Factors associated with long-term survival in gemcitabine-concurrent proton radiotherapy for non-metastatic locally advanced pancreatic cancer: a single-center retrospective study

Proton Beam Therapy for Pancreatic Tumors: A Consensus Statement from the Particle Therapy Cooperative Group Gastrointestinal Subcommittee

Radiation therapy manages pancreatic cancer in various settings; however, the proximity of gastrointestinal (GI) luminal organs at risk (OARs) poses challenges to conventional radiation therapy. Proton beam therapy (PBT) may reduce toxicities compared to photon therapy. This consensus statement summarizes PBT's safe and optimal delivery for pancreatic tumors. Our group has specific expertise using PBT for GI indications and has developed expert recommendations for treating pancreatic tumors with PBT. Computed tomography (CT) simulation: Patients should be simulated supine (arms above head) with custom upper body immobilization. For stomach/duodenum filling consistency, patients should restrict oral intake within 3 hours before simulation/treatments. Fiducial markers may be implanted for image guidance; however, their design and composition require scrutiny. The reconstruction field-of-view should encompass all immobilization devices at the target level (CT slice thickness 2-3 mm). Four-dimensional CT should quantify respiratory motion and guide motion mitigation. Respiratory gating is recommended when motion affects OAR sparing or reduces target coverage. Treatment planning: Beam-angle selection factors include priority OAR-dose minimization, water-equivalent-thickness stability along the beam path, and enhanced relative biological effect consideration due to the increased linear energy transfer at the proton beam end-of-range. Posterior and right-lateral beam angles that avoid traversing GI luminal structures are preferred (minimizing dosimetric impacts of variable anatomies). Pencil beam scanning techniques should use robust optimization. Single-field optimization is preferable to increase robustness, but if OAR constraints cannot be met, multifield optimization may be used. Treatment delivery: Volumetric image guidance should be used daily. CT scans should be acquired ad hoc as necessary (at minimum every other week) to assess the dosimetric impacts of anatomy changes. Adaptive replanning should be performed as required. Our group has developed recommendations for delivering PBT to safely and effectively manage pancreatic tumors.

Evaluation of the effect of metal stents on dose perturbation in the carbon beam irradiation field

PROPOSE

Carbon ion therapy is indicated for cases in which stents have been inserted, such as bile ducts, but the effect of metal stents on carbon ion therapy is unclear. In this study, the dose perturbation of carbon ion therapy caused by metallic bile duct stents was evaluated by dosimetry.

MATERIALS AND METHODS

Five different types of metal stents (EGIS Double Bear Biliary Stent, EGIS Single Bear Covered Biliary Stent, BileRush Selective, Niti-S Less Shortening D-type Stent, and ZEO Stent V) were placed between solid phantoms and Gafchromic film were placed around the stents and at each depth. The phantom was irradiated with a Carbon ion Beam to form a 5 cm × 5 cm × 5 cm spread-out Brag peak. The dose change due to the stent was evaluated by comparing the film values of similar irradiations without the stent in place.

RESULT

The results showed that the dose perturbation with and without the stent was <10%. A dose reduction area along the shape of the stent appeared at the end of the irradiation field.

CONCLUSION

The effect of metal stents on the carbon dose distribution was assumed to be comparable to that of x-rays and protons.

The Impact of Combined Chemotherapy and Intra-Tumoural Injection of Phosphorus-32 Microparticles on Vascularity in Locally Advanced Pancreatic Carcinoma

BACKGROUND

Poor intra-tumoural vascularity contributes to a lack of response to chemotherapy in pancreatic cancers. Preliminary data suggest that the addition of endoscopic ultrasound (EUS)-guided intra-tumoural injection of phosphorus-32 (32P) microparticles to standard chemotherapy is potentially beneficial in locally advanced pancreatic cancer (LAPC). We aimed to assess changes in pancreatic tumour vascularity following 32P implantation, using contrast-enhanced EUS (CE-EUS).

METHODS

This was a prospective single-centre trial from January 2022 to 2024 of patients with unresectable, non-metastatic LAPC undergoing standard FOLFIRINOX chemotherapy and 32P implantation. We performed CE-EUS pre-implantation after two chemotherapy cycles and 4 and 12 weeks after implantation. Time-intensity curves were analysed for 90 s after IV contrast bolus to ascertain peak intensity and intensity gain.

RESULTS

A total of 20 patients underwent 32P implantation, with 15 completing 12-week follow-up. The technical success of 32P implantation was 100%. The median primary tumour size reduced from 32 mm (IQR 27.5-38.75) pre-implantation to 24 mm (IQR 16-26) 12 weeks post-implantation (p < 0.001). Five patients (25%) had tumour downstaging, and four underwent resections. The baseline (pre-implantation, post-chemotherapy) median intensity gain of contrast enhancement within the tumour was 32.15 (IQR 18.08-54.35). This increased to 46.85 (IQR 35.05-76.6; p = 0.007) and 66.3 (IQR 54.7-76.3; p = 0.001) at 4 weeks and 12 weeks post-implantation, respectively. Over a median follow-up of 11.2 months (IQR 7.8-12.8), 15/20 (75%) of patients remained alive, with 3/20 (15%) demonstrating local disease progression. Overall survival was not significantly different between patients with or without an increased intensity of 10 a.u. or more at 12 weeks post-implantation.

CONCLUSION

This is the first clinical study to demonstrate treatment-induced increased vascularity within pancreatic primary tumours, which followed 32P implantation and FOLFIRINOX chemotherapy. Larger comparative trials are warranted.

Clinical Outcomes of Proton Beam Therapy for Unresectable Locally Advanced Pancreatic Cancer: A Single-Center Retrospective Study

Purpose

We retrospectively researched the treatment outcome of proton beam therapy (PBT) and assessed its efficacy for inoperable locally advanced pancreatic cancer (LAPC) at our institution.

Methods and Materials

Fifty-four patients (28 men and 26 women, median age 67 years ranging from 40-88 years) were diagnosed with unresectable stage III LAPC and administered PBT from April 2009 to March 2020. Patients who could not complete PBT, had new distant metastases during the treatment, or did not have enough follow-up time were excluded from this study. All patients were clinically staged based on the International Union of Cancer TNM staging system (eighth edition) using computed tomography, magnetic resonance imaging, and positron emission tomography and were diagnosed as stage III (histologic type: 18 patients with adenocarcinoma and 36 clinically diagnosed patients). PBT was performed using the passive method, with a median total dose of 67.5 GyE (range, 50-77 GyE/25-35 fractions).Chemotherapy was used in combination during PBT in 46 patients (85.2%). Overall survival (OS), local progression-free survival (LPFS), progression-free survival, and median OS time were analyzed by Kaplan-Meier and log-rank tests. Univariate and multivariate analyses were performed for the following factors: maximum standardized uptake value (SUVmax), Eastern Cooperative Group performance status (PS), tumor site, total irradiation dose, concurrent chemotherapy, and primary tumor site. Cutoff values for SUVmax and tumor diameter were estimated using receiver operating characteristic curves and the area under the curve based on OS. Multivariate analysis was evaluated using the Cox proportional hazards models. Adverse events were evaluated using the National Cancer Institute Common Terminology Criteria for Adverse Events version 5.0.

Results

The median observation period was 17.4 months, ranging from 4.0 to 89.7 months. The median tumor diameter was 36.5 mm, ranging from 15 to 90 mm, the median SUVmax was 5.85 (range, 2.1-27.6), and their cutoff values were estimated to be 37 mm and 4.8 mm, respectively. The 1- and 2-year OS was 77.8% and 35.2%, respectively, with a median OS time of 18.2 months, and only one patient survived >5 years. Twelve patients (22.2%) developed local recurrence, and 1- and 2-year LPFS rates were 89.7% and 74.5%, respectively; progression-free survival at 1 year was 58.8%. The PS score, tumor site, and irradiation dose were the prognostic factors related to OS that showed a significant difference. On the other hand, there was a significant difference in factors involved in LPFS, at 96.7%/77.9% in the first year and 86.6%/54.4% in the second year in the groups with tumor dose ≥67.5 GyE and <67.5 GyE, respectively (P = .015). Treatment-related acute toxicities were neutropenia (grade 1/2/3 at 3.7%/11.1%/31.5%, respectively), leukopenia (grade 1/2/3 at 1.8%/7.4%/20.4%, respectively), and thrombocytopenia (grade 1/2 at 1.8%/7.4%, respectively), whereas the late effects including peptic ulcer were captured only grade 2+. The late adverse events of grade 3 or higher were not observed.

Conclusions

PBT achieving 67.5 Gy combined with standard chemotherapy showed excellent local control for unresectable LAPC. Total irradiation dose, tumor site, and PS score at an initial diagnosis could be important prognostic factors. In this study, the dose-effect relationship was found, so an increase in dose should be considered to improve prognosis.

Comparing different boost concepts and beam configurations for proton therapy of pancreatic cancer

Background and Purpose

Interfractional geometrical and anatomical variations impact the accuracy of proton therapy for pancreatic cancer. This study investigated field-in-field (FIF) and simultaneous integrated boost (SIB) concepts for scanned proton therapy treatment with different beam configurations.

Materials and Methods

Robustly optimized treatment plans for fifteen patients were generated using FIF and SIB techniques with two, three, and four beams. The prescribed dose in 20 fractions was 60 Gy(RBE) for the internal gross tumor volume (IGTV) and 46 Gy(RBE) for the internal clinical target volume. Verification computed tomography (vCT) scans was performed on treatment days 1, 7, and 16. Initial treatment plans were recalculated on the rigidly registered vCTs. V100% and D95% for targets and D2cm3 for the stomach and duodenum were evaluated. Robustness evaluations (range uncertainty of 3.5 %) were performed to evaluate the stomach and duodenum dose-volume parameters.

Results

For all techniques, IGTV V100% and D95% decreased significantly when recalculating the dose on vCTs (p < 0.001). The median IGTV V100% and D95% over all vCTs ranged from 74.2 % to 90.2 % and 58.8 Gy(RBE) to 59.4 Gy(RBE), respectively. The FIF with two and three beams, and SIB with two beams maintained the highest IGTV V100% and D95%. In robustness evaluations, the ΔD2cm3 of stomach was highest in two beams plans, while the ΔD2cm3 of duodenum was highest in four beams plans, for both concepts.

Conclusion

Target coverage decreased when recalculating on CTs at different time for both concepts. The FIF with three beams maintained the highest IGTV coverage while sparing normal organs the most.

Treatment of primary or recurrent non-resectable pancreatic cancer with proton beam irradiation combined with gemcitabine-based chemotherapy

BACKGROUND

Pancreatic cancer accounts for around 4.6% of cancers deaths worldwide per year. Despite many advances in treatment regimes, the prognosis is still poor. Only 20% of tumors are primarily resectable. Recurrences-both with distant metastasis as well as locoregional-are frequent. For patients with primary nonresectable localized disease or localized recurrences, we offered chemoradiation to achieve local control over a long period of time. We here report our results on combined chemoradiation of pancreatic tumors and local recurrences using proton beam therapy.

MATERIALS AND METHODS

We report on 25 patients with localized nonresectable pancreatic cancer (15 patients) or local recurrent disease (10 patients). All patients were treated with combined proton radiochemotherapy. Overall survival, progression-free survival, local control, and treatment-related toxicity were analyzed using statistically methods.

RESULTS

Median RT dose was 54.0 Gy (RBE) for proton irradiation. The toxicity of treatment was acceptable. Four CTCAE grade III and IV adverse events (bone marrow disfunction, gastrointestinal [GI] disorders, stent dislocation, myocardial infarction) were recorded during or directly after the end of radiotherapy; two of them were related to combined chemoradiation (bone marrow disfunction, GI disorders). Six weeks after radiotherapy, one additional grade IV toxicity was reported (ileus, caused by peritoneal carcinomatosis, not treatment related). The median progression-free survival was 5.9 months and median overall survival was 11.0 months. The pretherapy CA19‑9 level was a statistically significant prognostic factor for enhanced overall survival. Local control at 6 months and 12 months were determined to be 86% and 80%, respectively.

CONCLUSION

Combined proton chemoradiation leads to high local control rates. Unfortunately, PFS and OS are driven by distant metastasis and were not improved compared to historical data and reports. With this in mind, enhanced chemotherapeutical regimes, in combination with local irradiation, should be evaluated.

Proton radiotherapy as a treatment strategy to increase survival in locally advanced pancreatic cancer in the body and tail: a retrospective study

BACKGROUND

Long-term outcomes and prognostic factors of proton radiotherapy for locally advanced pancreatic cancer (LAPC) in the body and tail are still unknown. The aim of this study was to determine the prognostic factors after proton radiotherapy in a large group of patients with LAPC in the body and tail.

METHODS

The medical records of 200 patients with LAPC in the body and tail who underwent proton radiotherapy between February 2009 and January 2021 at the Hyogo Ion Beam Medical Center were retrospectively reviewed to identify prognostic factors that contribute to long-term survival.

RESULTS

The overall survival rate at 1- and 2-year after PT was 69.6% and 35.4% with a median overall survival of 18.4 months. The 1- and 2-year local progression-free, and progression-free survival rates were 84.3% and 68.0%, and 44.3% and 19.4%, respectively. In multivariate analysis, superior mesenteric artery (SMA) invasion (SMA only invasion vs. celiac artery only invasion; P = 0.049: SMA and celiac artery invasion vs. celiac artery only invasion; P = 0.017), carbohydrate antigen 19-9 (CA 19-9) level ≥ 231.9 U/mL (P = 0.001), anterior peripancreatic invasion (P = 0.006), and incomplete scheduled concurrent chemotherapy (P = 0.009) were statistically significant prognostic factors for overall survival. There was no significant difference in local progression-free survival; however, distant metastasis-free survival was statistically worse in patients with prognostic factors than in those without.

CONCLUSIONS

Proton radiotherapy for LAPC in the body and tail may be a valuable multidisciplinary treatment option. Patients with SMA invasion, higher pre-proton radiotherapy serum CA 19-9 level, anterior peripancreatic invasion, or incomplete scheduled concurrent chemotherapy had worse overall survival because of worse distant metastasis-free survival, suggesting that distant metastases have a significant impact on overall survival in such patients.

TRIAL REGISTRATION

Retrospectively registered.

Normo- or Hypo-Fractionated Photon or Proton Radiotherapy in the Management of Locally Advanced Unresectable Pancreatic Cancer: A Systematic Review

LAPC is associated with a poor prognosis and requires a multimodal treatment approach. However, the role of radiation therapy in LAPC treatment remains controversial. This systematic review aimed to explore the role of proton and photon therapy, with varying radiation techniques and fractionation, in treatment outcomes and their respective toxicity profiles.

METHODS

Clinical studies published from 2012 to 2022 were systematically reviewed using PubMed, MEDLINE (via PubMed) and Cochrane databases. Different radiotherapy-related data were extracted and analyzed.

RESULTS

A total of 31 studies matched the inclusion criteria. Acute toxicity was less remarkable in stereotactic body radiotherapy (SBRT) compared to conventionally fractionated radiotherapy (CFRT), while in proton beam therapy (PBT) grade 3 or higher acute toxicity was observed more commonly with doses of 67.5 Gy (RBE) or higher. Late toxicity was not reported in most studies; therefore, comparison between groups was not possible. The range of median overall survival (OS) for the CFRT and SBRT groups was 9.3-22.9 months and 8.5-20 months, respectively. For the PBT group, the range of median OS was 18.4-22.3 months.

CONCLUSION

CFRT and SBRT showed comparable survival outcomes with a more favorable acute toxicity profile for SBRT. PBT is a promising new treatment modality; however, additional clinical studies are needed to support its efficacy and safety.

Proton Therapy in the Management of Pancreatic Cancer

Radiation therapy plays a central role in the treatment of pancreatic cancer. While generally shown to be feasible, proton irradiation, particularly when an ablative dose is planned, remains a challenge, especially due to tumor motion and the proximity to organs at risk, like the stomach, duodenum, and bowel. Clinically, standard doses of proton radiation treatment have not been shown to be statistically different from photon radiation treatment in terms of oncologic outcomes and toxicity rates as per non-randomized comparative studies. Fractionation schedules and concurrent chemotherapy combinations are yet to be optimized for proton therapy and are the subject of ongoing trials.