Comparison of Outcomes and Toxicity Between Extreme and Moderate Radiation Therapy Hypofractionation in Localized Prostate Cancer: A Propensity Score Analysis

Int J Radiat Oncol Biol Phys. 2019 Nov 15;105(4):735-744. doi: 10.1016/j.ijrobp.2019.07.027. Epub 2019 Aug 1.

Abstract

Purpose: To compare clinical outcomes and toxicities of 2 radiation therapy (RT) schemes for localized prostate cancer (PCa): extreme hypofractionation (EH; fractions of 6.5-7 Gy to a total dose of 32.5-35 Gy) and the moderate hypofractionation (MH; 26 fractions of 2.7 Gy to a total dose of 70.2 Gy). A propensity score method was used to compare the EH-RT and MH-RT groups.

Methods and materials: Our analysis included a total of 421 patients divided in 2 groups: 227 treated with MH-RT and 194 treated with EH-RT (43 and 30 months median follow-up, respectively). Propensity matching created comparable cohorts. Statistical evaluations were performed on the whole cohort, stratifying the analyses by risk strata factors identified with the propensity scores, and on a subgroup of patients matched by propensity score. Multivariate proportional hazard Cox models were used to compare the 2 groups, mainly for gastrointestinal and genitourinary toxicity and secondarily for clinical progression-free survival, biochemical progression-free survival, and overall survival.

Results: Considering the whole population, acute genitourinary and gastrointestinal greater than grade 1 was significantly more frequent in the whole MH-RT group (P < .001 and P < .002, respectively). A borderline significantly greater late genitourinary was confirmed with the multivariate analysis (P = .07). Concerning tumor outcome, no statistically significant differences were observed. After propensity score matching, 226 patients were included in the analysis. The 2 obtained propensity score matched groups did not differ for any of the clinical and pathologic variables considered for the analysis, resulting in well-balanced cohorts. The results obtained on the whole population were confirmed in the matched groups.

Conclusions: EH-RT yields a decreased risk of acute or late toxicities compared with MH-RT, and oncologic outcomes were comparable. Our data indicate that EH-RT might be considered as a treatment modality of choice for select patients with PCa.

Trial registration: ClinicalTrials.gov NCT01913717.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Cohort Studies
  • Gastrointestinal Tract / radiation effects
  • Humans
  • Male
  • Middle Aged
  • Propensity Score*
  • Proportional Hazards Models
  • Prostatic Neoplasms / pathology
  • Prostatic Neoplasms / radiotherapy*
  • Radiation Dose Hypofractionation*
  • Radiation Injuries / complications*
  • Retrospective Studies
  • Treatment Outcome
  • Urogenital System / radiation effects

Associated data

  • ClinicalTrials.gov/NCT01913717