Comparative effectiveness of moderate hypofractionation with volumetric modulated arc therapy versus conventional 3D-radiotherapy after radical prostatectomy

Evidences on the Use of Hypofractionation in Postoperative/Salvage Radiotherapy for Prostate Cancer: Systematic Review of the Literature and Recent Developments

BACKGROUND

Radical prostatectomy (RP) is one possible curative treatment for localized prostate cancer. Despite that, up to 40% of patients will later relapse. Currently, post-operative radiotherapy (PORT) courses deliver 1.8-2 Gy daily to reach a total dose ranging between 64 and 74 Gy, completed in 7-8 weeks. Several articles reported encouraging data in terms of the effectiveness and the related toxicities using hypofractionation schedules. The objective of the present systematic review was to evaluate the clinical outcomes and toxicity of the use of hypofractionation in adjuvant/salvage prostate cancer treatments.

METHODS

Medline was searched via PubMed and Scopus from inception to July 2024 to retrieve studies on hypofractionation in adjuvant/salvage prostate cancer treatments. This study was conducted under PRISMA guidelines.

RESULTS

A total of 139 articles were identified from the initial search. Subsequently, the 139 studies were reviewed by title and abstract. Ninety-five studies were excluded due to being either abstracts or articles not available in English. In the second step, the full texts of 44 studies were reviewed. Eleven studies were excluded for being reviews, study protocols, or focused on SBRT treatments. Finally, 33 studies were included in our analysis, with a total number of 4269 patients. Of the 33 selected studies, 20 were retrospective trials and 11 were phase I/II prospective trials, while 2 studies were prospective phase III trials. The follow-up ranged from 18 to 217 months. Failure-free survival, for those with the longer follow-up, ranged between 85% and 91% at 3 years, 47 and 78.6% at 5 years and 51.5% at 10 years. Genitourinary (GU) and gastrointestinal acute toxicity was mild to moderate with similar rates across the normofractionated and hypofractionated groups. Acute grade-3 GU toxicity events were unusual, occurring in less than 4% of the cases overall.

CONCLUSION

The present study is the first systematic review of the literature that includes the first two randomized phase III studies published in the literature. Hypofractionated treatment has been shown to be safe, effective, with moderate toxicity and not inferior to conventional RT, with good biochemical control rates.

10-yr Results of Moderately Hypofractionated Postoperative Radiotherapy for Prostate Cancer Focused on Treatment Related Toxicity

INTRODUCTION

To retrospectively report long term outcomes following postoperative hypofractionated radiotherapy (RT) for prostate cancer, emphasizing treatment related toxicity.

MATERIAL AND METHODS

Patients for whom adjuvant or salvage RT was indicated after prostatectomy were treated with a course of moderate hypofractionation consisting in the delivery of 62.5 Gy in 25 fractions (2.5 Gy per fraction) on the prostate bed in 5 consecutive weeks (EQD21.5 = 70 Gy) by means of 3D-CRT in most of them. Androgen deprivation therapy (ADT) was allowed at physician's discretion. Patients were evaluated for urinary and rectal complications according to the Common Terminology Criteria for Adverse Events v4 (CTCAE v.4). Overall survival (OS), biochemical recurrence free survival (bRFS), and metastasis-free survival (MFS) were estimated using the Kaplan-Meier method.

RESULTS

One hundred and ten patients with a median age of 67 years (range 51-78) were enrolled. The majority of them (82%) had adverse pathologic features only, while 31 (28%) had early biochemical relapse. Median PSA level before RT was 0.12 ng/mL (range 0-9 ng/mL). Median time from surgery was 4 months (range 1-136 months). Twenty-eight patients (25.4%) also received ADT. At a median follow up of 103 months (range 19-138 months), late Grade 3 and Grade 4 rectal toxicity were 0.9% (1 case of hematochezia) and 0.9% (1 case of fistula), respectively, while late Grade 3 GU side effects (urethral stenosis) occurred in 9 cases (8%). No late Grade 4 events were observed, respectively. Ten-year OS, b-RFS and MFS were 77.3% (95%CI: 82.1%-72.5%), 53.3% (95%CI: 59.9%-47.6%), and 76.7% (95%CI: 81.2%-72.2%), respectively.

CONCLUSION

Our study provides long term data that a shortened course of postoperative RT is as safe and effective as a long course of conventionally fractionated RT and would improve patients' convenience and significantly reduce RT department workloads.

Unraveling the safety of adjuvant radiotherapy in prostate cancer: impact of older age and hypofractionated regimens on acute and late toxicity - a multicenter comprehensive analysis

Background

The objective of this study was to assess the impact of age and other patient and treatment characteristics on toxicity in prostate cancer patients receiving adjuvant radiotherapy (RT).

Materials and methods

This observational study (ICAROS-1) evaluated both acute (RTOG) and late (RTOG/EORTC) toxicity. Patient- (age; Charlson's comorbidity index) and treatment-related characteristics (nodal irradiation; previous TURP; use, type, and duration of ADT, RT fractionation and technique, image-guidance systems, EQD2 delivered to the prostate bed and pelvic nodes) were recorded and analyzed.

Results

A total of 381 patients were enrolled. The median EQD2 to the prostate bed (α/β=1.5) was 71.4 Gy. The majority of patients (75.4%) were treated with intensity-modulated radiation therapy (IMRT) or volumetric-modulated arc therapy (VMAT). Acute G3 gastrointestinal (GI) and genitourinary (GU) toxicity rates were 0.5% and 1.3%, respectively. No patients experienced >G3 acute toxicity. The multivariable analysis of acute toxicity (binomial logistic regression) showed a statistically significant association between older age (> 65) and decreased odds of G≥2 GI acute toxicity (OR: 0.569; 95%CI: 0.329-0.973; p: 0.040) and decreased odds of G≥2 GU acute toxicity (OR: 0.956; 95%CI: 0.918-0.996; p: 0.031). The 5-year late toxicity-free survival rates for G≥3 GI and GU toxicity were 98.1% and 94.5%, respectively. The only significant correlation found (Cox's regression model) was a reduced risk of late GI toxicity in patients undergoing hypofractionation (HR: 0.38; 95% CI: 0.18-0.78; p: 0.008).

Conclusions

The unexpected results of this analysis could be explained by a "response shift bias" concerning the protective effect of older age and by treatment in later periods (using IMRT/VMAT) concerning the favorable effect of hypofractionation. However, overall, the study suggests that age should not be a reason to avoid adjuvant RT and that the latter is well-tolerated even with moderately hypofractionated regimens.