BACKGROUND:
Success rates with salvage radiotherapy (SRT) in men who have a postprostatectomy biochemical relapse are suboptimal. One treatment‐intensification strategy includes elective irradiation of the pelvic lymph nodes with whole pelvis radiotherapy (WPRT).
METHODS:
An inter‐institutional retrospective cohort study compared outcomes for patients who received SRT at 2 separate academic institutions with disparate treatment paradigms: almost exclusively favoring WPRT (n = 112) versus limiting treatment to the prostate bed (PBRT) (n = 135). Patients were excluded if they had lymph node involvement or if they received androgen‐deprivation therapy. The Cox proportional hazards model was used to adjust for potential confounders.
RESULTS:
In total, 247 patients were analyzed with a median follow‐up of 4 years. The pre‐SRT prostate‐specific antigen (PSA) level (adjusted hazard ratio [HR], 1.58; P < .0001) and a Gleason score of 8 to 10 (adjusted HR, 3.21; P < .0001) were identified as independent predictors of increased risk of biochemical PSA progression after SRT. However, WPRT was not independently associated with biochemical progression‐free survival in the multivariate model (adjusted HR, 0.79; P = .20). Neither low‐risk patients nor high‐risk patients (defined a priori by a preoperative PSA level ≥20 ng/mL, a pathologic Gleason score between 8 and 10, or pathologic T3 tumor classification) benefited from WPRT. Overall survival was similar between treatment groups. When restricting the analysis to patients with pre‐SRT PSA levels ≥0.4 ng/mL (n = 139), WPRT was independently associated with a 53% reduction in the risk of biochemical progression (adjusted HR, 0.47; P = .031).
CONCLUSIONS:
WPRT did not improve outcomes among the entire group but was independently associated with improved biochemical control among patients with pre‐SRT PSA levels ≥0.4 ng/mL. Cancer 2013. © 2012 American Cancer Society.