Stereotactic Body Radiation Therapy for Pancreatic Cancer

Impact of motion management strategies on abdominal organ at risk delineation for magnetic resonance-guided radiotherapy

Background and purpose

The impact of respiratory motion management strategies for abdominal radiotherapy, such as abdominal compression (AC) and breath hold (BH), on abdominal organ at risk (OAR) delineation on magnetic resonance imaging (MRI) is unknown. This feasibility study compared the inter- and intra- observer delineation variation on MRI acquired with AC, BH for three critical abdominal OAR.

Materials and methods

T2-weighted (W) 3D MRI in free-breathing (FB) and with AC, and T1W 3D mDixon exhale BH were acquired. Four observers blinded to motion management strategy used, delineated stomach, liver, and duodenum on all MRI. One case per strategy was repeated over 6 weeks later to quantify intra-observer variation. Simultaneous truth and performance level estimation (STAPLE) contours for each OAR were generated, median and IQR mean distance to agreement (mDTA) and maximum Hausdorff distance (HD) between observer and STAPLE contours were calculated. Observers scored organ visibility on each MRI using a four-point Likert scale.

Results

A total of 27 scans including repeats were delineated. Pooled mDTA for all OARs was 1.3 mm (0.5 mm) with AC, 1.4 mm (1.0 mm) with BH, and 1.3 mm (0.5 mm) in FB. Intra-observer mDTA was highest for all organs in FB with 10.8 mm for duodenum, 1.8 mm for liver, and 2.7 mm for stomach. The pooled mean perceptual quality score value was highest for AC across organs.

Conclusions

No motion management strategy demonstrated superior similarity across OAR, emphasizing the need for personalised approaches based on individual clinical and patient factors.

Stereotactic Body Radiotherapy for Locally Advanced Pancreatic Cancer Using Optical Surface Management System - AlignRT as an Optical Body Surface Motion Management in Deep Breath Hold Patients: Results from a Single-Arm Retrospective Study

Purpose

To assess the efficacy and safety of stereotactic body radiotherapy for patients with unresectable, locally advanced pancreatic cancer using Optical Surface Management System - AlignRT (OSMS-AlignRT) as an optical body surface motion management in deep breath hold.

Patients and Methods

Forty-five patients diagnosed with locally advanced pancreatic cancer were treated with stereotactic body radiotherapy in 3 or 5 fractions, and received varying BED₁₀ (median 79.5 Gy) from April 2017 to December 2020. All patients were treated in deep breath hold with OSMS-AlignRT used as optical body surface motion management. Thirty-three patients received systemic treatment before and/or after stereotactic body radiotherapy, and twelve patients received no systemic treatment. In this retrospective, observational, single-arm study, primary endpoints were overall survival and freedom from local progression (ie, local control). Secondary endpoints were progression-free survival and toxicity. Actuarial survival analysis and univariate analysis were investigated.

Results

Data from forty-five patients were analyzed. Median follow-up was 15 months. One-year freedom from local progression and survival were 95.5% and 71.1%, respectively. Median progression-free survival was 14 months. Median overall survival from diagnosis for all patients was 17 months, and 19 months for patients alive at the time of analysis. No patient had >G2 toxicity.

Conclusion

Stereotactic body radiotherapy for locally advanced pancreatic cancer using OSMS-AlignRT as optical body surface motion management in deep breath hold patients is an effective and safe local treatment option, with no >G2 toxicity, and could be a promising therapeutic option with acceptable toxicity, either as a single treatment or in a multimodal regimen. OSMS-AlignRT provided accurate and reliable body surface motion management during stereotactic body radiotherapy.

An Evaluation of Total Internal Motions of Locally Advanced Pancreatic Cancer during SABR Using Calypso® Extracranial Tracking, and Its Possible Clinical Impact on Motion Management

(1) Background: the aims of this study were to determine the total extent of pancreatic cancer’s internal motions, using Calypso^® extracranial tracking, and to indicate possible clinical advantages of continuous intrafractional fiducial-based tumor motion tracking during SABR. (2) Methods: thirty-four patients were treated with SABR for LAPC using Calypso^® for motion management. Planning MSCTs in FB and DBH, and 4D-CTs were performed. Using data from Calypso^® and 4D-CTs, the movements of the lesions in the CC, AP and LR directions, as well as the volumes of the 4D-CT-based ITV and the volumes of the Calypso^®-based ITV were compared. (3) Results: significantly larger medians of tumor excursions were found with Calypso^® than with 4D-CT: CC: 29 mm (p < 0.001); AP: 14 mm (p < 0.001) and LR: 11 mm (p < 0.039). The median volume of the Calypso^®-based ITV was significantly larger than that of the 4D-CT based ITV (p < 0.001). (4) Conclusion: beside known respiratory-induced internal motions, pancreatic cancer seems to have significant additional motions which should be considered during respiratory motion management. Only direct and continuous intrafractional fiducial-based motion tracking seems to provide complete coverage of the target lesion with the prescribed isodose, which could allow for safe tumor dose escalation.

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.

Induction of ADAM10 by Radiation Therapy Drives Fibrosis, Resistance, and Epithelial-to-Mesenchyal Transition in Pancreatic Cancer

Stromal fibrosis activates prosurvival and proepithelial-to-mesenchymal transition (EMT) pathways in pancreatic ductal adenocarcinoma (PDAC). In patient tumors treated with neoadjuvant stereotactic body radiation therapy (SBRT), we found upregulation of fibrosis, extracellular matrix (ECM), and EMT gene signatures, which can drive therapeutic resistance and tumor invasion. Molecular, functional, and translational analysis identified two cell-surface proteins, a disintegrin and metalloprotease 10 (ADAM10) and ephrinB2, as drivers of fibrosis and tumor progression after radiation therapy (RT). RT resulted in increased ADAM10 expression in tumor cells, leading to cleavage of ephrinB2, which was also detected in plasma. Pharmacologic or genetic targeting of ADAM10 decreased RT-induced fibrosis and tissue tension, tumor cell migration, and invasion, sensitizing orthotopic tumors to radiation killing and prolonging mouse survival. Inhibition of ADAM10 and genetic ablation of ephrinB2 in fibroblasts reduced the metastatic potential of tumor cells after RT. Stimulation of tumor cells with ephrinB2 FC protein reversed the reduction in tumor cell invasion with ADAM10 ablation. These findings represent a model of PDAC adaptation that explains resistance and metastasis after RT and identifies a targetable pathway to enhance RT efficacy. SIGNIFICANCE: Targeting a previously unidentified adaptive resistance mechanism to radiation therapy in PDAC tumors in combination with radiation therapy could increase survival of the 40% of PDAC patients with locally advanced disease.See related commentary by Garcia Garcia et al., p. 3158 GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/12/3255/F1.large.jpg.

Stereotactic ablative radiation therapy as a potential curative treatment in duodenal adenocarcinoma: a case report

PURPOSE

One of the rarest gastrointestinal neoplasm is small bowel cancer. Experience with its treatment modalities is limited. Stereotactic ablative radiation therapy (SABR) has improved, with image-guided radiation therapy becoming a curative option in many tumors. Especially when surgery cannot be performed due to comorbidities, SABR provides a good toxicity profile and an excellent tumor control rate owing to its specific schedule: high dose on a limited and well-defined area.

METHODS

An 83-year-old man had arterial hypertension and congestive cardiomyopathy, with recent history of upper abdominal pain, weight loss over 10 kg, and progressive severe fatigue. The patient underwent endoscopy that showed a large mass partially obstructing the second part of the duodenum; a biopsy revealed a moderately differentiated adenocarcinoma. A staging CT scan confirmed localized disease. Due to the patient's age and comorbidities, a SABR was proposed as the preferred treatment. In order to localize the tumor during radiotherapy sessions, surgical clips were placed endoscopically next to the lesion as fiducial markers. The patient received 25 Gy in 5 fractions on alternate days.

RESULTS

Resolution of duodenal obstruction and bleeding lasted for 14 months. The patient died of myocardial infarction.

CONCLUSIONS

This case suggests that SABR could have a role in the palliative treatment of small bowel cancers, with good toxicity profile, particularly in patients for whom surgical treatment is not a viable option.

Activation of PPARα by clofibrate sensitizes pancreatic cancer cells to radiation through the Wnt/β-catenin pathway

Radiotherapy is emerging as an important modality for the local control of pancreatic cancer, but pancreatic cancer cell radioresistance remains a serious concern. Peroxisome proliferator-activated receptor α (PPARα) is a member of the PPAR nuclear hormone receptor superfamily, which can be activated by fibrate ligands. The clinical relevance of PPARα and its biological function in pancreatic cancer radiosensitivity have not been previously described. In this study, we examined PPARα expression in tissue samples of pancreatic cancer patients. We found significantly higher expression of PPARα in pancreatic cancer tissues than in tumor-adjacent tissues and that the PPARα expression level is inversely associated with higher overall patient survival rate. We further observed that PPARα activation by its agonist clofibrate sensitizes pancreatic cancer cells to radiation by modulating cell cycle progression and apoptosis in several pancreatic cancer cell lines. Small interfering RNA-mediated PPARα silencing and PPARα blockade by the antagonist GW6471 abolish the effect of clofibrate on radiosensitization. An in vivo study showed that PANC1 xenografts treated with clofibrate are more sensitive to radiation than untreated xenografts. mRNA profiling by microarray analysis revealed that the expression of PTPRZ1 and Wnt8a, two core components of the β-catenin pathway, is downregulated by clofibrate. Chromatin immunoprecipitation analysis confirmed that clofibrate abrogates the binding of nuclear factor-κB to the PTPRZ1 and Wnt8a promoters, ultimately decreasing Wnt/β-catenin signaling activity, which is associated with radiosensitivity. Overall, we demonstrate that PPARα is overexpressed in pancreatic cancer tissues and clofibrate-mediated PPARα activation sensitizes pancreatic cancer cells to radiation through the Wnt/β-catenin pathway.

An evaluation of motion mitigation techniques for pancreatic SBRT

BACKGROUND AND PURPOSE

Ablative radiation therapy can be beneficial for pancreatic cancer, and motion mitigation helps to reduce dose to nearby organs-at-risk. Here, we compared two competing methods of motion mitigation-abdominal compression and respiratory gating.

MATERIALS AND METHODS

CBCT scans of 19 pancreatic cancer patients receiving stereotactic body radiation therapy were acquired with and without abdominal compression, and 3D target motion was reconstructed from CBCT projection images. Daily target motion without mitigation was compared against motion with compression and with simulated respiratory gating. Gating was free-breathing and based on an external surrogate. Target coverage was also evaluated for each scenario by simulating reduced target margins.

RESULTS

Without mitigation, average daily target motion in LR/AP/SI directions was 5.3, 7.3, and 13.9mm, respectively. With abdominal compression, these values were 5.2, 5.3, and 8.5mm, and with respiratory gating they were 3.2, 3.9, and 5.5mm, respectively. Reductions with compression were significant in AP/SI directions, while reductions with gating were significant in all directions. Respiratory gating also demonstrated better coverage in the reduced margins scenario.

CONCLUSION

Respiratory gating is the most effective strategy for reducing motion in pancreatic SBRT, and may allow for dose escalation through a reduction in target margin.

When, What, and Why of Perioperative Treatment of Potentially Curable Pancreatic Adenocarcinoma

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors' suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in Journal of Clinical Oncology, to patients seen in their own clinical practice. A 64-year-old woman with a history of hypertension and type 2 diabetes had been in her usual state of health until she developed symptoms of diarrhea, abdominal bloating, and discomfort in the midepigastrium. Evaluation with a contrast-enhanced abdominopelvic computed tomography (CT) scan demonstrated a mass in the pancreatic body that was approximately 3.1 cm × 2 cm × 2.1 cm in size with abutment of the portal vein-superior mesenteric vein confluence for less than 180°. The confluence was narrowed but without thrombosis. No tumor-vessel interface was noted at the superior mesenteric artery, celiac artery, or common hepatic artery. Several peripancreatic lymph nodes were observed that measured up to 11 mm × 5 mm. No evidence for distant spread of disease was identified. An upper endoscopy with endoscopic ultrasound was performed and fine-needle aspirates of the pancreas mass were positive for malignant cells that were consistent with adenocarcinoma. Chest CT scan without intravenous contrast demonstrated no evidence of metastatic disease. The patient came to the clinic to discuss management of her newly diagnosed malignancy.