Purpose
Stereotactic body radiation therapy (SBRT) has emerged as a potential treatment option for local tumor control of primary malignancies of the pancreas. We report on our experience with SBRT in patients with pancreatic adenocarcinoma whom were found not to be candidates for surgical resection.
Methods
The prospective database of the first 20 consecutive patients receiving SBRT for unresectable pancreatic adenocarcinomas and a neuroendocrine tumor under an IRB approved protocol was reviewed. Prior to SBRT, cylindrical solid gold fiducial markers were placed within or around the tumor endoscopically (n=13), surgically (n=4), or percutaneously under CT-guidance (n=3) to allow for tracking of tumor during therapy. Mean radiation dose was 25 Gray (range 22–30Gy) delivered over 1–3 fractions. Chemotherapy was given to 68% of patients in various schedules/timing.
Results
Patients had a mean gross tumor volume of 57.2 cm3 (range 10.1–118 cm3) before SBRT. The mean total gross tumor volume reduction at 3 and 6 months after SBRT were 21 and 38%, respectively (P<0.05). Median follow-up was 14.57 months (range 5–23 months). The overall rate of freedom from local progression at 6 and 12 months were 88 and 65%. The probability of overall survival at 6 and 12 months were 89 and 56%. No patient had a complication related to fiducial markers placement regardless of modality. The rate of radiation induced adverse events was: grade 1–2 (11%) and grade 3 (16%). There were no grade 4/5 adverse events seen.
Conclusion
Our preliminary results showed SBRT as a safe and likely effective local treatment modality for pancreatic primary malignancy with acceptable rate of adverse events.
The present work illustrated an accurate GC/MS measurement for the low isotopomer enrichment assay of formic acid, acetic acid, propionic aicd, butyric acid and pentanoic acid. The pentafluorobenzyl bromide derivatives of these very short chain fatty acids have high sensitivity of isotopoic enrichment due to their low natural isotopomer distribution in negative chemical ionization mass spectrometric mode. Pentafluorobenzyl bromide derivatization reaction was optimized in terms of pH, temperature, reaction time and the amount of pentafluorobenzyl bromide versus to sample. The precision, stability and accuracy of this method for the isotopomer analysis were validated. This method was applied to measure the enrichments of formic acid, acetic acid and propionic acid in the perfusate from rat liver exposed to Krebs-Ringer bicarbonate buffer only, 0-1 mM [3,4-13 C 2 ]-4-hydroxynonanoate and 0-2 mM of [5,6,[7][8][9][10][11][12][13] C 3 ]heptanoate. The enrichments of acetic acid and propionic acid in the perfusate are comparable to the labeling pattern of acetyl-CoA and propionyl-CoA in the rat liver tissues. The enrichment of acetic acid assay is much more sensitive and precise than the enrichment of acetyl-CoA by LC-MS/MS. The reversibility of propionyl-CoA from succinyl-CoA was confirmed by the low labeling of M1 and M2 of propionic acid from [5,6,[7][8][9][10][11][12][13] C 3 ]heptanoate perfusates.
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