Effect of dose to penile bulb (PB) on patient and clinician-reported erectile function (EF) in standard (SF) and hypofractionated (HF) prostate IGRT.
2017; Lippincott Williams & Wilkins; Volume: 35; Issue: 6_suppl Linguagem: Inglês
10.1200/jco.2017.35.6_suppl.71
ISSN1527-7755
AutoresJulia Murray, Jamie Dean, Helen Mossop, Clare Griffin, Emma Hall, David P. Dearnaley, S. Gulliford,
Tópico(s)Urinary Bladder and Prostate Research
Resumo71 Background: PB dose has been hypothesised as predictor of EF post RT, however, PB dose volume effects are not well established. We determined PB dose response characteristics & dose volume constraints using data from randomised trial of prostate IGRT with patient (PRO) & clinician reported (CRO) outcomes. Methods: 293 men were treated within CHHiP IGRT substudy (CRUK/06/16) & randomised to receive 2Gy (SF) or 3Gy (HF) per fraction, without or with daily online IGRT with standard (SM) or reduced (RM) CTV-PTV margins. EF was assessed with RMH CRO & at one time-point (>3 years after RT) with IIEF-5. Men were excluded if impotent at baseline. Planning CT & dose distributions were imported into analysis software (VODCA) & PB contoured. All dose distributions were converted into EQD2 (α/β ratio 3Gy), a separate analysis was done using physical dose (PD) for HF cohort. PB dose volume parameters were analysed & atlases of complication incidence (ACI) evaluated using PRO & CRO. Dose volume constraints using PD & EQD2 were derived using ROC analysis (Youden index) & assessed against the no information rate. Results: Complete dosimetric with CRO & PRO data were available for 175 & 100 men respectively. Of these, men treated with SM vs RM had a higher rate of impotence at 2 & 4 years (49% vs 40% & 47% vs 39%). This was also seen in men recording severe ED (46% vs 37%). ACI indicated a dose volume response. Statistically significant PB dose constraints were derived using EQD2 (SF & HF) & PD for HF cohort (Table). Results using PRO were more pronounced than with CRO. Conclusions: There is a dose volume effect between PB & EF characterised using PRO & CRO. Results suggest that reduction of mean PB dose to <20Gy may lead to an increase of potency preservation rates after prostate RT for both 2Gy & 3Gy schedules. Clinical trial information: ISRCTN97182923. [Table: see text]
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