Presentation Authors: Henk Luiting*, Sebastiaan Remmers, Monique Roobol, Rotterdam, Netherlands
Introduction: Adjuvant radiotherapy (aRT) in patients with adverse pathology following radical prostatectomy (RP) improves biochemical progression-free survival. Nevertheless, a wait-and-see policy followed by salvage radiotherapy (sRT) if biochemical recurrence (BCR) occurs is often preferred, reducing overtreatment. Prospective randomized controlled trials to determine if aRT is superior to sRT are ongoing, but due to the long-term oncologic outcome will take several years to become available. To determine predictors for BCR (defined by two consecutive rising PSA values >0.2 ng/ml) following RP in patients with adverse pathology, supporting decision making which patients to select for aRT.
Methods: We retrospectively analysed all patients with adverse pathology following RP (defined by pT2R1 or pT3), with no lymph node involvement, undetectable postoperative PSA values ( < 0.1 ng/ml) and no adjuvant treatment from the ERSPC Rotterdam database. A Cox proportional hazard model was used to assess the association between prognostic factors comprising of grade group (GG), pathological stage, surgical margin, preoperative PSA (log2(PSA)), and BCR. Follow-up was defined as the time between RP and BCR, death, or censoring (2016-12-31).
Results: Our cohort consisted of 355 patients who underwent RP between 1991 and 2016. Median follow up was 12.2 (IQR 7.9 â€“ 16.9) years. A total of 128 men experienced BCR. GG, pathological stage, log2(PSA) and surgical margin were independent predictors for BCR, see Figure 1. Patients in GG 4-5 are most at risk of experiencing BCR (hazard ratio (HR): 5.57 95%CI: 3.00-10.3 p < 0.001 in comparison to GG1). Low-risk patients, defined as GG 1 and â‰¤pT3a, have a risk of 11% (95% CI 6%-16%) of experiencing BCR at 10 years following RP. For all other patients, this risk is 38% (95%CI 30%-44%).
Conclusions: GG, pathological stage, log2(PSA) and surgical margins can be used to select patients who probably benefit most for aRT. Especially patients with GG 4-5 and/or pT3b are at risk for BCR and therefore might benefit most from aRT. In the low-risk group (39% of our cohort) aRT would be considered overtreatment in almost 9 out of 10 patients. Overtreatment, being the major problem of aRT, can be reduced drastically by avoiding its use in low-risk patients.