Clinical outcomes of definitive whole pelvic radiotherapy for clinical lymph node metastatic prostate cancer

Abstract

Background In this study, we aim to present the clinical outcomes of radiotherapy (RT) in clinical pelvic lymph node‐positive prostate cancer (cN1) patients. We also analyze the prognostic factors with focus on RT dose escalation to metastatic lymph nodes (LN). Methods We retrospectively analyzed the data from cN1 patients who were treated with definitive RT and androgen deprivation therapy (ADT) between June 2004 and February 2016. All patients received localized irradiation to the prostate region and whole pelvis irradiation. Some patients received intensity‐modulated radiation therapy with RT dose escalation to metastatic LN. Univariate analyses using log‐rank test were performed to find prognostic factors between patient subgroups. Results Fifty‐one consecutive patients were identified. The median follow‐up period for all patients was 88 (range 20‐157) months. Primary Gleason pattern and LN RT dose were statistically significant prognostic factors for relapse‐free survival (RFS) and distant metastasis‐free survival (DMFS). Especially, RT dose escalation (60 Gy or more) to metastatic LN significantly improved RFS and DMFS compared with standard dose RT (4‐year RFS 90.6% vs 82.1%, 7‐year RFS 90.6% vs 58.0%, P = .015; 4‐year DMFS 90.6% vs 82.1%, 7‐year DMFS 90.6% vs 62.8%, P = .023). The following factors were all statistically significant for biochemical relapse‐free survival (BRFS): T stage, LN RT dose, local RT dose, and ADT duration period. Any significantly different toxicity was not seen for each LN or local RT dose except for the incident rate of grade 2 or more acute urinary retention, which was significantly higher in the higher LN RT dose (60 Gy or more) group by the Chi‐square test. Conclusions RT dose escalation to metastatic LN in cN1 patients improves BRFS, RFS, and DMFS at 4 and 7 years, without increasing severe adverse events.

Ten‐year outcomes of whole‐pelvic intensity‐modulated radiation therapy for prostate cancer with regional lymph node metastasis

“…However, recent multiple retrospective studies and database analyses showed the efficacy of local treatment (prostatectomy or EBRT) for N1M0 prostate cancer patients. 10 , 15 , 16…”

“…There are only two published report regarding WP IMRT for N1M0 prostate cancer. 9 , 10 However, in one report, more than half (18/31) of the cases were pN+ patients treated with radical prostatectomy, and in another report more than half of the patients were treated with conventional radiotherapy (RT), not IMRT. There has been no report on clinical outcomes of cN1M0 prostate cancer uniformly treated with high‐dose WP IMRT.…”

“…To date, WP IMRT has been applied mainly to high‐risk, localized, and locally advanced cases. There are only two published report regarding WP IMRT for N1M0 prostate cancer 9,10 . However, in one report, more than half (18/31) of the cases were pN+ patients treated with radical prostatectomy, and in another report more than half of the patients were treated with conventional radiotherapy (RT), not IMRT.…”

“…One of the reasons for this was the rarity of N1M0 prostate cancer and lack of prospective trials comparing ADT alone versus ADT with RT. However, recent multiple retrospective studies and database analyses showed the efficacy of local treatment (prostatectomy or EBRT) for N1M0 prostate cancer patients 10,15,16. F I G U R E 4…”

Elective nodal radiotherapy in prostate cancer

“…Table 1 gives an overview of prospective trials evaluating the value of whole pelvis radiotherapy in four different settings: (1) patients with cN0 (clinically node negative) disease and a substantial risk (term varies largely between studies) 1,3,7,8,11,14,20,24 of pathologically involved nodes in the primary setting, (2) patients with cN1 (clinically node positive) disease in the primary setting, [25][26][27][28][29][30][31] (3) patients with adjuvant pN1 (pathologically node positive) disease in the postoperative setting, 12,[32][33][34][35][36][37] and (4) patients with pNx (unknown node status) and pN0 (pathologically node negative) disease in the postoperative salvage setting. [38][39][40] Patients with cN0 disease in the primary setting…”