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Effect of Dose and Image Guided Radiation Therapy (IGRT) on Patient-Reported Sexual Function in Prostate Radiation Therapy

2016; Elsevier BV; Volume: 96; Issue: 2 Linguagem: Inglês

10.1016/j.ijrobp.2016.06.1207

1879-355X

Julia Murray, Jamie Dean, Helen Mossop, Clare Griffin, Emma Hall, S. Gulliford, David P. Dearnaley,

Genital Health and Disease

Erectile dysfunction (ED) is a significant toxicity associated with prostate RT & can be evaluated using patient reported outcomes. The penile bulb (PB) has been postulated as a surrogate for the essential apparatus of erectile function, but PB dose volume effects are not well established. We determined the dose response characteristics of the PB in men treated within a randomized trial assessing prostate IGRT. A total of 293 men with previously untreated localized prostate cancer entered the IGRT substudy of the CHHiP trial (CRUK/06/16). Men were randomized to receive 2 or 3 Gy per fraction, and to RT delivery with or without daily online IGRT, with standard or reduced CTV-PTV margins. Short course hormone therapy was allowed. At one time point, at least 2 years after completion of RT, the EPIC & IIEF-5 questionnaires were posted to men treated within the substudy. An additional IIEF-5 questionnaire was retrospectively scored by men to reflect their pre-RT status. Planning CT scans& reference dose distributions were imported into analysis software (VODCA). One clinician retrospectively contoured the PB. Dose distributions were converted into equivalent dose in 2Gy per fraction using the Withers formula (α/β ratio 3Gy). PB dose volume (DVH) parameters were analyzed. Atlases of complication incidence (ACI) were created from PB DVH data evaluated against severe ED according to the IIEF-5 scale & moderate or big sexual bother from a computer algorithm. Dose volume constraints were derived using ROC analysis (Youden index) & assessed against the no information rate. 182 men returned completed questionnaires for EPIC-sexual domain & IIEF-5; median time from end of RT to completion was 46.5 (range 35-55) months. Dosimetric data were available for 138 of these men. IIEF-5 data was not evaluated if pre-RT IIEF-5 was incomplete or recorded severe ED, leaving n = 90. The ACI generated indicated a dose volume response, with regions of higher volume & dose possessing a higher proportion of men with severe ED or moderate/big sexual bother. This response was more pronounced with the IIEF-5 scores. Men with severe ED had higher doses to the PB & statistically significant dose volume constraints for severe ED were derived.Abstract 2565; Table 1.% PB volume receiving doseGy20Gy30Gy40Gy50Gy60GyMean doseMax doseSevere ED(n = 41)Median53.743.037.629.715.029.766.2IQR19.1-82.412.7-77.78.4-62.30-46.50-30.411.1-46.345.4-70.0Other ED(n = 49)Median24.716.911.20015.346.0IQR0-47.50-41.00-32.50-18.905.8–25.319.6-63.5Constraints42353120-2358 Open table in a new tab There is a dose volume effect between PB& patient reported sexual function. Discriminatory PB dose-volume constraints predicted patient reported severe ED. This suggests using the PB as an avoidance structure in RT planning. A separate cohort will be assessed to validate findings.