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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.

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At least 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Prostate-Specific Antigen at 4 to 5 Years After Low-Dose-Rate Prostate Brachytherapy Is a Strong Predictor of Disease-Free Survival

Purpose: To determine (1) the prognostic utility of prostate-specific antigen (PSA) concentration at 45 to 60 months (48mPSA) after low-dose-rate prostate brachytherapy (LDR-PB); (2) the predictors of 48mPSA; and (3) the prognostic utility of directional trends between PSA levels at 24, 36, and 48 months after LDR-PB. Methods and Materials: Between 1998 and 2008, 2223 patients with low- and intermediate-risk prostate cancer received LDR-PB monotherapy. A cohort of 1434 of these patients was identified with a documented 48mPSA and no evidence of disease relapse prior to the 48mPSA. In addition, a subset of this cohort (n=585) was identified with ≥72 months of follow-up and documented PSA values at both 24 and 36 months after implantation. Results: Median follow-up time was 76 months. Eight-year Kaplan-Meier disease-free survival (DFS) rates were 100% vs 73.4% for patients with 48mPSA ≤0.2 vs those with >0.2 ng/mL; 99.1% versus 53.8% for a 48mPSA threshold of ≤0.4 versus >0.4 ng/mL, respectively; and 97.3% versus 0% for a threshold of ≤1.0 versus >1.0 ng/mL, respectively. On multivariate analysis, the only factor predictive of DFS was 48mPSA (P<.0001). On subset analysis (n=585), 29 patients had a PSA rise (defined as >0.2 ng/mL) between 24 and 36 months, 24 patients had a rise between 36 and 48 months, and 11 patients had rises over both intervals. Failure rates in these patients were 52%, 79%, and 100%, respectively. On multivariate analysis, initial PSA, androgen deprivation therapy, and dose to 90% of the prostate significantly correlated with 48mPSA but together accounted for only ∼5% of its total variance. Conclusions: The 48mPSA after LDR-PB is highly predictive of long-term DFS. Patients with 48mPSA ≤0.4 ng/mL had a <1% risk of disease relapse at 8 years, whereas all patients with 48mPSA >1.0 ng/mL relapsed. Consecutive PSA rises of >0.2 ng/mL from 24 to 36 months and from 36 to 48 months were also highly predictive of subsequent failure.

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

Patterns of Failure for Rhabdomyosarcoma of the Perineal and Perianal Region

Purpose: To analyze prognostic factors and patterns of failure for rhabdomyosarcoma of the perineal and perianal region (PRMS), with an emphasis on radiation therapy for locoregional control. Methods and Materials: Detailed records of all 14 patients treated for PRMS at Memorial Sloan-Kettering Cancer Center between 1998 and 2012 were reviewed. The Kaplan-Meier method was used to assess the event-free survival (EFS) and overall survival (OS), and a competing-risks analysis was used to assess the cumulative incidence of local, regional, and distant failures. Results: Median age was 15.8 years (range, 1.1-31.9 years). High-risk features were identified: 9 of 14 patients (64%) had group 3 disease and 3 of 14 (21%) had group 4; 11 of 14 tumors (78%) were alveolar; 12 of 14 tumors (86%) were ≥5 cm; and 9 of 14 patients (64%) had involved lymph nodes (N1). Of those aged ≥10 years at diagnosis, 9 of 10 (90%) had alveolar histology, all had tumors ≥5 cm, and 8 of 10 (80%) presented with N1 disease. The rates of local, regional, and distant failure at 5 years were 17%, 31%, and 52%, respectively. Although 3 of the 4 patients with regional failure received nodal irradiation, only one of the nodal failures occurred in the radiation therapy field. The 5-year EFS was 33%, and OS was 39%. Age ≥10 years was associated with poor outcomes: EFS was 13% in patients aged ≥10 years, compared with 75% in those aged <10 years (P=.04); the OS was 13% in patients aged ≥10 years, compared with 100% in those aged <10 years (P=.04). Conclusions: Patients with PRMS, especially those aged ≥10 years, present with poor prognostic features and continue to have poor outcomes. Given the high incidence of regional node recurrence, we recommend prophylactic ilioinguinal lymph node irradiation for all patients aged ≥10 years. For children aged <10 years, nodal evaluation is essential to determine the role for lymph node irradiation.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Positron Emission Tomography/Computed Tomography Findings During Therapy Predict Outcome in Patients With Diffuse Large B-Cell Lymphoma Treated With Chemotherapy Alone but Not in Those Who Receive Consolidation Radiation

Purpose: To assess the value of mid-therapy positron emission tomography (PET) findings for predicting survival and disease progression in patients with diffuse large B-cell lymphoma, considering type of therapy (chemotherapy with or without radiation therapy). Methods and Materials: We retrospectively evaluated 294 patients with histologically confirmed diffuse large B-cell lymphoma with respect to age, sex, disease stage, International Prognostic Index score, mid-therapy PET findings (positive or negative), and disease status after therapy and at last follow-up. Overall survival (OS) and progression-free survival (PFS) were compared according to mid-therapy PET findings. Results: Of the 294 patients, 163 (55%) were male, 144 (49%) were age >61 years, 110 (37%) had stage I or II disease, 219 (74%) had International Prognostic Index score ≤2, 216 (73%) received ≥6 cycles of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone, and 88 (30%) received consolidation radiation therapy. Five-year PFS and OS rates were associated with mid-therapy PET status: PFS was 78% for those with PET-negative (PET−) disease versus 63% for PET-positive (PET+) disease (P=.024), and OS was 82% for PET− versus 62% for PET+ (P<.002). These associations held true for patients who received chemotherapy only (PFS 71% for PET− vs 52% PET+ [P=.012], OS 78% for PET− and 51% for PET+ [P=.0055]) but not for those who received consolidation radiation therapy (PFS 84% PET− vs 81% PET+ [P=.88]; OS 90% PET− vs 81% PET+ [P=.39]). Conclusion: Mid-therapy PET can predict patient outcome, but the use of consolidation radiation therapy may negate the significance of mid-therapy findings.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Pattern of Ipsilateral Breast Tumor Recurrence After Breast-Conserving Therapy

Purpose: To analyze the incidence and prognostic factors of ipsilateral breast tumor recurrence (IBTR) after breast-conserving therapy (BCT) in a large, population-based, single-center study with long-term follow-up. Methods and Materials: We analyzed 3595 cases in which BCT was performed in 3824 women with stage I or II breast cancer. The incidence of IBTR was analyzed over time and was based on IBTR as first event. Results: The 15-year local relapse-free survival was 90.9%. The hazard estimates for IBTR showed a time course with 2 peaks, the first at approximately 5 years and the second, twice as high, at 12 years. Stratifying subjects by age and margin status showed that, for women ≤40 years old with negative margins, adjuvant systemic therapy led to a 5-fold reduced risk of recurrence compared to none, and the presence of lymph vascular space invasion (LVSI) had a 3-fold increased risk compared to its absence. For women >40 years old, the presence of LVSI (hazard ratio [HR] 2.5) and the presence of lobular carcinoma in situ in the lumpectomy specimen (HR 2.3) were the only 2 risk factors. Conclusions: We demonstrated a pattern in risk of IBTR over time, with 2 peaks, first at approximately 5 years and a second, much higher peak at approximately 12 years, especially for women ≤40 years old. For women ≤40 years old with tumor-free resection margins, we noted that the absence of adjuvant systemic therapy and the presence of LVSI were independent prognostic factors of IBTR. For women >40 years old, the presence of LVSI and the presence of lobular carcinoma in situ were independent risk factors.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Brachytherapy Improves Biochemical Failure–Free Survival in Low- and Intermediate-Risk Prostate Cancer Compared With Conventionally Fractionated External Beam Radiation Therapy: A Propensity Score Matched Analysis

Purpose: To compare, in a retrospective study, biochemical failure-free survival (bFFS) and overall survival (OS) in low-risk and intermediate-risk prostate cancer patients who received brachytherapy (BT) (either low-dose-rate brachytherapy [LDR-BT] or high-dose-rate brachytherapy with external beam radiation therapy [HDR-BT+EBRT]) versus external beam radiation therapy (EBRT) alone. Methods and Materials: Patient data were obtained from the ProCaRS database, which contains 7974 prostate cancer patients treated with primary radiation therapy at four Canadian cancer institutions from 1994 to 2010. Propensity score matching was used to obtain the following 3 matched cohorts with balanced baseline prognostic factors: (1) low-risk LDR-BT versus EBRT; (2) intermediate-risk LDR-BT versus EBRT; and (3) intermediate-risk HDR-BT+EBRT versus EBRT. Kaplan-Meier survival analysis was performed to compare differences in bFFS (primary endpoint) and OS in the 3 matched groups. Results: Propensity score matching created acceptable balance in the baseline prognostic factors in all matches. Final matches included 2 1:1 matches in the intermediate-risk cohorts, LDR-BT versus EBRT (total n=254) and HDR-BT+EBRT versus EBRT (total n=388), and one 4:1 match in the low-risk cohort (LDR-BT:EBRT, total n=400). Median follow-up ranged from 2.7 to 7.3 years for the 3 matched cohorts. Kaplan-Meier survival analysis showed that all BT treatment options were associated with statistically significant improvements in bFFS when compared with EBRT in all cohorts (intermediate-risk EBRT vs LDR-BT hazard ratio [HR] 4.58, P=.001; intermediate-risk EBRT vs HDR-BT+EBRT HR 2.08, P=.007; low-risk EBRT vs LDR-BT HR 2.90, P=.004). No significant difference in OS was found in all comparisons (intermediate-risk EBRT vs LDR-BT HR 1.27, P=.687; intermediate-risk EBRT vs HDR-BT+EBRT HR 1.55, P=.470; low-risk LDR-BT vs EBRT HR 1.41, P=.500). Conclusions: Propensity score matched analysis showed that BT options led to statistically significant improvements in bFFS in low- and intermediate-risk prostate cancer patient populations.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Molecular Imaging Biomarkers of Resistance to Radiation Therapy for Spontaneous Nasal Tumors in Canines

Purpose: Imaging biomarkers of resistance to radiation therapy can inform and guide treatment management. Most studies have so far focused on assessing a single imaging biomarker. The goal of this study was to explore a number of different molecular imaging biomarkers as surrogates of resistance to radiation therapy. Methods and Materials: Twenty-two canine patients with spontaneous sinonasal tumors were treated with accelerated hypofractionated radiation therapy, receiving either 10 fractions of 4.2 Gy each or 10 fractions of 5.0 Gy each to the gross tumor volume. Patients underwent fluorodeoxyglucose (FDG)-, fluorothymidine (FLT)-, and Cu(II)-diacetyl-bis(N4-methylthiosemicarbazone) (Cu-ATSM)-labeled positron emission tomography/computed tomography (PET/CT) imaging before therapy and FLT and Cu-ATSM PET/CT imaging during therapy. In addition to conventional maximum and mean standardized uptake values (SUV{sub max}; SUV{sub mean}) measurements, imaging metrics providing response and spatiotemporal information were extracted for each patient. Progression-free survival was assessed according to response evaluation criteria in solid tumor. The prognostic value of each imaging biomarker was evaluated using univariable Cox proportional hazards regression. Multivariable analysis was also performed but was restricted to 2 predictor variables due to the limited number of patients. The best bivariable model was selected according to pseudo-R{sup 2}. Results: The following variables were significantly associated with poor clinical outcome following radiation therapy according to univariable analysis: tumor volume (P=.011), midtreatment FLT SUV{sub mean} (P=.018), and midtreatment FLT SUV{sub max} (P=.006). Large decreases in FLT SUV{sub mean} from pretreatment to midtreatment were associated with worse clinical outcome (P=.013). In the bivariable model, the best 2-variable combination for predicting poor outcome was high midtreatment FLT SUV{sub max} (P=.022) in combination with large FLT response from pretreatment to midtreatment (P=.041). Conclusions: In addition to tumor volume, pronounced tumor proliferative response quantified using FLT PET, especially when associated with high residual FLT PET at midtreatment, is a negative prognostic biomarker of outcome in canine tumors following radiation therapy. Neither FDG PET nor Cu-ATSM PET were predictive of outcome.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Non-Rhabdomyosarcoma Soft Tissue Sarcomas in Children: A Surveillance, Epidemiology, and End Results Analysis Validating COG Risk Stratifications

Purpose: Non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) are a heterogeneous group of sarcomas that encompass over 35 histologies. With an incidence of ∼500 cases per year in the United States in those <20 years of age, NRSTS are rare and therefore difficult to study in pediatric populations. We used the large Surveillance, Epidemiology, and End Results (SEER) database to validate the prognostic ability of the Children's Oncology Group (COG) risk classification system and to define patient, tumor, and treatment characteristics. Methods and Materials: From SEER data from 1988 to 2007, we identified patients ≤18 years of age with NRSTS. Data for age, sex, year of diagnosis, race, registry, histology, grade, primary size, primary site, stage, radiation therapy, and survival outcomes were analyzed. Patients with nonmetastatic grossly resected low-grade tumors of any size or high-grade tumors ≤5 cm were considered low risk. Cases of nonmetastatic tumors that were high grade, >5 cm, or unresectable were considered intermediate risk. Patients with nodal or distant metastases were considered high risk. Results: A total of 941 patients met the review criteria. On univariate analysis, black race, malignant peripheral nerve sheath (MPNST) histology, tumors >5 cm, nonextremity primary, lymph node involvement, radiation therapy, and higher risk group were associated with significantly worse overall survival (OS) and cancer-specific survival (CSS). On multivariate analysis, MPNST histology, chemotherapy-resistant histology, and higher risk group were significantly poor prognostic factors for OS and CSS. Compared to low-risk patients, intermediate patients showed poorer OS (hazard ratio [HR]: 6.08, 95% confidence interval [CI]: 3.53-10.47, P<.001) and CSS (HR: 6.27; 95% CI: 3.44-11.43, P<.001), and high-risk patients had the worst OS (HR: 13.35, 95% CI: 8.18-21.76, P<.001) and CSS (HR: 14.65, 95% CI: 8.49-25.28, P<.001). Conclusions: The current COG risk group stratification for children with NRSTS has been validated with a large number of children in the SEER database.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Interim PET After Two ABVD Cycles in Early-Stage Hodgkin Lymphoma: Outcomes Following the Continuation of Chemotherapy Plus Radiotherapy

Purpose: This multicenter retrospective study was designed to evaluate the prognostic role of interim fluorodeoxyglucose-labeled positron emission tomography (i-FDG-PET) in a cohort of patients affected with early-stage Hodgkin lymphoma (HL) treated initially with adriamycin, bleomycin, vinblastine, dacarbazine (ABVD) chemotherapy followed by radiation therapy, and to assess the role of chemotherapy continuation plus radiation therapy for i-FDG-PET-positive patients. Methods and Materials: Data from 257 patients were retrieved from 4 hematology and radiation oncology departments. Inclusion criteria were stage I to IIAB HL, “intention-to-treat” AVBD plus radiation therapy, and FDG-PET at diagnosis and after the first 2 ABVD cycles. All i-FDG-PET scans underwent blinded local review by using the Deauville 5-point scoring system; patients were stratified as negative or positive using 2 Deauville score cutoff values, ≥3 or ≥4. Results: Median follow-up time was 56 months (range: 9-163 months); 5-year overall survival (OS) and disease-specific survival (DSS) for the whole cohort were 97.5% and 98.3%, respectively. Five-year progression-free survival (PFS) was 95.6%. After i-FDG-PET revision, 43 of 257 patients (16.7%) had a positive i-FDG-PET (Deauville scores: 3-5). Five-year PFS rates for i-FDG-PET-negative and i-FDG-PET-positive patients were 98.1% and 83.7%, respectively, if using a Deauville score cutoff of 3, and 97.7% and 78.6%, respectively, if using a cutoff of 4 (P=.0001). Five-year OS for i-FDG-PET-negative and i-FDG-PET-positive patients was 98.5% and 93.0%, respectively, if using a cutoff of 3, and 98.6% and 89.3%, respectively, if using a cutoff of 4 (P=.029 and P=.002). At univariate regression analysis, i-FDG-PET positivity was associated with worse OS and PFS. At multivariate analysis, performed only for PFS, i-FDG-PET positivity confirmed its negative impact (P=.002). Conclusions: i-FDG-PET is prognostic for PFS and OS in early-stage HL patients treated with combined modality therapy; the continuation of chemotherapy followed by radiation therapy is able to obtain durable, complete remission in most i-FDG-PET-positive patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Repeat Courses of Stereotactic Radiosurgery (SRS), Deferring Whole-Brain Irradiation, for New Brain Metastases After Initial SRS

Purpose: To report the outcomes of repeat stereotactic radiosurgery (SRS), deferring whole-brain radiation therapy (WBRT), for distant intracranial recurrences and identify factors associated with prolonged overall survival (OS). Patients and Methods: We retrospectively identified 652 metastases in 95 patients treated with 2 or more courses of SRS for brain metastases, deferring WBRT. Cox regression analyzed factors predictive for OS. Results: Patients had a median of 2 metastases (range, 1-14) treated per course, with a median of 2 courses (range, 2-14) of SRS per patient. With a median follow-up after first SRS of 15 months (range, 3-98 months), the median OS from the time of the first and second course of SRS was 18 (95% confidence interval [CI] 15-24) and 11 months (95% CI 6-17), respectively. On multivariate analysis, histology, graded prognostic assessment score, aggregate tumor volume (but not number of metastases), and performance status correlated with OS. The 1-year cumulative incidence, with death as a competing risk, of local failure was 5% (95% CI 4-8%). Eighteen (24%) of 75 deaths were from neurologic causes. Nineteen patients (20%) eventually received WBRT. Adverse radiation events developed in 2% of SRS sites. Conclusion: Multiple courses of SRS, deferring WBRT, for distant brain metastases after initial SRS, seem to be a safe and effective approach. The graded prognostic assessment score, updated at each course, and aggregate tumor volume may help select patients in whom the deferral of WBRT might be most beneficial.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Efficacy and Safety of Adjuvant Proton Therapy Combined With Surgery for Chondrosarcoma of the Skull Base: A Retrospective, Population-Based Study

Purpose: Chondrosarcoma is a rare malignant tumor of the cartilage affecting young adults. Surgery, followed by charged-particle irradiation, is considered the reference standard for the treatment of patients with grade I to II skull base chondrosarcoma. The present study was conducted to assess the effect of the quality of surgery and radiation therapy parameters on local control (LC) and overall survival (OS). Methods and Materials: From 1996 to 2013, 159 patients (median age 40 years, range 12-83) were treated with either protons alone or a combination of protons and photons. The median total dose delivered was 70.2 Gy (relative biologic effectiveness [RBE]; range 67-71). Debulking and biopsy were performed in 133 and 13 patients, respectively. Results: With a median follow-up of 77 months (range 2-214), 5 tumors relapsed based on the initial gross tumor volume. The 5- and 10-year LC rates were 96.4% and 93.5%, respectively, and the 5- and 10-year OS rates were 94.9% and 87%, respectively. A total of 16 patients died (13 of intercurrent disease, 3 of disease progression). On multivariate analysis, age <40 years and primary disease status were independent favorable prognostic factors for progression-free survival and OS, and local tumor control was an independent favorable predictor of OS. In contrast, the extent of surgery, dosimetric parameters, and adjacent organs at risk were not prognostic factors for LC or OS. Conclusions: Systematic high-dose postoperative proton therapy for skull base chondrosarcoma can achieve a high LC rate with a low toxicity profile. Maximal safe surgery, followed by high-dose conformal proton therapy, is therefore recommended.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Outcomes of Sinonasal Cancer Treated With Proton Therapy

Purpose: To report disease outcomes after proton therapy (PT) for sinonasal cancer. Methods and Materials: Eighty-four adult patients without metastases received primary (13%) or adjuvant (87%) PT for sinonasal cancers (excluding melanoma, sarcoma, and lymphoma). Common histologies were olfactory neuroblastoma (23%), squamous cell carcinoma (22%), and adenoid cystic carcinoma (17%). Advanced stage (T3 in 25% and T4 in 69%) and high-grade histology (51%) were common. Surgical procedures included endoscopic resection alone (45%), endoscopic resection with craniotomy (12%), or open resection (30%). Gross residual disease was present in 26% of patients. Most patients received hyperfractionated PT (1.2 Gy [relative biological effectiveness (RBE)] twice daily, 99%) and chemotherapy (75%). The median PT dose was 73.8 Gy (RBE), with 85% of patients receiving more than 70 Gy (RBE). Prognostic factors were analyzed using Kaplan-Meier analysis and proportional hazards regression for multiple regression. Dosimetric parameters were evaluated using logistic regression. Serious, late grade 3 or higher toxicity was reported using the National Cancer Institute Common Terminology Criteria for Adverse Events, version 4. The median follow-up was 2.4 years for all patients and 2.7 years among living patients. Results: The local control (LC), neck control, freedom from distant metastasis, disease-free survival, cause-specific survival, and overall survival rates were 83%, 94%, 73%, 63%, 70%, and 68%, respectively, at 3 years. Gross total resection and PT resulted in a 90% 3-year LC rate. The 3-year LC rate was 61% for primary radiation therapy and 59% for patients with gross disease. Gross disease was the only significant factor for LC on multivariate analysis, whereas grade and continuous LC were prognostic for overall survival. Six of 12 local recurrences were marginal. Dural dissemination represented 26% of distant recurrences. Late toxicity occurred in 24% of patients (with grade 3 or higher unilateral vision loss in 2%). Conclusions: Dose-intensified, hyperfractionated PT with or without concurrent chemotherapy results in excellent LC after gross total resection, and results in patients with gross disease are encouraging. Patients with high-grade histology are at greater risk of death from distant dissemination. Continuous LC is a major determinant of survival justifying aggressive local therapy in nearly all cases.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Robust Intratumor Partitioning to Identify High-Risk Subregions in Lung Cancer: A Pilot Study

Purpose: To develop an intratumor partitioning framework for identifying high-risk subregions from {sup 18}F-fluorodeoxyglucose positron emission tomography (FDG-PET) and computed tomography (CT) imaging and to test whether tumor burden associated with the high-risk subregions is prognostic of outcomes in lung cancer. Methods and Materials: In this institutional review board–approved retrospective study, we analyzed the pretreatment FDG-PET and CT scans of 44 lung cancer patients treated with radiation therapy. A novel, intratumor partitioning method was developed, based on a 2-stage clustering process: first at the patient level, each tumor was over-segmented into many superpixels by k-means clustering of integrated PET and CT images; next, tumor subregions were identified by merging previously defined superpixels via population-level hierarchical clustering. The volume associated with each of the subregions was evaluated using Kaplan-Meier analysis regarding its prognostic capability in predicting overall survival (OS) and out-of-field progression (OFP). Results: Three spatially distinct subregions were identified within each tumor that were highly robust to uncertainty in PET/CT co-registration. Among these, the volume of the most metabolically active and metabolically heterogeneous solid component of the tumor was predictive of OS and OFP on the entire cohort, with a concordance index or CI of 0.66-0.67. When restricting the analysis to patients with stage III disease (n=32), the same subregion achieved an even higher CI of 0.75 (hazard ratio 3.93, log-rank P=.002) for predicting OS, and a CI of 0.76 (hazard ratio 4.84, log-rank P=.002) for predicting OFP. In comparison, conventional imaging markers, including tumor volume, maximum standardized uptake value, and metabolic tumor volume using threshold of 50% standardized uptake value maximum, were not predictive of OS or OFP, with CI mostly below 0.60 (log-rank P>.05). Conclusion: We propose a robust intratumor partitioning method to identify clinically relevant, high-risk subregions in lung cancer. We envision that this approach will be applicable to identifying useful imaging biomarkers in many cancer types.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Histologic Appearance After Preoperative Radiation Therapy for Soft Tissue Sarcoma: Assessment of the European Organization for Research and Treatment of Cancer–Soft Tissue and Bone Sarcoma Group Response Score

Purpose: To critically assess the prognostic value of the European Organization for Research and Treatment of Cancer–Soft Tissue and Bone Sarcoma Group (EORTC-STBSG) response score and define histologic appearance after preoperative radiation therapy (RT) for soft tissue sarcoma (STS). Methods and Materials: For a cohort of 100 patients with STS of the extremity/trunk treated at our institution with preoperative RT followed by resection, 2 expert sarcoma pathologists evaluated the resected specimens for percent residual viable cells, necrosis, hyalinization/fibrosis, and infarction. The EORTC response score and other predictors of recurrence-free survival (RFS) and overall survival (OS) were assessed by Kaplan-Meier and proportional hazard models. Results: Median tumor size was 7.5 cm; 92% were intermediate or high grade. Most common histologies were unclassified sarcoma (34%) and myxofibrosarcoma (25%). Median follow-up was 60 months. The 5-year local recurrence rate was 5%, 5-year RFS was 68%, and 5-year OS was 75%. Distribution of cases according to EORTC response score tiers was as follows: no residual viable tumor for 9 cases (9% pathologic complete response); <1% viable tumor for 0, ≥1% to <10% for 9, ≥10% to <50% for 44, and ≥50% for 38. There was no association between EORTC-STBSG response score and RFS or OS. Conversely, hyalinization/fibrosis was a significant independent favorable predictor for RFS (hazard ratio 0.49, P=.007) and OS (hazard ratio 0.36, P=.02). Conclusion: Histologic evaluation after preoperative RT for STS showed a 9% pathologic complete response rate. The EORTC-STBSG response score and percent viable cells were not prognostic. Hyalinization/fibrosis was associated with favorable outcome, and if validated, may become a valid endpoint for neoadjuvant trials.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Exosomes and Exosomal MicroRNAs in Prostate Cancer Radiation Therapy

Despite current risk stratification systems using traditional clinicopathologic factors, many localized and locally advanced prostate cancers fail radical treatment (ie, radical prostatectomy, radiation therapy with or without androgen deprivation therapy). Therefore, a pressing need exists for enhanced methods of disease stratification through novel prognostic and predictive tools that can reliably be applied in clinical practice. Exosomes are 50- to 150-nm small vesicles released by cancer cells that reflect the genetic and nongenetic materials of parent cancer cells. Cancer cells can contain distinct sets of microRNA profiles, the expression of which can change owing to stress such as radiation therapy. These alterations or distinctions in contents allow exosomes to be used as prognostic and/or predictive biomarkers and to monitor the treatment response. Additionally, microRNAs have been shown to influence multiple processes in prostate tumorigenesis, including cell proliferation, induction of apoptosis, migration, oncogene inhibition, and radioresistance. Thus, comparative exosomal microRNA profiling at different levels could help portray tumor aggressiveness and response to radiation therapy. Although technical challenges persist in exosome isolation and characterization, recent improvements in microRNA profiling have evolved toward in-depth analyses of the exosomal cargo and its functions. We have reviewed the role of exosomes and exosomal microRNAs in biologic processes of prostate cancer progression and radiation therapy response, with a particular focus on the development of clinical assays for treatment personalization.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2021

The Role of Circulating Tumor Cells in Breast Cancer and Implications for Radiation Treatment Decisions

Tumor biomarkers are used routinely in oncology to assign risk categorization, screen and assist in diagnosis of malignancy, allow for prognostication and prediction of outcomes and treatment response, and allow for monitoring of patients after treatment completion. Although tissue-based biomarkers have a long history of use, the emergence of liquid-based biomarkers, including circulating tumor cells (CTCs), may soon revolutionize the management of patients with cancer. Here, we review the discovery of CTCs and their role as prognostic and predictive biomarkers, with an emphasis on breast cancer. We discuss the platforms for CTC enumeration and focus on studies using the only US Food and Drug Administration–approved platform for CTC enumeration (CellSearch). In addition, we examine the role of CTCs in women with metastatic, inflammatory, and nonmetastatic breast cancer, as well as the clinical evidence for their use as a surrogate for radiation treatment response as well as surveillance after treatment. Finally, we conclude by investigating ongoing clinical studies assessing CTCs as radiation response predictors and discuss unanswered questions.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2022

The Influence of Severe Radiation-Induced Lymphopenia on Overall Survival in Solid Tumors: A Systematic Review and Meta-Analysis

Emerging evidence suggests a detrimental prognostic association between radiation-induced lymphopenia (RIL) and pathologic response, progression-free survival, and overall survival (OS) in patients who undergo radiation therapy for cancer. The aim of this study was to systematically review and meta-analyze the prognostic impact of RIL on OS in patients with solid tumors.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2022

The Clinical Cell-Cycle Risk (CCR) score Is Associated With Metastasis After Radiation Therapy and Provides Guidance on When to Forgo Combined Androgen Deprivation Therapy With Dose-Escalated Radiation

The clinical cell-cycle risk (CCR) score, which combines the University of California, San Francisco's Cancer of the Prostate Risk Assessment (CAPRA) and the cell cycle progression (CCP) molecular score, has been validated to be prognostic of disease progression for men with prostate cancer. This study evaluated the ability of the CCR score to prognosticate the risk of metastasis in men receiving dose-escalated radiation therapy (RT) with or without androgen deprivation therapy (ADT).

62 RADIOLOGY AND NUCLEAR MEDICINE↗