Reirradiation of Locally Recurrent Prostate Cancer with Cyberknife® System or Volumetric Modulated Arc Therapy (VMAT) and IGRT-Clarity®: Outcomes, Toxicities and Dosimetric Evaluation

Abstract

The management of prostate cancer recurrence following external beam radiotherapy is not defined yet. Stereotaxic body reirradiation therapy showed encouraging results for local and biochemical control. From April 2017 to December 2020, 29 patients with prostate cancer recurrence were collected, joining the retrospective studies CyPro (prot. 46/19 OSS) and CLARO (Prot. 19/20 OSS) trials. Patients received Cyberknife® treatment (17 pts) or alternatively VMAT (Volumetric Modulated Arc Technique) therapy by IGRT (Image-Guided Radiation Therapy)/Clarity® (12 pts). By comparing the reirradiation of two groups, urinary (GU), rectal (GI) toxicities, and biochemical control were investigated. Further, the two techniques were dosimetrically compared by rival plans. The VMAT-IGRT Clarity® treatments were replanned with an optimized template developed for prostate VMAT-SBRT in FFF mode keeping the same dose and fractionation scheduled for Cyberknife Group (30 Gy in 5 fx, at 80% isodose). In the CK group, 23% of patients experienced grade 2 acute GU, while 6% grade 2 acute GI. In the VMAT-Clarity® group, acute GU toxicity was recorded in 17%, while for 8% grade 2 late toxicity was recorded. The dosimetric analysis shows that the VMAT-FFF allows to deliver a biological equivalent dose to CK, with the advantage of reducing the likelihood of toxicities arising.

Linac-based stereotactic salvage reirradiation for intraprostatic prostate cancer recurrence: toxicity and outcomes

“…Brachytherapy allows delivery of high doses to the target volume with remarkable OAR sparing in view of a rapid dose fall-off outside the sources, and more and more experiences have been published on this [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51], so that it is recommended by NCCN guidelines, too. Some other reports describe prostate stereotactic Re-I using the Cyber Knife [52][53][54][55][56][57], or external beam Re-I with VMAT [14,15,58,59]. According to the aforementioned latest systematic review of the literature [31], 18 articles are available in the current literature concerning salvage prostate Re-I, accounting for a total of 511 patients with a median follow-up of 22 months (range 9.6-77.6).…”

PSMA PET‐based stereotactic body radiotherapy for locally recurrent prostate cancer after definitive first‐line therapy

“…Jereczek‐Fossa et al 11 included patients with lymphatic and distant oligometastatic disease. In most studies re‐RT was performed with CyberKnife‐SBRT although there are studies using other modalities as well 20,21 . Because of patient wish or long interval to surgery, we included patients with macroscopic recurrence in the prostatic bed after RPE who would traditionally be subjected to salvage EBRT of the whole fossa first.…”

“…In two other articles, the rates of BNED (biologically no evidence of disease) at the time of FU were given as 41%–82% 17 . After re‐irradiation the median time to biochemical recurrence was 10–16.5 months 11,21 without differentiation of local, regional, and distant recurrences. Since most published data had shorter FU reliable conclusion about long‐term side effects >30 months are difficult to draw 30 .…”

“…In most studies re-RT was performed with CyberKnife-SBRT although there are studies using other modalities as well. 20,21 Because of patient wish or long interval to surgery, we included patients with macroscopic recurrence in the prostatic bed after RPE who would traditionally be subjected to salvage EBRT of the whole fossa first. Francolini et al showed the equivalence of both approaches in a propensity score analysis.…”

“…After re-irradiation the median time to biochemical recurrence was 10-16.5 months11,21 without differentiation of local, regional, and distant recurrences. Since most published T A B L E 1 Patients' charcteristics.…”