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abstract

abstract

092

Impact of PDE5 inhibitor (PDE5i) use on biochemical recurrence rates in prostate cancers patients following radiotherapy (RT)

Miranda, EP1; Jenkins, L1; Zelefsky, M1; Schofield, E1; Nelson, C1; Mulhall, J1

1: MSKCC, USA

Objective: There is conflicting data surrounding the concept that PDE5i use is associated with biochemical recurrence (BCR) after radical prostatectomy. To our knowledge, this association has never been studied in prostate cancer patients treated with radiation therapy (RT).
Methods: Prostate cancer patients treated with RT, including brachytherapy (BT), intensity modulated radiation therapy (IMRT), combined therapy (CT), as part of a long-term quality of life study constituted the study population. Patients were evaluated according to PDE5i utilization at 3 months (m), 6m, 9m, 12m, 24m, 36m and 48m. PDE5i groups were: low use (never/sometimes) vs. high use (regularly). BCR was defined as an increase of 2.0 ng/mL from the nadir. The tested predictors of BCR were: age, baseline PSA, PSA nadir, Gleason score (GS), type of RT and PDE5i use at 3 months post-RT. Patients who received ADT were excluded. Cox proportional hazards regression was used for analysis; follow-up time was defined as time from nadir to recurrence, if applicable, or otherwise the final PSA measurement date. Kaplan-Meier (KM) curves were generated to demonstrate the chronology of BCR.

Results: 269 men with at least one available PSA value (total of 3,329 test results) post-nadir were included in our analysis. Mean age at baseline = 66.7±7.6 years. Mean follow-up 81m (12.7-.165.6) after RT completion. RT modality: 39% BT, 49% IMRT, and 11% CT. Mean nadir value= 0.56±0.9 ng/ml. 30 men (9%) had BCR. The mean time to nadir was 59m and to BCR was 21 (2-76)m post-nadir. PDE5i utilization at 3 months post RT: 85% low use, 15% high use. On univariable regression analysis, age, baseline PSA, GS, type of RT were not associated with BCR (all p>0.05). PDE5i group assignment was also not significant. At 24 months post-nadir, there were 8% in the low use PDE5i group with BCR vs. 20% in the high use PDE5i group with BCR (HR=1.19: 95% CI: 0.45-3.13, p=0.73).

Conclusions: These data indicate that there appears to be no link between PDE5i utilization and BCR in prostate cancer patients treated with radiation.

Disclosure:

Work supported by industry: no.

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