Author Disclosure: S. Grimm: None. L.J. Scharf: None. M.L. Sobczak: None. 2497 ... above 3.7 ng/mL, average T was greater than 4.0 ng/mL in 53 patients and.
Volume 93 Number 3S Supplement 2015
Poster Viewing Session E197
patient, and the dose-volume histograms (DVHs) were calculated. A SHIM score decline of 5 points or greater from the consult baseline value was considered a moderate-to-significant sexual function decline, whereas a SHIM score decline of 4 points or less was considered a mild-to-no sexual function decline. We compared the DVH differences between these 2 groups of patients. Results: One year after external beam radiation (either definitive or adjuvant), 22 of the evaluable 51 patients (43.1%) have SHIM score declines of 5 points or greater from the baseline value. Twenty-nine patients (56.9%) have SHIM score declines of 4 points or less from the baseline value. Thirteen patients (25.5%) developed severe erectile dysfunction (ED) with 1 year follow-up SHIM scores of 7 or less. The average DVH of penile bulb dose differences between these 3 groups was insignificant. Conclusion: Our study result does not demonstrate a correlation between penile bulb dose and sexual function decline 1 year post-RT for prostate cancer. Author Disclosure: S. Grimm: None. L.J. Scharf: None. M.L. Sobczak: None.
posttreatment physiological variations in T do not affect biochemical disease progression, supporting the “saturation hypothesis. “ These data add to a growing body of literature consistent with the notion that cautious replacement of T in hypogonadal men with treated prostate cancer may be reasonable in selected patients, though further investigation is needed.
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Author Disclosure: N.B. Tennyson: None. N.D. Mukhopadhyay: None. D. Moghanaki: None. M.G. Chang: None. M. Hagan: Employment as above; US Fed Gov’t. Dept. of Veterans Affairs. Member; CARS patient safety organization.
Posttreatment Testosterone Levels Do Not Affect Rates of Biochemical Failure in Men Who Have Undergone Definitive Radiation for Prostate Cancer: Implications for Testosterone Replacement N.B. Tennyson,1,2 N.D. Mukhopadhyay,1 D. Moghanaki,3 M.G. Chang,1 and M.P. Hagan4; 1Virginia Commonwealth University, Richmond, VA, 2 Virginia Hunter Holmes Mcguire VA medical center, Richmond, VA, 3 Virginia Commonwealth University Medical Center, Richmond, VA, 4 Virginia Commonwealth University, Richmond, VA Purpose/Objective(s): Testosterone (T) replacement remains controversial in men who have undergone definitive radiation therapy (RT) for prostate cancer. Recent evidence suggests that T replacement in men with treated prostate cancer may be safe because the androgen receptor saturates at low serum levels. However, in prostate cancer patients treated with RT there is limited data published describing the relationship between posttreatment testosterone levels and biochemical failure. We examined the relationship between T and biochemical failure in men who had undergone definitive RT for prostate cancer. Materials/Methods: We studied retrospectively consecutive patients undergoing brachytherapy with or without external beam RT without androgen deprivation therapy (ADT) between 1998 and 2006. Patient, tumor, and treatment characteristics along with T levels and PSA control rates were examined. Patients were stratified into 3 groups by T levels: 3.7 ng/mL. Kaplan-Meier analysis was used to examine if biochemical failure differed between the groups. Results: A total of 239 patients were evaluated. Median follow-up was 6.1 years (range 0.7- 11.1 years). The majority had low-risk disease as shown in Table 1; no patients had cT3 disease. Crude rates of biochemical failure for each group are shown in Table 1. Overall rate of biochemical failure in the cohort was 6%. Kaplan-Meier estimates reveal no difference (PZ.47) in rate of biochemical failure between the different T groups. There was no significant difference in either Gleason score or initial prostate-specific antigen among the 3 groups tested by Wilcoxon rank. In the group with T above 3.7 ng/mL, average T was greater than 4.0 ng/mL in 53 patients and none had biochemical failure. Conclusion: In our cohort of mostly low-risk prostate cancer patients, higher posttreatment T was not associated with increased levels of biochemical failure. Men with lower physiological T often have physical symptoms of hypogonadism; however, our data would seem to imply
Poster Viewing Abstracts 2497; Table 1 Testosterone level
2.3 ng/mL
2.3-3.7 ng/mL
>3.7 ng/mL
patients
nZ34
nZ128
nZ76
Pretreatment characteristics GS 6 GS 7-10 PSA 10 PSA >10 T1-2 cT3 Posttreatment PSA failure
25 9 30 4 34 0 3
(74%) (26%) (88%) (12%)
(8%)
94 28 120 8 128 0 8
(73%) (27%) (94%) (6%)
(6%)
62 14 74 2 76 0 3
(82%) (18%) (97%) (3%)
(4%)
2498 Hypofractionated Stereotactic Body Radiation Therapy for Low- and Intermediate-Risk Prostate Cancer: A Multi-institutional Phase 2 Analysis B.S. Gill,1 M.E. Olsheski,2 D.J. DAmbrosio,3 D.A. Clump, II,1 R.E. Wegner,4 R. Iyer,3 S.A. Burton,1 K. Holeva,1 and D.E. Heron1; 1 University of Pittsburgh Cancer Institute, Pittsburgh, PA, 2Springfield Radiation Oncology Associates, Springfield, MA, 3East Coast Radiation Oncology Associates, PA, Toms River, NJ, 4Forbes Regional Hospital, Pittsburgh, PA Purpose/Objective(s): Stereotactic body radiation therapy (SBRT) provides the opportunity to treat prostate cancer patients in a shorter treatment course with decreased financial cost compared to conventionally fractionated radiation. We report interim results for an ongoing, multi-institution phase 2 trial evaluating efficacy and safety of SBRT for low- and intermediate-risk prostate cancer. Materials/Methods: Patients with biopsy-proven prostate cancer, defined as low-risk (cT1b-T2a, Gleason 2-6, and prostate-specific antigen [PSA] 10) or intermediate-risk (cT2b, Gleason 2-6, and PSA 10; cT1b-T2a, Gleason 2-6, and PSA 10-20; or cT1b-T2a, Gleason 7, and PSA 10), with prostate volume 100 mL and life expectancy of 10 years were enrolled. Patients received hypofractionated SBRT, consisting of 36.25 Gy in 5 fractions delivered on nonconsecutive days using a medical linear accelerator treatment delivery system (57.1%) or robotic radiosurgery (42.9%). Primary endpoints include late gastrointestinal (GI) and genitourinary (GU) toxicity and biochemical progression-free survival (bPFS) using the Phoenix definition of >2 ng/mL above nadir. PSA bounce was defined as 0.2 ng/mL above nadir with a subsequent decrease. Results: Forty-two consecutive patients were analyzed from 2011 to 2013. Median age was 66 years with a median KPS of 100%. Overall, 19 (45.2%) and 23 (54.8%) met low- and intermediate-risk criteria. The following characteristics were noted: T1c (73.8%), initial PSA
