Treatment-related toxicity of prostate bed versus whole pelvis post-prostatectomy radiation therapy

Abstract

Purpose or Objective There is debate about the effectiveness and toxicity of pelvic lymph node (PLN) irradiation when used for disease recurrence following radical prostatectomy. This study compared the toxicity of radiation therapy (RT) to the prostate bed and pelvic lymph nodes (PBPLN-RT) with prostate-bed only radiation therapy (PBO-RT). Material and Methods Patients with prostate cancer who underwent post-prostatectomy RT in the English National Health Service between 2010-2016 were identified by using data from the Cancer Registry, the National Radiotherapy Dataset, and Hospital Episode Statistics, an administrative database of all hospital admissions. Follow-up was available up to December 31, 2018. Validated indicators were used to identify patients with ≥ Grade 2 gastrointestinal (GI) and genitourinary (GU) toxicity according to the presence of both a procedure code and diagnostic code in patient Hospital Episode Statistics records. A competing risks regression analysis, with adjustment for patient and tumour characteristics, estimated subdistribution hazard ratios by comparing GI and GU toxicity for PBPLN-RT vs PBO-RT. Results 5-year cumulative incidences in the PBO-RT (n= 5,087) and PBPLN-RT (n= 593) groups was 18.2% and 15.9% for GI toxicity, respectively. For GU toxicity it was and 19.1% and 20.7%, respectively. There was no difference in GI or GU toxicity between PBO-RT and PBPLN-RT (GI: adjusted sHR, 0.90, 95% CI, 0.67 to 1.19; P= 0.45); (GU: adjusted sHR, 1.18, 95% CI, 0.98 to 1.44; P= 0.09). Conclusion Including PLNs in the radiation field following radical prostatectomy is not associated with a significant increase in rates of ≥ Grade 2 GI or GU toxicity at 5 years.