MRI-Based Radiotherapy Planning to Reduce Rectal Dose in Excess of Tolerance.

MATERIALS AND METHODS: This prospective single-arm study enrolled 15 men treated with IG-IMRT for localized prostate cancer. All participants received a dedicated 3 Tesla MRI examination of the prostate in addition to a pelvic CT examination for treatment planning. Two volumetric modulated arc therapy (VMAT) plans with a prescription dose of 79.2 Gy were designed using identical constraints based on CT- and MRI-defined consensus volumes. The volume of rectum exposed to 70 Gy or more was compared using the Wilcoxon paired signed rank test. RESULTS: For CT-based treatment plans, the median volume of rectum receiving 70 Gy or more was 9.3 cubic centimeters (cc) (IQR 7.0 to 10.2) compared with 4.9 cc (IQR 4.1 to 7.8) for MRI-based plans. This resulted in a median volume reduction of 2.1 cc (IQR 0.5 to 5.3, P < .001). CONCLUSIONS: Using MRI to plan prostate IG-IMRT to a dose of 79.2 Gy reduces the volume of rectum receiving radiation dose in excess of tolerance (70 Gy or more) and should be considered in men who are at high risk for late rectal toxicity and are not good candidates for other rectal sparing techniques such as hydrogel spacer. This trial is registered with NCT02470910.

Early Versus Delayed Initiation of Salvage Androgen Deprivation Therapy and Risk of Prostate Cancer-Specific Mortality.

Background: This study sought to ascertain whether there is an association between prostate cancer (PC)-specific mortality (PCSM) and timing of salvage androgen deprivation therapy (ADT) among men with short versus long prostate-specific antigen doubling times (PSA-DTs). Methods: The study cohort was selected from 206 men with localized unfavorable-risk PC randomized to radiation therapy (RT) or RT plus 6 months of ADT between 1995 and 2001. A total of 54 men who received salvage ADT for PSA failure after a median follow-up of 18.72 years following randomization defined the study cohort. The Fine-Gray competing risks regression model was used to analyze whether the timing of salvage ADT was associated with an increased risk of PCSM after adjusting for age, comorbidity, known PC prognostic factors, and previously identified interactions. Results: After a median follow-up of 5.68 years (interquartile range, 3.05-9.56) following salvage ADT, 49 of the 54 men (91%) died, of which 27 from PC (54% of deaths). Increasing PSA-DT as a continuous covariate (per month increase) was associated with a decreasing risk of PCSM (adjusted hazard ratio [HR], 0.33; 95% CI, 0.13-0.82; P=.02). Among men with a long PSA-DT (≥6 months), initiating salvage ADT later (PSA level >12 ng/mL, upper quartile) versus earlier was associated with an increased risk of PCSM (adjusted HR, 8.84; 95% CI, 1.99-39.27; P=.004), whereas for those with a short PSA-DT (<6 months; adjusted HR, 1.16; 95% CI, 0.38-3.54; P=.79) this was not true. Conclusions: Early initiation of salvage ADT for post-RT PSA failure in men with a PSA-DT of ≥6 months may reduce the risk of PCSM.

Impact of time to testosterone rebound and comorbidity on the risk of cause-specific mortality in men with unfavorable-risk prostate cancer.

BACKGROUND: Herein, the authors evaluated how the time to testosterone rebound (TTR) after radiotherapy (RT) and 6 months of androgen deprivation therapy (ADT) impacted the risk of prostate cancer-specific mortality (PCSM) and cardiovascular-specific mortality (CVM) among men with varying comorbidity extent. METHODS: Between 1995 and 2001, a total of 206 men who were randomized to receive RT either alone or with 6 months of ADT for unfavorable-risk PC and who had a comorbidity score assigned using the Adult Comorbidity Evaluation 27 metric comprised the study cohort. Multivariable competing risk regression was used to evaluate the impact of and possible interaction between comorbidity and TTR on PCSM and CVM. RESULTS: After a median follow-up of 18.19 years, 30 men (18.6%), 39 men (24.2%), and 92 men (57.1%), respectively, had died of PC, CV disease, or other causes. As TTR increased, PCSM significantly decreased in men with no or minimal (adjusted hazard ratio [AHR], 0.53, 95% confidence interval [95% CI], 0.34-0.84 [P =.007]) and moderate to severe (AHR, 0.37; 95% CI, 0.14-0.99 [P = .048]) comorbidity. However, increasing TTR significantly increased the risk of CVM among men with moderate to severe comorbidity (AHR, 1.87; 95% CI, 1.40-2.49 [P <.001]), but not those with no or minimal comorbidity (AHR, 0.86; 95% CI, 0.57-1.29 [P =.46]), leading to a significant interaction between TTR and comorbidity (P = .001). CONCLUSIONS: The results of the current study indicate that considering an intermittent course of ADT such that the TTR approaches 18 months, instead of continuous long-term administration of ADT, in men with moderate to severe comorbidity and high-risk PC may reduce the increased risk of CVM without increasing the risk of PCSM. Cancer 2018;124:1391-9. © 2018 American Cancer Society.

Greatest Percentage Involved Core Length and Risk of Clinically Significant Prostate-Specific Antigen Failure After Radical Prostatectomy.

BACKGROUND: Radical prostatectomy (RP) can cure men with unfavorable intermediate- or high-risk prostate cancer (PC). However, some will experience short prostate-specific antigen (PSA) doubling time (PSADT) failure that requires additional treatment with increased toxicity. The present study investigated whether the greatest percentage of involved biopsy core length (GPC) can preoperatively identify men at risk of short PSADT failure. PATIENTS AND METHODS: A total of 503 men with biopsy-proven PC underwent RP at an academic institution from January 2005 to December 2008. Men with incomplete pathologic information, those who had received neoadjuvant or adjuvant hormonal therapy or chemotherapy, and those who had undergone adjuvant radiation therapy were excluded. The median follow-up period was 4.89 years (interquartile range, 1.97-5.68 years). A competing risk regression was used to assess whether an increasing GPC value was associated with an increased PSADT at < 10-month failure risk, adjusting for age, percentage of positive biopsy results, and risk group. RESULTS: Of the 402 men, 34 (8.46%) developed PSA failure, 17 (50.0%) of whom had a PSADT of < 10 months. An increasing GPC value was significantly associated with an increased PSADT of < 10-month failure risk (adjusted hazard ratio, 1.03; 95% confidence interval, 1.01-1.06; P = .015). Men with a GPC > 30% (median) versus ≤ 30% and unfavorable intermediate- or high-risk PC (P = .011), but not low or favorable intermediate-risk PC (P = .57), had a significantly greater incidence of PSADT < 10-month failure estimates (30% vs. 0% at 5 years). CONCLUSION: Men planning to undergo RP for unfavorable intermediate- or high-risk PC with a GPC of > 30% should be considered for randomized trials evaluating the effect on survival of the neoadjuvant use of treatment that extends survival in those with castrate-resistant metastatic PC.

Maximum tumor diameter and the risk of prostate-specific antigen recurrence after radical prostatectomy.

INTRODUCTION/BACKGROUND: The aim of this study was to investigate whether the MTD could identify men at low risk of PSA recurrence after RP who might not benefit from ART despite other adverse features. PATIENTS AND METHODS: The study cohort consisted of 354 men with T1c to T2 prostate cancer diagnosed between September 2001 and December 2008 who underwent RP without adjuvant therapy. Multivariable Cox regression was used to assess the effect of MTD on the risk of PSA recurrence (> 0.1 ng/mL and verified), adjusting for known predictors. RESULTS: After a median follow-up of 4.0 years, 34 men (9.6%) experienced PSA failure. In multivariable analysis, increasing MTD was significantly associated with an increased PSA recurrence risk (hazard ratio, 2.74; 95% confidence interval, 1.23-6.10; P = .01) within the interaction model. Estimates of PSA recurrence-free survival stratified around the median MTD value (1.2 cm) were significantly different in men with a pre-RP PSA > 4 ng/mL (P < .001; 5-year estimate: 74.5% vs. 99.0%) but not in men with PSA ≤ 4 ng/mL (P = .59; 5-year estimate: 89.6% vs. 92.6%), consistent with the significant interaction (P = .004) between PSA and MTD. Moreover, in men with a pre-RP PSA > 4 ng/mL these estimates were significantly different if at least 1 adverse feature (pT3, R1, or Gleason score ≥ 8) was present at RP (P = .01; 5-year estimate: 46.6% vs. 100%) versus none (P = .09; 5-year estimate: 93.4% vs. 98.9%). CONCLUSION: Men with a low MTD (≤ 1.2 cm) appear to be at low risk of PSA recurrence despite adverse features at RP and might not benefit from ART.

Natural history of untreated prostate specific antigen radiorecurrent prostate cancer in men with favorable prognostic indicators.

Background and Purpose. Life expectancy data could identify men with favorable post-radiation prostate-specific antigen (PSA) failure kinetics unlikely to require androgen deprivation therapy (ADT). Materials and Methods. Of 206 men with unfavorable-risk prostate cancer in a randomized trial of radiation versus radiation and ADT, 53 experienced a PSA failure and were followed without salvage ADT. Comorbidity, age and established prognostic factors were assessed for relationship to death using Cox regression analyses. Results. The median age at failure, interval to PSA failure, and PSA doubling time were 76.6 years (interquartile range [IQR]: 71.8-79.3), 49.1 months (IQR: 37.7-87.4), and 25 months (IQR: 13.1-42.8), respectively. After a median follow up of 4.0 years following PSA failure, 45% of men had died, none from prostate cancer and no one had developed metastases. Both increasing age at PSA failure (HR: 1.14; 95% CI: 1.03-1.25; P = 0.008) and the presence of moderate to severe comorbidity (HR: 12.5; 95% CI: 3.81-41.0; P < 0.001) were significantly associated with an increased risk of death. Conclusions. Men over the age of 76 with significant comorbidity and a PSA doubling time >2 years following post-radiation PSA failure appear to be good candidates for observation without ADT intervention.

The effect of differing Gleason scores at biopsy on the odds of upgrading and the risk of death from prostate cancer.

INTRODUCTION/BACKGROUND: The GS is an established prostate cancer prognostic factor. Whether the presence of differing GSs at biopsy (eg, 4+3 and 3+3), which we term ComboGS, improves the prognosis that would be predicted based on the highest GS (eg, 4+3) because of decreased upgrading is unknown. Therefore, we evaluated the odds of upgrading at time of radical prostatectomy (RP) and the risk of PCSM when ComboGS was present versus absent. PATIENTS AND METHODS: Logistic and competing risks regression were performed to assess the effect that ComboGS had on the odds of upgrading at time of RP in the index (n = 134) and validation cohorts (n = 356) and the risk of PCSM after definitive therapy in a long-term cohort (n = 666), adjusting for known predictors of these end points. We calculated and compared the area under the curve using a receiver operating characteristic analysis when ComboGS was included versus excluded from the upgrading models. RESULTS: ComboGS was associated with decreased odds of upgrading (index: adjusted odds ratio [AOR], 0.14; 95% confidence interval [CI], 0.04-0.50; P = .003; validation: AOR, 0.24; 95% CI, 0.11-0.51; P < .001) and added significantly to the predictive value of upgrading for the in-sample index (P = .02), validation (P = .003), and out-of-sample prediction models (P = .002). ComboGS was also associated with a decreased risk of PCSM (adjusted hazard ratio, 0.40; 95% CI, 0.19-0.85; P = .02). CONCLUSION: Differing biopsy GSs are associated with a lower odds of upgrading and risk of PCSM. If validated, future randomized noninferiority studies evaluating deescalated treatment approaches in men with ComboGS could be considered.

Greatest percentage of involved core length and the risk of death from prostate cancer in men with highest Gleason score ≥ 7.

INTRODUCTION/BACKGROUND: Men with highest GS ≥ 7 and a differing, lower GS core (ComboGS) have decreased PC-specific mortality (PCSM) risk after RT or RT and androgen deprivation therapy (ADT). Whether the greatest percentage of involved core length (GPC) modulates this risk is unknown. PATIENTS AND METHODS: Men with GS ≥ 7 PC (n = 333) consecutively treated between December 1989 and July 2000 using RT (n = 268; 80%) or RT and 6 months of ADT (n = 65; 20%) comprised the study cohort. The GPC was calculated using biopsy core and tumor lengths. We used competing risks regression to assess whether increasing GPC was associated with increased PCSM risk in men with or without ComboGS adjusting for risk group, age, and treatment. RESULTS: After a median follow-up of 5.36 years (interquartile range, 3.22-7.61 years), 92 (28%) men died, 28 (30%) of PC. Increasing GPC was significantly associated with increased risk of PCSM (adjusted hazard ratio, 1.02; 95% confidence interval, 1.01-1.03; P = .005). Men with GPC ≥ 50% versus < 50% had significantly greater PCSM estimates when ComboGS was present (P < .001) versus absent (P = .55). Of the 127 men with ComboGS and GPC < 50%, 83% were treated with RT alone and 2 PC deaths were observed; neither in men with GS 7 and favorable intermediate-risk PC. CONCLUSION: Men treated with RT for ComboGS, GPC < 50%, GS 7, and favorable intermediate-risk PC have a very low risk of early PCSM. The RTOG 0815 trial will establish whether ADT is necessary to optimize curability in these men.

The likelihood of death from prostate cancer in men with favorable or unfavorable intermediate-risk disease.

BACKGROUND: Recently, men with intermediate-risk prostate cancer (PC) were classified into favorable and unfavorable categories; however, whether the risk of PC-specific mortality (PCSM) among men with high-risk PC versus unfavorable intermediate-risk PC is increased is unknown. METHODS: In a prospective, randomized trial conducted between 1995 and 2001, 206 men with intermediate-risk or high-risk PC were randomized to receive 70 Gy with or without 6 months of androgen-suppression therapy (AST). The subgroup of 197 patients with information available on the percentage of positive biopsies formed the cohort. Fine and Gray regression analysis was used to assess whether men with high-risk PC versus unfavorable intermediate-risk PC had an increased risk of PCSM. RESULTS: After a median follow-up of 14.3 years, there were 127 deaths (64.5%), including 22 deaths (17.3%) from PC. There were no PC deaths in the favorable intermediate-risk group. There was an increase in the risk of PCSM among men with high-risk PC versus unfavorable intermediate-risk PC, but the difference was not significant (adjusted hazard ratio, 1.59; 95% confidence interval, 0.66-3.83; P = .30) after adjusting for age, randomized treatment arm, and comorbidity. CONCLUSIONS: The lack of PC deaths among men with favorable intermediate-risk PC suggests that adding AST may not reduce their risk of PCSM; whereas many men with unfavorable intermediate-risk PC are at risk for harboring occult PC with Gleason scores from 8 to 10 and, if proven, would benefit from long-term AST. Multiparametric magnetic resonance imaging and targeted biopsy of suspicious lesions should be considered to identify PC with Gleason scores from 8 to 10 in these men.

Biopsy Gleason score and the duration of testosterone suppression among men treated with external beam radiation and 6 months of combined androgen blockade.

UNLABELLED: Study Type - Therapy (case series) Level of Evidence 4. What's known on the subject? and What does the study add? The return of testosterone to normal levels following short-course androgen blockade in prostate cancer is variable. Factors associated with a longer time to recovery include older age and lower baseline testosterone level. In this study, we found that among men treated with 6 months of combined androgen blockade and radiation therapy, higher biopsy Gleason grade was associated with a shorter time to testosterone normalization. OBJECTIVE: • To determine whether the biopsy Gleason score is associated with duration of testosterone suppression following 6 months of combined androgen blockade (CAB) and radiation therapy (RT) in men with prostate cancer (PCa). PATIENTS AND METHODS: • The study cohort consisted of 221 men with PCa treated with RT and 6 months of CAB between 1996 and 2005. • We defined the duration of testosterone suppression as the time between the last day of CAB and the date the testosterone returned to ≥ 252 ng/dL. We used Cox regression multivariable analysis to relate biopsy Gleason score to duration of testosterone suppression following cessation of CAB. RESULTS: • A biopsy Gleason score of 8-10 had an adjusted hazard ratio (AHR) of 1.56 (95% confidence interval [CI] 1.04, 2.34; P= 0.03) for a shorter time to testosterone normalization relative to Gleason 6. Specifically, the 51 men with biopsy Gleason score of 8-10 had a median time to testosterone normalization of 17.0 months compared with 22.1 months and 23.8 months for those with biopsy Gleason ≤ 6 and 7, respectively. • Increasing age was significantly associated with a longer duration of testosterone suppression (AHR of 0.95 [95% CI 0.92, 0.97; P < 0.001]) as was a higher baseline PSA (AHR 0.82 [95% CI 0.69, 0.97; P= 0.02]). CONCLUSION: • A biopsy Gleason score of 8-10 was associated with a shorter period of testosterone suppression following 6 months of CAB and RT. These data are consistent with the hypothesis that a factor released from high-grade PCa cells may impact on testosterone production.

Evaluating the combined effect of comorbidity and prostate-specific antigen kinetics on the risk of death in men after prostate-specific antigen recurrence.

PURPOSE: We examined whether time-dependent continuous prostate-specific antigen (PSA) velocity at recurrence was associated with all cause mortality (ACM) adjusting for comorbidity levels among men treated with definitive radiation therapy (RT) alone with or without androgen suppression therapy (AST) in the setting of a randomized controlled trial. PATIENTS AND METHODS: From 1995 to 2001, 206 men with localized, unfavorable prostate cancer were randomly assigned to receive RT alone or RT and AST combined. Cox multivariate regression analysis was performed to evaluate the relationship between PSA velocity at recurrence and ACM, adjusting for known prostate cancer prognostic factors, including Adult Comorbidity Evaluation 27 comorbidity level. RESULTS: With a median follow-up of 8.4 years, 89 biochemical recurrences and 74 ACM deaths occurred. Among all patients, higher PSA velocity was associated with increased ACM (hazard ratio [HR], 1.47; 95% CI, 1.07 to 1.44; P < .001) after adjusting for age, treatment arm, comorbidity score, and salvage AST. For 89 patients with biochemical recurrence, increasing PSA velocity at recurrence (HR, 1.60; 95% CI, 1.23 to 2.09; P < or = .001) and moderate to severe comorbidity score (HR, 7.94; 95% CI, 1.55 to 40.52; P = .01) were associated with increased ACM. PSA velocity at recurrence was associated with significantly higher risk of ACM among patients with no or minimal comorbidity (P < .001), but not moderate to severe comorbidity (P = .12). CONCLUSION: Rapid PSA velocity at recurrence is significantly associated with an increased risk of ACM among patients with no or minimal comorbidity but not moderate to severe comorbidity. These findings support judicious use of salvage AST, particularly in men with moderate to severe comorbidities, where prospective surveillance protocols are needed.

Influence of body mass index on prostate-specific antigen failure after androgen suppression and radiation therapy for localized prostate cancer.

BACKGROUND: Increasing body mass index (BMI) is associated with shorter time to prostate-specific antigen (PSA) failure after radical prostatectomy. Whether BMI is associated with time to PSA failure was investigated in men treated with androgen suppression therapy (AST) and radiation therapy (RT) for clinically localized prostate cancer. METHODS: The observational prospective cohort study consisted of 102 men with clinically localized prostate cancer who received 70 Gy RT with 6 months of AST on a single arm of a randomized trial between December 1995 and April 2001. Height and weight data were available at baseline for 99 (97%) of the men, from which BMI was calculated. Adjusting for age (continuous) and known prognostic factors including PSA level (continuous), Gleason score, and T-category, Cox regression analyses were performed to analyze whether BMI (continuous) was associated with time to PSA failure (PSA >1.0 ng/mL and increasing >0.2 ng/mL on 2 consecutive visits). RESULTS: Median age and median BMI (interquartile range [IQR]) at baseline was 72 (69.1-74.7) years and 27.4 (24.8-30.7) kg/m,(2) respectively. In addition to an increasing PSA level (P = .006) and Gleason 8-10 cancer (P = .024), after a median follow-up (IQR) of 6.9 (5.6-8.5) years, an increasing BMI was also significantly associated with a shorter time to PSA failure (adjusted hazard ratio [HR]: 1.10; 95% confidence interval [CI]: 1.01-1.19; P = .026) after RT and AST. CONCLUSIONS: After adjusting for known prognostic factors, baseline BMI is significantly associated with time to PSA failure after RT and AST for men with clinically localized prostate cancer. Further study is warranted to assess the impact of an increasing BMI after AST administration on PSA failure, prostate cancer-specific, and all-cause mortality.