Long-Term Outcomes of Stereotactic Body Radiotherapy (SBRT) for Intraprostatic Relapse after Definitive Radiotherapy for Prostate Cancer: Patterns of Failure and Association between Volume of Irradiation and Late Toxicity

Stereotactic body radiotherapy (SBRT) re-irradiation for local failures following radical prostatectomy and post-operative radiotherapy

PURPOSE

Local recurrences after radical prostatectomy (RP) and postoperative radiotherapy (RT) are challenging for salvage treatment. Retrospective analysis of own experiences with salvage re-irradiation was performed.

METHODS

The study included all consecutive patients treated with salvage stereotactic body radiotherapy (sSBRT) for prostate bed recurrence following RP and postoperative RT at a single tertiary center between 2014 and 2021. Treatment toxicity defined as the occurrence of CTCAE grade ≥ 2 genito-urinary (GU) or gastro-intestinal (GI) adverse events (AEs) was assessed. A PSA response, biochemical control (BC) and overall survival (OS) were also evaluated.

RESULTS

The study group included 32 patients with a median age of 68 years and a median follow-up of 41 months, treated with CyberKnife (53%) or Linac (47%) sSBRT. Total dose of 33.75-36.25 Gy in five fractions (72%) was applied in the majority of them. Approximately 19% patients reported grade ≥ 2 GU AEs both at baseline and at three months, and grade ≥ 2 GI toxicity increased from 0% at baseline to 6% at three months after sSBRT. There was some clinically relevant increase in late toxicity with 31% patients reporting late ≥ 2 GU, and 12.5% late ≥ 2 GI AEs. Two grade 3 AEs were recorded: recto-urinary fistulas. The majority of patients showed a PSA response (91% at one year post-sSBRT). The 3‑year BC was 40% and 3‑year OS was 87%.

CONCLUSIONS

Manageable toxicity profile and satisfactory biochemical response suggest that SBRT in patients with local recurrence following RP and postoperative RT might be a salvage option for selected patients.

Efficacy and safety analysis in metastatic cancer patients treated with multiple courses of repeat radiation therapy

Background and purpose

Due to advances in oncology, a growing proportion of patients is treated with repetitive courses of radiotherapy. The aim of this study is to analyze whether radiotherapy maintains its safety and efficacy profile in patients treated with multiple repeat courses of irradiation.

Material and methods

All patients treated between 2011 and 2019 at our institution were screened for a minimum of five repeat irradiation courses, to analyze treatment characteristics, survival, safety and efficacy. The type of re-irradiation was classified according to ESTRO-EORTC consensus guidelines.

Results

A total of n = 112 patients receiving n = 660 radiotherapy courses were included in this retrospective cohort study. The most frequent primary tumors were lung cancer in 41.9 % (n = 47) and malignant melanoma in 8.9 % (n = 10). The most frequent re-irradiation types were repeat irradiation and Type 2 re-irradiation in 309 (46.8 %) and 113 (17.1 %) cases, respectively. Median survival after the first course of radiotherapy was 3.6 (0.3-13.4) years. Response to radiotherapy was observed in 548 (83.0 %) cases and CTCAE toxicity grade ≥ 3 was observed in 21 (3.2 %) cases. An increasing number of RT courses (HR: 1.30, p=<0.0001), Type 1 re-irradiation (HR 3.50, p = 0.008) and KPS ≤ 80 % (HR: 2.02, p = 0.002) were associated with significantly worse treatment responses. Toxicity rates remained stable with increasing numbers of RT courses.

Conclusion

Multiple courses of repeat radiotherapy maintain a favorable therapeutic ratio of high response combined with reasonable safety profile.

Effectiveness of Robotic Stereotactic Radiotherapy in Patients Undergoing Re-irradiation: A Review

Stereotactic ablative radiotherapy (SABR) is a possible treatment option for patients who develop recurrence within or at the edge of a previously irradiated volume. Robotic stereotactic radiotherapy is the result of technological advances in robotic precision, real-time imaging, non-invasive, highly customizable treatment plan, and delivery with sub-millimeter accuracy. This article reviews the radiobiologic, technical, and clinical aspects of robotic-based SABR re-irradiation for various anatomical sites. An extensive literature search was performed to identify articles on the utilization of robotic stereotactic radiotherapy for patients undergoing re-irradiation. The reported prescription dose and fractionation data along with outcomes such as overall survival, local control rates, and toxicities were qualitatively reviewed. The findings consistently indicate that re-irradiation using robotic SABR provides encouraging survival rates with minimal toxicity in the clinical setting of various anatomical sites delivered using locally non-invasive means where other treatment options are scarce.