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Gloi A.M.,St. Vincent Hospital | Buchanan R.,Southeast Alabama Medical Center
Journal of Applied Clinical Medical Physics | Year: 2013

The aims of this study were twofold: first, to determine the impact of variance in dose-volume histograms (DVH) on patient-specific toxicity after 2 high-dose fractions in a sample of 22 men with prostate cancer; and second, to compare the effectiveness of traditional DVH analysis and principal component analysis (PCA) in predicting rectum and urethra toxicity. A series of 22 patients diagnosed with prostate adenocarcinoma was treated with 45 Gy external beam and 20 Gy dose rate brachytherapy. Principal component analysis was applied to model the shapes of the rectum and urethra dose-volume histograms. We used logistic regression to measure the correlations between the principal components and the incidence of rectal bleeding and urethra stricture. We also calculated the equivalent uniform dose (EUD) and normal tissue complication probability (NTCP) for the urethra and rectum, and tumor control probability (TCP) for the prostate using BioSuite software. We evaluated their correlations with rectal and urethra toxicity. The rectum DVHs are well described by one principal component (PC1), which accounts for 93.5% of the variance in their shapes. The urethra DVHs are described by two principal components, PC1 and PC2, which account for 94.98% and 3.15% of the variance, respectively. Multivariate exact logistic regression suggests that urethra PC2 is a good predictor of stricture, with Nagelkerke's R2 estimated at 0.798 and a Wald criterion of 5.421 (p < 0.021). The average NTCPs were 0.06% ± 0.04% and 1.25% ± 0.22% for the rectum and urethra, respectively. The average TCP was 85.29% ± 2.28%. This study suggests that principal component analysis can be used to identify the shape variation in dose-volume histograms, and that the principal components can be correlated with the toxicity of a treatment plan based on multivariate analysis. The principal components are also correlated with traditional dosimetric parameters.

Gloi A.M.,St. Vincent Hospital | Buchanan R.,Southeast Alabama Medical Center
Journal of Medical Physics | Year: 2012

The aim of this study was to compare lumpectomy cavity depth measurements obtained through ultrasound (U/S) and retrospective computed tomography (CT). Twenty-five patients with stage T1-2 invasive breast cancer formed the cohort of this study. Their U/S and CT measurements were converted into electron energy and compared. The mean U/S depth was 3.6±1.3 cm, while the mean CT depth was 4.9±1.9 cm; the listed error ranges are one standard deviation. Electron energies for treatment ranged from 6 MeV to 12 MeV based on the U/S determination. There was no significant correlation between cavity depths measured by U/S and CT (R 2 = 0.459, P < 0.002). Furthermore, only 20% of CT-based electron energy determinations matched the corresponding U/S determinations. This ratio increased to 40% when taking into account an upper limit based on the depth of organs at risk below the cavity. The study shows that there is a significant discrepancy between cavity depths determined by U/S and CT. It also supports the concept that post-lumpectomy radiotherapy boosts should be tailored according to the needs and comfort of individual practices and institutions.

Cannon D.M.,University of Wisconsin - Madison | McHaffie D.R.,Levine Cancer Institute | Patel R.R.,Targeted Radiation Institute at VMOC | Adkison J.B.,Southeast Alabama Medical Center | And 5 more authors.
Annals of Surgical Oncology | Year: 2013

Background: Understanding risk factors for locoregional recurrence (LRR) after accelerated partial breast irradiation (APBI) can help to guide patient selection for treatment with APBI. Published findings to date have not been consistent. More data are needed as these risk factors continue to be defined. Methods: A total of 277 women with early-stage invasive breast cancer underwent lumpectomy and were treated adjuvantly at our institution with APBI using high-dose rate brachytherapy. APBI was delivered using multicatheter interstitial brachytherapy (91 %) or single-entry catheter brachytherapy (9 %) to a dose of 32-34 Gy in 8-10 twice daily fractions. Failure patterns and risk factors for recurrence were analyzed. Results: With a median follow-up of 61 months, the 5-year locoregional control rate was 94.4 %. Negative estrogen receptor (ER) status was strongly associated with LRR on multivariate analysis (p < 0.005). Lobular histology, the presence of an extensive intraductal component, and lymphovascular invasion also were significant but to a lesser degree than ER-negative status. Patients with multiple risk factors were at highest risk for LRR. Age was not significantly associated with increased risk for LRR. Conclusions: The presence of specific pathological features, particularly ER negative status, was associated with increased risk of LRR in this cohort of women treated with APBI. Further investigation is warranted to determine whether patients with adverse pathological risk factors are at higher risk of LRR after APBI than after conventional whole breast irradiation (WBI), as these same features also may place women at risk for LRR after WBI. © 2013 Society of Surgical Oncology.

Cannon D.M.,University of Wisconsin - Madison | Mehta M.P.,University of Maryland, Baltimore | Adkison J.B.,Southeast Alabama Medical Center | Khuntia D.,Varian Medical Systems | And 7 more authors.
Journal of Clinical Oncology | Year: 2013

Purpose Local failure rates after radiation therapy (RT) for locally advanced non-small-cell lung cancer (NSCLC) remain high. Consequently, RT dose intensification strategies continue to be explored, including hypofractionation, which allows for RT acceleration that could potentially improve outcomes. The maximum-tolerated dose (MTD) with dose-escalated hypofractionation has not been adequately defined. Patients and Methods Seventy-nine patients with NSCLC were enrolled on a prospective single-institution phase I trial of dose-escalated hypofractionated RT without concurrent chemotherapy. Escalation of dose per fraction was performed according to patients' stratified risk for radiation pneumonitis with total RT doses ranging from 57 to 85.5 Gy in 25 daily fractions over 5 weeks using intensity-modulated radiotherapy. The MTD was defined as the maximum dose with ≤ 20% risk of severe toxicity. Results No grade 3 pneumonitis was observed and an MTD for acute toxicity was not identified during patient accrual. However, with a longer follow-up period, grade 4 to 5 toxicity occurred in six patients and was correlated with total dose (P = .004). An MTD was identified at 63.25 Gy in 25 fractions. Late grade 4 to 5 toxicities were attributable to damage to central and perihilar structures and correlated with dose to the proximal bronchial tree. Conclusion Although this dose-escalation model limited the rates of clinically significant pneumonitis, dose-limiting toxicity occurred and was dominated by late radiation toxicity involving central and perihilar structures. The identified dose-response for damage to the proximal bronchial tree warrants caution in future dose-intensification protocols, especially when using hypofractionation. © 2013 by American Society of Clinical Oncology.

Maddox J.J.,Southeast Alabama Medical Center | Pruitt D.R.,University of Washington | Agel J.,University of Washington | Bransford R.J.,University of Washington
Spine Journal | Year: 2014

Background context Improvements in surgical techniques and medical support have made reconstruction of adult scoliosis more feasible. In an attempt to reduce the risk of complications, some surgeons have chosen to stage these procedures. Purpose We sought to compare a staged group versus an unstaged group of patients undergoing posterior-only instrumentation and fusion from the thoracic spine to the pelvis by a single surgeon for degenerative kyphoscoliosis or residual, progressive adolescent idiopathic scoliosis to assess for a difference in complications. Study design/setting Retrospective chart review. Patient sample We included 143 consecutive patients treated between January 1, 2000, and December 31, 2010. Outcome measure The primary outcome assessed was perioperative complications. Secondary outcomes included intraoperative blood loss, intraoperative transfusions, ICU stay, and disposition. Methods After institutional review board approval, records were analyzed to identify comorbidities and determine whether the management of each patient was planned in an unstaged or staged fashion. "Failures" were identified in which the plan was for an unstaged procedure but were converted to a staged procedure. Complications were defined as unplanned additional procedures or unexpected medical outcomes within 90 days of surgery. We considered p<.005 to be significant. Results Fifty-two patients underwent planned staged surgery and 90 underwent planned unstaged surgical procedures. Baseline demographics including American Society of Anesthesiologists (ASA) score, body mass index, and preoperative diabetic and cardiac status were not different between the two groups. Age was greater in the staged group (68 vs. 63 y; p=.001). Intraoperative transfusion and invasiveness index as defined by Mirza, were also higher in the staged group (p<.005). No difference was identified between the two intent-to-treat groups for complications including infection rate, death, myocardial infarction, stroke, pulmonary embolism, other pulmonary complication, or blindness. Eleven of the 90 unstaged patients were unable to have their surgical procedure completed at the time of the index procedure. The 11 "failures" demonstrated a higher ASA compared with the 79 successfully treated unstaged procedures (p<.005), although no differences in complications. Conclusions There were no differences in complications between the intent-to-treat groups of staged and unstaged procedures, nor was there a difference comparing the "failures" of unstaged care to successful unstaged patients. Although fraught with potential complications, both techniques may be reasonable approaches. © 2014 Elsevier Inc. All rights reserved.

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