Search NASA⌕ Search

SEARCH · Search NASA

Results for “Multivariate Analysis”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Prognostic Importance of Small Prostate Size in Men Receiving Definitive Prostate Brachytherapy

Purpose: To assess whether small prostate size is an adverse prognostic factor in men undergoing brachytherapy in the same manner in which it seems to be for men undergoing radical prostatectomy. Methods and Materials: From April 1995 to June 2008, 2024 patients underwent brachytherapy by a single brachytherapist. Median follow-up was 7.4 years. The role of small prostate size ({<=}20 cm{sup 3}) as a prognostic factor for biochemical progression-free survival, cause-specific survival, and all-cause mortality was investigated. The differences in survival between men with small and larger prostates were compared using Kaplan-Meier curves and log-rank tests. Results: Median prostate size for the entire cohort was 32.7 cm{sup 3}. For the 167 men with small prostates, median prostate size was 17.4 cm{sup 3}. There was no difference in biochemical progression-free survival (95.2% vs 96.2%, P=.603), cause-specific survival (97.7% vs 98.3%, P=.546), or all-cause mortality (78.0% vs 77.2%, P=.838) at 10 years for men with small prostates compared with men with larger prostates. On univariate and multivariate analysis, small prostate size was not associated with any of the primary outcome measures. Conclusion: Men with small prostates treated with brachytherapy have excellent outcomes and are at no higher risk of treatment failure than men with larger glands. High-quality implants with adequate margins seem sufficient to address the increased adverse risk factors associated with small prostate size.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2011

Urethra-Sparing, Intraoperative, Real-Time Planned, Permanent-Seed Prostate Brachytherapy: Toxicity Analysis

Purpose: To report the toxicity outcome in patients with localized prostate cancer undergoing {sup 125}I permanent-seed brachytherapy (BT) according to a urethra-sparing, intraoperative (IO), real-time planned conformal technique. Methods and Materials: Data were analyzed on 250 patients treated consecutively for low- or intermediate-risk prostate cancer between 2005 and 2009. The planned goal was urethral V{sub 150} = 0. Acute and late genitourinary (GU), gastrointestinal (GI), and erectile toxicities were scored with the International Prostate Symptom Score (IPSS) questionnaire and Common Terminology Criteria for Adverse Events (version 3.0). Median follow-up time for patients with at least 2 years of follow-up (n = 130) was 34.4 months (range, 24-56.9 months). Results: Mean IO urethra V{sub 150} was 0.018% {+-} 0.08%. Mean prostate D{sub 90} and V{sub 100} on day-30 computed tomography scan were 158.0 {+-} 27.0 Gy and 92.1% {+-} 7.2%, respectively. Mean IPSS peak was 9.5 {+-} 6.3 1 month after BT (mean difference from baseline IPSS, 5.3). No acute GI toxicity was observed in 86.8% of patients. The 3-year probability of Grade {>=}2 late GU toxicity-free survival was 77.4% {+-} 4.0%, with Grade 3 late GU toxicity encountered in only 3 patients. Three-year Grade 1 late GI toxicity-free survival was 86.1% {+-} 3.2%. No patient presented Grade {>=}2 late GI toxicity. Of patients with normal sexual status at baseline, 20.7% manifested Grade {>=}2 erectile dysfunction after BT. On multivariate analysis, elevated baseline IPSS (p = 0.016) and high-activity sources (median 0.61 mCi) (p = 0.033) predicted increased Grade {>=}2 late GU toxicity. Conclusions: Urethra-sparing IO BT results in low acute and late GU toxicity compared with the literature. High seed activity and elevated IPSS at baseline increased long-term GU toxicity.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Vaginal Dose Is Associated With Toxicity in Image Guided Tandem Ring or Ovoid-Based Brachytherapy

Purpose: To calculate vaginal doses during image guided brachytherapy with volume-based metrics and correlate with long-term vaginal toxicity. Methods and Materials: In this institutional review board–approved study, institutional databases were searched to identify women undergoing computed tomography and/or magnetic resonance–guided brachytherapy at the Duke Cancer Center from 2009 to 2015. All insertions were contoured to include the vagina as a 3-dimensional structure. All contouring was performed on computed tomography or magnetic resonance imaging and used a 0.4-cm fixed brush to outline the applicator and/or packing, expanded to include any grossly visible vagina. The surface of the cervix was specifically excluded from the contour. High-dose-rate (HDR) and low-dose-rate (LDR) doses were converted to the equivalent dose in 2-Gy fractions using an α/β of 3 for late effects. The parameters D0.1cc, D1cc, and D2cc were calculated for all insertions and summed with prior external beam therapy. Late and subacute toxicity to the vagina were determined by the Common Terminology Criteria for Adverse Events version 4.0 and compared by the median and 4th quartile doses, via the log-rank test. Univariate and multivariate hazard ratios were calculated via Cox regression. Results: A total of 258 insertions in 62 women who underwent definitive radiation therapy including brachytherapy for cervical (n=48) and uterine cancer (n=14) were identified. Twenty HDR tandem and ovoid, 32 HDR tandem and ring, and 10 LDR tandem and ovoid insertions were contoured. The median values (interquartile ranges) for vaginal D0.1cc, D1cc, and D2cc were 157.9 (134.4-196.53) Gy, 112.6 (96.7-124.6) Gy, and 100.5 (86.8-108.4) Gy, respectively. At the 4th quartile cutoff of 108 Gy for D2cc, the rate of late grade 1 toxicity at 2 years was 61.2% (95% confidence interval [CI] 43.0%-79.4%) below 108 Gy and 83.9% (63.9%-100%) above (P=.018); grade 2 or greater toxicity was 36.2% (95% CI 15.8%-56.6%) below 108 Gy and 70.7% (95% CI 45.2%-96.2%) above (P=.004); and grade 3 or worse toxicity was 9.9% (95% CI 0.0%-23.6%) below 108 Gy and 30.0% (95% CI 4.7%-55.3%) above (P=.025). This association was maintained on multivariate analysis, independent of covariates such as applicator type, age, and dose rate. Conclusions: Vaginal dose was associated with all grades of vaginal toxicity. Confirmation at other sites using this methodology will be necessary to establish reproducibility; however, the integration of routine calculation of vaginal dose may be warranted.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Higher Biologically Effective Dose of Radiotherapy Is Associated With Improved Outcomes for Locally Advanced Non-Small Cell Lung Carcinoma Treated With Chemoradiation: An Analysis of the Radiation Therapy Oncology Group

Purpose: Patients treated with chemoradiotherapy for locally advanced non-small-cell lung carcinoma (LA-NSCLC) were analyzed for local-regional failure (LRF) and overall survival (OS) with respect to radiotherapy dose intensity. Methods and Materials: This study combined data from seven Radiation Therapy Oncology Group (RTOG) trials in which chemoradiotherapy was used for LA-NSCLC: RTOG 88-08 (chemoradiation arm only), 90-15, 91-06, 92-04, 93-09 (nonoperative arm only), 94-10, and 98-01. The radiotherapeutic biologically effective dose (BED) received by each individual patient was calculated, as was the overall treatment time-adjusted BED (tBED) using standard formulae. Heterogeneity testing was done with chi-squared statistics, and weighted pooled hazard ratio estimates were used. Cox and Fine and Gray's proportional hazard models were used for OS and LRF, respectively, to test the associations between BED and tBED adjusted for other covariates. Results: A total of 1,356 patients were analyzed for BED (1,348 for tBED). The 2-year and 5-year OS rates were 38% and 15%, respectively. The 2-year and 5-year LRF rates were 46% and 52%, respectively. The BED (and tBED) were highly significantly associated with both OS and LRF, with or without adjustment for other covariates on multivariate analysis (p < 0.0001). A 1-Gy BED increase in radiotherapy dose intensity was statistically significantly associated with approximately 4% relative improvement in survival; this is another way of expressing the finding that the pool-adjusted hazard ratio for survival as a function of BED was 0.96. Similarly, a 1-Gy tBED increase in radiotherapy dose intensity was statistically significantly associated with approximately 3% relative improvement in local-regional control; this is another way of expressing the finding that the pool-adjusted hazard ratio as a function of tBED was 0.97. Conclusions: Higher radiotherapy dose intensity is associated with improved local-regional control and survival in the setting of chemoradiotherapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Clinical Outcomes Among Children With Standard-Risk Medulloblastoma Treated With Proton and Photon Radiation Therapy: A Comparison of Disease Control and Overall Survival

Purpose: The purpose of this study was to compare long-term disease control and overall survival between children treated with proton and photon radiation therapy (RT) for standard-risk medulloblastoma. Methods and Materials: This multi-institution cohort study includes 88 children treated with chemotherapy and proton (n=45) or photon (n=43) RT between 2000 and 2009. Overall survival (OS), recurrence-free survival (RFS), and patterns of failure were compared between the 2 cohorts. Results: Median (range) age was 6 years old at diagnosis (3-21 years) for proton patients versus 8 years (3-19 years) for photon patients (P=.011). Cohorts were similar with respect to sex, histology, extent of surgical resection, craniospinal irradiation (CSI) RT dose, total RT dose, whether the RT boost was delivered to the posterior fossa (PF) or tumor bed (TB), time from surgery to RT start, or total duration of RT. RT consisted of a median (range) CSI dose of 23.4 Gy (18-27 Gy) and a boost of 30.6 Gy (27-37.8 Gy). Median follow-up time is 6.2 years (95% confidence interval [CI]: 5.1-6.6 years) for proton patients versus 7.0 years (95% CI: 5.8-8.9 years) for photon patients. There was no significant difference in RFS or OS between patients treated with proton versus photon RT; 6-year RFS was 78.8% versus 76.5% (P=.948) and 6-year OS was 82.0% versus 87.6%, respectively (P=.285). On multivariate analysis, there was a trend for longer RFS with females (P=.058) and higher CSI dose (P=.096) and for longer OS with females (P=.093). Patterns of failure were similar between the 2 cohorts (P=.908). Conclusions: Disease control with proton and photon radiation therapy appears equivalent for standard risk medulloblastoma.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Hemorrhagic Complications of Percutaneous Cryoablation for Renal Tumors: Results from a 7-year Prospective Study

PurposeCryoablation of renal tumors is assumed to have a higher risk of hemorrhagic complications compared to other ablative modalities. Our purpose was to establish the exact risk and to identify hemorrhagic risk factors.Materials and MethodsThis IRB approved, 7-year prospective study included 261 renal cryoablations. Procedures were under conscious sedation and CT guidance. Pre- and postablation CT was obtained, and hemorrhagic complications were CTCAE tabulated. Age, gender, tumor size, histology, and probes number were tested based on averages or proportions using their exact permutation distribution. “High-risk” subgroups (those exceeding the thresholds of all variables) were tested for each variable alone, and for all combinations of variable threshold values. We compared the subgroup with the best PPV using one variable, with the subgroup with the best PPV using all variables (McNemmar test).ResultsThe hemorrhagic complication rate was 3.5 %. Four patients required transfusions, two required emergent angiograms, one required both a transfusion and angiogram, and two required bladder irrigation for outlet obstruction. Perirenal space hemorrhage was more clinically significant than elsewhere. Univariate risks were tumor size >2 cm, number of probes >2, and malignant histology (P = 0.005, 0.002, and 0.033, respectively). Multivariate analysis showed that patients >55 years with malignant tumors >2 cm requiring 2 or more probes yielded the highest PPV (7.5 %).ConclusionsAlthough older patients (>55 years old) with larger (>2 cm), malignant tumors have an increased risk of hemorrhagic complications, the low PPV does not support the routine use of embolization. Percutaneous cryoablation has a 3.5 % risk of significant hemorrhage, similar to that reported for other types of renal ablative modalities.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Concurrent Androgen Deprivation Therapy During Salvage Prostate Radiotherapy Improves Treatment Outcomes in High-Risk Patients

Purpose: To determine whether concurrent androgen deprivation therapy (ADT) during salvage radiotherapy (RT) improves prostate cancer treatment outcomes. Methods and Materials: A total of 630 postprostatectomy patients were retrospectively identified who were treated with three-dimensional conformal RT. Of these, 441 were found to be treated for salvage indications. Biochemical failure was defined as prostate-specific antigen (PSA) of 0.2 ng/mL or greater above nadir with another PSA increase or the initiation of salvage ADT. Progression-free survival (PFS) was defined as the absence of biochemical failure, continued PSA rise despite salvage therapy, initiation of systemic therapy, clinical progression, or distant failure. Multivariate-adjusted Cox proportional hazards modeling was performed to determine which factors predict PFS. Results: Low-, intermediate-, and high-risk patients made up 10%, 24%, and 66% of patients, respectively. The mean RT dose was 68 Gy. Twenty-four percent of patients received concurrent ADT (cADT). Regional pelvic nodes were treated in 16% of patients. With a median follow-up of 3 years, the 3-year PFS was 4.0 years for cADT vs. 3.4 years for cADT patients (p = 0.22). Multivariate analysis showed that concurrent ADT (p = 0.05), Gleason score (p < 0.001), and pre-RT PSA (p = 0.03) were independent predictors of PFS. When patients were stratified by risk group, the benefits of cADT (hazard ratio, 0.65; p = 0.046) were significant only for high-risk patients. Conclusions: This retrospective study showed a PFS benefit of concurrent ADT during salvage prostate RT. This benefit was observed only in high-risk patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Physician Beliefs and Practices for Adjuvant and Salvage Radiation Therapy After Prostatectomy

Purpose: Despite results of randomized trials that support adjuvant radiation therapy (RT) after radical prostatectomy (RP) for prostate cancer with adverse pathologic features (APF), many clinicians favor selective use of salvage RT. This survey was conducted to evaluate the beliefs and practices of radiation oncologists (RO) and urologists (U) regarding RT after RP. Methods and Materials: We designed a Web-based survey of post-RP RT beliefs and policies. Survey invitations were e-mailed to a list of 926 RO and 591 U. APF were defined as extracapsular extension, seminal vesicle invasion, or positive surgical margin. Differences between U and RO in adjuvant RT recommendations were evaluated by comparative statistics. Multivariate analyses were performed to evaluate factors predictive of adjuvant RT recommendation. Results: Analyzable surveys were completed by 218 RO and 92 U (overallresponse rate, 20%). Adjuvant RT was recommended based on APF by 68% of respondents (78% RO, 44% U, p <0.001). U were less likely than RO to agree that adjuvant RT improves survival and/or biochemical control (p < 0.0001). PSA thresholds for salvage RT were higher among U than RO (p < 0.001). Predicted rates of erectile dysfunction due to RT were higher among U than RO (p <0.001). On multivariate analysis, respondent specialty was the only predictor of adjuvant RT recommendations. Conclusions: U are less likely than RO to recommend adjuvant RT. Future research efforts should focus on defining the toxicities of post-RP RT and on identifying the subgroups of patients who will benefit from adjuvant vs. selective salvage RT.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Long-term Outcomes of Hypofractionation Versus Conventional Radiation Therapy After Breast-Conserving Surgery for Ductal Carcinoma In Situ of the Breast

Purpose: Whole-breast radiation therapy (XRT) after breast-conserving surgery (BCS) for ductal carcinoma in situ (DCIS) may decrease the risk of local recurrence, but the optimal dose regimen remains unclear. Past studies administered 50 Gy in 25 fractions (conventional); however, treatment pattern studies report that hypofractionated (HF) regimens (42.4 Gy in 16 fractions) are frequently used. We report the impact of HF (vs conventional) on the risk of local recurrence after BCS for DCIS. Methods and Materials: All women with DCIS treated with BCS and XRT in Ontario, Canada from 1994 to 2003 were identified. Treatment and outcomes were assessed through administrative databases and validated by chart review. Survival analyses were performed. To account for systematic differences between women treated with alternate regimens, we used a propensity score adjustment approach. Results: We identified 1609 women, of whom 971 (60%) received conventional regimens and 638 (40%) received HF. A total of 489 patients (30%) received a boost dose, of whom 143 (15%) received conventional radiation therapy and 346 (54%) received HF. The median follow-up time was 9.2 years. The median age at diagnosis was 56 years (interquartile range [IQR], 49-65 years). On univariate analyses, the 10-year actuarial local recurrence–free survival was 86% for conventional radiation therapy and 89% for HF (P=.03). On multivariable analyses, age <45 years (hazard ratio [HR] = 2.4; 95% CI: 1.6-3.4; P<.0001), high (HR=2.9; 95% CI: 1.2-7.3; P=.02) or intermediate nuclear grade (HR=2.7; 95% CI: 1.1-6.6; P=.04), and positive resection margins (HR=1.4; 95% CI: 1.0-2.1; P=.05) were associated with an increased risk of local recurrence. HF was not significantly associated with an increased risk of local recurrence compared with conventional radiation therapy on multivariate analysis (HR=0.8; 95% CI: 0.5-1.2; P=.34). Conclusions: The risk of local recurrence among individuals treated with HF regimens after BCS for DCIS was similar to that among individuals treated with conventional radiation therapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Moderate Hypofractionated Protracted Radiation Therapy and Dose Escalation for Prostate Cancer: Do Dose and Overall Treatment Time Matter?

Purpose: This was a retrospective study of 2 sequential dose escalation regimens of twice-weekly 4 Gy/fractions hypofractionated intensity modulated radiation therapy (IMRT): 56 Gy and 60 Gy delivered within a protracted overall treatment time (OTT) of 6.5 and 7 weeks, respectively. Methods and Materials: 163 prostate cancer patients with cT1c-T3a disease and nodal involvement risk ≤20% (Roach index) were treated twice weekly to the prostate ± seminal vesicles with 2 sequential dose-escalated IMRT schedules: 56 Gy (14 × 4 Gy, n=81) from 2003 to 2007 and 60 Gy (15 × 4 Gy, n=82) from 2006 to 2010. Patient repositioning was made with bone matching on portal images. Gastrointestinal (GI) and genitourinary (GU) toxicities were scored according to the Common Terminology Criteria for Adverse Events version 3.0 grading scale. Results: There were no significant differences regarding the acute GU and GI toxicities in the 2 dose groups. The median follow-up times were 80.2 months (range, 4.5-121 months) and 56.5 months (range, 1.4-91.2 months) for patients treated to 56 and 60 Gy, respectively. The 5-year grade ≥2 late GU toxicity-free survivals with 56 Gy and 60 Gy were 96 ± 2.3% and 78.2 ± 5.1% (P=.001), respectively. The 5-year grade ≥2 late GI toxicity-free survivals with 56 Gy and 60 Gy were 98.6 ± 1.3% and 85.1 ± 4.5% (P=.005), respectively. Patients treated with 56 Gy showed a 5-year biochemical progression-free survival (bPFS) of 80.8 ± 4.7%, worse than patients treated with 60 Gy (93.2 ± 3.9%, P=.007). A trend for a better 5-year distant metastasis-free survival was observed among patients treated in the high-dose group (95.3 ± 2.7% vs 100%, P=.073, respectively). On multivariate analysis, only the 60-Gy group predicted for a better bPFS (P=.016, hazard ratio = 4.58). Conclusions: A single 4-Gy additional fraction in patients treated with a hypofractionated protracted IMRT schedule of 14 × 4 Gy resulted in a similar and minimal acute toxicity, in worse moderate to severe urinary and GI late effects, but a significantly better biochemical control.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Late Consequential Surgical Bed Soft Tissue Necrosis in Advanced Oropharyngeal Squamous Cell Carcinomas Treated With Transoral Robotic Surgery and Postoperative Radiation Therapy

Purpose: A subset of patients with oropharyngeal squamous cell carcinoma (OP-SCC) managed with transoral robotic surgery (TORS) and postoperative radiation therapy (PORT) developed soft tissue necrosis (STN) in the surgical bed months after completion of PORT. We investigated the frequency and risk factors. Materials and Methods: This retrospective analysis included 170 consecutive OP-SCC patients treated with TORS and PORT between 2006 and 2012, with >6 months' of follow-up. STN was defined as ulceration of the surgical bed >6 weeks after completion of PORT, requiring opioids, biopsy, or hyperbaric oxygen therapy. Results: A total of 47 of 170 patients (28%) had a diagnosis of STN. Tonsillar patients were more susceptible than base-of-tongue (BOT) patients, 39% (41 of 104) versus 9% (6 of 66), respectively. For patients with STN, median tumor size was 3.0 cm (range 1.0-5.6 cm), and depth of resection was 2.2 cm (range 1.0-5.1 cm). Median radiation dose and dose of fraction to the surgical bed were 6600 cGy and 220 cGy, respectively. Thirty-one patients (66%) received concurrent chemotherapy. Median time to STN was 2.5 months after PORT. All patients had resolution of STN after a median of 3.7 months. Multivariate analysis identified tonsillar primary (odds ratio [OR] 4.73, P=.01), depth of resection (OR 3.12, P=.001), total radiation dose to the resection bed (OR 1.51 per Gy, P<.01), and grade 3 acute mucositis (OR 3.47, P=.02) as risk factors for STN. Beginning May 2011, after implementing aggressive avoidance of delivering >2 Gy/day to the resection bed mucosa, only 8% (2 of 26 patients) experienced STN (all grade 2). Conclusions: A subset of OP-SCC patients treated with TORS and PORT are at risk for developing late consequential surgical bed STN. Risk factors include tonsillar location, depth of resection, radiation dose to the surgical bed, and severe mucositis. STN risk is significantly decreased with carefully avoiding a radiation dosage of >2 Gy/day to the surgical bed.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Investigation of goodness of model data fit using PLSR and PCR regression models to determine informative wavelength band in NIR region for non-invasive blood glucose prediction

Diabetes mellitus is a metabolic disorder characterized by the deficiency in insulin secretion or insulin action on target tissues. Diabetes being diagnosed, requires frequent monitoring. Current measurement techniques are invasive in nature, which is painful. Non-invasive measurement methods for the prediction of blood glucose is a big challenge. Hence this paper focuses on a comparative study to analyze the performance of the two regression models: partial least square regression (PLSR) and principal component regression (PCR) models to arrive at the best regression model for the prediction of blood glucose non-invasively based on NIR diffuse reflectance spectroscopy. The regression model developed involves spectral data collected from 32 subjects from a diabetic center using diffuse reflectance spectrometer (DRS). The spectroscopic data were acquired from the subjects both invasively using clinical method and non-invasively using DRS setup in the NIR spectral range whose wavelength ranges from 750 to 1040 nm. Multivariate analysis using PLSR is found to be a better regression model in terms of the fitted response and estimated mean square prediction error. It is observed that the mean square error value is 0.04 mg/dl for the tenth component in the PLSR model. The developed regression model also proves to be a useful tool in identifying the informative wavelength bands for blood glucose measurement.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2012

Determination of Prognostic Factors for Vaginal Mucosal Toxicity Associated With Intravaginal High-Dose Rate Brachytherapy in Patients With Endometrial Cancer

Purpose: The objective of this study was to determine the patient- and treatment-related prognostic factors associated with vaginal toxicity in patients who received intravaginal high dose rate (HDR) brachytherapy alone as adjuvant treatment for endometrial cancer. Secondary goals of this study included a quantitative assessment of optimal dilator use frequency and a crude assessment of clinical predictors for compliant dilator use. Methods and Materials: We retrospectively reviewed the charts of 100 patients with histologically confirmed endometrial cancer who underwent total hysterectomy and bilateral salpingo-oophorectomy with or without lymph node dissection and adjuvant intravaginal brachytherapy between 1995 and 2009 at the Hospital of University of Pennsylvania. The most common treatment regimen used was 21 Gy in three fractions (71 patients). Symptoms of vaginal mucosal toxicity were taken from the history and physical exams noted in the patients' charts and were graded according to the Common Toxicity Criteria for Adverse Events v. 4.02. Results: The incidence of Grade 1 or asymptomatic vaginal toxicity was 33% and Grade 2-3 or symptomatic vaginal toxicity was 14%. Multivariate analysis of age, active length, and dilator use two to three times a week revealed odds ratios of 0.93 (p = 0.013), 3.96 (p = 0.008), and 0.17 (p = 0.032) respectively. Conclusion: Increasing age, vaginal dilator use of at least two to three times a week, and shorter active length were found to be significantly associated with a decreased risk of vaginal stenosis. Future prospective studies are necessary to validate our findings.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Subclassification of Recursive Partitioning Analysis Class II Patients With Brain Metastases Treated Radiosurgically

Purpose: Although the recursive partitioning analysis (RPA) class is generally used for predicting survival periods of patients with brain metastases (METs), the majority of such patients are Class II and clinical factors vary quite widely within this category. This prompted us to divide RPA Class II patients into three subclasses. Methods and Materials: This was a two-institution, institutional review board-approved, retrospective cohort study using two databases: the Mito series (2,000 consecutive patients, comprising 787 women and 1,213 men; mean age, 65 years [range, 19-96 years]) and the Chiba series (1,753 patients, comprising 673 female and 1,080 male patients; mean age, 65 years [range, 7-94 years]). Both patient series underwent Gamma Knife radiosurgery alone, without whole-brain radiotherapy, for brain METs during the same 10-year period, July 1998 through June 2008. The Cox proportional hazard model with a step-wise selection procedure was used for multivariate analysis. Results: In the Mito series, four factors were identified as favoring longer survival: Karnofsky Performance Status (90% to 100% vs. 70% to 80%), tumor numbers (solitary vs. multiple), primary tumor status (controlled vs. not controlled), and non-brain METs (no vs. yes). This new index is the sum of scores (0 and 1) of these four factors: RPA Class II-a, score of 0 or 1; RPA Class II-b, score of 2; and RPA Class II-c, score of 3 or 4. Next, using the Chiba series, we tested whether our index is valid for a different patient group. This new system showed highly statistically significant differences among subclasses in both the Mito series and the Chiba series (p < 0.001 for all subclasses). In addition, this new index was confirmed to be applicable to Class II patients with four major primary tumor sites, that is, lung, breast, alimentary tract, and urogenital organs. Conclusions: Our new grading system should be considered when designing future clinical trials involving brain MET patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2011

Adoption of Preoperative Radiation Therapy for Rectal Cancer From 2000 to 2006: A Surveillance, Epidemiology, and End Results Patterns-of-Care Study

Purpose: The German rectal study determined that preoperative radiation therapy (RT) as a component of combined-modality therapy decreased local tumor recurrence, increased sphincter preservation, and decreased treatment toxicity compared with postoperative RT for rectal cancer. We evaluated the use of preoperative RT after the presentation of the landmark German rectal study results and examined the impact of tumor and sociodemographic factors on receiving preoperative RT. Methods and Materials: In total, 20,982 patients who underwent surgical resection for T3-T4 and/or node-positive rectal adenocarcinoma diagnosed from 2000 through 2006 were identified from the Surveillance, Epidemiology, and End Results tumor registries. We analyzed trends in preoperative RT use before and after publication of the findings from the German rectal study. We also performed multivariate logistic regression to identify factors associated with receiving preoperative RT. Results: Among those treated with RT, the proportion of patients treated with preoperative RT increased from 33.3% in 2000 to 63.8% in 2006. After adjustment for age; gender; race/ethnicity; marital status; Surveillance, Epidemiology, and End Results registry; county-level education; T stage; N stage; tumor size; and tumor grade, there was a significant association between later year of diagnosis and an increase in preoperative RT use (adjusted odds ratio, 1.26/y increase; 95% confidence interval, 1.23-1.29). When we compared the years before and after publication of the German rectal study (2000-2003 vs. 2004-2006), patients were more likely to receive preoperative RT than postoperative RT in 2004-2006 (adjusted odds ratio, 2.35; 95% confidence interval, 2.13-2.59). On multivariate analysis, patients who were older, who were female, and who resided in counties with lower educational levels had significantly decreased odds of receiving preoperative RT. Conclusions: After the publication of the landmark German rectal study, there was widespread, rapid adoption of preoperative RT for locally advanced rectal cancer. However, preoperative RT may be underused in certain sociodemographic groups.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2011

Identifying Differences Between Biochemical Failure and Cure: Incidence Rates and Predictors

Background: Patients treated with radiation therapy (RT) for prostate cancer were evaluated to estimate the length of time required to document biochemical cure (BC) after treatment and the variables associated with long-term treatment efficacy. Patients and Methods: 2,100 patients received RT alone for localized prostate carcinoma (external-beam RT, n = 1,504; brachytherapy alone, n = 241; or brachytherapy + pelvic radiation, n = 355). The median external-beam dose was 68.4 Gy, and the median follow-up time was 8.6 years. Biochemical failure (BF) was defined according to the Phoenix definition. Results: Biochemical failure was experienced by 685 patients (32.6%). The median times to BF for low-, intermediate-, and high-risk groups were 6.0, 5.6, and 4.5 years respectively (p < 0.001). The average annual incidence rates of BF for years 1-5, 5-10,11-15, and 16-20 in low-risk patients were 2.0%, 2.0%, 0.3%, and 0.06% (p < 0.001); for intermediate-risk patients, 4%, 3%, 0.3%, and 0% (p < 0.001); and for high-risk patients, 10.0%, 5.0%, 0.3%, and 0.3% (p < 0.001). After 5 years of treatment, 36.9% of all patients experienced BF. The percentage of total failures occurring during years 1-5, 5-10, 11-15, and 16-20 were 48.7%, 43.5%, 6.5%, and 1.3% for low-risk patients; 64.0%, 32.2%, 3.8%, and 0% for intermediate-risk patients; and 71.9%, 25.9%, 1.1%, and 1.1% for high-risk patients, respectively. Increasing time to nadir was associated with increased time to BF. On multivariate analysis, factors significantly associated with 10-year BC included prostate-specific antigen nadir and time to nadir. Conclusions: The incidence rates for BF did not plateau until later than 10 years after treatment, suggesting that extended follow-up time is required to monitor patients after treatment. Prostate-specific antigen nadir and time to nadir have the strongest association with long-term BC.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2011

Radiation-Induced Middle Ear and Mastoid Opacification in Skull Base Tumors Treated With Radiotherapy

Purpose: To assess the incidence of middle ear (ME) pathology in patients treated with radiotherapy (RT) for skull base tumors. Methods and Materials: A retrospective analysis of 61 patients treated with RT between 2003 and 2008 for skull base tumors was conducted. Clinical outcomes and demographics were reviewed. Dose-volume histogram analysis was performed on the eustachian canal (EC), ME, mastoid air cells, vestibular apparatus, cochlea, internal auditory canal, lateral and posterior nasopharynx, and temporal lobes to relate doses to symptoms and radiographic change. Otomastoid opacification was rated 0 (none), 1 (mild), 2 (moderate), and 3 (severe) by a neuroradiologist blinded to clinical outcomes and doses. Results: The median prescribed dose was 50.4 Gy (range, 14-74 Gy). The ME mean dose was 14 Gy and 34 Gy for Grade 0-1 and 2-3 opacification, respectively (p < 0.0001). The mean mastoid dose was 10 Gy and 26 Gy for Grade 0-1 and 2-3, respectively (p < 0.0001). The mean EC dose was 17 Gy and 32 Gy for Grade 0-1 and 2-3, respectively (p = 0.0001). Otomastoid opacification resolved in 17 of 40 patients (42.5%), at a mean of 17 months after RT (range, 2-45 months). Otomastoid opacification persisted in 23 of 40 patients (57.5%), with a mean follow-up of 23 months (range, 2-55 months). Multivariate analysis showed that mastoid dose >30 Gy (odds ratio = 28.0, p < 0.001) and posterior nasopharynx dose of >30 Gy (odds ratio = 4.9, p = 0.009) were associated with Grade 2-3 effusions, whereas other factors including dose to EC and ME were not significant. Conclusions: A mean RT dose >30 Gy to the mastoid air cells or posterior nasopharynx is associated with increased risk of moderate to severe otomastoid opacification, which persisted in more than half of patients at 2-year follow-up.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Additional Survival Benefit of Involved-Lesion Radiation Therapy After R-CHOP Chemotherapy in Limited Stage Diffuse Large B-Cell Lymphoma

Purpose: The purpose of this study was to evaluate the role of involved-lesion radiation therapy (ILRT) after rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) chemotherapy in limited stage diffuse large B-cell lymphoma (DLBCL) by comparing outcomes of R-CHOP therapy alone with R-CHOP followed by ILRT. Methods and Materials: We identified 198 patients treated with R-CHOP (median, 6 cycles) for pathologically confirmed DLBCL of limited stage from July 2004 to December 2012. Clinical characteristics of these patients were 33% with stage I and 66.7% with stage II; 79.8% were in the low or low-intermediate risk group; 13.6% had B symptoms; 29.8% had bulky tumors (≥7 cm); and 75.3% underwent ≥6 cycles of R-CHOP therapy. RT was given to 43 patients (21.7%) using ILRT technique, which included the prechemotherapy tumor volume with a median margin of 2 cm (median RT dose: 36 Gy). Results: After a median follow-up of 40 months, 3-year progression-free survival (PFS) and overall survival (OS) were 85.8% and 88.9%, respectively. Multivariate analysis showed ≥6 cycles of R-CHOP (PFS, P=.004; OS, P=.004) and ILRT (PFS, P=.021; OS, P=.014) were favorable prognosticators of PFS and OS. A bulky tumor (P=.027) and response to R-CHOP (P=.012) were also found to be independent factors of OS. In subgroup analysis, the effect of ILRT was prominent in patients with a bulky tumor (PFS, P=.014; OS, P=.030) or an elevated level of serum lactate dehydrogenase (LDH; PFS, P=.004; OS, P=.012). Conclusions: Our results suggest that ILRT after R-CHOP therapy improves PFS and OS in patients with limited stage DLBCL, especially in those with bulky disease or an elevated serum LDH level.

62 RADIOLOGY AND NUCLEAR MEDICINE↗