Retrospective Study
Copyright ©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Oncol. Jul 24, 2022; 13(7): 652-662
Published online Jul 24, 2022. doi: 10.5306/wjco.v13.i7.652
Assessing radiation dose for postoperative radiotherapy in prostate cancer: Real world data
Asunción Hervás-Morón, Jose Domínguez-Rullán, Victor Duque Santana, Mireia Valero, Carmen Vallejo, Sonsoles Sancho, Juan David García Fuentes, Miguel Cámara Gallego, Fernando López-Campos
Asunción Hervás-Morón, Jose Domínguez-Rullán, Victor Duque Santana, Mireia Valero, Carmen Vallejo, Sonsoles Sancho, Fernando López-Campos, Department of Radiation Oncology, Hospital Universitario Ramón Y Cajal, Madrid 28034, Spain
Juan David García Fuentes, Miguel Cámara Gallego, Department of Medical Physics, Hospital Universitario Ramón Y Cajal, Madrid 28034, Spain
Author contributions: Hervás A, Domínguez-Rullán JA, Duque Santana V, Valero M, Vallejo C, Sancho S, García Fuentes JD, Cámara Gallego M and López-Campos F contributed to writing, review, editing and supervision; all authors have read and approve the final manuscript.
Institutional review board statement: The study was reviewed and approved by the Ethics Research Committee of Hospital Universitario Ramón y Cajal.
Informed consent statement: Patients were not required to give informed consent to the study because the analysis used anonymous clinical data that were obtained after each patient agreed to treatment by written consent.
Conflict-of-interest statement: The manuscript has been read and approved for submission by all the named authors. All authors declare no conflict of interests for this article.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Fernando López-Campos, MD, PhD, Professor, Department of Radiation Oncology, Hospital Universitario Ramón Y Cajal, Carretera de Colmenar Viejo Km 9100, Madrid 28034, Spain. fernando_lopez_campos@hotmail.com
Received: March 27, 2022
Peer-review started: March 27, 2022
First decision: May 12, 2022
Revised: June 4, 2022
Accepted: July 5, 2022
Article in press: July 5, 2022
Published online: July 24, 2022
Abstract
BACKGROUND

Approximately 30% of patients with localized prostate cancer (PCa) who undergo radical prostatectomy will develop biochemical recurrence. In these patients, the only potentially curative treatment is postoperative radiotherapy (PORT) with or without hormone therapy. However, the optimal radiotherapy dose is unknown due to the limited data available.

AIM

To determine whether the postoperative radiotherapy dose influences biochemical failure-free survival (BFFS) in patients with PCa.

METHODS

Retrospective analysis of patients who underwent radical prostatectomy for PCa followed by PORT-either adjuvant radiotherapy (ART) or salvage radiotherapy (SRT)-between April 2002 and July 2015. From 2002 to 2010, the prescribed radiation dose to the surgical bed was 66-70 Gy in fractions of 2 Gy; from 2010 until July 2015, the prescribed dose was 70-72 Gy. Patients were grouped into three categories according to the total dose administered: 66-68 Gy, 70 Gy, and 72 Gy. The primary endpoint was BFFS, defined as the post-radiotherapy prostate-specific antigen (PSA) nadir + 0.2 ng/mL. Secondary endpoints were overall survival (OS), cancer-specific survival (CSS), and metastasis-free survival (MFS; based on conventional imaging tests). Treatment-related genitourinary (GU) and gastrointestinal (GI) toxicity was evaluated according to Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer criteria. Finally, we aimed to identify potential prognostic factors. BFFS, OS, CSS, and MFS were calculated with the Kaplan-Meier method and the log-rank test. Univariate and multivariate Cox regression models were performed to explore between-group differences in survival outcome measures.

RESULTS

A total of 301 consecutive patients were included. Of these, 93 (33.6%) received ART and 186 (66.4%) SRT; 22 patients were excluded due to residual macroscopic disease or local recurrence in the surgical bed. In this subgroup (n = 93), 43 patients (46.2%) were Gleason score (GS) ≤ 6, 44 (47.3%) GS 7, and 6 (6.5%) GS ≥ 8; clinical stage was cT1 in 51 (54.8%), cT2 in 35 (39.3%), and cT3 in one patient (1.1%); PSA was < 10 ng/mL in 58 (63%) patients, 10-20 ng/mL in 28 (30.6%), and ≥ 20 ng/mL in 6 (6.4%) patients. No differences were found in BFFS in this patient subset versus the entire cohort of patients (P = 0.66). At a median follow-up of 113 months (range, 4-233), 5- and 10-year BFFS rates were 78.8% and 73.7%, respectively, with OS rates of 93.3% and 81.4%. The 5-year BFFS rates in three groups were as follows: 69.6% (66-68 Gy), 80.5% (70 Gy) and 82.6% (72 Gy) (P = 0.12):the corresponding 10-year rates were 63.9%, 72.9%, and 82.6% (P = 0.12), respectively. No significant between-group differences were observed in MFS, CSS, or OS. On the univariate analysis, the following variables were significantly associated with BFFS: PSA at diagnosis; clinical stage (cT1 vs cT2); GS at diagnosis; treatment indication (ART vs SRT); pre-RT PSA levels; and RT dose 66 -68 Gy vs. 72 Gy (HR: 2.05; 95%CI: 1.02-4.02, P = 0.04). On the multivariate analysis, the following variables remained significant: biopsy GS (HR: 2.85; 95%CI: 1.83-4.43, P < 0.001); clinical stage (HR: 2.31; 95%CI: 1.47-4.43, P = 0.01); and treatment indication (HR: 4.11; 95%CI: 2.06-8.17, P < 0.001). Acute grade (G) 1 GU toxicity was observed in 11 (20.4%), 17 (19.8%), and 3 (8.3%) patients in each group (66-68 Gy, 70 Gy and 72 Gy), respectively (P = 0.295). Acute G2 toxicity was observed in 2 (3.7%), 4 (4.7%) and 2 (5.6%) patients, respectively (P = 0.949). Acute G1 GI toxicity was observed in 16 (29.6%), 23 (26.7%) and 2 (5.6%) patients in each group, respectively (P = 0.011). Acute G2 GI toxicity was observed in 2 (3.7%), 6 (6.9%) and 1 (2.8%) patients, respectively (P = 0.278). No cases of acute G3 GI toxicity were observed.

CONCLUSION

The findings of this retrospective study suggest that postoperative radiotherapy dose intensification in PCa is not superior to conventional radiotherapy treatment.

Keywords: Prostate cancer, Postoperative radiotherapy, Dose intensified, Radiation dose, Biochemical relapse free survival

Core Tip: This retrospective study was performed to evaluate whether higher doses of postoperative radiotherapy influence biochemical failure-free survival rates in patients with prostate cancer. Our results show no significant differences in biochemical failure-free survival, cancer-specific survival, metastasis-free survival, or overall survival regardless of the radiotherapy dose (66-68 vs 70 vs 72 Gy). No differences in treatment-related toxicity were observed. These findings suggest that radiation dose intensification is not superior to conventional radiotherapy treatment.