Radiotherapy of prostate cancer: impact of treatment characteristics on the incidence of second tumors

Milly Buwenge,Francesco Deodato,Silvia Cammelli,Erica Scirocco,Maria Ntreta,Silvia Bisello,Vincenzo Valentini,Lidia Strigari,Gabriella Macchia,Alessio G Morganti,Giambattista Siepe,Anna Rita Alitto,Savino Cilla

doi:10.1186/s12885-020-6581-5

Abstract

BackgroundIt has been hypothesized that radiotherapy (RT) techniques delivering radiations to larger volumes (IMRT, VMAT) are potentially associated with a higher risk of second primary tumors. The aim of this study was to analyse the impact of RT technique (3D-CRT vs IMRT/VMAT) on the incidence of second tumors in prostate cancer (PCa) patients.MethodsA retrospective study on 2526 previously irradiated PCa patients was performed. Patients were treated with 3D-CRT (21.3%), IMRT (68.1%), or VMAT (10.6%). Second tumors incidence was analysed in 3 categories: pelvic, pelvic and abdominal, and “any site”. The correlation with RT technique was analysed using log-rank test and Cox’s proportional hazard method.ResultsWith a median follow-up of 72 months (range: 9–185), 92 (3.6%) cases of second tumors were recorded with 48 months (range: 9–152) median interval from RT. Actuarial 10-year second tumor free survival (STFS) was 87.3%. Ten-year STFS in patients treated with 3D-CRT and IMRT/VMAT was 85.8 and 84.5%, respectively (p: .627). A significantly higher 10-year cumulative incidence of second tumors in the pelvis was registered in patients treated with IMRT/VMAT compared to 3D-CRT (10.7% vs 6.0%; p: .033). The lower incidence of second pelvic cancers in patients treated with 3D-CRT was confirmed at multivariable analysis (HR: 2.42, 95%CI: 1.07–5.47, p: .034).ConclusionsThe incidence of second pelvic tumors after RT of PCa showed a significant correlation with treatment technique. Further analyses in larger series with prolonged follow-up are needed to confirm these results.

Highlights

It has been hypothesized that radiotherapy (RT) techniques delivering radiations to larger volumes (IMRT, volumetric modulated arc therapy (VMAT)) are potentially associated with a higher risk of second primary tumors
Patients were treated with 3-dimensional conformal RT (3D-CRT) technique (21.3%), intensity-modulated RT (IMRT) (68.1%), or VMAT (10.6%)
A significantly higher 10-year cumulative incidence of second tumors in the pelvis was registered in patients treated with IMRT/VMAT compared to 3D-CRT (10.7% vs 6.0%; p: .033)

Summary

Introduction

It has been hypothesized that radiotherapy (RT) techniques delivering radiations to larger volumes (IMRT, VMAT) are potentially associated with a higher risk of second primary tumors. The aim of this study was to analyse the impact of RT technique (3D-CRT vs IMRT/VMAT) on the incidence of second tumors in prostate cancer (PCa) patients. Prostate cancer (PCa) is the second most common cancer in men worldwide [1]. In the USA, data from the Surveillance, Epidemiology and End Results database led to a forecast of approximately 174,650 new diagnoses and 31,620 deaths from PCa in 2019 [2]. In the late 1990s, 3-dimensional conformal RT (3DCRT) emerged as the optimal RT technique for this tumor due to improved dose distribution compared to conventional 2-dimensional RT.

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