Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “ANDROGENS”

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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

PSA Nadir of <0.5 ng/mL Following Brachytherapy for Early-Stage Prostate Adenocarcinoma is Associated With Freedom From Prostate-Specific Antigen Failure

Purpose: Because limited information exists regarding whether the rate or magnitude of PSA decline following brachytherapy predicts long-term clinical outcomes, we evaluated whether achieving a prostate-specific antigen (PSA) nadir (nPSA) <0.5 ng/mL following brachytherapy is associated with decreased PSA failure and/or distant metastasis. Methods and Materials: We retrospectively analyzed our database of early-stage prostate adenocarcinoma patients who underwent brachytherapy, excluding those receiving androgen-deprivation therapy and those with <2 years follow-up. Median and mean pretreatment PSA were 6 ng/mL and 7.16 ng/mL, respectively. By clinical stage, 775 were low risk ({<=}T2a), 126 were intermediate risk (T2b), and 20 were high risk (>T2b). By Gleason score, 840 were low risk ({<=}6), 71 were intermediate risk (7), and 10 were high risk (>7). Patients were treated with brachytherapy only (I-125, n = 779, or Pd-103, n = 47), or brachytherapy + external-beam radiation therapy (n = 95). Median follow-up was 6.3 years. We noted whether nPSA <0.5 ng/mL was achieved and the time to achieve this nadir and tested for associations with pretreatment risk factors. We also determined whether this PSA endpoint was associated with decreased PSA failure or distant metastasis. Results: Absence of high-risk factors in clinical stage ({<=}T2b), Gleason score ({<=}7), and pretreatment PSA ({<=}20 ng/mL) was significantly associated with achieving nPSA <0.5 ng/mL. By Kaplan-Meier analysis, patients achieving nPSA <0.5 ng/mL had significantly higher long-term freedom from biochemical failure (FFBF) than nonresponders (5-year FFBF: 95.2 {+-} 0.8% vs. 71.5 {+-} 6.7%; p < 0.0005). Among responders, those who achieved nPSA <0.5 ng/mL in {<=}5 years had higher FFBF than those requiring >5 years (5-year FFBF: 96.7 {+-} 0.7% vs. 80.8 {+-} 4.6%; p < 0.0005). On multivariate analysis, patients who achieved nPSA <0.5 ng/mL in {<=}5 years had significantly higher FFBF than other patients. Conclusions: Pretreatment risk factors (clinical tumor stage, Gleason score, pretreatment PSA) strongly predict for patients achieving nPSA <0.5 ng/mL following brachytherapy, and this cohort had significantly higher long-term FFBF.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Predictors of Metastatic Disease After Prostate Brachytherapy

Purpose: To identify predictors of metastatic disease after brachytherapy treatment for prostate cancer. Methods and Materials: All patients who received either brachytherapy alone (implant) or brachytherapy in combination with external beam radiation therapy for treatment of localized prostate cancer at The Mount Sinai Hospital between June 1990 and March 2007 with a minimum follow-up of 2 years were included. Univariate and multivariable analyses were performed on the following variables: risk group, Gleason score (GS), clinical T stage, pretreatment prostate-specific antigen level, post-treatment prostate-specific antigen doubling time (PSA-DT), treatment type (implant vs. implant plus external beam radiation therapy), treatment era, total biological effective dose, use of androgen deprivation therapy, age at diagnosis, and race. PSA-DT was analyzed in the following ordinate groups: 0 to 90 days, 91 to 180 days, 180 to 360 days, and greater than 360 days. Results: We included 1,887 patients in this study. Metastases developed in 47 of these patients. The 10-year freedom from distant metastasis (FFDM) rate for the entire population was 95.1%. Median follow-up was 6 years (range, 2-15 years). The only two significant predictors of metastatic disease by multivariable analyses were GS and PSA-DT (p < 0.001 for both variables). Estimated 10-year FFDM rates for GS of 6 or less, GS of 7, and GS of 8 or greater were 97.9%, 94.3%, and 76.1%, respectively (p < 0.001). Estimated FFDM rates for PSA-DT of 0 to 90 days, 91 to 180 days, 181 to 360 days, and greater than 360 days were 17.5%, 67.9%, 74%, and 94.8%, respectively (p < 0.001). Estimated 10-year FFDM rates for the low-, intermediate-, and high-risk groups were 98.6%, 96.2%, and 86.7%, respectively. A demographic shift to patients presenting with higher-grade disease in more recent years was observed. Conclusions: GS and post-treatment PSA-DT are both statistically significant independent predictors of metastatic disease. Patients with a high GS and/or short PSA-DT have a higher likelihood of developing metastatic disease and should be considered for systemic therapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Castration Therapy of Prostate Cancer Results in Downregulation of HIF-1{alpha} Levels

Background and Purpose: Neoadjuvant androgen deprivation in combination with radiotherapy of prostate cancer is used to improve radioresponsiveness and local tumor control. Currently, the underlying mechanism is not well understood. Because hypoxia causes resistance to radiotherapy, we wanted to test whether castration affects the degree of hypoxia in prostate cancer. Methods and Materials: In 14 patients with locally advanced prostate cancer, six to 12 prostatic needle core biopsy specimens were taken prior to castration therapy. Bilateral orchidectomy was performed in 7 patients, and 7 were treated with a GnRH-agonist (leuprorelin). After castrationm two to four prostatic core biopsy specimens were taken, and the level of hypoxia-inducible factor-1{alpha} (HIF-1{alpha}) in cancer was determined by immunofluorescence. Results: Among biopsy specimens taken before castration, strong HIF-1{alpha} expression (mean intensity above 30) was shown in 5 patients, weak expression (mean intensity 10-30) in 3 patients, and background levels of HIF-1{alpha} (mean intensity 0-10) in 6 patients. Downregulation of HIF-1{alpha} expression after castration was observed in all 5 patients with strong HIF-1{alpha} precastration expression. HIF-1{alpha} expression was also reduced in 2 of 3 patients with weak HIF-1{alpha} precastration expression. Conclusions: Our data suggest that neoadjuvant castration decreases tumor cell hypoxia in prostate cancer, which may explain increased radiosensitivity after castration.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

The Number of High-Risk Factors and the Risk of Prostate Cancer-Specific Mortality After Brachytherapy: Implications for Treatment Selection

Purpose: To determine whether an increasing number of high-risk factors is associated with higher prostate cancer-specific mortality (PCSM) among men treated with brachytherapy (BT)-based treatment, and whether supplemental therapy has an impact on this risk. Methods and Materials: We analyzed the cases of 2234 men with localized prostate cancer treated between 1991 and 2007 with low-dose rate BT monotherapy (n = 457) or BT with supplemental external-beam radiotherapy (EBRT, n = 229), androgen suppression therapy (AST, n = 424), or both (n = 1124). All men had at least one high-risk factor (prostate-specific antigen >20 ng/mL, biopsy Gleason score 8-10, or clinical stage {>=}T2c). Competing-risks multivariable regressions were performed to determine whether the presence of at least two high-risk factors was associated with an increased risk of PCSM, with adjustment for age, comorbidity, and the type of supplemental treatment. Results: The median follow-up time was 4.3 years. The number of men with at least two high-risk factors was highest in the group treated with BT, EBRT, and AST (21%), followed by BT plus EBRT or AST (13%), and BT alone (8%) (p{sub trend} < 0.001). The adjusted hazard ratio (AHR) for PCSM for those with at least two high-risk factors (as compared with one) was 4.8 (95% confidence interval [CI], 2.8-8.0; p < 0.001). The use of both supplemental EBRT and AST was associated with a decreased risk of PCSM (AHR 0.5; 95% CI, 0.2-0.9; p = 0.03) compared with BT alone. When the high-risk factors were analyzed separately, Gleason score 8-10 was most significantly associated with increased PCSM (AHR 6.2; 95% CI, 3.5-11.2; p < 0.001). Conclusions: Men with high-risk prostate adenocarcinoma treated with BT have decreased PCSM if they receive trimodailty therapy that includes EBRT and AST. This benefit is likely most important in men with multiple determinants of high risk.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Postoperative Radiotherapy for Prostate Cancer: A Comparison of Four Consensus Guidelines and Dosimetric Evaluation of 3D-CRT Versus Tomotherapy IMRT

Purpose: Despite the benefits of adjuvant radiotherapy after radical prostatectomy, approximately one-half of patients relapse. Four consensus guidelines have been published (European Organization for Research and Treatment of Cancer, Faculty of Radiation Oncology Genito-Urinary Group, Princess Margaret Hospital, Radiation Therapy Oncology Group) with the aim of standardizing the clinical target volume (CTV) delineation and improve outcomes. To date, no attempt has been made to compare these guidelines in terms of treatment volumes or organ at risk (OAR) irradiation. The extent to which the guideline-derived plans meet the dosimetric constraints of present trials or of the Quantitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC) trial is also unknown. Our study also explored the dosimetric benefits of intensity-modulated radiotherapy (IMRT). Methods and Materials: A total of 20 patients treated with postoperative RT were included. The three-dimensional conformal radiotherapy (3D-CRT) plans were applied to cover the guideline-generated planning target volumes (66 Gy in 33 fractions). Dose-volume histograms (DVHs) were analyzed for CTV/planning target volume coverage and to evaluate OAR irradiation. The OAR DVHs were compared with the constraints proposed in the QUANTEC and Radiotherapy and Androgen Deprivation In Combination After Local Surgery (RADICALS) trials. 3D-CRT plans were compared with the tomotherapy plans for the Radiation Therapy Oncology Group planning target volume to evaluate the advantages of IMRT. Results: The CTV differed significantly between guidelines (p < 0.001). The European Organization for Research and Treatment of Cancer-CTVs were significantly smaller than the other CTVs (p < 0.001). Differences in prostate bed coverage superiorly accounted for the major volumetric differences between the guidelines. Using 3D-CRT, the DVHs rarely met the QUANTEC or RADICALS rectal constraints, independent of the guideline used. The RADICALS bladder constraints were met most often by the European Organization for Research and Treatment of Cancer consensus guideline (14 of 20). The tomotherapy IMRT plans resulted in significant OAR sparing compared with the 3D-CRT plans; however, the RADICALS and QUANTEC criteria were still missed in a large percentage of cases. Conclusion: Treatment volumes using the current consensus guidelines differ significantly. For the four CTV guidelines, the rectal and bladder DVH constraints proposed in the QUANTEC and RADICALS trials are rarely met with 3D-CRT. IMRT results in significant OAR sparing; however, the RADICALS dose constraints are still missed for a large percentage of cases. The rectal and bladder constraints of RADICALS should be modified to avoid a reduction in the CTVs.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Pretreatment Endorectal Coil Magnetic Resonance Imaging Findings Predict Biochemical Tumor Control in Prostate Cancer Patients Treated With Combination Brachytherapy and External-Beam Radiotherapy

Purpose: To investigate the utility of endorectal coil magenetic resonance imaging (eMRI) in predicting biochemical relapse in prostate cancer patients treated with combination brachytherapy and external-beam radiotherapy. Methods and Materials: Between 2000 and 2008, 279 men with intermediate- or high-risk prostate cancer underwent eMRI of their prostate before receiving brachytherapy and supplemental intensity-modulated radiotherapy. Endorectal coil MRI was performed before treatment and retrospectively reviewed by two radiologists experienced in genitourinary MRI. Image-based variables, including tumor diameter, location, number of sextants involved, and the presence of extracapsular extension (ECE), were incorporated with other established clinical variables to predict biochemical control outcomes. The median follow-up was 49 months (range, 1-13 years). Results: The 5-year biochemical relapse-free survival for the cohort was 92%. Clinical findings predicting recurrence on univariate analysis included Gleason score (hazard ratio [HR] 3.6, p = 0.001), PSA (HR 1.04, p = 0.005), and National Comprehensive Cancer Network risk group (HR 4.1, p = 0.002). Clinical T stage and the use of androgen deprivation therapy were not correlated with biochemical failure. Imaging findings on univariate analysis associated with relapse included ECE on MRI (HR 3.79, p = 0.003), tumor size (HR 2.58, p = 0.04), and T stage (HR 1.71, p = 0.004). On multivariate analysis incorporating both clinical and imaging findings, only ECE on MRI and Gleason score were independent predictors of recurrence. Conclusions: Pretreatment eMRI findings predict for biochemical recurrence in intermediate- and high-risk prostate cancer patients treated with combination brachytherapy and external-beam radiotherapy. Gleason score and the presence of ECE on MRI were the only significant predictors of biochemical relapse in this group of patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

High-Dose Conformal Radiotherapy Reduces Prostate Cancer-Specific Mortality: Results of a Meta-analysis

Purpose: To determine in a meta-analysis whether prostate cancer-specific mortality (PCSM), biochemical or clinical failure (BCF), and overall mortality (OM) in men with localized prostate cancer treated with conformal high-dose radiotherapy (HDRT) are better than those in men treated with conventional-dose radiotherapy (CDRT). Methods and Materials: The MEDLINE, Embase, CANCERLIT, and Cochrane Library databases, as well as the proceedings of annual meetings, were systematically searched to identify randomized, controlled studies comparing conformal HDRT with CDRT for localized prostate cancer. Results: Five randomized, controlled trials (2508 patients) that met the study criteria were identified. Pooled results from these randomized, controlled trials showed a significant reduction in the incidence of PCSM and BCF rates at 5 years in patients treated with HDRT (p = 0.04 and p < 0.0001, respectively), with an absolute risk reduction (ARR) of PCSM and BCF at 5 years of 1.7% and 12.6%, respectively. Two trials evaluated PCSM with 10 years of follow up. The pooled results from these trials showed a statistical benefit for HDRT in terms of PCSM (p = 0.03). In the subgroup analysis, trials that used androgen deprivation therapy (ADT) showed an ARR for BCF of 12.9% (number needed to treat = 7.7, p < 0.00001), whereas trials without ADT had an ARR of 13.6% (number needed to treat = 7, p < 0.00001). There was no difference in the OM rate at 5 and 10 years (p = 0.99 and p = 0.11, respectively) between the groups receiving HDRT and CDRT. Conclusions: This meta-analysis is the first study to show that HDRT is superior to CDRT in preventing disease progression and prostate cancer-specific death in trials that used conformational technique to increase the total dose. Despite the limitations of our study in evaluating the role of ADT and HDRT, our data show no benefit for HDRT arms in terms of BCF in trials with or without ADT.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Updated Results and Patterns of Failure in a Randomized Hypofractionation Trial for High-risk Prostate Cancer

Purpose: To report long-term results and patterns of failure after conventional and hypofractionated radiation therapy in high-risk prostate cancer. Methods and Materials: This randomized phase III trial compared conventional fractionation (80 Gy at 2 Gy per fraction in 8 weeks) vs hypofractionation (62 Gy at 3.1 Gy per fraction in 5 weeks) in combination with 9-month androgen deprivation therapy in 168 patients with high-risk prostate cancer. Freedom from biochemical failure (FFBF), freedom from local failure (FFLF), and freedom from distant failure (FFDF) were analyzed. Results: In a median follow-up of 70 months, biochemical failure (BF) occurred in 35 of the 168 patients (21%) in the study. Among these 35 patients, local failure (LF) only was detected in 11 (31%), distant failure (DF) only in 16 (46%), and both LF and DF in 6 (17%). In 2 patients (6%) BF has not yet been clinically detected. The risk reduction by hypofractionation was significant in BF (10.3%) but not in LF and DF. We found that hypofractionation, with respect to conventional fractionation, determined only an insignificant increase in the actuarial FFBF but no difference in FFLF and FFDF, when considering the entire group of patients. However, an increase in the 5-year rates in all 3 endpoints-FFBF, FFLF, and FFDF-was observed in the subgroup of patients with a pretreatment prostate-specific antigen (iPSA) level of 20 ng/mL or less. On multivariate analysis, the type of fractionation, iPSA level, Gleason score of 4+3 or higher, and T stage of 2c or higher have been confirmed as independent prognostic factors for BF. High iPSA levels and Gleason score of 4+3 or higher were also significantly associated with an increased risk of DF, whereas T stage of 2c or higher was the only independent variable for LF. Conclusion: Our results confirm the isoeffectiveness of the 2 fractionation schedules used in this study, although a benefit in favor of hypofractionation cannot be excluded in the subgroup of patients with an iPSA level of 20 ng/mL or less. The {alpha}/{beta} ratio might be more appropriately evaluated by FFLF than FFBF results, at least in high-risk disease.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Impact of Neoadjuvant Prostate-Specific Antigen Kinetics on Biochemical Failure and Prostate Cancer Mortality: Results From a Prospective Patient Database

Purpose: To confirm findings from an earlier report showing that neoadjuvant (NA) prostate-specific antigen (PSA) halving time (PSAHT) impacts biochemical failure (BF) rates, and to examine its association with prostate cancer-specific survival (PCSS), in a large prospective cohort of patients. Methods and Materials: A total of 502 patients were selected from a prospective database, who had localized prostate adenocarcinoma treated with 2-12 months of neoadjuvant androgen deprivation therapy (N-ADT) followed by external beam radiation therapy (EBRT) between 1994 and 2000, and had at least 2 NA PSA values. Seventy-four percent of patients had high-risk prostate cancer. Median initial PSA value, N-ADT duration, total ADT duration, and radiation therapy dose were 14 ng/mL, 6.9 months, 10.8 months, and 68 Gy, respectively. Results: At a median follow-up of 9.9 years, 210 patients have had a BF. Median PSAHT was 18 days. On univariate analysis, PSAHT was not shown to predict for BF (P=.69) or PCSS (P=.28). However, NA nadir PSA (nanPSA) and post-therapy nadir PSA (ptnPSA), when analyzed as continuous or categoric variables, predicted for BF (P<.001) and PCSS (P<.001). On multivariate analysis, nanPSA (P=.037) and ptnPSA (P<.001) continued to be significantly associated with BF. However, N-ADT duration lost significance (P=.67), and PSAHT remained a nonsignificant predictor (P=.97). For PCSS, multivariate analysis showed nanPSA (P=.049) and ptnPSA (P<.001) to be significant. Again PSAHT (P=.49) remained nonsignificant. Conclusions: In this large, prospective cohort of patients, NA PSA kinetics, expressed as PSAHT, did not predict BF or PCSS. However, nadir PSAs, in both the NA and post-therapy settings, were significant predictors of BF and PCSS. Optimization of therapy could potentially be based on early PSA response, with shorter durations of ADT for those predicted to do favorably, and intensification of therapy for those likely to have poorer outcomes.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Long-term Survival and Toxicity in Patients Treated With High-Dose Intensity Modulated Radiation Therapy for Localized Prostate Cancer

Purpose: To report long-term survival and toxicity outcomes with the use of high-dose intensity modulated radiation therapy (IMRT) to 86.4 Gy for patients with localized prostate cancer. Methods and Materials: Between August 1997 and December 2008, 1002 patients were treated to a dose of 86.4 Gy using a 5-7 field IMRT technique. Patients were stratified by prognostic risk group based on National Comprehensive Cancer Network risk classification criteria. A total of 587 patients (59%) were treated with neoadjuvant and concurrent androgen deprivation therapy. The median follow-up for the entire cohort was 5.5 years (range, 1-14 years). Results: For low-, intermediate-, and high-risk groups, 7-year biochemical relapse-free survival outcomes were 98.8%, 85.6%, and 67.9%, respectively (P<.001), and distant metastasis-free survival rates were 99.4%, 94.1%, and 82.0% (P<.001), respectively. On multivariate analysis, T stage (P<.001), Gleason score (P<.001), and >50% of initial biopsy positive core (P=.001) were predictive for distant mestastases. No prostate cancer-related deaths were observed in the low-risk group. The 7-year prostate cancer-specific mortality (PCSM) rates, using competing risk analysis for intermediate- and high-risk groups, were 3.3% and 8.1%, respectively (P=.008). On multivariate analysis, Gleason score (P=.004), percentage of biopsy core positivity (P=.003), and T-stage (P=.033) were predictive for PCSM. Actuarial 7-year grade 2 or higher late gastrointestinal and genitourinary toxicities were 4.4% and 21.1%, respectively. Late grade 3 gastrointestinal and genitourinary toxicity was experienced by 7 patients (0.7%) and 22 patients (2.2%), respectively. Of the 427 men with full potency at baseline, 317 men (74%) retained sexual function at time of last follow-up. Conclusions: This study represents the largest cohort of patients treated with high-dose radiation to 86.4 Gy, using IMRT for localized prostate cancer, with the longest follow-up to date. Our findings indicate that this treatment results in excellent clinical outcomes with acceptable toxicity.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Direct 2-Arm Comparison Shows Benefit of High-Dose-Rate Brachytherapy Boost vs External Beam Radiation Therapy Alone for Prostate Cancer

Purpose: To evaluate the outcomes of patients treated for intermediate- and high-risk prostate cancer with a single schedule of either external beam radiation therapy (EBRT) and high-dose-rate brachytherapy (HDRB) boost or EBRT alone. Methods and Materials: From 2001-2006, 344 patients received EBRT with HDRB boost for definitive treatment of intermediate- or high-risk prostate cancer. The prescribed EBRT dose was 46 Gy in 23 fractions, with a HDR boost of 19.5 Gy in 3 fractions. This cohort was compared to a contemporaneously treated cohort who received EBRT to 74 Gy in 37 fractions, using a matched pair analysis. Three-dimensional conformal EBRT was used. Matching was performed using a propensity score matching technique. High-risk patients constituted 41% of the matched cohorts. Five-year clinical and biochemical outcomes were analyzed. Results: Initial significant differences in prognostic indicators between the unmatched treatment cohorts were rendered negligible after matching, providing a total of 688 patients. Median biochemical follow-up was 60.5 months. The 5-year freedom from biochemical failure was 79.8% (95% confidence interval [CI], 74.3%-85.0%) and 70.9% (95% CI, 65.4%-76.0%) for the HDRB and EBRT groups, respectively, equating to a hazard ratio of 0.59 (95% CI, 0.43-0.81, P=.0011). Interaction analyses showed no alteration in HDR efficacy when planned androgen deprivation therapy was administered (P=.95), but a strong trend toward reduced efficacy was shown compared to EBRT in high-risk cases (P=.06). Rates of grade 3 urethral stricture were 0.3% (95% CI, 0%-0.9%) and 11.8% (95% CI, 8.1%-16.5%) for EBRT and HDRB, respectively (P<.0001). No differences in clinical outcomes were observed. Conclusions: This comparison of 2 individual contemporaneously treated HDRB and EBRT approaches showed improved freedom from biochemical progression with the HDR approach. The benefit was more pronounced in intermediate- risk patients but needs to be weighed against an increased risk of urethral toxicity.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Chromosome Damage and Cell Proliferation Rates in In Vitro Irradiated Whole Blood as Markers of Late Radiation Toxicity After Radiation Therapy to the Prostate

Purpose: In vitro irradiated blood samples from prostate cancer patients showing late normal tissue damage were examined for lymphocyte response by measuring chromosomal aberrations and proliferation rate. Methods and Materials: Patients were selected from a randomized trial evaluating the optimal timing of dose-escalated radiation and short-course androgen deprivation therapy. Of 438 patients, 3% experienced grade 3 late radiation proctitis and were considered to be radiosensitive. Blood samples were taken from 10 of these patients along with 20 matched samples from patients with grade 0 proctitis. The samples were irradiated at 6 Gy and, along with control samples, were analyzed for dicentric chromosomes and excess fragments per cell. Cells in first and second metaphase were also enumerated to determine the lymphocyte proliferation rate. Results: At 6 Gy, there were statistically significant differences between the radiosensitive and control cohorts for 3 endpoints: the mean number of dicentric chromosomes per cell (3.26 ± 0.31, 2.91 ± 0.32; P=.0258), the mean number of excess fragments per cell (2.27 ± 0.23, 1.43 ± 0.37; P<.0001), and the proportion of cells in second metaphase (0.27 ± 0.10, 0.46 ± 0.09; P=.0007). Conclusions: These results may be a valuable indicator for identifying radiosensitive patients and for tailoring radiation therapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Ki-67 Is an Independent Predictor of Metastasis and Cause-Specific Mortality for Prostate Cancer Patients Treated on Radiation Therapy Oncology Group (RTOG) 94-08

Purpose: The association of Ki-67 staining index (Ki67-SI) with overall survival (OS), disease-specific mortality (DSM), distant metastasis (DM), and biochemical failure (BF) was examined in men with favorable- to intermediate-risk prostate cancer receiving radiation therapy (RT) alone or with short-term androgen deprivation (ADT) in Radiation Therapy Oncology Group (RTOG) 94-08. Methods and Materials: 468 patients (23.6%) on RTOG 94-08 had sufficient tissue for Ki67-SI analysis. The median follow-up time was 7.9 years. Ki67-SI was determined by immunohistochemistry and quantified manually and by image analysis. Correlative analysis versus clinical outcome was performed using the third quartile (≥Q3) cutpoint. A proportional hazards multivariable analysis (MVA) dichotomized covariates in accordance with trial stratification and randomization criteria. Results: In MVAs adjusted for all treatment covariates, high Ki67-SI (≥Q3) was correlated with increased DSM (hazard ratio [HR] 2.48, P=.03), DM (HR 3.5, P=.002), and BF (HR 3.55, P<.0001). MVA revealed similar Ki67-associated hazard ratios in each separate treatment arm for DSM, DM, and BF; these reached significance only for DM in the RT-alone arm and for BF in both arms. Ki67-SI was not a significant predictor of intraprostatic recurrence assessed by repeated biopsy 2 years after treatment. Patients with a high or low Ki67-SI seemed to experience a similar relative benefit from the addition of ADT to radiation. Conclusions: High Ki67-SI independently predicts for increased DSM, DM, and protocol BF in primarily intermediate-risk prostate cancer patients treated with RT with or without ADT on RTOG 94-08 but does not predict for local recurrence or for increased relative benefit from ADT. This and prior studies lend support for the use of Ki67-SI as a stratification factor in future trials.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

The Interval to Biochemical Failure Is Prognostic for Metastasis, Prostate Cancer-Specific Mortality, and Overall Mortality After Salvage Radiation Therapy for Prostate Cancer

Purpose: To investigate the utility of the interval to biochemical failure (IBF) after salvage radiation therapy (SRT) after radical prostatectomy (RP) for prostate cancer as a surrogate endpoint for distant metastasis (DM), prostate cancer-specific mortality (PCSM), and overall mortality (OM). Methods and Materials: A retrospective analysis of 575 patients treated with SRT after RP from a single institution. Of those, 250 patients experienced biochemical failure (BF), with the IBF defined as the time from commencement of SRT to BF. The IBF was evaluated by Kaplan-Meier and Cox proportional hazards models for its association with DM, PCSM, and OM. Results: The median follow-up time was 85 (interquartile range [IQR] 49.8-121.1) months, with a median IBF of 16.8 (IQR, 8.5-37.1) months. With a cutoff time of 18 months, as previously used, 129 (52%) of patients had IBF ≤18 months. There were no differences among any clinical or pathologic features between those with IBF ≤ and those with IBF >18 months. On log–rank analysis, IBF ≤18 months was prognostic for increased DM (P<.0001, HR 4.9, 95% CI 3.2-7.4), PCSM (P<.0001, HR 4.1, 95% CI 2.4-7.1), and OM (P<.0001, HR 2.7, 95% CI 1.7-4.1). Cox proportional hazards models with adjustment for other clinical variables demonstrated that IBF was independently prognostic for DM (P<.001, HR 4.9), PCSM (P<.0001, HR 4.0), and OM (P<.0001, HR 2.7). IBF showed minimal change in performance regardless of androgen deprivation therapy (ADT) use. Conclusion: After SRT, a short IBF can be used for early identification of patients who are most likely to experience progression to DM, PCSM, and OM. IBF ≤18 months may be useful in clinical practice or as an endpoint for clinical trials.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Decision Regret in Men Undergoing Dose-Escalated Radiation Therapy for Prostate Cancer

Purpose: Decision regret (DR) is a negative emotion associated with medical treatment decisions, and it is an important patient-centered outcome after therapy for localized prostate cancer. DR has been found to occur in up to 53% of patients treated for localized prostate cancer, and it may vary depending on treatment modality. DR after modern dose-escalated radiation therapy (DE-RT) has not been investigated previously, to our knowledge. Our primary aim was to evaluate DR in a cohort of patients treated with DE-RT. Methods and Materials: We surveyed 257 consecutive patients with localized prostate cancer who had previously received DE-RT, by means of a validated questionnaire. Results: There were 220 responses (85.6% response rate). Image-guided intensity modulated radiation therapy was given in 85.0% of patients and 3-dimensional conformal radiation therapy in 15.0%. Doses received included 73.8 Gy (34.5% patients), 74 Gy (53.6%), and 76 Gy (10.9%). Neoadjuvant androgen deprivation (AD) was given in 51.8% of patients and both neoadjuvant and adjuvant AD in 34.5%. The median follow-up time was 23 months (range, 12-67 months). In all, 3.8% of patients expressed DR for their choice of treatment. When asked whether they would choose DE-RT or AD again, only 0.5% probably or definitely would not choose DE-RT again, compared with 8.4% for AD (P<.01). Conclusion: Few patients treated with modern DE-RT express DR, with regret appearing to be lower than in previously published reports of patients treated with radical prostatectomy or older radiation therapy techniques. Patients experienced more regret with the AD component of treatment than with the radiation therapy component, with implications for informed consent. Further research should investigate regret associated with individual components of modern therapy, including AD, radiation therapy and surgery.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Interval to Biochemical Failure Predicts Clinical Outcomes in Patients With High-Risk Prostate Cancer Treated by Combined-Modality Radiation Therapy

Purpose: To validate the prognostic value of interval to biochemical failure (IBF) in patients with high-risk prostate cancer (HiRPCa) treated with combined-modality radiation therapy (CMRT) with or without androgen deprivation therapy (ADT). Methods and Materials: We conducted a retrospective review of HiRPCa (prostate-specific antigen >20 ng/mL, Gleason score [GS] 8-10, or clinical T stage T3-T4) treated with either dose-escalated external beam radiation therapy (EBRT) or CMRT. Interval to biochemical failure was classified as ≤18 or >18 months from the end of all therapy to the date of biochemical failure (BF). Kaplan-Meier methods and Cox proportional hazards regression were used to evaluate the prognostic value of IBF ≤18 months for distant metastasis (DM) and prostate cancer-specific mortality (PCSM). Results: Of 958 patients with a median follow-up of 63.2 months, 175 patients experienced BF. In those with BF, there were no differences in pretreatment clinical characteristics between the EBRT and CMRT groups, except for a higher proportion of patients with GS 8-10 in the CMRT group (70% vs 52%, P=.02). Median IBF after all therapy was 24.0 months (interquartile range 9.6-46.0) in the EBRT group and 18.9 months (interquartile range 9.2-34.5) in the CMRT group (P=.055). On univariate analysis, IBF ≤18 months was associated with increased risk of DM and PCSM in the entire cohort and the individual EBRT and CMRT groups. On multivariate analysis, only GS 9-10 and IBF ≤18 months, but not the radiation therapy regimen or ADT use, predicted DM (hazard ratio [HR] 3.7, P<.01, 95% confidence interval [CI] 1.4-10.3 for GS 9-10; HR 3.9, P<.0001, 95% CI 2.4-6.5 for IBF ≤18 months) and PCSM (HR 14.8, P<.009, 95% CI 2.0-110 for GS 9-10; HR 4.4, P<.0001, 95% CI 2.4-8.1 for IBF ≤18 months). Conclusions: Short IBF was highly prognostic for higher DM and PCSM in patients with HiRPCa. The prognostic value of IBF for DM and PCSM was not affected by the radiation therapy regimen or ADT use.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Predictive Factors and Management of Rectal Bleeding Side Effects Following Prostate Cancer Brachytherapy

Purpose: To report on the incidence, nature, and management of rectal toxicities following individual or combination brachytherapy following treatment for prostate cancer over a 17-year period. We also report the patient and treatment factors predisposing to acute ≥grade 2 proctitis. Methods and Materials: A total of 2752 patients were treated for prostate cancer between October 1990 and April 2007 with either low-dose-rate brachytherapy alone or in combination with androgen depletion therapy (ADT) or external beam radiation therapy (EBRT) and were followed for a median of 5.86 years (minimum 1.0 years; maximum 19.19 years). We investigated the 10-year incidence, nature, and treatment of acute and chronic rectal toxicities following BT. Using univariate, and multivariate analyses, we determined the treatment and comorbidity factors predisposing to rectal toxicities. We also outline the most common and effective management for these toxicities. Results: Actuarial risk of ≥grade 2 rectal bleeding was 6.4%, though notably only 0.9% of all patients required medical intervention to manage this toxicity. The majority of rectal bleeding episodes (72%) occurred within the first 3 years following placement of BT seeds. Of the 27 patients requiring management for their rectal bleeding, 18 underwent formalin treatment and nine underwent cauterization. Post-hoc univariate statistical analysis revealed that coronary artery disease (CAD), biologically effective dose, rectal volume receiving 100% of the prescription dose (RV100), and treatment modality predict the likelihood of grade ≥2 rectal bleeding. Only CAD, treatment type, and RV100 fit a Cox regression multivariate model. Conclusions: Low-dose-rate prostate brachytherapy is very well tolerated and rectal bleeding toxicities are either self-resolving or effectively managed by medical intervention. Treatment planning incorporating adjuvant ADT while minimizing RV100 has yielded the best toxicity-free survival following BT.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Prognostic Utility of Cell Cycle Progression Score in Men With Prostate Cancer After Primary External Beam Radiation Therapy

Purpose: To evaluate the prognostic utility of the cell cycle progression (CCP) score, a RNA signature based on the average expression level of 31 CCP genes, for predicting biochemical recurrence (BCR) in men with prostate cancer treated with external beam radiation therapy (EBRT) as their primary curative therapy. Methods and Materials: The CCP score was derived retrospectively from diagnostic biopsy specimens of men diagnosed with prostate cancer from 1991 to 2006 (n=141). All patients were treated with definitive EBRT; approximately half of the cohort was African American. Outcome was time from EBRT to BCR using the Phoenix definition. Median follow-up for patients without BCR was 4.8 years. Association with outcome was evaluated by Cox proportional hazards survival analysis and likelihood ratio tests. Results: Of 141 patients, 19 (13%) had BCR. The median CCP score for patient samples was 0.12. In univariable analysis, CCP score significantly predicted BCR (P=.0017). The hazard ratio for BCR was 2.55 for 1-unit increase in CCP score (equivalent to a doubling of gene expression). In a multivariable analysis that included Gleason score, prostate-specific antigen, percent positive cores, and androgen deprivation therapy, the hazard ratio for CCP changed only marginally and remained significant (P=.034), indicating that CCP provides prognostic information that is not provided by standard clinical parameters. With 10-year censoring, the CCP score was associated with prostate cancer-specific mortality (P=.013). There was no evidence for interaction between CCP and any clinical variable, including ethnicity. Conclusions: Among men treated with EBRT, the CCP score significantly predicted outcome and provided greater prognostic information than was available with clinical parameters. If validated in a larger cohort, CCP score could identify high-risk men undergoing EBRT who may need more aggressive therapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗