic tumor and systemic R848 is effective in controlling established liver metastases.

RESULTS

We demonstrated that intravenous administration of the TLR7/8 agonist R848, in combination with local SBRT, leads to superior tumor control compared with either treatment alone. The combination of R848 and SBRT results in significant immune activation of the pancreatic TME, including increased tumor antigen-specific CD8+ T cells, decreased regulatory T cells, and enhanced antigen-presenting cells maturation, as well as increased interferon gamma, granzyme B, and CCL5 along with decreased levels of interleukin 4 (IL-4), IL-6, and IL-10. Importantly, the combination of SBRT and systemic R848 also resulted in similar immunostimulatory changes in liver metastases, leading to improved metastatic control. CD8+ T cell depletion studies highlighted the necessity of these effector cells at both the local and hepatic metastatic sites. T cell receptor (TCR) clonotype analysis indicated that systemic R848 not only diversified the TCR repertoire but also conditioned the metastatic foci to facilitate entry of CD8+ T cells generated by SBRT therapy.

CONCLUSIONS

These findings suggest that systemic administration of TLR7/8 agonists in combination with SBRT may be a promising avenue for metastatic PDAC treatment.

Predictive Value of Delta-Radiomics Texture Features in 0.35 Tesla Magnetic Resonance Setup Images Acquired During Stereotactic Ablative Radiotherapy of Pancreatic Cancer

Purpose

The purpose of this work is to explore delta-radiomics texture features for predicting response using setup images of pancreatic cancer patients treated with magnetic resonance image guided (MRI-guided) stereotactic ablative radiotherapy (SBRT).

Methods

The total biological effective dose (BED) was calculated for 30 patients treated with MRI-guided SBRT that delivered physical doses of 30–60 Gy in three to five fractions. Texture features were then binned into groups based upon BED per fraction by dividing BED by the number of fractions. Delta-radiomics texture features were calculated after delivery of 20 Gy BED (BED20 features) and 40 Gy BED (BED40 features). A random forest (RF) model was constructed using BED20 and then BED40 features to predict binary outcome. During model training, the Gini Index, a measure of a variable’s importance for accurate prediction, was calculated for all features, and the two features that ranked the highest were selected for internal validation. The two features selected from each bin were used in a bootstrapped logistic regression model to predict response and performance quantified using the area under the receiver operating characteristic curve (AUC). This process was an internal validation analysis.

Results

After RF model training, the Gini Index was highest for gray-level co-occurrence matrix-based (GLCM) sum average, and neighborhood gray tone difference matrix-based (NGTDM) busyness for BED20 features and gray-level size zone matrix-based (GLSZM) large zones low gray-level emphasis and gray-level run length matrix-based (GLRLM) run percentage was selected from the BED40-based features. The mean AUC obtained using the two BED20 features was AUC = 0.845 with the 2.5 percentile and 97.5 percentile values ranging from 0.794 to 0.856. Internal validation of the BED40 delta-radiomics features resulted in a mean AUC = 0.567 with a 2.5 and 97.5 percentile range of 0.502–0.675.

Conclusion

Early changes in treatment quantified with the BED20 delta-radiomics texture features in low field images acquired during MRI-guided SBRT demonstrated better performance in internal validation than features calculated later in treatment. Further analysis of delta-radiomics texture analysis in low field MRI is warranted.

Ablative Radiotherapy (ART) for Locally Advanced Pancreatic Cancer (LAPC): Toward a New Paradigm?

Locally advanced pancreatic cancer (LAPC) represents a major urgency in oncology. Due to the massive involvement of the peripancreatic vessels, a curative-intent surgery is generally precluded. Historically, LAPC has been an indication for palliative systemic therapy. In recent years, with the introduction of intensive multi-agent chemotherapy regimens and aggressive surgical approaches, the survival of LAPC patients has significantly improved. In this complex and rapidly evolving scenario, the role of radiotherapy is still debated. The use of standard-dose conventional fractionated radiotherapy in LAPC has led to unsatisfactory oncological outcomes. However, technological advances in radiation therapy over recent years have definitively changed this paradigm. The use of ablative doses of radiotherapy, in association with image-guidance, respiratory organ-motion management, and adaptive protocols, has led to unprecedented results in terms of local control and survival. In this overview, principles, clinical applications, and current pitfalls of ablative radiotherapy (ART) as an emerging treatment option for LAPC are discussed.

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.

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.

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.

The timing and design of stereotactic radiotherapy approaches as a part of neoadjuvant therapy in pancreatic cancer: Is it time for change?

Stereotactic Radiotherapy (SRT) over 5-15 days can be interdigitated without delaying chemotherapy. Bridging chemotherapy may allow for extended intervals to surgery, potentially improving sterilization of surgical margins and overall survival. SRT for pancreatic adenocarcinoma should not be limited to the tumor, and should consider hypofractionated approaches to regional nodes.

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.

A phase II trial proposal of total neoadjuvant treatment with primary chemotherapy, stereotactic body radiation therapy, and intraoperative radiation therapy in borderline resectable pancreatic adenocarcinoma

BACKGROUND

The current management guidelines recommend that patients with borderline resectable pancreatic adenocarcinoma (BRPC) should initially receive neoadjuvant chemotherapy. The addition of advanced radiation therapy modalities, including stereotactic body radiation therapy (SBRT) and intraoperative radiation therapy (IORT), could result in a more effective neoadjuvant strategy, with higher rates of margin-free resections and improved survival outcomes.

METHODS/DESIGN

In this single-center, single-arm, intention-to-treat, phase II trial newly diagnosed BRPC will receive a "total neoadjuvant" therapy with FOLFIRINOX (5-fluorouracil, irinotecan and oxaliplatin) and hypofractionated SBRT (5 fractions, total dose of 30 Gy with simultaneous integrated boost of 50 Gy on tumor-vessel interface). Following surgical exploration or resection, IORT will be also delivered (10 Gy). The primary endpoint is 3-year survival. Secondary endpoints include completion of neoadjuvant treatment, resection rate, acute and late toxicities, and progression-free survival. In the subset of patients undergoing resection, per-protocol analysis of disease-free and disease-specific survival will be performed. The estimated sample size is 100 patients over a 36-month period. The trial is currently recruiting.

TRIAL REGISTRATION

NCT04090463 at clinicaltrials.gov.

Deep Learning-Based Fluence Map Prediction for Pancreas Stereotactic Body Radiation Therapy With Simultaneous Integrated Boost

Purpose

Treatment planning for pancreas stereotactic body radiation therapy (SBRT) is a challenging task, especially with simultaneous integrated boost treatment approaches. We propose a deep learning (DL) framework to accurately predict fluence maps from patient anatomy and directly generate intensity modulated radiation therapy plans.

Methods and Materials

The framework employs 2 convolutional neural networks (CNNs) to sequentially generate beam dose prediction and fluence map prediction, creating a deliverable 9-beam intensity modulated radiation therapy plan. Within the beam dose prediction CNN, axial slices of combined structure contour masks are used to predict 3-dimensional (3D) beam doses for each beam. Each 3D beam dose is projected along its beam’s-eye-view to form a 2D beam dose map, which is subsequently used by the fluence map prediction CNN to predict its fluence map. Finally, the 9 predicted fluence maps are imported into the treatment planning system to finalize the plan by leaf sequencing and dose calculation. One hundred patients receiving pancreas SBRT were retrospectively collected for this study. Benchmark plans with unified simultaneous integrated boost prescription (25/33 Gy) were manually optimized for each case. The data set was split into 80/20 cases for training and testing. We evaluated the proposed DL framework by assessing both the fluence maps and the final predicted plans. Further, clinical acceptability of the plans was evaluated by a physician specializing in gastrointestinal cancer.

Results

The DL-based planning was, on average, completed in under 2 minutes. In testing, the predicted plans achieved similar dose distribution compared with the benchmark plans (-1.5% deviation for planning target volume 33 V_33Gy), with slightly higher planning target volume maximum (+1.03 Gy) and organ at risk maximum (+0.95 Gy) doses. After renormalization, the physician rated 19 cases clinically acceptable and 1 case requiring minor improvement.

Conclusions

The DL framework can effectively plan pancreas SBRT cases within 2 minutes. The predicted plans are clinically deliverable, with plan quality approaching that of manual planning.

SPARC, a phase-I trial of pre-operative, margin intensified, stereotactic body radiation therapy for pancreatic cancer

BACKGROUND AND PURPOSE

Following resection of pancreatic cancer, risk of positive margins and local recurrence remain high, especially for borderline-resectable pancreatic cancer (BRPC). We aimed to establish the maximum tolerated dose of a margin-intensified five-fraction stereotactic body radiotherapy (SBRT) regimen designed to treat the region at risk.

MATERIALS AND METHODS

We conducted a prospective multicentre phase-1 rolling-six dose-escalation study. BRPC patients received pre-operative SBRT, with one dose to the primary tumour and an integrated boost to the region where tumour was in contact with vasculature. Four dose-levels were proposed, with starting dose 30 Gy to primary PTV and 45 Gy to boost volume (PTV_R), in five daily fractions. Primary endpoint was maximum tolerated dose (MTD), defined as highest dose where zero of three or one of six patients experienced dose-limiting toxicity (DLT).

RESULTS

Twelve patients were registered, eleven received SBRT. Radiotherapy was well tolerated with all treatment completed as scheduled. Dose was escalated one level up from starting dose without encountering any DLT (prescribed 32.5 Gy PTV, 47.5 Gy PTV_R). Nine serious adverse reactions or events occurred (seven CTCAE Grade 3, two Grade 4). Two patients went on to have surgical resection. Median overall survival for SBRT patients was 8.1 months. The study closed early when it was unable to recruit to schedule.

CONCLUSION

Toxicity of SBRT was low for the two dose-levels that were tested, but MTD was not established. Few patients subsequently underwent resection of pancreatic tumour after SBRT, and it is difficult to draw conclusions regarding the safety or toxicity of these therapies in combination.

Dose-escalated simultaneously integrated boost photon or proton therapy in pancreatic cancer in an in-silico study: Gastrointestinal organs remain critical

•

Robustly optimized proton plans (rMFO-IMPT) with simultaneously integrated boost (SIB) were clinically applicable.

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Gastrointestinal organs reached critical dose values in rMFO-IMPT, VMAT and Tomotherapy techniques.

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rMFO-IMPT significantly reduced the low and intermediate dose to organs at risk.

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No clinically significant differences on results depending on tumor location or surgical status were observed.

Purpose

To compare the dosimetric results of an in-silico study among intensity-modulated photon (IMRT) and robustly optimized intensity-modulated proton (IMPT) treatment techniques using a dose-escalated simultaneously integrated boost (SIB) approach in locally recurrent or advanced pancreatic cancer patients.

Material and methods

For each of 15 locally advanced pancreatic cancer patients, a volumetric-modulated arc therapy (VMAT), a Tomotherapy (TOMO), and an IMPT treatment plan was optimized on free-breathing treatment planning computed tomography (CT) images. For the photon treatment plans, doses of 66 Gy and 51 Gy, both as SIB in 30 fractions, were prescribed to the gross tumor volume (GTV) and to the planning target volume (PTV), respectively. For the proton plans, a dose prescription of 66 Gy(RBE) to the GTV and of 51 Gy(RBE) to the clinical target volume (CTV) was planned. For each SIB-treatment plan, doses to the targets and OARs were evaluated and statistically compared.

Results

All treatment techniques reached the prescribed doses to the GTV and CTV or PTV. The stomach and the bowel, in particular the duodenum and the small bowel, were found to be frequently exposed to doses exceeding 50 Gy, irrespective of the treatment technique. For doses below 50 Gy, the IMPT technique was statistically significant superior to both IMRT techniques regarding decreasing dose to the OARs, e.g. volume of the bowel receiving 15 Gy (V_15Gy) was reduced for IMPT compared to VMAT (p = 0.003) and TOMO (p < 0.001).

Conclusion

With all photon and proton techniques investigated, the radiation dose to gastrointestinal OARs remained critical when treating patients with unresectable locally recurrent or advanced pancreatic cancer using a dose-escalated SIB approach.

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.

Chemotherapy-based split stereotactic body radiation therapy for borderline resectable and locally advanced pancreatic cancer: study protocol of a prospective, single-arm phase II trial

INTRODUCTION

The question of how to administer adequate chemotherapy to synchronise stereotactic body radiation therapy (SBRT) treatment strategy to maximise the benefits of neoadjuvant therapy for the improved prognosis of patients with borderline resectable (BRPC) and locally advanced (LAPC) pancreatic cancer is a challenging and debatable issue. No studies have yet evaluated the efficacy of split-course SBRT as the neoadjuvant chemoradiotherapy regimen. We aimed to study whether neoadjuvant chemotherapy plus split-course SBRT results in better outcomes in BRPC and LAPC patients.

METHODS AND ANALYSIS

Treatment-naïve patients with radiographically confirmed BRPC or LAPC, supporting biopsy results and no severe comorbidities will be enrolled. They will be treated with nab-paclitaxel plus gemcitabine (nab-P+Gem) chemotherapy plus split-course SBRT, followed by an investigator's choice of continuation of treatment with nab-P+Gem or surgery. nab-P+Gem chemotherapy will commence on day 1 for each of six cycles: nab-paclitaxel 125 mg/m² intravenous infusion over approximately 30-45 min, followed by gemcitabine 1000 mg/m² intravenous infusion over about 30 min on days 1 and 15 of each 28-day cycle. During the first and second cycles of chemotherapy, SBRT will be given as a single irradiation of 10 Gy four times (days 2 and 16 of each 28-day cycle). The primary endpoint is progression-free survival; while the secondary outcomes are the time to treatment failure, disease control rate, overall response rate, overall survival, R0 resection rate and incidence of adverse effects.

ETHICS AND DISSEMINATION

The study protocol was approved by the Ethics Committee of Xiehe Affiliated Hospital of Fujian Medical University (No. 2019YF015-01). Results from our study will be disseminated in international peer-reviewed journals. All study procedures were developed in order to assure data protection and confidentiality.

TRIAL REGISTRATION NUMBER

NCT04289792.

Dose-Escalated Radiation Therapy for Pancreatic Cancer: A Simultaneous Integrated Boost Approach

PURPOSE

To provide a detailed description of practical approaches to dose escalation in pancreatic cancer.

METHODS AND MATERIALS

The current paper represents an international collaborative effort of radiation oncologists from the MR-linac consortium with expertise in pancreatic dose escalation.

RESULTS

A 15-fraction hypofractionated intensity modulated radiation therapy (67.5 Gy in 15 fractions) and 5-fraction stereotactic body radiation therapy case (50 Gy in 5 fractions) are presented with information regarding patient selection, target volumes, organs at risk, dose constraints, and specific considerations regarding quality assurance. Additionally, we address barriers to dose escalation and briefly discuss future directions in dose escalation for pancreatic cancer, including particle therapy and magnetic resonance guided radiation therapy.

CONCLUSIONS

This article on dose escalation for pancreatic cancer may help to guide academic and community based physicians and to serve as a reference for future therapeutic trials.

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.

Radiation as a Single-Modality Treatment in Localized Pancreatic Cancer

OBJECTIVES

Locally advanced pancreatic cancer (LAPC) is managed with multimodality therapy. We aim to evaluate the outcome of single-modality radiation therapy for LAPC.

METHODS

Locally advanced pancreatic cancer patients were identified between 2004 and 2013 using the National Cancer Database excluding patients who received chemotherapy or surgery.

RESULTS

A total of 6590 patients were included. The mean age was 73.5 (range, 28-90) years, 83.2% were white, and 54.4% were female. Tumors of 4 cm or greater (>T3 stage) accounted for 52.7%. The median radiation dose was 39.6 Gy. Stereotactic body radiation (SBRT) delivered to 64 patients and external-beam/intensity modulated radiotherapy in 416 patients. Radiation therapy was associated with improved overall survival (OS) compared with no treatment in univariate and multivariable analyses. The medians OS for patients who received SBRT, external-beam/intensity modulated radiotherapy, or no radiation were 8.6, 6.7, and 3.4 months, respectively (P < 0.001). There is a significant difference in 12-month OS for the SBRT cohort (31.9%; 95% confidence interval [CI], 20.9%-43.5%) compared with patients who received no radiation (15.1%; 95% CI, 14.2%-16.0%), and on multivariable analysis (hazard ratio, 0.50; 95% CI, 0.38-0.65; P < 0.001).

CONCLUSIONS

The current study suggests potential benefit for radiation therapy alone in comparison with no treatment in LAPC.

Basics and Frontiers on Pancreatic Cancer for Radiation Oncology: Target Delineation, SBRT, SIB technique, MRgRT, Particle Therapy, Immunotherapy and Clinical Guidelines

Pancreatic cancer represents a modern oncological urgency. Its management is aimed to both distal and local disease control. Resectability is the cornerstone of treatment aim. It influences the clinical presentation’s definitions as up-front resectable, borderline resectable and locally advanced (unresectable). The main treatment categories are neoadjuvant (preoperative), definitive and adjuvant (postoperative). This review will focus on (i) the current indications by the available national and international guidelines; (ii) the current standard indications for target volume delineation in radiotherapy (RT); (iii) the emerging modern technologies (including particle therapy and Magnetic Resonance [MR]-guided-RT); (iv) stereotactic body radiotherapy (SBRT), as the most promising technical delivery application of RT in this framework; (v) a particularly promising dose delivery technique called simultaneous integrated boost (SIB); and (vi) a multimodal integration opportunity: the combination of RT with immunotherapy.

Assessing the Magnitude of Immunogenic Cell Death Following Chemotherapy and Irradiation Reveals a New Strategy to Treat Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) continues to have a dismal prognosis, in part, due to ineffective treatment strategies. The efficacy of some chemotherapies and especially radiotherapy is mediated partially by the immune system. Therefore, we hypothesized that profiling the immune response following chemotherapy and/or irradiation can be used as a readout for treatment efficacy but also to help identify optimal therapeutic schedules for PDAC. Using murine models of PDAC, we demonstrated that concurrent administration of stereotactic body radiotherapy (SBRT) and a modified dose of FOLFIRINOX (mFX) resulted in superior tumor control when compared with single or sequential treatment groups. Importantly, this combined treatment schedule enhanced the magnitude of immunogenic cell death, which in turn amplified tumor antigen presentation by dendritic cells and intratumoral CD8+ T-cell infiltration. Concurrent therapy also resulted in systemic immunity contributing to the control of established metastases. These findings provide a rationale for pursuing concurrent treatment schedules of SBRT with mFX in PDAC.

Determining Optimal Routes to Surgery for Borderline Resectable Venous Pancreatic Cancer-Where Is the Least Harm and Most Benefit?

Surgery among patients with borderline resectable pancreatic cancer (BRPC) and venous disease has emerged as a viable strategy to achieve curative treatment. By definition, these patients are at increased risk of a positive resection margin, however, controversy exists with regards to necessity of radical surgery and optimum pathways with no consensus on definitive treatment. A surgery first approach is possible though outcomes vary but patients can have an efficient pathway to surgery, particularly if biliary drainage is avoided which limits overall complications. Neoadjuvant therapy (NAT) is emerging as a widely used strategy to improve oncological outcomes, including resection margin status. However, some patients progress on NAT whilst others suffer major complications whilst elderly patients are unlikely to be offered effective NAT limiting the widespread applicability of this therapy. In this article an overview of the entire pathway is presented along with assimilation of current best evidence to determine optimal routes to surgery for BRPC with venous involvement.

Neoadjuvant FOLFIRINOX in Patients With Borderline Resectable Pancreatic Cancer: A Systematic Review and Patient-Level Meta-Analysis

BACKGROUND

FOLFIRINOX is a standard treatment for metastatic pancreatic cancer patients. The effectiveness of neoadjuvant FOLFIRINOX in patients with borderline resectable pancreatic cancer (BRPC) remains debated.

METHODS

We performed a systematic review and patient-level meta-analysis on neoadjuvant FOLFIRINOX in patients with BRPC. Studies with BRPC patients who received FOLFIRINOX as first-line neoadjuvant treatment were included. The primary endpoint was overall survival (OS), and secondary endpoints were progression-free survival, resection rate, R0 resection rate, and grade III-IV adverse events. Patient-level survival outcomes were obtained from authors of the included studies and analyzed using the Kaplan-Meier method.

RESULTS

We included 24 studies (8 prospective, 16 retrospective), comprising 313 (38.1%) BRPC patients treated with FOLFIRINOX. Most studies (n = 20) presented intention-to-treat results. The median number of administered neoadjuvant FOLFIRINOX cycles ranged from 4 to 9. The resection rate was 67.8% (95% confidence interval [CI] = 60.1% to 74.6%), and the R0-resection rate was 83.9% (95% CI = 76.8% to 89.1%). The median OS varied from 11.0 to 34.2 months across studies. Patient-level survival data were obtained for 20 studies representing 283 BRPC patients. The patient-level median OS was 22.2 months (95% CI = 18.8 to 25.6 months), and patient-level median progression-free survival was 18.0 months (95% CI = 14.5 to 21.5 months). Pooled event rates for grade III-IV adverse events were highest for neutropenia (17.5 per 100 patients, 95% CI = 10.3% to 28.3%), diarrhea (11.1 per 100 patients, 95% CI = 8.6 to 14.3), and fatigue (10.8 per 100 patients, 95% CI = 8.1 to 14.2). No deaths were attributed to FOLFIRINOX.

CONCLUSIONS

This patient-level meta-analysis of BRPC patients treated with neoadjuvant FOLFIRINOX showed a favorable median OS, resection rate, and R0-resection rate. These results need to be assessed in a randomized trial.

Induction Therapy in Localized Pancreatic Cancer

OBJECTIVES

Pancreatic cancer (PDAC) with localized stage includes resectable (RPC), borderline resectable (BRPC), or locally advanced unresectable (LAPC). Standard of care for RPC is adjuvant chemotherapy. There are no prospective randomized trials for best treatment of BRPC and LAPC. We evaluate the impact of induction chemotherapy on localized PDAC.

METHODS

Charts of PDAC patients treated at Emory University between 2009 and 2016 were reviewed. The primary end point was overall survival (OS).

RESULTS

A total of 409 localized PDACs were identified. Resectability was prospectively determined at a multidisciplinary tumor conference. Median age was 67 years (range, 30-92 years), 49% were male, 66% were white, 171 had RPC, 131 had BRPC, and 107 had LAPC. Median OSs for RPC, BRPC, and LAPC were 19.5, 16.1, and 12.7 months, respectively. Type of chemotherapy and age were predictors of OS. Induction chemotherapy was used in 106 with BRPC (81%) and 74 with RPC (56.5%); patients with BRPC who received combination chemotherapy and resection had a median OS of 31.5 compared with 19.5 months in patients with RPC (P = 0.0049). Patients with LAPC had a median OS of 12.7 months.

CONCLUSIONS

In patients with BRPC who undergo resection after induction treatment, the OS was significantly better than in patients with RPC. Neoadjuvant treatment should be considered for all localized PDACs.

Phase 2 Study of Neoadjuvant Treatment of Sequential S-1-Based Concurrent Chemoradiation Therapy Followed by Systemic Chemotherapy with Gemcitabine for Borderline Resectable Pancreatic Adenocarcinoma (HOPS-BR 01)

PURPOSE

Preoperative treatment is recommended for borderline resectable pancreatic ductal adenocarcinoma. However, the standard treatment has not yet been determined. We conducted a multicenter phase 2 study to investigate the efficacy of neoadjuvant treatment of sequential chemoradiation followed by chemotherapy.

METHODS AND MATERIALS

All enrolled patients were treated by preoperative chemoradiation (a total dose of 50.4 Gy in 28 fractions and orally administered S-1 at 80 mg/m² on the day of irradiation) followed by chemotherapy (administration of gemcitabine at 1000 mg/m²/dose on days 1, 8, and 15 in 3 cycles of 4 weeks) and attempted curative resection. The primary outcome was an R0 resection rate among patients who completed preoperative treatment and pancreatectomy. The threshold of the R0 resection rate was defined as 74% based on a previous study of up-front surgery.

RESULTS

Forty-five patients were included. Twenty-one patients could not undergo pancreatectomy because of progressive diseases (n = 14), adverse events (n = 5), or consent withdrawal (n = 2), and 4 patients underwent additional resection after dropping out. The resection rates were 53.3% and 62.2% in the per-protocol set (PPS) and full analysis set (FAS) populations, respectively. The R0 resection rates were 95.8% (95% confidence interval, 78.9%-99.9%) and 96.4% (81.7%-99.9%) in the PPS and FAS populations, respectively. The median overall survival and progression-free survival of all the included patients were 17.3 and 10.5 months, respectively. The median survival time of the patients with pancreatectomy was significantly longer than that of the patients without pancreatectomy in the PPS (27.9 vs 12.3 months; P = .001) and FAS populations (32.2 vs 11.8 months; P < .001).

CONCLUSIONS

This study revealed that a long duration of preoperative treatment of sequential chemoradiation followed by systemic chemotherapy provides a high rate of R0 resection and sufficient survival time in patients undergoing pancreatectomy.

Comparison of the dose escalation potential for two hypofractionated radiotherapy regimens for locally advanced pancreatic cancer

OBJECTIVES

To determine the potential for dose escalation to a biological equivalent dose BED10 ≅ 100 Gy in hypofractionated radiotherapy for locally advanced pancreatic cancer (LAPC).

MATERIALS AND METHODS

Ten unselected LAPC patients were retrospectively included in the study. Two fractionation regimens were compared (5 and 15 fractions). The aim was to cover 95% of the Planning Target Volume (PTV) with a BED10 = 54 Gy (base dose = 33 Gy in 5 fractions, 42.5 Gy in 15 fractions) whilst respecting organs-at-risk (OAR) constraints. Once the highest PTV coverage was achieved dose escalation to a BED10 ≅ 100 Gy (escalated dose = 50 Gy in 5 fractions, 67.5 Gy in 15 fractions) was attempted, limiting the PTV maximum dose to 130% of the escalated dose.

RESULTS

In 5 fractions, 95% PTV coverage by both base and escalated doses could be achieved for one patient with PTV more than 1 cm away from OAR. 95% and 90% PTV coverage by the base dose was achieved in one and two patients respectively. In all other patients, coverage even by the base dose had to be compromised to comply with OAR constraints. In 15 fractions, 95% PTV coverage by the base dose was feasible for all patients except one. Dose escalation allowed improvement in target coverage by the base dose in both fractionation regimen whilst covering a sub-volume of the PTV with a BED10 ≅ 100 Gy. Both fractionation schemes were equivalent in terms of dose escalation potential.

CONCLUSION

LAPC patients with OAR close to the PTV are generally not eligible for hypofractionation with dose escalation. However, this planning study shows that it is possible to cover PTV sub-volumes with a BED10 ≅ 100 Gy in addition to delivering a BED10 = 54 Gy to 90-95% of the PTV as commonly prescribed to this population. Combined with an adaptive approach, this may maximize PTV coverage by a high BED on days with favourable anatomy.

Dose escalation for locally advanced pancreatic cancer: How high can we go?

Purpose

There are limited treatment options for locally advanced, unresectable pancreatic cancer (LAPC) and no likelihood of cure without surgery. Radiation offers an option for local control, but radiation dose has previously been limited by nearby bowel toxicity. Advances in on-board imaging and treatment planning may allow for dose escalation not previously feasible and improve local control. In preparation for development of clinical trials of dose escalation in LAPC, we undertook a dosimetric study to determine the maximum possible dose escalation while maintaining known normal tissue constraints.

Methods and Materials

Twenty patients treated at our institution with either SBRT or dose-escalated hypofractionated IMRT (DE-IMRT) were re-planned using dose escalated SBRT to 70 Gy in 5 fractions to the GTV and 40 Gy in 5 fractions to the PTV. Standard accepted organ at risk (OAR) constraints were used for planning. Descriptive statistics were generated for homogeneity, conformality, OAR's and GTV/PTV.

Results

Mean iGTV coverage by 50 Gy was 91% (±0.07%), by 60 Gy was 61.3% (±0.08%) and by 70 Gy was 24.4% (±0.05%). Maximum PTV coverage by 70 Gy was 33%. Maximum PTV coverage by 60 Gy was 77.5%. The following organ at risk (OAR) constraints were achieved for 90% of generated plans: Duodenum V20 < 30 cc, V30 < 3 cc, V35 < 1 cc; Small Bowel V20 < 15 cc, V30 < 1 cc, V35 < 0.1 cc; Stomach V20 < 20 cc, V30 < 2 cc, V35 < 1 cc. V40 < 0.5 cc was achieved for all OAR.

Conclusions

Dose escalation to 60 Gy is dosimetrically feasible with adequate GTV coverage. The identified constraints for OAR's will be used in ongoing clinical trials.

Phase I Trial Evaluating the Safety of Preoperative Gemcitabine/nab-Paclitaxel With Concurrent Radiation Therapy for Borderline Resectable Pancreatic Cancer

OBJECTIVES

The objectives of this study were to assess the feasibility of preoperative gemcitabine/nab-paclitaxel-based chemoradiation therapy (CRT) for patients with borderline resectable pancreatic cancer (BRPC), which consists of induction chemotherapy and subsequent CRT, and to determine the recommended dose (RD) of gemcitabine/nab-paclitaxel with concurrent radiation therapy in a phase I trial.

METHODS

Patients with BRPC received gemcitabine (1000 mg/m(2))/nab-paclitaxel (125 mg/m(2)) on days 1, 8, and 15 during each 4-week cycle, which was repeated for 2 cycles as induction chemotherapy. After induction chemotherapy, the patients received gemcitabine/nab-paclitaxel with concurrent radiation therapy. During CRT, the patients were scheduled to receive gemcitabine/nab-paclitaxel at 7 dose levels using a standard 3 + 3 dose escalation scheme. Radiation therapy was concurrently delivered at a total dose of 60 Gy.

RESULTS

Thirty-eight patients initiated induction gemcitabine/nab-paclitaxel. Among these patients, 30 received subsequent gemcitabine/nab-paclitaxel-based CRT. The RD was determined to be level 5 (gemcitabine, 800 mg/m(2); nab-paclitaxel, 100 mg/m(2)). The dose-limiting toxicities included hematologic toxicity, infection, febrile neutropenia, and peripheral neuropathy. Twenty-four of 30 patients underwent pancreatectomy, and the R0 resection rate was 96%.

CONCLUSIONS

The RD of gemcitabine/nab-paclitaxel-based CRT after induction gemcitabine/nab-paclitaxel for patients with BRPC was 800 and 100 mg/m(2), respectively.

Altering the response to radiation: radiosensitizers and targeted therapies in pancreatic ductal adenocarcinoma: preclinical and emerging clinical evidence

Radiation therapy continues to have an evolving role in pancreatic ductal adenocarcinoma. While metastatic failure likely contributes to the majority of patient mortality, achieving local control through surgery and/or radiation appears to be important as certain studies suggest that mortality is contributed by local failure. Many studies support that pancreatic cancer is a relatively radiation resistant tumor type. In addition, the ability to further improve radiation through dose escalation strategies in the non-metastatic setting is hampered by closeness of normal organs, including small bowel and stomach, to the tumor. Thus subverting molecular pathways that promote radiation resistance will be critical to further success of radiation in this disease. There is a wealth of preclinical data supporting the targeting of various molecular pathways in combination with radiation therapy, including DNA repair, cell cycle checkpoint proteins, receptor tyrosine kinases, oncoproteins, stem cells, and immunomodulation. A number of clinical trials have been completed or are on-going with novel molecular inhibitors. In this review, we summarize existing preclinical and clinical molecular strategies for improving the efficacy of radiation in pancreatic cancer, and highlight recent and ongoing clinical trials combining radiation and various targeted therapies.

Improving prediction of surgical resectability over current staging guidelines in patients with pancreatic cancer who receive stereotactic body radiation therapy

Purpose

For patients with localized pancreatic cancer (PC) with vascular involvement, prediction of resectability is critical to define optimal treatment. However, the current definitions of borderline resectable (BR) and locally advanced (LA) disease leave considerable heterogeneity in outcomes within these classifications. Moreover, factors beyond vascular involvement likely affect the ability to undergo resection. Herein, we share our experience developing a model that incorporates detailed radiologic, patient, and treatment factors to predict surgical resectability in patients with BR and LA PC who undergo stereotactic body radiation therapy (SBRT).

Methods and materials

Patients with BR or LA PC who were treated with SBRT between 2010 and 2016 were included. The primary endpoint was margin negative resection, and predictors included age, sex, race, treatment year, performance status, initial staging, tumor volume and location, baseline and pre-SBRT carbohydrate antigen 19-9 levels, chemotherapy regimen and duration, and radiation dose. In addition, we characterized the relationship between tumors and key arteries (superior mesenteric, celiac, and common hepatic arteries), using overlap volume histograms derived from computed tomography data. A classification and regression tree was built, and leave-one-out cross-validation was performed. Prediction of surgical resection was compared between our model and staging in accordance with the National Comprehensive Care Network guidelines using McNemar's test.

Results

A total of 191 patients were identified (128 patients with LA and 63 with BR), of which 87 patients (46%) underwent margin negative resection. The median total dose was 33 Gy. Predictors included the chemotherapy regimen, amount of arterial involvement, and age. Importantly, radiation dose that covers 95% of gross tumor volume (GTV D95), was a key predictor of resectability in certain subpopulations, and the model showed improved accuracy in the prediction of margin negative resection compared with National Comprehensive Care Network guideline staging (75% vs 63%; P < .05).

Conclusions

We demonstrate the ability to improve prediction of surgical resectabiliy beyond the current staging guidelines, which highlights the value of assessing vascular involvement in a continuous manner. In addition, we show an association between radiation dose and resectability, which suggests the potential importance of radiation to allow for resection in certain populations. External data are needed for validation and to increase the robustness of the model.

Meta-analysis comparing upfront surgery with neoadjuvant treatment in patients with resectable or borderline resectable pancreatic cancer

Background

Studies comparing upfront surgery with neoadjuvant treatment in pancreatic cancer may report only patients who underwent resection and so survival will be skewed. The aim of this study was to report survival by intention to treat in a comparison of upfront surgery versus neoadjuvant treatment in resectable or borderline resectable pancreatic cancer.

Methods

MEDLINE, Embase and the Cochrane Library were searched for studies reporting median overall survival by intention to treat in patients with resectable or borderline resectable pancreatic cancer treated with or without neoadjuvant treatment. Secondary outcomes included overall and R0 resection rate, pathological lymph node rate, reasons for unresectability and toxicity of neoadjuvant treatment.

Results

In total, 38 studies were included with 3484 patients, of whom 1738 (49·9 per cent) had neoadjuvant treatment. The weighted median overall survival by intention to treat was 18·8 months for neoadjuvant treatment and 14·8 months for upfront surgery; the difference was larger among patients whose tumours were resected (26·1 versus 15·0 months respectively). The overall resection rate was lower with neoadjuvant treatment than with upfront surgery (66·0 versus 81·3 per cent; P < 0·001), but the R0 rate was higher (86·8 (95 per cent c.i. 84·6 to 88·7) versus 66·9 (64·2 to 69·6) per cent; P < 0·001). Reported by intention to treat, the R0 rates were 58·0 and 54·9 per cent respectively (P = 0·088). The pathological lymph node rate was 43·8 per cent after neoadjuvant therapy and 64·8 per cent in the upfront surgery group (P < 0·001). Toxicity of at least grade III was reported in up to 64 per cent of the patients.

Conclusion

Neoadjuvant treatment appears to improve overall survival by intention to treat, despite lower overall resection rates for resectable or borderline resectable pancreatic cancer.

PROSPERO registration number: CRD42016049374.

Improved survival with neoadjuvant treatment

Management of Borderline Resectable Pancreatic Cancer

With the rapid development of imaging modalities and surgical techniques, the clinical entity representing tumors that are intermediate between resectable and unresectable pancreatic adenocarcinoma has been identified has been termed "borderline resectable" (BR). These tumors are generally amenable for resection but portend an increased risk for positive margins after surgery and commonly necessitate vascular resection and reconstruction. Although there is a lack of consensus regarding the appropriate definition of what constitutes a BR pancreatic tumor, it has been demonstrated that this intermediate category carries a particular prognosis that is in between resectable and unresectable disease. In order to downstage the tumor and increase the probability of clear surgical margins, neoadjuvant therapy is being increasingly utilized and studied. There is a lack of high-level evidence to establish the optimal treatment regimen for BR tumors. When resection with negative margins is achieved after neoadjuvant therapy, the prognosis for BR tumors approaches and even exceeds that for resectable disease. This review presents the current definitions, different treatment approaches, and the clinical outcomes of BR pancreatic cancer.

Impact of sarcopenia in borderline resectable and locally advanced pancreatic cancer patients receiving stereotactic body radiation therapy

Background

Total psoas area (TPA), a marker of sarcopenia, has been used as an independent predictor of clinical outcomes in gastrointestinal (GI) cancers as a proxy for frailty and nutritional status. Our study aimed to evaluate whether TPA, in contrast to traditional measurements of nutrition like body mass index (BMI) and body surface area (BSA), was predictive of outcomes in borderline resectable pancreatic cancer (BRPC) and locally advanced pancreatic cancer (LAPC) patients receiving stereotactic body radiation therapy (SBRT).

Methods

Retrospective analysis of an institutional review board approved database of 222 BRPC and LAPC treated with SBRT from 2009-2016 yielded 183 patients that met our selection criteria of pre-SBRT computed tomography (CT) imaging with an identifiable L4 vertebra. Once the L4 vertebral level was identified, the bilateral psoas muscles were manually contoured. This area was normalized by patient height, with units described in mm²/m². Receiver operating characteristic (ROC) curves were generated for TPA, BMI, and BSA to elicit clinically relevant cutoffs. Regression and Kaplan-Meier analyses were used to correlate toxicity with survival functions.

Results

Low TPA (OR =1.903, P=0.036) was predictive of acute toxicities, and only TPA was predictive of Grade 3 or higher acute toxicities (OR =10.24, P=0.007). Both findings were independent of tumor resectability. Pain (P=0.003), fatigue (P=0.040), and nausea (P=0.039) were significantly associated with low TPA. No association was identified between any measurement of nutritional status and the development of late toxicities, overall survival, local progression or local recurrence. However, BRPC patients survived longer (median =21.98 months) than their LAPC (median =16.2 months) counterparts (P=0.002), independent of nutritional status.

Conclusions

TPA measurement is readily available and more specific than BMI or BSA as a predictor of acute radiotoxic complications following SBRT in BRPC/LAPC patients. A TPA of <500 mm²/m² is a clinically relevant cutoff that can direct physicians to address expected complications of pain, fatigue, and nausea. However, tumor resectability remains as the only predictor of overall survival in this cohort.

Chemotherapy with or Without Definitive Radiation Therapy in Inoperable Pancreatic Cancer

BACKGROUND

The LAP07 randomized trial calls into question the role of radiation therapy (RT) in the modern treatment of locally advanced pancreatic cancer (LAPC). However, advances in chemotherapy and RT limit application of the LAP07 results to current clinical practice. Here we utilize the National Cancer Database (NCDB) to evaluate the effects of RT in patients receiving chemotherapy for LAPC.

METHODS

Using the NCDB, patients with American Joint Committee on Cancer (AJCC) clinical stage T2-4, N0-1, M0 adenocarcinoma of the pancreas from 2004 to 2014 were analyzed. Patients were stratified into chemotherapy only (CT) and chemoradiation (CRT) cohorts. Patients undergoing definitive RT, defined as at least 20 fractions or ≥ 5 Gy per fraction [i.e., stereotactic body radiation therapy (SBRT)] were included in the CRT cohort. Propensity-score matching (PSM) and landmark analysis were used to address selection bias and lead-time bias, respectively.

RESULTS

13,004 patients met inclusion criteria, of whom 7034 (54%) received CT and 5970 (46%) received CRT. After PSM, 5215 patients remained in each cohort. The CRT cohort demonstrated better overall survival (OS) compared with CT alone, with median and 1-year OS of 12 versus 10 months, and 50% and 41%, respectively (p < 0.001). On multivariable analysis, CRT was associated with superior OS with hazard ratio of 0.79 (95% confidence interval 0.76-0.83) compared with CT alone.

CONCLUSIONS

In our series, addition of definitive radiotherapy to CT was associated with better OS when compared with CT alone in LAPC. Definitive radiotherapy should remain a treatment option for LAPC, but optimal selection criteria remain unclear.

Effective radiotherapeutic treatment intensification in patients with pancreatic cancer: higher doses alone, higher RBE or both?

Pancreatic cancer, especially in case of locally advanced stage has a poor prognosis. Radiotherapy in general can lead to tumor volume reduction, but further improvements, such as ion beam therapy have to be promoted in order to enable dose escalation, which in turn results in better local control rates and downsizing of the tumor itself. Ion beam therapy with its highly promising physical properties is also accompanied by distinct inter- and intrafractional challenges in case of robustness. First clinical results are promising, but further research in motion mitigation and biological treatment planning is necessary, in order to determine the best clinical rationales and conditions of ion beam therapy of pancreatic cancer. This review summarizes the current knowledge and studies on ion beam therapy of pancreatic cancer.

The Role of Radiation Therapy for Pancreatic Cancer in the Adjuvant and Neoadjuvant Settings

Pancreatic cancer is the third leading cause of cancer-related death in the United States. Although surgery remains the only curative treatment, chemotherapy and radiation therapy are frequently used. In the adjuvant setting, radiation is usually delivered with chemotherapy to eradicate residual microscopic or macroscopic disease in the resection bed. Neoadjuvant radiation therapy has become more frequently utilized. This article reviews the historical and modern literature regarding radiation therapy in the neoadjuvant and adjuvant settings, focusing on the evolution of radiation therapy techniques and clinical trials in an attempt to identify patients best suited to receiving radiation therapy.

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

BACKGROUND

As systemic therapy has improved for locally advanced pancreatic cancer (LAPC), efforts to improve local control with optimal radiotherapy may be critical. Although conventionally fractionated radiation therapy (CFRT) has more recently shown a limited role in LAPC, stereotactic body radiation therapy (SBRT) is an emerging approach with promising results. With no studies to date comparing SBRT with CFRT for LAPC, this study used the National Cancer Data Base (NCDB) to evaluate these 2 modalities.

METHODS

With the NCDB, patients with American Joint Committee on Cancer cT2-4/N0-1/M0 adenocarcinoma of the pancreas diagnosed from 2004 to 2013 were analyzed. Radiation therapy delivered at ≤2 Gy was deemed CFRT, and radiation therapy delivered at ≥4 Gy per fraction was considered SBRT. Kaplan-Meier analysis, log-rank testing, and multivariate Cox proportional hazards regression were performed with overall survival (OS) as the primary outcome. Propensity score matching was used.

RESULTS

Among 8450 patients, 7819 (92.5%) were treated with CFRT, and 631 (7.5%) underwent SBRT. Receipt of SBRT was associated with superior OS in the multivariate analysis (hazard ratio, 0.84; 95% confidence interval, 0.75-0.93; P < .001). With propensity score matching, 988 patients in all were matched, with 494 patients in each cohort. Within the propensity-matched cohorts, the median OS (13.9 vs 11.6 months) and the 2-year OS rate (21.7% vs 16.5%) were significantly higher with SBRT versus CFRT (P = .0014).

CONCLUSIONS

In this retrospective review using a large national database, SBRT was associated with superior OS in comparison with CFRT for LAPC, and these findings remained significant in a propensity-matched analysis. Further prospective studies investigating these hypothesis-generating results are warranted. Cancer 2017;123:3486-93. © 2017 American Cancer Society.

Integration of Stereotactic Body Radiation Therapy into the Multidisciplinary Management of Pancreatic Cancer

Although most patients with pancreatic cancer die of metastatic disease, an autopsy study showed that up to one-third of patients die of predominantly local disease. This patient population stands to benefit the most from radiation, surgery, or both. Unfortunately, however, single-agent chemotherapy has had minimal benefit in pancreatic cancer, and most patients progress distantly before receiving radiation therapy (RT). With the addition of multiagent chemotherapy, patients are living longer, and RT has emerged as an important modality in preventing local progression. Standard chemoradiation delivered over 5-6 weeks has been shown to improve local control, but this approach delays full-dose systemic therapy and increases toxicity when compared to chemotherapy alone. Stereotactic body RT (SBRT) delivered in 3-5 fractions can be used to accurately target the pancreatic tumor with small margins and limited acute treatment-related toxicity. Given the favorable toxicity profile, SBRT can easily be integrated with other therapies in all stages of pancreatic cancer. However, future studies are necessary to determine optimal dose or fractionation regimens and sequencing with targeted therapies and immunotherapy. The purpose of this review is to discuss our current understanding of SBRT in the multidisciplinary management of patients with pancreatic cancer and future implications.