S598 I. J. Radiation Oncology d Biology d Physics Volume 78, Number 3, Supplement, 2010

dysfunction (ED) was measured using the Sexual Health Inventory for Men (SHIM) questionnaire (22-25 = no ED, 17-21 = mildED, 12-16 = mild to moderate ED, 8-11 = moderate ED, and 1-7 = severe); ED was also graded by the physician-assessed MountSinai Erectile Function (MSEF) score (0 = no erectile function, 1 = erections insufficient for intercourse, 2 = erections sufficient forintercourse but suboptimal, and 3 = optimal erections). Multivariate analysis was also performed to take into account HR and totaldose delivered (measured in BED).

Results: Mean IPSS scores for group 1 at 1 yr, 2 yr, 5 yr, and 7 yr follow-up, were 10.2, 9.4, 7.4, and 7.5, respectively. Incomparison, mean IPSS scores for group 2 at 1 yr, 2 yr, 5 yr, and 7 yr follow-up, were 10.2, 9.6, 8.5, and 8.3, respectively.For groups 1 and 2, average changes in SHIM scores were, respectively, -4.0 and -6.6 at 1yr (p = 2, post-treatment scores =\1 were noted, respectively, in 26% and 56% of patients at 1yr; 27% and 47% at 2yr; 35% and 60% at 5yr; and 42% and64% at 7yr (p \ .001 for all years). Of note, more patients received HR in group 2 than in group 1 (87% vs. 38%, respectively);the median duration of HR was longer for group 2 than group 1 (9 mo vs. 6 mo, respectively). Multivariable analyses identifiedboth treatment group and HR as significant causes of decreases in MSEF at year 1 (p \ 0.001 and p = .001, respectively), but atyear 2, only the treatment group was significant and HR was not (p = .005 and p = .191, respectively); at year 5, treatment groupremained significant and HR was not (p = .016 and p = .507, respectively). Total dose delivered did not independently predicta decrease in MSEF.

Conclusions: Patients receiving BR + EBRT are more likely to experience erectile dysfunction than patients receiving BR alone;HR was also noted to independently predict decreases in ED in the first year after treatment, but was no longer significant after 2 yrfollow-up. No differences in urinary symptoms were observed.

Author Disclosure: I.E. Friedman, None; K. Forsythe, None; N.N. Stone, Prologics, LLC, E. Ownership Interest; Nihon Medi-Physics, F. Consultant/Advisory Board; B-K Medical, F. Consultant/Advisory Board; R.G. Stock, None.

2882 Does Hormone Therapy Exacerbate the Adverse Effects of Radiotherapy in the Treatment of Men with

Prostate Cancer? A Quality of Life Study

J. D. Grant, M. S. Litwin, L. Kwan, S. P. Lee, M. L. Steinberg, C. R. King

University of California, Los Angeles, Los Angeles, CA

Purpose/Objective(s): This study examines whether Androgen Deprivation Therapy (ADT) as an adjunct to radiotherapy impactshealth-related quality of life (HRQOL) outcomes in patients with localized prostate cancer treated definitively with either externalbeam radiation therapy (EBRT) or brachytherapy (BT).

Materials/Methods: From 1999 to 2003, patients anticipating treatment for localized prostate cancer were enrolled in a pro-spective study at UCLA. At defined pre- and post-treatment intervals out to 48 months, participants completed validatedtools including the Medical Outcomes Study Short Form-36 (SF-36), the University of California, Los Angeles ProstateCancer Index (PCI), and the American Urological Association Symptoms Index (AUASI). 81 men were treated withEBRT alone and 67 were treated with EBRT+ADT. 67 patients had EBRT only, 63 had BT monotherapy, and 18 hadEBRT+BT. Median ADT duration was 4 months. We compared the time to return to baseline for men who did or didnot receive ADT in 6 HRQOL domains: physical and mental composite scores, AUASI, urinary control, sexual function,and bowel function. Univariate and multivariate analysis were performed. Covariates included age, clinical stage, and co-morbidities.

Results: Multivariate analysis identified factors associated with longer time to return to baseline mental health, including non-white race (2 months, p = 0.008), history of stroke (6 months, p \ 0.001) and history of alcohol use (3 months, p = 0.037).Men treated with BT monotherapy experienced longer time to return to baseline for urinary control (PCI, 2.8 months, p =0.006) and urinary symptoms (AUASI, 7.4 months, p \ 0.001). The time to return to baseline levels in any of the 6 HRQOL do-mains was not significantly affected by the addition of ADT. Use of erectile dysfunction medications or alpha blockers did notdiffer between patients receiving ADT or not. Men receiving ADT as an adjunct to radiotherapy had significantly higher-risk pros-tate cancer.

Conclusions: Our study shows that the addition of ADT to definitive radiotherapy does not significantly impact the time to return tobaseline scores in 6 patient-reported HRQOL domains. These data may be valuable for patients and physicians when weighing thetoxicity and benefits of ADT when added to definitive radiation.

Author Disclosure: J.D. Grant, None; M.S. Litwin, None; L. Kwan, None; S.P. Lee, None; M.L. Steinberg, None; C.R. King, None.

2883 A Comparison of the Impact of Isotope on Acute Urinary Toxicity following Interstitial Brachytherapy and

External Beam Radiation Therapy for Clinically Localized Prostate Cancer

M. A. Kollmeier, E. Algur, M. Schechter, X. Pei, G. Cohen, Y. Yamada, B. Cox, M. J. Zelefsky

Memorial Sloan-Kettering Cancer Center, New York, NY

Purpose/Objective(s): To compare acute urinary toxicities associated with combined interstitial brachytherapy and externalbeam radiation therapy (EBRT) using various isotopes (I-125, Pd-103, or Ir-192) in patients with clinically localized prostatecancer.

Materials/Methods: Three hundred forty-six patients who underwent prostate brachytherapy (I-125: n = 199; Pd-103: n = 60;HDR: n = 87) followed by EBRT (median dose 50.4 Gy) between 2002 and 2008 were included. Brachytherapy prescription doseswere as follows: I-125, 110 Gy; Pd-103, 100 Gy; Ir-192, median 21 Gy. All patients had baseline and a minimum of 1 year post-implant follow-up with urinary toxicity assessment using CTCAE v 3.0 and IPSS questionnaires (median follow-up, 31 months).Urinary quality of life (QOL) from the IPSS was collected. The mean number of IPSS scores per patient was 4. A post-implant CTwas obtained at day 0 for all patients. The median D90 for I-125 and Pd-103 was 111.4 Gy and 107.1 Gy, respectively. A total of115 (33%) patients received neoadjuvant hormonal therapy. Patient and treatment-related factors were examined for an associationwith urinary toxicity including prostate volume, use of hormone therapy (HT), pre-implant urinary medication use, isotope type,