ESTRO 2024 - Abstract Book

S2634

Clinical - Urology

ESTRO 2024

The evident shift from conventional to new generation imaging with enhanced sensitivity underscores the evolving landscape of MDT, showing the tight connection between the imaging modality and the PSA levels. The enhanced sensitivity of new generation techniques has led to a decrease in PSA levels at the time of imaging, establishing them as the preferred method for directing MDT.

Keywords: mdt, prostate cancer, imaging

3184

Digital Poster

Post-prostatectomy salvage radiotherapy: the importance of margins

Austin B Hopper 1 , John P Einck 2 , Brent S Rose 1 , Ajay P Sandhu 1

1 UC San Diego, Radiation Medicine and Applied Sciences, La Jolla, USA. 2 University of Kansas, Radiation Oncology, Kansas City, USA

Purpose/Objective:

The recent RTOG 0534 trial publication reported that the addition of short term androgen deprivation therapy (ADT) and pelvic nodal irradiation (PLNRT) to standard prostate bed radiation in patients undergoing salvage radiation therapy (SRT) led to improvement in 5 year freedom from progression compared to prostate bed radiation alone. However, it remains unclear whether this benefit applies to all patients while PLNRT clearly increased the risk of grade 2 or worse adverse events. Prognostic factors for the success of salvage radiation have been reported to include margin status, grade, PSA doubling time, pathologic stage and PSA level at the time of salvage. We sought to analyze clinical pathologic risk factors as predictors of biochemical failure after SRT with particular attention to the significance of margin status and PLNRT to determine if a more tailored approach to SRT might be indicated.

Material/Methods:

227 patients were treated with salvage radiotherapy post-prostatectomy at our institution between January 2005 and December 2013. Patients with positive lymph nodes at surgery were excluded, as were those treated with adjuvant radiation (defined as both RT within 6 months of surgery and at an undetectable PSA) and patients with evident nodal or distant metastases prior to RT, leaving 196 patients for further analysis. All patients were treated with intensity modulated radiotherapy or volumetric arc therapy using daily image guidance. When pelvic lymph nodes were treated the pelvic CTV included the external and internal iliac nodes up to the level of L5/S1 as per the standards of care during the treatment period. Use of androgen deprivation (ADT) and treatment to the pelvic nodes were at discretion of the treating physician.

Data were abstracted from each patient’s electronic medical record for analysis. Biochemical recurrence (BCR) was defined as post-SRT PSA nadir + 0.4 ng/mL. Multivariate Cox regression models were utilized to evaluate the