Adaptive versus non-adaptive MRI-guided radiation treatments for pancreatic cancer: A dosimetric study.

2018 ◽  
Vol 36 (4_suppl) ◽  
pp. 336-336
Author(s):  
Benjamin Oren Spieler ◽  
Nancy El Bared ◽  
Kyle Padgett ◽  
Karen Moya Brown ◽  
Lorraine Portelance ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Radiation Therapy ◽  
Organs At Risk ◽  
Locally Advanced ◽  
Advanced Pancreatic Cancer ◽  
Target Volume ◽  
Adaptive Techniques ◽  
Dose Adaptation ◽  
Dose Constraint ◽  
Radiation Treatments

336 Background: Combination MRI and radiation therapy systems enable magnetic resonance image guided radiation therapy (MR-IGRT). MR-IGRT allows clear visualization of the target and organs at risk (OARs) allowing for dose adaptation. Using adaptive MR-IGRT with Cobalt-60 for stereotactic body radiation therapy (SBRT) in locally advanced pancreatic cancer (LAPC), we hypothesized that MR-IGRT would improve dose to pancreatic tumor without increasing doses to OARs. Methods: Ten LAPC patients received five fraction SBRT with a total dose of 33-40 Gy. For each fraction, the original plan dose was compared to the dose that would be delivered if the original radiotherapy plan was applied to the anatomy that day (non-adaptive). An adaptive plan was then created for each fraction. The plan was re-optimized based on the anatomy as seen on the daily MRI and re-normalized so the volume of the PTV receiving 100% of the prescription (PTV100) would be 90%. Both the non-adaptive and adaptive doses to the target volume and the OARs were recorded to evaluate the value of adaptation. We used a paired t-test to compare PTV100 between the adaptive and non-adaptive techniques and Chi2 tests to compare the probability of dose constraint failures for OARs. Results: Adaptive MR-IGRT improved target coverage. Mean PTV100 for adaptive and non-adaptive techniques was 89.9% [88.4-90.4] and 78.4% [27.3-96.6] respectively, p = 0.0017. There were no statistically significant differences for violations of dose constraints of OARs using adaptive vs. non-adaptive techniques. Point maxima violations above 35 Gy to duodenum occurred in 6 adaptive fractions (renormalized to 90%) vs. 12 non-adaptive fractions (p = 0.118); to stomach in 8 adaptive fractions vs. 9 non-adaptive fractions (p = 0.790), and to bowel in 9 adaptive fractions vs. 6 non-adaptive fractions (p = 0.401). When adapting, attention must be paid to other OARs in the area: Spinal cord point maxima were violated in 4 adaptive fractions. Conclusions: This study demonstrates that adaptive techniques significantly increase SBRT dose delivered to LAPC without significantly increasing dose constraint violations to OARs. Adaptive MR-IGRT may allow for further SBRT dose escalations.

Stereotactic body radiation therapy for pancreatic cancer: Assessing motion with and without abdominal compression.

2016 ◽  
Vol 34 (4_suppl) ◽  
pp. 234-234 ◽  
Author(s):  
Priscilla K. Stumpf ◽  
Bernard Jones ◽  
Supriya K. Jain ◽  
Arya Amini ◽  
Dale A. Thornton ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Radiation Therapy ◽  
Stereotactic Body Radiation Therapy ◽  
Organs At Risk ◽  
Locally Advanced ◽  
Advanced Pancreatic Cancer ◽  
Free Breathing ◽  
Tumor Motion ◽  
Abdominal Compression ◽  
Stereotactic Body Radiation

234 Background: Stereotactic body radiation therapy (SBRT) is an emerging treatment option for locally advanced pancreatic cancer. This ablative therapy requires highly accurate delivery due to nearby organs at risk. To minimize tumor motion, our institution applies abdominal compression during computed tomography (CT) simulation. The purpose of this study is to evaluate the effect of compression in the context of pancreatic SBRT. Methods: In the last 6 months, 32 patients who completed SBRT to the pancreas at our institution were selected for analysis. In each patient, two 4DCT images were acquired, one with and one without abdominal compression. Abdominal compression was achieved with an indexed compression belt with a customized degree of inflation. Each patient had fiducial markers implanted in or near the pancreatic tumor prior to simulation. These fiducials were contoured on both planning CT scans for each gated phase. Motion was assessed by fiducial position changes throughout each gated phase. Results: In the anterior to posterior, transverse, and superior to inferior dimension, compression decreased motion in 19 of 32 cases (59%), 21 of 32 cases (66%), and 28 of 32 cases (88%) respectively. In the anterior to posterior (AP) dimension compression decreased motion by a mean of 0.43mm ± 1.7mm with a range of -2.1-6.5mm (p = 0.16). The mean decrease in motion with compression in the transverse dimension was 0.93mm ± 1.9mm with a range of -1.6-8.6mm (p = 0.01). In the superior to inferior dimension, compression decreased motion by a mean of 2.72mm ± 2.8mm with a range of -1.2-11.5mm (p < 0.001). Displacement of tissue due to compression led to increased patient AP separation at the level of T12 by a mean of 9.1±5.8mm (p < 0.001). Conclusions: Abdominal compression significantly reduced tumor motion in the superior to inferior and transverse directions for patients undergoing SBRT to the pancreas. This decrease in motion allows for significant reductions in the size of the volume necessary to treat the tumor. Given our findings, we would recommend using abdominal compression over free-breathing for pancreatic SBRT.

Stereotactic MR-guided on-table adaptive radiation therapy (SMART) for locally advanced pancreatic cancer.

2020 ◽  
Vol 38 (4_suppl) ◽  
pp. TPS786-TPS786
Author(s):  
Parag Parikh ◽  
Daniel Low ◽  
Olga L. Green ◽  
Percy P. Lee
Keyword(s):  
Pancreatic Cancer ◽  
Radiation Therapy ◽  
Adaptive Radiation ◽  
Standard Dose ◽  
Organs At Risk ◽  
Power Level ◽  
Locally Advanced ◽  
Advanced Pancreatic Cancer ◽  
High Dose ◽  
Adaptive Radiation Therapy

TPS786 Background: Standard dose radiation therapy has been unsuccessful in inoperable pancreatic cancer; with a negative study (LAP07) for conventional chemoradiation and dropping of the stereotactic body radiation therapy arm in Alliance A021501. Recently, reports of using high dose ablative radiation therapy has been associated with increased survival in retrospective studies. Moreover, technological advances with MRI-guided radiation therapy offer improved targeting and the ability to change the radiation delivery on a daily fashion; allowing ablative radiation doses over one week. However, it is not clear whether this can be done safely on a multiinstitutional basis. Methods: We are conducting the largest prospective study of ablative radiation therapy in pancreatic cancer. The study is a single arm, multi-institutional phase II, industry sponsored study to investigate the safety and efficacy of Stereotactic, MR guided, on-table-Adaptive Radiation Therapy (SMART). Eligibility criteria include locally advanced and borderline resectable pancreatic cancer patients with ECOG PS of 0 or 1; who have non-metastatic disease after a minimum of 3 months of any systemic therapy; including investigational agents. Patients will receive MR-guided radiation therapy to a dose of 50 Gy / 5 fractions; with maximum tumor coverage delivered each fraction that allows keeping the gastrointestinal organs at risk to a dose of 33 Gy or less. Primary endpoint is grade 3 of higher gastrointestinal toxicity at 90 days. Secondary endpoints are overall survival at 2 years, distant progression free survival at 6 months, and changes in patient related quality of life at 3 and 12 months. Target sample size was calculated to show at a significance level 0.05, a reduction of the toxicity rate to 8% or lower by using SMART compared with 15.8%, the toxicity rate of conventionally delivered chemoradiation at a power level 0.8. Given an expected 15% drop-out, the enrollment goal is 133. Descriptive statistics will be used for secondary objectives. The study opened in January, 2019 and is currently opened at 4 centers; with other US and international sites pending. Sponsored by Viewray, Inc. Clinical trial information: NCT03621644.

The role of radiotherapy in locally advanced pancreatic cancer

2021 ◽  
pp. 20210044
Author(s):  
Florence Huguet ◽  
Victoire Dabout ◽  
Eleonor Rivin del Campo ◽  
Sébastien Gaujoux ◽  
Jean Baptiste Bachet
Keyword(s):  
Pancreatic Cancer ◽  
Radiation Therapy ◽  
Technical Progress ◽  
Vascular Invasion ◽  
Locally Advanced ◽  
Advanced Pancreatic Cancer ◽  
Metastatic Tumour ◽  
Borderline Resectable ◽  
Made In

At diagnosis, about 15% of patients with pancreatic cancer present with a resectable tumour, 50% have a metastatic tumour, and 35% a locally advanced tumour, non-metastatic but unresectable due to vascular invasion, or borderline resectable. Despite the technical progress made in the field of radiation therapy and the improvement of the efficacy of chemotherapy, the prognosis of these patients remains very poor. Recently, the role of radiation therapy in the management of pancreatic cancer has been much debated. This review aims to evaluate the role of radiation therapy for patients with locally advanced tumours.

Sign in / Sign up

Export Citation Format

Share Document