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 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Stereotactic Body Radiation Therapy in Recurrent Hepatocellular Carcinoma

Purpose: To examine the safety and efficacy of Cyberknife stereotactic body radiation therapy (SBRT) and its effect on survival in patients of recurrent hepatocellular carcinoma (HCC). Methods and Materials: This was a matched-pair study. From January 2008 to December 2009, 36 patients with 42 lesions of unresectable recurrent HCC were treated with SBRT. The median prescribed dose was 37 Gy (range, 25 to 48 Gy) in 4-5 fractions over 4-5 consecutive working days. Another 138 patients in the historical control group given other or no treatments were selected for matched analyses. Results: The median follow-up time was 14 months for all patients and 20 months for those alive. The 1- and 2-year in-field failure-free rates were 87.6% and 75.1%, respectively. Out-field intrahepatic recurrence was the main cause of failure. The 2-year overall survival (OS) rate was 64.0%, and median time to progression was 8.0 months. In the multivariable analysis of all 174 patients, SBRT (yes vs. no), tumor size ({<=}4 cm vs. >4 cm), recurrent stage (stage IIIB/IV vs. I) and Child-Pugh classification (A vs. B/C) were independent prognostic factors for OS. Matched-pair analysis revealed that patients undergoing SBRT had better OS (2-year OS of 72.6% vs. 42.1%, respectively, p = 0.013). Acute toxicities were mild and tolerable. Conclusion: SBRT is a safe and efficacious modality and appears to be well-tolerated at the dose fractionation we have used, and its use correlates with improved survival in this cohort of patients with recurrent unresectable HCC. Out-field recurrence is the major cause of failure. Further studies of combinations of SBRT and systemic therapies may be reasonable.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

External Beam Accelerated Partial-Breast Irradiation Using 32 Gy in 8 Twice-Daily Fractions: 5-Year Results of a Prospective Study

Purpose: External beam accelerated partial breast irradiation (APBI) is an increasingly popular technique for treatment of patients with early stage breast cancer following breast-conserving surgery. Here we present 5-year results of a prospective trial. Methods and Materials: From October 2003 through November 2005, 98 evaluable patients with stage I breast cancer were enrolled in the first dose step (32 Gy delivered in 8 twice-daily fractions) of a prospective, multi-institutional, dose escalation clinical trial of 3-dimensional conformal external beam APBI (3D-APBI). Median age was 61 years; median tumor size was 0.8 cm; 89% of tumors were estrogen receptor positive; 10% had a triple-negative phenotype; and 1% had a HER-2-positive subtype. Median follow-up was 71 months (range, 2-88 months; interquartile range, 64-75 months). Results: Five patients developed ipsilateral breast tumor recurrence (IBTR), for a 5-year actuarial IBTR rate of 5% (95% confidence interval [CI], 1%-10%). Three of these cases occurred in patients with triple-negative disease and 2 in non-triple-negative patients, for 5-year actuarial IBTR rates of 33% (95% CI, 0%-57%) and 2% (95% CI, 0%-6%; P<.0001), respectively. On multivariable analysis, triple-negative phenotype was the only predictor of IBTR, with borderline statistical significance after adjusting for tumor grade (P=.0537). Conclusions: Overall outcomes were excellent, particularly for patients with estrogen receptor-positive disease. Patients in this study with triple-negative breast cancer had a significantly higher IBTR rate than patients with other receptor phenotypes when treated with 3D-APBI. Larger, prospective 3D-APBI clinical trials should continue to evaluate the effect of hormone receptor phenotype on IBTR rates.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Role of Early Proctoscopy in Predicting Late Symptomatic Proctitis After External Radiation Therapy for Prostate Carcinoma

Purpose: To determine whether acute radiation-proctitis, diagnosed by proctoscopy after radiation therapy for prostate cancer, can predict late clinical proctitis. Methods and Materials: A prospective study of 130 patients who underwent external radiation therapy (RT) for stage T1 to T4 prostate cancer between 1997 and 2008 was performed. Treatments were conventional (2-dimensional [2D]) in 61 patients and 3D conformal in 69, with a median target dose of 72 Gy (70-74 Gy). Within 1 week after RT, proctoscopy was performed to detect possible acute endoscopic proctitis (AEP). Acute clinical proctitis (ACP) and late clinical proctitis (LCP) were also evaluated. The median follow-up was 84 months (20-180 months). The influence of AEP and ACP on LCP occurrence was studied using the Cox model controlling for age, dose, prostatectomy, RT technique (2D vs 3D), and hormone therapy. Results: AEP was detected in 15 patients (11.5%) and ACP in 67 (51.5%); in 13 cases (10%) AEP and ACP occurred simultaneously. Thirty-five cases of LCP were recorded. The 5-year probability of developing LCP was highest in patients with AEP and ACP (77%, 95% confidence interval [CI] 53%-94%) and lowest in asymptomatic patients (14%, 95% CI 7%-26%; P<.001). Compared to asymptomatic patients, the 5-year probability also was slightly increased in patients with ACP only (26%, 95% CI 16%-40%; P=.052). In multivariable analysis, the combination of AEP and ACP was the main predictor of LCP: compared to asymptomatic patients, the hazard ratio was 5.6 (2.1-15.2) in patients with AEP plus ACP (P=.001) and 2.1 (0.9-4.9) in those with ACP only (P=.103). Conclusions: In patients with AEP and ACP, the risk of LCP was more than 5-fold increased compared to those who were asymptomatic, while a much smaller increase in risk occurred in patients with ACP only. Early proctoscopy can provide valuable information regarding the likelihood of late proctitis.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Chemoradiation With Paclitaxel and Carboplatin in High-Risk Cervical Cancer Patients After Radical Hysterectomy: A Korean Gynecologic Oncology Group Study

Purpose: To evaluate the efficacy and toxicity of concurrent chemoradiation with paclitaxel and carboplatin in patients with high-risk cervical cancer. Methods and Materials: Patients after radical hysterectomy for cervical cancer, with at least 1 high-risk characteristic, were administered paclitaxel 135 mg/m{sup 2}, carboplatin area under the curve = 5 every 3 weeks for 3 cycles concomitant with radiation therapy as adjuvant treatment. Results: This prospective study enrolled 71 consecutive patients. Sixty-six patients (93%) completed the planned treatment. The majority of grade 3/4 neutropenia or nonhematologic toxicities were usually self-limited. Diarrhea grades 3/4 were observed in 4 patients (5.6%). One patient developed anaphylactic shock after infusion of paclitaxel. With a median follow-up of 57 months, recurrences occurred in 16 patients. Multivariable analysis indicated that common iliac lymph node involvement is an independent risk factor for disease recurrence (odds ratio 13.48; 95% confidence interval 2.93-62.03). In the intent-to-treat population (n=71), the estimated 5-year disease-free survival and overall survival rates were 77.3% and 80.3% respectively. In the per-protocol population (n=62), disease-free survival was 78.9% and overall survival was 83.9%. Conclusions: Concurrent chemoradiation with paclitaxel/carboplatin is well tolerated and seems to be effective for patients who undergo radical hysterectomy. Therefore, a prospective, randomized controlled study should be designed to evaluate efficacy of this approach for patients with high-risk cervical cancer.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

A Novel Method for Predicting Late Genitourinary Toxicity After Prostate Radiation Therapy and the Need for Age-Based Risk-Adapted Dose Constraints

Background: There are no well-established normal tissue sparing dose–volume histogram (DVH) criteria that limit the risk of urinary toxicity from prostate radiation therapy (RT). The aim of this study was to determine which criteria predict late toxicity among various DVH parameters when contouring the entire solid bladder and its contents versus the bladder wall. The area under the histogram curve (AUHC) was also analyzed. Methods and Materials: From 1993 to 2000, 503 men with prostate cancer received 3-dimensional conformal RT (median follow-up time, 71 months). The whole bladder and the bladder wall were contoured in all patients. The primary endpoint was grade ≥2 genitourinary (GU) toxicity occurring ≥3 months after completion of RT. Cox regressions of time to grade ≥2 toxicity were estimated separately for the entire bladder and bladder wall. Concordance probability estimates (CPE) assessed model discriminative ability. Before training the models, an external random test group of 100 men was set aside for testing. Separate analyses were performed based on the mean age (≤ 68 vs >68 years). Results: Age, pretreatment urinary symptoms, mean dose (entire bladder and bladder wall), and AUHC (entire bladder and bladder wall) were significant (P<.05) in multivariable analysis. Overall, bladder wall CPE values were higher than solid bladder values. The AUHC for bladder wall provided the greatest discrimination for late bladder toxicity when compared with alternative DVH points, with CPE values of 0.68 for age ≤68 years and 0.81 for age >68 years. Conclusion: The AUHC method based on bladder wall volumes was superior for predicting late GU toxicity. Age >68 years was associated with late grade ≥2 GU toxicity, which suggests that risk-adapted dose constraints based on age should be explored.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Novel Parameter Predicting Grade 2 Rectal Bleeding After Iodine-125 Prostate Brachytherapy Combined With External Beam Radiation Therapy

Purpose: To propose a novel parameter predicting rectal bleeding on the basis of generalized equivalent uniform doses (gEUD) after {sup 125}I prostate brachytherapy combined with external beam radiation therapy and to assess the predictive value of this parameter. Methods and Materials: To account for differences among radiation treatment modalities and fractionation schedules, rectal dose–volume histograms (DVHs) of 369 patients with localized prostate cancer undergoing combined therapy retrieved from corresponding treatment planning systems were converted to equivalent dose-based DVHs. The gEUDs for the rectum were calculated from these converted DVHs. The total gEUD (gEUD{sub sum}) was determined by a summation of the brachytherapy and external-beam radiation therapy components. Results: Thirty-eight patients (10.3%) developed grade 2+ rectal bleeding. The grade 2+ rectal bleeding rate increased as the gEUD{sub sum} increased: 2.0% (2 of 102 patients) for <70 Gy, 10.3% (15 of 145 patients) for 70-80 Gy, 15.8% (12 of 76 patients) for 80-90 Gy, and 19.6% (9 of 46 patients) for >90 Gy (P=.002). Multivariate analysis identified age (P=.024) and gEUD{sub sum} (P=.000) as risk factors for grade 2+ rectal bleeding. Conclusions: Our results demonstrate gEUD to be a potential predictive factor for grade 2+ late rectal bleeding after combined therapy for prostate cancer.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Long-term Cardiac Mortality After Hypofractionated Radiation Therapy in Breast Cancer

Purpose: To explore very-long-term mortality from ischemic heart disease (IHD) after locoregional radiation therapy of breast cancer (BC) in relation to degree of hypofractionation and other treatment variables. Methods and Materials: Two hypofractionated regimens used for locoregional radiation therapy for BC from 1975 to 1991 were considered. Patients received 4.3 Gy × 2/week (10 fractions; target dose 43 Gy; n=1107) or 2.5 Gy × 5/week (20 fractions; target dose 50 Gy; n=459). To estimate cardiac doses, radiation fields were reconstructed in a planning system. Time to death from IHD was the endpoint, comparing the groups with each other and with age-matched, cancer-free control individuals, modeled with the Cox proportional hazards model. Results: Patients given 4.3 Gy × 10 had an increased risk of dying of IHD compared with both the 2.5 Gy group (hazard ratio [HR] = 2.37; 95% confidence interval [CI]: 1.06-5.32; P=.036) and the control group (HR = 1.59; 95% CI: 1.13-2.23; P=.008). Photon beams for parasternal fields gave an increased risk of dying of IHD compared with electron beams (HR = 2.56; 95% CI: 1.12-5.84; P=.025). Multivariate analysis gave an increased risk for the 4.3-Gy versus 2.5-Gy regimen with borderline significance (HR = 2.90; 95% CI: 0.97-8.79; P=.057) but not for parasternal irradiation. Conclusions: The degree of hypofractionation and parasternal photon beams contributed to increased cardiac mortality in this patient cohort. Differences emerged after 12 to 15 years, indicating the need of more studies with observation time of 2 decades.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Symptomatic Pericardial Effusion After Chemoradiation Therapy in Esophageal Cancer Patients

Purpose: We investigated clinical and treatment-related factors as predictors of symptomatic pericardial effusion in esophageal cancer patients after concurrent chemoradiation therapy. Methods and Materials: We reviewed 214 consecutive primary esophageal cancer patients treated with concurrent chemoradiation therapy between 2001 and 2010 in our institute. Pericardial effusion was detected on follow-up computed tomography. Symptomatic effusion was defined as effusion ≥grade 3 according to Common Terminology Criteria for Adverse Events v4.0 criteria. Percent volume irradiated with 5 to 65 Gy (V5-V65) and mean dose to the pericardium were evaluated employing dose-volume histograms. To evaluate dosimetry for patients treated with two-dimensional planning in the earlier period (2001-2005), computed tomography data at diagnosis were transferred to a treatment planning system to reconstruct three-dimensional plans without modification. Optimal dosimetric thresholds for symptomatic pericardial effusion were calculated by receiver operating characteristic curves. Associating clinical and treatment-related risk factors for symptomatic pericardial effusion were detected by univariate and multivariate analyses. Results: The median follow-up was 29 (range, 6-121) months for eligible 167 patients. Symptomatic pericardial effusion was observed in 14 (8.4%) patients. Dosimetric analyses revealed average values of V30 to V45 for the pericardium and mean pericardial doses were significantly higher in patients with symptomatic pericardial effusion than in those with asymptomatic pericardial effusion (P<.05). Pericardial V5 to V55 and mean pericardial doses were significantly higher in patients with symptomatic pericardial effusion than in those without pericardial effusion (P<.001). Mean pericardial doses of 36.5 Gy and V45 of 58% were selected as optimal cutoff values for predicting symptomatic pericardial effusion. Multivariate analysis identified mean pericardial dose as the strongest risk factor for symptomatic pericardial effusion. Conclusions: Dose-volume thresholds for the pericardium facilitate predicting symptomatic pericardial effusion. Mean pericardial dose was selected based not only on the optimal dose-volume threshold but also on the most significant risk factor for symptomatic pericardial effusion.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Risk of Local Failure in Breast Cancer Patients With Lobular Carcinoma In Situ at the Final Surgical Margins: Is Re-excision Necessary?

Purpose: To compare the outcome of patients with invasive breast cancer both with and without lobular carcinoma in situ (LCIS)-positive/close surgical margins after breast-conserving treatment. Methods and Materials: We retrospectively studied 2358 patients with T1-T2 invasive breast cancer treated with lumpectomy and radiation therapy from January 1980 to December 2009. Median age was 57 years (range, 24-91 years). There were 82 patients (3.5%) with positive/close LCIS margins (<0.2 cm) and 2232 patients (95.7%) with negative margins. A total of 1789 patients (76%) had negative lymph nodes. Patients who received neoadjuvant chemotherapy were excluded. A total of 1783 patients (76%) received adjuvant systemic therapy. Multivariable analysis (MVA) was performed using Cox's proportional hazards model. Results: The 5-year cumulative incidence of locoregional recurrence (LRR) was 3.2% (95% confidence interval [CI] 2.5%-4.1%) for the 2232 patients with LCIS-negative surgical margins (median follow-up 104 months) and 2.8% (95% CI 0.7%-10.8%) for the 82 patients with LCIS-positive/close surgical margins (median follow-up 90 months). This was not statistically significant (P=.5). On MVA, LCIS-positive margins after the final surgery were not associated with increased risk of LRR (hazard ratio [HR] 3.4, 95% CI 0.5-24.5, P=.2). Statistically significant prognostic variables on Cox's MVA for risk of LRR included systemic therapy (HR 0.5, 95% CI 0.33-0.75, P=.001), number of positive lymph nodes (HR 1.11, 95% CI 1.05-1.18, P=.001), menopausal status (HR 0.96, 95% CI 0.95-0.98, P=.001), and histopathologic grade (grade 3 vs grade 1/2) (HR 2.6, 95% CI 1.4-4.7, P=.003). Conclusion: Our results suggest that the presence of LCIS at the surgical margin after lumpectomy does not increase the risk of LRR or the final outcome. These findings suggest that re-excision or mastectomy in patients with LCIS-positive/close final surgical margins is unnecessary.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Hypofractionated Radiation Therapy for Breast Ductal Carcinoma In Situ

Purpose: Conventional radiation therapy (RT) administered in 25 fractions after breast-conserving surgery (BCS) is the standard treatment for ductal carcinoma in situ (DCIS) of the breast. Although accelerated hypofractionated regimens in 16 fractions have been shown to be equivalent to conventional RT for invasive breast cancer, few studies have reported results of using hypofractionated RT in DCIS. Methods and Materials: In this multicenter collaborative effort, we retrospectively reviewed the records of all women with DCIS at 3 institutions treated with BCS followed by hypofractionated whole-breast RT (WBRT) delivered in 16 fractions. Results: Between 2003 and 2010, 440 patients with DCIS underwent BCS followed by hypofractionated WBRT in 16 fractions for a total dose of 42.5 Gy (2.66 Gy per fraction). Boost RT to the surgical bed was given to 125 patients (28%) at a median dose of 10 Gy in 4 fractions (2.5 Gy per fraction). After a median follow-up time of 4.4 years, 14 patients had an ipsilateral local relapse, resulting in a local recurrence-free survival of 97% at 5 years. Positive surgical margins, high nuclear grade, age less than 50 years, and a premenopausal status were all statistically associated with an increased occurrence of local recurrence. Tumor hormone receptor status, use of adjuvant hormonal therapy, and administration of additional boost RT did not have an impact on local control in our cohort. On multivariate analysis, positive margins, premenopausal status, and nuclear grade 3 tumors had a statistically significant worse local control rate. Conclusions: Hypofractionated RT using 42.5 Gy in 16 fractions provides excellent local control for patients with DCIS undergoing BCS.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Is Biological Subtype Prognostic of Locoregional Recurrence Risk in Women With pT1-2N0 Breast Cancer Treated With Mastectomy?

Purpose: To examine locoregional and distant recurrence (LRR and DR) in women with pT1-2N0 breast cancer according to approximated subtype and clinicopathologic characteristics. Methods and Materials: Two independent datasets were pooled and analyzed. The study participants were 1994 patients with pT1-2N0M0 breast cancer, treated with mastectomy without radiation therapy. The patients were classified into 1 of 5 subtypes: luminal A (ER+ or PR+/HER 2−/grade 1-2, n=1202); luminal B (ER+ or PR+/HER 2−/grade 3, n=294); luminal HER 2 (ER+ or PR+/HER 2+, n=221); HER 2 (ER−/PR−/HER 2+, n=105) and triple-negative breast cancer (TNBC) (ER−/PR−/HER 2−, n=172). Results: The median follow-up time was 4.3 years. The 5-year Kaplan-Meier (KM) LRR were 1.8% in luminal A, 3.1% in luminal B, 1.7% in luminal HER 2, 1.9% in HER 2, and 1.9% in TNBC cohorts (P=.81). The 5-year KM DR was highest among women with TNBC: 1.8% in luminal A, 5.0% in luminal B, 2.4% in luminal HER 2, 1.1% in HER 2, and 9.6% in TNBC cohorts (P<.001). Among 172 women with TNBC, the 5-year KM LRR were 1.3% with clear margins versus 12.5% with close or positive margins (P=.04). On multivariable analysis, factors that conferred higher LRR risk were tumors >2 cm, lobular histology, and close/positive surgical margins. Conclusions: The 5-year risk of LRR in our pT1-2N0 cohort treated with mastectomy was generally low, with no significant differences observed between approximated subtypes. Among the subtypes, TNBC conferred the highest risk of DR and an elevated risk of LRR in the presence of positive or close margins. Our data suggest that although subtype alone cannot be used as the sole criterion to offer postmastectomy radiation therapy, it may reasonably be considered in conjunction with other clinicopathologic factors including tumor size, histology, and margin status. Larger cohorts and longer follow-up times are needed to define which women with node-negative disease have high postmastectomy LRR risks in contemporary practice.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Pretreatment [{sup 18}F]-fluoro-2-deoxy-glucose Positron Emission Tomography Maximum Standardized Uptake Value as Predictor of Distant Metastasis in Early-Stage Non-Small Cell Lung Cancer Treated With Definitive Radiation Therapy: Rethinking the Role of Positron Emission Tomography in Personalizing Treatment Based on Risk Status

Purpose: The aim of this study was to determine whether the preradiation maximum standardized uptake value (SUV{sub max}) of the primary tumor for [{sup 18}F]-fluoro-2-deoxy-glucose positron emission tomography (FDG-PET) has a prognostic significance in patients with Stage T1 or T2N0 non-small cell lung cancer (NSCLC) treated with curative radiation therapy, whether conventional or stereotactic body radiation therapy (SBRT). Methods and Materials: Between January 2007 and December 2011, a total of 163 patients (180 tumors) with medically inoperable histologically proven Stage T1 or T2N0 NSCLC and treated with radiation therapy (both conventional and SBRT) were entered in a research ethics board approved database. All patients received pretreatment FDG-PET / computed tomography (CT) at 1 institution with consistent acquisition technique. The medical records and radiologic images of these patients were analyzed. Results: The overall survival at 2 years and 3 years for the whole group was 76% and 67%, respectively. The mean and median SUV{sub max} were 8.1 and 7, respectively. Progression-free survival at 2 years with SUV{sub max} <7 was better than that of the patients with tumor SUV{sub max} ≥7 (67% vs 51%; P=.0096). Tumors with SUV{sub max} ≥7 were associated with a worse regional recurrence-free survival and distant metastasis-free survival. In the multivariate analysis, SUV{sub max} ≥7 was an independent prognostic factor for distant metastasis-free survival. Conclusion: In early-stage NSCLC managed with radiation alone, patients with SUV{sub max} ≥7 on FDG-PET / CT scan have poorer outcomes and high risk of progression, possibly because of aggressive biology. There is a potential role for adjuvant therapies for these high-risk patients with intent to improve outcomes.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Receipt of Guideline-Concordant Treatment in Elderly Prostate Cancer Patients

Purpose: To examine the proportion of elderly prostate cancer patients receiving guideline-concordant treatment, using the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database. Methods and Materials: A total of 29,001 men diagnosed in 2004-2007 with localized prostate cancer, aged 66 to 79 years, were included. We characterized the proportion of men who received treatment concordant with the National Comprehensive Cancer Network guidelines, stratified by risk group and age. Logistic regression was used to examine covariates associated with receipt of guideline-concordant management. Results: Guideline concordance was 79%-89% for patients with low- or intermediate-risk disease. Among high-risk patients, 66.6% of those aged 66-69 years received guideline-concordant management, compared with 51.9% of those aged 75-79 years. Discordance was mainly due to conservative management—no treatment or hormone therapy alone. Among the subgroup of patients aged ≤76 years with no measured comorbidity, findings were similar. On multivariable analysis, older age (75-79 vs 66-69 years, odds ratio 0.51, 95% confidence interval 0.50-0.57) was associated with a lower likelihood of guideline concordance for high-risk prostate cancer, but comorbidity was not. Conclusions: There is undertreatment of elderly but healthy patients with high-risk prostate cancer, the most aggressive form of this disease.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Increasing Use of Dose-Escalated External Beam Radiation Therapy for Men With Nonmetastatic Prostate Cancer

Purpose: To examine recent practice patterns, using a large national cancer registry, to understand the extent to which dose-escalated external beam radiation therapy (EBRT) has been incorporated into routine clinical practice for men with prostate cancer. Methods and Materials: We conducted a retrospective observational cohort study using the National Cancer Data Base, a nationwide oncology outcomes database in the United States. We identified 98,755 men diagnosed with nonmetastatic prostate cancer between 2006 and 2011 who received definitive EBRT and classified patients into National Comprehensive Cancer Network (NCCN) risk groups. We defined dose-escalated EBRT as total prescribed dose of ≥75.6 Gy. Using multivariable logistic regression, we examined the association of patient, clinical, and demographic characteristics with the use of dose-escalated EBRT. Results: Overall, 81.6% of men received dose-escalated EBRT during the study period. The use of dose-escalated EBRT did not vary substantially by NCCN risk group. Use of dose-escalated EBRT increased from 70.7% of patients receiving treatment in 2006 to 89.8% of patients receiving treatment in 2011. On multivariable analysis, year of diagnosis and use of intensity modulated radiation therapy were significantly associated with receipt of dose-escalated EBRT. Conclusions: Our study results indicate that dose-escalated EBRT has been widely adopted by radiation oncologists treating prostate cancer in the United States. The proportion of patients receiving dose-escalated EBRT increased nearly 20% between 2006 and 2011. We observed high utilization rates of dose-escalated EBRT within all disease risk groups. Adoption of intensity modulated radiation therapy was strongly associated with use of dose-escalated treatment.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Effectiveness of Chemoradiation for Head and Neck Cancer in an Older Patient Population

Purpose: The purpose of this study was to compare chemoradiation therapy (CRT) with radiation therapy (RT) only in an older patient population with head and neck squamous cell carcinoma (HNSCC). Methods and Materials: Using the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database (1992-2007), we identified a retrospective cohort of nonmetastatic HNSCC patients and divided them into treatment groups. Comparisons were made between CRT and RT cohorts. Propensity scores for CRT were estimated from covariates associated with receipt of treatment using multivariable logistic regression. Standardized mortality ratio weights (SMRW) were created from the propensity scores and used to balance groups on measured confounders. Multivariable and SMR-weighted Cox proportional hazard models were used to estimate the hazard ratio (HR) of death for receipt of CRT versus RT among the whole group and for separate patient and tumor categories. Results: The final cohort of 10,599 patients was 68% male and 89% white. Median age was 74 years. Seventy-four percent were treated with RT, 26% were treated with CRT. Median follow-up points for CRT and RT survivors were 4.6 and 6.3 years, respectively. On multivariable analysis, HR for death with CRT was 1.13 (95% confidence interval [CI]: 1.07-1.20; P<.01). Using the SMRW model, the HR for death with CRT was 1.08 (95% CI: 1.02-1.15; P=.01). Conclusions: Although the addition of chemotherapy to radiation has proven efficacious in many randomized controlled trials, it may be less effective in an older patient population treated outside of a controlled trial setting.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Refusal of Curative Radiation Therapy and Surgery Among Patients With Cancer

Purpose: Surgery and radiation therapy represent the only curative options for many patients with solid malignancies. However, despite the recommendations of their physicians, some patients refuse these therapies. This study characterized factors associated with refusal of surgical or radiation therapy as well as the impact of refusal of recommended therapy on patients with localized malignancies. Methods and Materials: We used the Surveillance, Epidemiology, and End Results program to identify a population-based sample of 925,127 patients who had diagnoses of 1 of 8 common malignancies for which surgery and/or radiation are believed to confer a survival benefit between 1995 and 2008. Refusal of oncologic therapy, as documented in the SEER database, was the primary outcome measure. Multivariable logistic regression was used to investigate factors associated with refusal. The impact of refusal of therapy on cancer-specific mortality was assessed with Fine and Gray's competing risks regression. Results: In total, 2441 of 692,938 patients (0.4%) refused surgery, and 2113 of 232,189 patients (0.9%) refused radiation, despite the recommendations of their physicians. On multivariable analysis, advancing age, decreasing annual income, nonwhite race, and unmarried status were associated with refusal of surgery, whereas advancing age, decreasing annual income, Asian American race, and unmarried status were associated with refusal of radiation (P<.001 in all cases). Refusal of surgery and radiation were associated with increased estimates of cancer-specific mortality for all malignancies evaluated (hazard ratio [HR], 2.80, 95% confidence interval [CI], 2.59-3.03; P<.001 and HR 1.97 [95% CI, 1.78-2.18]; P<.001, respectively). Conclusions: Nonwhite, less affluent, and unmarried patients are more likely to refuse curative surgical and/or radiation-based oncologic therapy, raising concern that socioeconomic factors may drive some patients to forego potentially life-saving care.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Definitive Primary Therapy in Patients Presenting With Oligometastatic Non-Small Cell Lung Cancer

Purpose: Although palliative chemotherapy is the standard of care for patients with diagnoses of stage IV non-small cell lung cancer (NSCLC), patients with a small metastatic burden, “oligometastatic” disease, may benefit from more aggressive local therapy. Methods and Materials: We identified 186 patients (26% of stage IV patients) prospectively enrolled in our institutional database from 2002 to 2012 with oligometastatic disease, which we defined as 5 or fewer distant metastatic lesions at diagnosis. Univariate and multivariable Cox proportional hazards models were used to identify patient and disease factors associated with improved survival. Using propensity score methods, we investigated the effect of definitive local therapy to the primary tumor on overall survival. Results: Median age at diagnosis was 61 years of age; 51% of patients were female; 12% had squamous histology; and 33% had N0-1 disease. On multivariable analysis, Eastern Cooperate Oncology Group performance status ≥2 (hazard ratio [HR], 2.43), nodal status, N2-3 (HR, 2.16), squamous pathology, and metastases to multiple organs (HR, 2.11) were associated with a greater hazard of death (all P<.01). The number of metastatic lesions and radiologic size of the primary tumor were not significantly associated with overall survival. Definitive local therapy to the primary tumor was associated with prolonged survival (HR, 0.65, P=.043). Conclusions: Definitive local therapy to the primary tumor appears to be associated with improved survival in patients with oligometastatic NSCLC. Select patient and tumor characteristics, including good performance status, nonsquamous histology, and limited nodal disease, may predict for improved survival in these patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Genomic Prostate Cancer Classifier Predicts Biochemical Failure and Metastases in Patients After Postoperative Radiation Therapy

Purpose: To test the hypothesis that a genomic classifier (GC) would predict biochemical failure (BF) and distant metastasis (DM) in men receiving radiation therapy (RT) after radical prostatectomy (RP). Methods and Materials: Among patients who underwent post-RP RT, 139 were identified for pT3 or positive margin, who did not receive neoadjuvant hormones and had paraffin-embedded specimens. Ribonucleic acid was extracted from the highest Gleason grade focus and applied to a high-density-oligonucleotide microarray. Receiver operating characteristic, calibration, cumulative incidence, and Cox regression analyses were performed to assess GC performance for predicting BF and DM after post-RP RT in comparison with clinical nomograms. Results: The area under the receiver operating characteristic curve of the Stephenson model was 0.70 for both BF and DM, with addition of GC significantly improving area under the receiver operating characteristic curve to 0.78 and 0.80, respectively. Stratified by GC risk groups, 8-year cumulative incidence was 21%, 48%, and 81% for BF (P<.0001) and for DM was 0, 12%, and 17% (P=.032) for low, intermediate, and high GC, respectively. In multivariable analysis, patients with high GC had a hazard ratio of 8.1 and 14.3 for BF and DM. In patients with intermediate or high GC, those irradiated with undetectable prostate-specific antigen (PSA ≤0.2 ng/mL) had median BF survival of >8 years, compared with <4 years for patients with detectable PSA (>0.2 ng/mL) before initiation of RT. At 8 years, the DM cumulative incidence for patients with high GC and RT with undetectable PSA was 3%, compared with 23% with detectable PSA (P=.03). No outcome differences were observed for low GC between the treatment groups. Conclusion: The GC predicted BF and metastasis after post-RP irradiation. Patients with lower GC risk may benefit from delayed RT, as opposed to those with higher GC; however, this needs prospective validation. Genomic-based models may be useful for improved decision-making for treatment of high-risk prostate cancer.

62 RADIOLOGY AND NUCLEAR MEDICINE↗