The Role of Intraoperative Radiation Therapy in Patients With Pancreatic Cancer

Hyperthermic intra-operative intraperitoneal chemotherapy as an adjuvant to pancreatic cancer resection

Background

Even after potentially curative resection the long-term survival of pancreatic cancer is poor. The local-regional failures are frequent. Previous studies have shown that adjuvant treatment with hyperthermic intra-operative intraperitoneal chemotherapy (HIPEC) may effectively control local disease. The objective of the study is to update the results of the prior publications by integrating data from recently accrued cases. Also, to revisit the clinical and pharmacological rationale for the intraperitoneal administration of chemotherapy in pancreatic cancer patients undergoing potentially curative resection.

Methods

This is a prospective study of pancreatic cancer patients that underwent R₀ resection in combination with HIPEC-gemcitabine. Morbidity and mortality were recorded. Survival was calculated and the sites for recurrent disease were recorded.

Results

The updated results for 33 patients that underwent treatment until 2016 and for 6 more patients that were included until 2018 were presented. The hospital mortality and morbidity rate were 5.1% (2 patients), and 28.2% (11 patients) respectively. The median and 5-year survival rate was 17 months and 24% respectively. With a median follow-up time of 13 months 23 patients (59%) were recorded with recurrence. Local regional failures were recorded in 4 patients (10.3%).

Conclusions

HIPEC following R₀ resection is a feasible and safe adjuvant treatment for pancreatic cancer. The local-regional failures appear to be significantly decreased and to result in an increased overall survival. Further studies with combined intraperitoneal and systemic perioperative chemotherapy may serve to supplement our data with an increased benefit for patients having pancreas cancer resection.

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.

Intraoperative Radiation Mitigates the Effect of Microscopically Positive Tumor Margins on Survival Among Pancreatic Adenocarcinoma Patients Treated with Neoadjuvant FOLFIRINOX and Chemoradiation

BACKGROUND

Microscopically positive margins (R1) negatively impact survival in pancreatic ductal adenocarcinoma (PDAC). For patients with close/positive margins, intraoperative radiotherapy (IORT) can improve local control. The prognostic impact of an R1 resection in patients who receive total neoadjuvant therapy (TNT; FOLFIRINOX with chemoradiation) and IORT is unknown.

METHODS

Clinicopathologic data were retrospectively collected for borderline/locally advanced (BR/LA) PDAC patients who received TNT and underwent resection between 2011 and 2019. Disease-free (DFS) and overall survival (OS) measured from time of diagnosis were compared between groups.

RESULTS

Two hundred one patients received TNT and were resected, with a median DFS and OS of 24 months and 47 months, respectively. Eighty-eight patients (44%) received IORT; of these, 69 (78%) underwent an R0 and 19 (22%) an R1 resection. There was no significant difference in clinicopathologic factors between the IORT and no-IORT groups, except for resectability status (LA: IORT 69%, no-IORT 53%, p = 0.021) and surgeons' concern for a positive/close margin. R1 resection was associated with worse DFS and OS in the no-IORT population. However, among patients who received IORT, there was no difference in DFS (R0: 29 months, IQR 14-47 vs R1: 20 months, IQR 15-28; p = 0.114) or OS (R0: 48 months, IQR 25-not reached vs R1: 37 months, IQR 30-47; p = 0.307) between patients who underwent R0 vs R1 resection. In multivariate analysis, within the IORT group, R1 resection was not associated with DFS or OS.

CONCLUSION

IORT may mitigate the adverse effect of an R1 resection on DFS and OS in BR/LA PDAC patients receiving TNT.

First report on the feasibility of a permanently implantable uni-directional planar low dose rate brachytherapy sheet for patients with resectable or borderline resectable pancreatic cancer

BACKGROUND

Margin negative resection in pancreatic cancer remains the only curative option but is challenging, especially with the retroperitoneal margin. Intraoperative radiation therapy (IORT) can improve rates of local control but requires specially designed facilities and equipment. This retrospective review describes initial results of a novel implantable mesh of uni-directional low dose rate (LDR) Pd-103 sources (sheet) used to deliver a focal margin-directed high-dose boost in patients with concern for close or positive margins.

METHODS

Eleven consecutive patients from a single institution with resectable or borderline resectable pancreatic cancer with concern for positive margins were selected for sheet placement and retrospectively reviewed. Procedural outcomes, including the time to implant the device and complications, and clinical outcomes, including survival and patterns of failure, are reported. A dosimetric comparison of the LDR sheet with hypothetical stereotactic body radiotherapy (SBRT) boost is reported.

RESULTS

One patient had a resectable disease, and 10 patients had a borderline resectable disease and underwent neoadjuvant treatment. Sheet placement added 15 min to procedural time with no procedural or sheet-related complications. At a median follow up of 13 months, 64% (n = 7) of patients are alive and 55% (n = 6) are disease-free. Compared to a hypothetical SBRT boost, the LDR sheet delivered a negligible dose to kidneys, liver, and spinal cord with a 50% reduction in max dose to the small bowel.

CONCLUSION

This is the first report of the use of an implantable uni-directional LDR brachytherapy sheet in patients with resected pancreatic cancer with concern for margin clearance, with no associated toxicity and favorable clinical outcomes.

The role of intraoperative radiation therapy in resectable pancreatic cancer: a systematic review and meta-analysis

PURPOSE

Several studies investigating the role of intraoperative radiotherapy (IORT) in the treatment of resectable pancreatic cancer (PC) have been published; however, their results remain inconsistent. By conducting a systematic review and meta-analysis, this study aimed to compare clinical outcomes in patients with resectable PC who underwent surgery with or without IORT.

METHODS AND MATERIALS

The MEDLINE/PubMed, EMBASE, and Cochrane Library databases were searched to identify relevant studies published up to February 28, 2019. The main outcome measures included median survival time (MST), local recurrence (LR), postoperative complications, and operation-related mortality. Pooled effect estimates were obtained by performing a random-effects meta-analysis.

RESULTS

A total of 1095 studies were screened for inclusion, of which 15 studies with 834 patients were included in the meta-analysis. Overall, 401 patients underwent pancreatic resection with IORT and 433 underwent surgery without IORT. The pooled analysis revealed that IORT group experienced favorable overall survival (median survival rate [MSR], 1.20; 95% confidence interval [CI], 1.06-1.37, P = 0.005), compared with patients who did not receive IORT. Additionally, the pooled data showed a significantly reduced LR rate in the IORT group compared with that in the non-IORT group (relative risk [RR], 0.70; 95% CI, 0.51-0.97, P = 0.03). The incidences of postoperative complications (RR, 0.95; 95% CI, 0.73-1.23) and operation-related mortality (RR, 1.07; 95% CI, 0.44-2.63) were similar between the IORT and non-IORT groups.

CONCLUSION

IORT significantly improved locoregional control and overall survival in patients with resectable PC, without increasing postoperative complications and operation-related mortality rates.

The American Brachytherapy Society consensus statement on intraoperative radiation therapy

PURPOSE

Although radiation therapy has traditionally been delivered with external beam or brachytherapy, intraoperative radiation therapy (IORT) represents an alternative that may shorten the course of therapy, reduce toxicities, and improve patient satisfaction while potentially lowering the cost of care. At this time, there are limited evidence-based guidelines to assist clinicians with patient selection for IORT. As such, the American Brachytherapy Society presents a consensus statement on the use of IORT.

METHODS

Physicians and physicists with expertise in intraoperative radiation created a site-directed guideline for appropriate patient selection and utilization of IORT.

RESULTS

Several IORT techniques exist including radionuclide-based high-dose-rate, low-dose-rate, electron, and low-energy electronic. In breast cancer, IORT as monotherapy should only be used on prospective studies. IORT can be considered in the treatment of sarcomas with close/positive margins or recurrent sarcomas. IORT can be considered in conjunction with external beam radiotherapy for retroperitoneal sarcomas. IORT can be considered for colorectal malignancies with concern for positive margins and in the setting of recurrent gynecologic cancers. For thoracic, head and neck, and central nervous system malignancies, utilization of IORT should be evaluated on a case-by-case basis.

CONCLUSIONS

The present guidelines provide clinicians with a summary of current data regarding IORT by treatment site and guidelines for the appropriate patient selection and safe utilization of the technique. High-dose-rate, low-dose-rate brachytherapy methods are appropriate when IORT is to be delivered as are electron and low-energy based on the clinical scenario.

A phase II study of intraoperative radiotherapy using a low-energy x-ray source for resectable pancreatic cancer: a study protocol

BACKGROUND

The current standard treatment for resectable pancreatic cancer is surgical resection followed by adjuvant chemotherapy. Local recurrence rates are high even after curative resection; thus, the long-term outcome of locally advanced pancreatic cancer remains poor. Intraoperative radiotherapy (IORT) uses a low-energy x-ray source to deliver a single fraction of high-dose radiation to the tumor bed during a surgical procedure, while effectively sparing the surrounding normal tissues. IORT has the potential to improve the efficacy of radiation therapy for pancreatic cancer.

METHODS/DESIGN

This prospective, one-armed, phase II study will investigate the role of IORT in improving local control in patients with resectable pancreatic adenocarcinoma. The patients will receive surgery and IORT of 10 Gy prescribed at a 5-mm depth of the tumor bed, followed by adjuvant gemcitabine chemotherapy according to the current standard of care. The aim is to enroll 42 patients.

DISCUSSION

The primary endpoint of this trial is to evaluate the feasibility of IORT and the local recurrence rate after one year. The secondary endpoints include the acute and late toxicities, and disease-free survival and overall survival rates.

TRIAL REGISTRATION

The trial was prospectively registered at Clinicaltrials.gov NCT03273374 on September 6, 2017.

Intraoperative radiotherapy with the Intrabeam® device for the treatment of resectable pancreatic adenocarcinoma

INTRODUCTION

The application of intraoperative radiation therapy to the tumor bed after resection of pancreatic cancer has been shown to be beneficial in the local control of the disease. The objective of this study was to evaluate the preliminary outcomes after the application of a single intraoperative dose to the tumor bed with a new intraoperative radiotherapy device (Intrabeam^®) in terms of viability, safety and short-term results.

METHODS

We studied 5 patients who underwent pancreaticoduodenectomy for resectable pancreatic cancer in which a radiotherapy boost (5Gy) was intraoperatively applied to the tumoral bed using the portable Intrabeam^® device, a low-energy point-source X-ray. Postoperative complications, hospital stay and mortality, recurrences and short-term survival were analyzed.

RESULTS

Mean patient age was 68 years. All patients had a T3-stage tumor and one of them N1. In 3 patients, R0 resection was performed, while R1 resection was conducted in 2. Perioperative mortality was 0%. The only complications included delayed gastric emptying and postoperative hemorrhage. There were no pancreatic fistulas. During follow-up (mean: 11.2 months), there was a relapse in the patient who had undergone R1 resection.

CONCLUSIONS

The application of radiotherapy with the Intrabeam^® device in selected patients has not resulted in increased perioperative morbidity or mortality; therefore, this is a safe procedure for the treatment of resectable cancer.

Adjuvant therapeutic strategies for resectable pancreatic adenocarcinoma

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

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.

Design of a compact collimator and 3D imaging system for a scanning beam low-energy intraoperative radiation therapy system for pancreatic cancer

Intraoperative radiation therapy (IORT) involves delivering high doses of radiation directly to tumors while sparing healthy tissues in a surgical setting. Current IORT systems are limited in their lack of image guidance and variable needs for shielded operating rooms. They also lack the capability to deliver non-uniform therapeutic radiation to irregular shaped clinical targets. We developed a scanning beam IORT system (SBIORT) to overcome these limitations. SBIORT consists of a low energy x-ray source, a custom compact dynamic x-ray collimator system, a robotic arm, and a 3D surface imaging module. Here we describe the design and validation of the compact dynamic x-ray collimator system and the 3D surface imaging module for use in SBIORT. The proposed collimator can achieve a leaf position accuracy of ± 0.25 mm (95% confidence interval). Phantom studies indicated the 3D surface-imaging module has an accuracy of 1.0 ± 0.6 mm with ability to obtain high resolution surface image within 5 seconds. SBIORT is a novel approach to deliver conformal intensity-modulated intraoperative radiation therapy.

Intraoperative radiation therapy (IORT) in pancreatic cancer

Despite the important improvements made in the fields of surgery, chemotherapy and radiation therapy, pancreatic cancer remains one of the most lethal malignancies. Improved outcomes with novel chemotherapy regimes led again to increased attention on the role of localized radiotherapy, since local tumor progression causes significant morbidity and mortality in patients. Even after resection local failure rates are as high as 50-80%. The immediate proximity to critical structures (bone marrow, spinal cord, kidneys, liver, and intestine) limits the dose of radiation that can be administered to the tumor bed with conventional external beam radiation therapy (EBRT). The intraoperative radiotherapy (IORT) appears to be an ideal therapeutic strategy for this disease, having the advantage of enabling the delivery of high doses of radiation to areas that are at risk for microscopic disease, saving critical organs and reducing the possibility of inducing radiotoxicity. This technique allows a theoretical increase in the radiation therapeutic index to tumor compared to the adjacent organs at risk (OAR). The aim of this review is to update and comment on IORT in the multidisciplinary management of pancreatic cancer.