Can quantifying free-circulating DNA be a diagnostic and prognostic marker in oral epithelial dysplasia and oral squamous cell carcinoma?

PURPOSE: Previous studies have reported significantly higher concentrations of serum DNA in various types of cancers. Thus the study aims to determine whether circulating free DNA (CFDNA) can aid in the diagnosis and prognosis of oral epithelial dysplasia and oral squamous cell carcinoma (OSCC). MATERIALS AND METHODS: A nonrandomized case-control study was planned where cases were derived from patients who presented to the KLE Institute of Dental Sciences, Belgaum, India, for evaluation and management of oral lesions between 2007 and 2009. In this study the predictor variable was status of the disease in the patients, and the outcome variable was CFDNA. Demographic variables included age, gender, tobacco consumption, and stage at diagnosis of cancer. Subjects with any known systemic disease, other tumors, or metastatic OSCC were excluded (CFDNA is altered in cases of tissue destruction and inflammatory diseases). The amount of CFDNA was determined through spectrophotometry (NanoDrop ND-1000 spectrophotometer; Thermo Fisher Scientific, Waltham, MA) in sampled blood and plasma. Mean and range for DNA quantification in plasma and blood were calculated in all groups and compared by use of the analysis of variance test. RESULTS: A total of 390 cases (90 potentially malignant lesions, 150 OSCC cases, and 150 post-treatment OSCC cases) and 150 control subjects were studied. No significant difference was observed in levels of CFDNA in blood between the groups. Similarly, levels of CFDNA in plasma showed no significant difference except between the OSCC and potentially malignant groups, which was probably artifactual. CONCLUSIONS: This study shows that disease progression in oral malignancy does not correlate with changes in levels of CFDNA in blood or plasma.

MAGAT gel and EBT2 film-based dosimetry for evaluating source plugging-based treatment plan in Gamma Knife stereotactic radiosurgery.

This work illustrates a procedure to assess the overall accuracy associated with Gamma Knife treatment planning using plugging. The main role of source plugging or blocking is to create dose falloff in the junction between a target and a critical structure. We report the use of MAGAT gel dosimeter for verification of an experimental treatment plan based on plugging. The polymer gel contained in a head-sized glass container simulated all major aspects of the treatment process of Gamma Knife radiosurgery. The 3D dose distribution recorded in the gel dosimeter was read using a 1.5T MRI scanner. Scanning protocol was: CPMG pulse sequence with 8 equidistant echoes, TR = 7 s, echo step = 14 ms, pixel size = 0.5mm × 0.5mm, and slice thickness of 2 mm. Using a calibration relationship between absorbed dose and spin-spin relaxation rate (R2), we converted R2 images to dose images. Volumetric dose comparison between treatment planning system (TPS) and gel measurement was accomplished using an in-house MATLAB-based program. The isodose overlay of the measured and computed dose distribution on axial planes was in close agreement. Gamma index analysis of 3D data showed more than 94% voxel pass rate for different tolerance criteria of 3%/2 mm, 3%/1 mm and 2%/2 mm. Film dosimetry with GAFCHROMIC EBT 2 film was also performed to compare the results with the calculated TPS dose. Gamma index analysis of film measurement for the same tolerance criteria used for gel measurement evaluation showed more than 95% voxel pass rate. Verification of gamma plan calculated dose on account of shield is not part of acceptance testing of Leksell Gamma Knife (LGK). Through this study we accomplished a volumetric comparison of dose distributions measured with a polymer gel dosimeter and Leksell GammaPlan (LGP) calculations for plans using plugging. We propose gel dosimeter as a quality assurance (QA) tool for verification of plug-based planning.

MRI-based polymer gel dosimetry for validating plans with multiple matrices in Gamma Knife stereotactic radiosurgery.

One of treatment planning techniques with Leksell GammaPlan (LGP) for Gamma Knife stereotactic radiosurgery (GKSRS) uses multiple matrices with multiple dose prescriptions. Computational complexity increases when shots are placed in multiple matrices with different grid sizes. Hence, the experimental validation of LGP calculated dose distributions is needed for those cases. For the current study, we used BANG3 polymer gel contained in a head-sized glass bottle to simulate the entire treatment process of GKSRS. A treatment plan with three 18 mm shots and one 8 mm shot in separate matrices was created with LGP. The prescribed maximum dose was 8 Gy to three shots and 16 Gy to one of the 18 mm shots. The 3D dose distribution recorded in the gel dosimeter was read using a Siemens 3T MRI scanner. The scanning parameters of a CPMG pulse sequence with 32 equidistant echoes were as follows: TR = 7 s, echo step = 13.6 ms, field-of-view = 256 mm × 256 mm, and pixel size = 1 mm × 1 mm. Interleaved acquisition mode was used to obtain 15 to 45 2-mm-thick slices. Using a calibration relationship between absorbed dose and the spin-spin relaxation rate (R2), we converted R2 images to dose images. MATLAB-based in-house programs were used for R2 estimation and dose comparison. Gamma-index analysis for the 3D data showed gamma values less than unity for 86% of the voxels. Through this study we accomplished the first application of polymer gel dosimetry for a true comparison between measured 3D dose distributions and LGP calculations for plans using multiple matrices for multiple targets.

Comparison of piezosurgery and conventional rotatory technique in transalveolar extraction of mandibular third molars: A pilot study.

OBJECTIVES: To compare the postoperative outcomes in impacted mandibular third molar extraction using piezosurgery and conventional rotary technique; and to assess the stress levels in both the techniques by measuring salivary cortisol levels. METHODS: Ten patients with symmetrical impacted lower third molars were included in this split mouth pilot study. Measurements for mouth opening and swelling were taken preoperatively on the day of surgery and 1 week after surgery. Pain was evaluated using Visual Analog Scale (VAS) from first postoperative day for six consecutive days. Saliva collection for analysis of cortisol levels was done at four time intervals - before starting the procedure, immediately after the procedure, 20 min and 1 week later. The mean in two groups was compared using paired t-test/Wilcoxon signed rank test as applicable. Friedman test was used to compare multiple readings of pain and salivary cortisol. RESULTS: Reduction in mouth opening was more in rotary group than piezosurgery group but was not statistically significant (p = 0.092). Increase in facial swelling was more in the rotary group than piezosurgery group with statistically significant values (p = 0.020). Rotary group had higher values for postoperative pain as compared to piezosurgery on all the days and the difference was statistically significant on each day except second postoperative day. Salivary cortisol levels were elevated in both the groups with the mean values higher in group I (rotary) than in group II (Piezosurgery). CONCLUSION: Extraction of impacted lower third molar results in more favourable outcome when carried out by piezosurgery technique. Further studies are needed to compare the salivary cortisol response in rotary and piezosurgery techniques.