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

BMC Cancer. 2020 Feb 3;20(1):90. doi: 10.1186/s12885-020-6581-5.

Abstract

Background: 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.

Methods: A 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.

Results: With 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).

Conclusions: The 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.

Keywords: 3D-conformal radiotherapy; Intensity modulated radiotherapy; Prostate neoplasms; Second malignancy; Volumetric modulated arc therapy.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Humans
  • Incidence
  • Male
  • Middle Aged
  • Neoplasms, Second Primary / epidemiology*
  • Neoplasms, Second Primary / etiology
  • Proportional Hazards Models
  • Prostatic Neoplasms / radiotherapy*
  • Radiotherapy, Conformal / adverse effects
  • Radiotherapy, Conformal / methods*
  • Radiotherapy, Intensity-Modulated
  • Retrospective Studies
  • Treatment Outcome