Repeated TURP predicted late urinary toxicity more strongly than focal prostate dose escalation

KEY POINTS

• The retrospective analysis included 201 prostate cancer patients with prior TURP treated with contemporary definitive image-guided RT. 98 received an intraprostatic SIB to 86 Gy in 39 fractions, while 103 received 78 Gy in 39 fractions without focal boost.
• Median follow-up was 9.5 years, providing unusually mature toxicity data. Overall, late grade ≥2 GU toxicity occurred in 18.0% and late grade ≥3 toxicity in 11.9%.
• Crude late toxicity did not differ significantly between groups: grade ≥2 events occurred in 20.4% with SIB versus 15.7% without, while grade ≥3 events occurred in 11.2% versus 12.6%, respectively.
• Kaplan-Meier estimates showed a numerical difference in 5-year grade ≥2 toxicity — 41.8% with SIB versus 28.5% without SIB — but this did not reach statistical significance. Five-year grade ≥3 rates were 13.8% versus 12.1%.
• After propensity weighting, grade ≥2 toxicity remained statistically similar at 31.9% versus 25.6%, and grade ≥3 toxicity at 10.9% versus 10.1%. These results do not demonstrate equivalence because confidence intervals remained compatible with clinically relevant excess risk.
• Multiple TURP procedures consistently emerged as the strongest marker of severe urinary morbidity, while anticoagulant use and development of acute grade ≥2 GU toxicity also identified patients at higher risk of subsequent late events.
• The manuscript reports differing adjusted odds-ratio estimates for some predictors between the abstract and detailed results. The consistent finding across analyses is the direction of effect: repeated TURP and acute urinary toxicity were associated with greater late GU morbidity, whereas no statistically significant increase in grade ≥3 toxicity was demonstrated with SIB.

CLINICAL TAKEAWAY

SOURCE

Strahlentherapie und Onkologie