Can we avoid high levels of dose escalation for high-risk prostate cancer in the setting of androgen deprivation?

Grade and stage misclassification in intermediate unfavorable-risk prostate cancer radiotherapy candidates

BACKGROUND

We tested for upgrading (Gleason grade group [GGG] ≥ 4) and/or upstaging to non-organ-confined stage ([NOC] ≥ pT3/pN1) in intermediate unfavorable-risk (IU) prostate cancer (PCa) patients treated with radical prostatectomy, since both change the considerations for dose and/or type of radiotherapy (RT) and duration of androgen deprivation therapy (ADT).

METHODS

We relied on Surveillance, Epidemiology, and End Results (2010-2015). Proportions of (a) upgrading, (b) upstaging, or (c) upgrading and/or upstaging were tabulated and tested in multivariable logistic regression models.

RESULTS

We identified 7269 IU PCa patients. Upgrading was recorded in 479 (6.6%) and upstaging in 2398 (33.0%), for a total of 2616 (36.0%) upgraded and/or upstaged patients, who no longer fulfilled the IU grade and stage definition. Prostate-specific antigen, clinical stage, biopsy GGG, and percentage of positive cores, neither individually nor in multivariable logistic regression models, discriminated between upgraded and/or upstaged patients versus others.

CONCLUSIONS

IU PCa patients showed very high (36%) upgrading and/or upstaging proportion. Interestingly, the overwhelming majority of those were upstaged to NOC. Conversely, very few were upgraded to GGG ≥ 4. In consequence, more than one-third of IU PCa patients treated with RT may be exposed to suboptimal dose and/or type of RT and to insufficient duration of ADT, since their true grade and stage corresponded to high-risk PCa definition, instead of IU PCa. Data about magnetic resonance imaging were not available but may potentially help with better stage discrimination.

PSMA-PET guided dose-escalated volumetric arc therapy (VMAT) for newly diagnosed lymph node positive prostate cancer: Efficacy and toxicity outcomes at two years

PURPOSE/OBJECTIVES

There are no published reports of prostate specific membrane antigen (PSMA) positron emission tomography (PET) guided dose-escalated intensity-modulated radiation therapy (DE-IMRT) in newly diagnosed lymph node (LN) positive prostate cancer. We report early toxicity and efficacy outcomes with this approach.

MATERIALS/METHODS

Patients with newly diagnosed high-risk prostate cancer were staged using PSMA PET, computed tomography (CT) and bone scans. Patients with LN positive-only metastases were offered curative therapy using 3 months androgen deprivation therapy (ADT) followed by DE-IMRT (using volumetric arc therapy), and 3 years adjuvant ADT. All patients had fiducial marker insertion, with privately insured patients having spacer hydrogel insertion. PET and prostate magnetic resonance imaging were fused with the planning CT. We aimed to deliver 81 Gy in 45 fractions (Fx) to the prostate and PET-positive LNs, and 60 Gy in 45Fx to bilateral elective pelvic LNs.

RESULTS

In all, 46 patients were treated, with 83% Gleason 8-10, 67% T3/T4, median number of LNs 2 (range 1-6), and median PET-positive LN volume 1.14 cc (range 0.15-4.14). LNs were outside of standard contouring guidelines in 37% of patients. The mean PET-positive LN clinical target volume dose ranged from 73.3 to 85.9 Gy (median 83.6 Gy). With 24 months median follow-up, two year failure-free survival was 100%, and 2 year overall survival 95.7%. Acute grade 1 and 2 GI toxicity occurred in 48 and 11% of patients, and GU toxicity in 72 and 24%. Late grade 1, 2 and 3 GI toxicity occurred in 13, 2 and 0%, and GU toxicity 28, 13 and 4%. No toxicity was attributable to the high dose LN boost.

CONCLUSIONS

PSMA PET-guided DE-IMRT up to 81 Gy to the prostate and involved LNs, and long term ADT, is a promising approach for newly diagnosed LN positive prostate cancer. LN contouring guidelines require re-evaluation in the era of PSMA PET imaging.

Long-term outcomes in 1121 Australian prostate cancer patients treated with definitive radiotherapy

INTRODUCTION

Optimal definitive treatment of prostate cancer is controversial, especially in high-risk patients. We report the largest prospective cohort of Australian patients treated with radiotherapy for localised prostate cancer.

METHODS

One thousand, one hundred and twenty-one patients with prostate cancer were prospectively registered and treated to a dose of 70-74 Gy. Patients were classified as low, intermediate or high risk based on PSA, clinical staging and Gleason score. Intermediate-risk patients were treated with 0-6 months of hormonal therapy (ADT) and high-risk patients were offered neoadjuvant and adjuvant ADT. Overall survival (OS) and biochemical relapse-free survival (bNED) were calculated using the Kaplan-Meier method.

RESULTS

Median follow-up was 92 months. Eight-year OS and bNED were 78.4% and 68.1% respectively in the entire cohort. OS for the low, intermediate and high-risk groups was 84.5%, 78.4% and 68% respectively. For these risk groups, bNED was 80.3%, 65.7% and 53.7% respectively. In the intermediate and high-risk group, OS and bNED decreased with increasing number of risk factors.

CONCLUSION

Definitive radiotherapy is an effective treatment for prostate cancer, including in high-risk cases.

Effects of dose-escalated radiotherapy in combination with long-term androgen deprivation on prostate cancer

OBJECTIVE

We aimed to examine the effects of a dose escalation for prostate cancer patients receiving long-term androgen deprivation therapy (ADT).

METHODS

A retrospective analysis of 605 patients treated with radiotherapy (RT) and long-term ADT (National Comprehensive Cancer Network criteria-defined intermediate-risk, minimum 10 months; high-risk and very-high-risk, minimum 20 months) was performed. The median ADT time was 31 months. Cox's proportional hazards models were used to compare biochemical disease-free survival (bDFS), clinical relapse-free survival (cRFS) and overall survival (OS) between the ≥70, <78 Gy group and 78 Gy group in a univariate analysis and to assess the effects of the dose escalation on bDFS in a multivariate analysis.

RESULTS

After a median follow-up of 70 months, 5-year bDFS was significantly better in the 78 Gy group than in the ≥70, <78 Gy group [96 vs 83%; hazard ratio 3.6 (95% confidence interval 2.2-6.1); p < 0.001]. 5-year cRFS and OS were similar between the two groups. The multivariate analysis showed that RT dose was still an independent prognostic factor of bDFS (p = 0.005).

CONCLUSION

The results of the present study suggest that dose escalations result in significant improvements in bDFS, even when used in combination with long-term ADT. A longer follow-up is needed to clarify the effects of dose escalations on cRFS and OS. Advances in knowledge: It remains unclear whether high-dose RT is necessary for improving the outcomes of patients receiving long-term ADT. The results suggest that dose escalations result in significant improvements in biochemical control.

Clinical outcome and toxicity evaluation of simultaneous integrated boost pelvic IMRT/VMAT at different dose levels combined with androgen deprivation therapy in prostate cancer patients

Background

The role of dose escalation in patients receiving long-term androgen deprivation therapy (ADT) is still a controversial issue. The aim of the current study was to evaluate whether dose escalation for ≥76–80 Gy had any advantage in terms of biochemical disease-free survival (BDFS), distant metastasis-free survival (DMFS), or overall survival outcomes over the dose levels from 70 to <76 Gy.

Patients and methods

The study included a cohort of 24 patients classified with high- and intermediate-risk localized prostate cancer. All patients received ADT, starting at 4–6 months before radiation therapy and continued for a total period of 12–24 months in high-risk patients. The treatment plan was given in two phases. In the first phase, the nodal planning target volume (PTV) and the prostate PTV received 48.6 and 54 Gy, respectively, over 27 fractions. The treatment was applied through intensity-modulated radiation therapy or volumetric modulated arc therapy with a simultaneous integrated boost technique.

Results

More than half of the patients were in T3–T4 stage, 79.1% of the patients were in the high-risk category, and all patients received ADT. The rate of acute grade II gastrointestinal and genitourinary toxicities in all patients were 41.7% and 62.5%, respectively. The rate of freedom from grade II rectal toxicity at 2 years was 89% and 83% for patients treated with dose levels <76 and ≥76 Gy, respectively. The rate of BDFS at 2 years was 90% and 85% for doses <76 and ≥76 Gy, respectively. The DMFS at 2 years was 100% and 76% for dose levels <76 and ≥76 Gy, respectively.

Conclusion

In the current study, there were no significant differences in the BDFS and DMFS between patients treated with a dose of <76 and ≥76 Gy, including elective pelvic lymph nodes irradiation combined with ADT.