Adjuvant radiotherapy in node positive prostate cancer patients: a debate still on. when, for whom?

Abstract

Objective To evaluate the impact of adjuvant radiotherapy (aRT) in patients with prostate cancer (PCa) found to have pathological positive lymph nodes (pN1s) after radical prostatectomy (RP) and extended pelvic lymph node dissection (ePLND) with regard to distant recurrence‐free survival (RFS), according to both main tumour pathological characteristics and number of positive lymph nodes. Biochemical RFS, local RFS, overall survival (OS) and acute and late toxicity were assessed as secondary endpoints. Patients and Methods A retrospective cohort of 187 consecutive patients with pN1 PCa were treated with aRT at the IEO, European Institute of Oncology IRCCS, Milan, Italy. aRT on the tumour bed and pelvis was administered within 6 months of RP. Androgen deprivation therapy was administered according to the guidelines. Univariate and multivariate Cox regression analyses predicting biochemical RFS, local RFS, distant RFS and OS rates were performed to assess whether the number of pN1s represented an independent prognostic factor. The Youden index was computed to find the optimal threshold for the number of pN1s able to discriminate between patients with or without biochemical and clinical relapse. Results At 5 years, local RFS, distant RFS, biochemical RFS and OS were 68%, 71%, 56% and 94%, respectively. The median follow‐up was 49 months. The number of pN1s was significantly associated with biochemical RFS, local RFS and distant RFS. The best threshold for discriminating between patients with or without biochemical and clinical relapse was five pN1s. In multivariate analyses, the number of pN1s was confirmed to be an independent predictor of biochemical RFS, local RFS and distant RFS, but not of OS. Multivariate analyses also showed an increased risk of biochemical relapse for increasing values of initial prostate‐specific antigen and for patients with tumour vascular invasion. Local and distant RFS were also inversely correlated with significantly reduced risk for International Society of Urological Pathology grade group <3 (group 1 or 2 compared to group 3). Conclusions Our data confirmed the encouraging outcomes of patients with pN1 PCa treated with adjuvant treatments and the key role represented by the number of pN1s in predicting biochemical RFS, clinical RFS and distant RFS. Large prospective cohort studies and randomized clinical trials are needed to confirm these results and to identify the subgroup of patients with pN1 PCa who would most benefit from aRT.

What is the best time for postoperative radiation therapy in pN1 prostate cancer?

“…We retrospectively identified all patients treated with RARP and ePLND at a single high-volume center (European Institute of Oncology-IEO) between 2010 and 2020. A subset of the included cohort has already been included in a previous mono-institutional publication [19]. Specifically, the ePLND template consisted of the removal of all external iliac, internal iliac, and obturator LN.…”

“…Conversely, as esRT were considered all treatments administered after more than 6 months after RARP. All patients that underwent aRT or esRT received ADT for 9-12 months as a standard practice in our institution for this setting of patients [19]. Lastly, the population was divided according to the treatments received: the first group encompassed all the patients who underwent adjuvant radiotherapy (aRT) vs. the second group which encompassed all the patients who did not receive RT or received just salvage radiotherapy (no-aRT/esRT).…”

Corrigendum

“…In the article by Marvaso et al. [1], page 458, the data in Table 2, in the ‘Contrast’ column reading ‘6 vs 8’ and ‘7 vs 8’ are incorrect and should be replaced with ‘1 vs 3’ and ‘2 vs 3’, respectively.…”