- Email: [email protected]
Migration Evaluation of Gold Markers Implanted in a Prostate Bed for Salvage Focal Irradiation
Volume 87 Number 2S Supplement 2013 Author Disclosure: R. Zeitlin: None. M. McPhillips: None. Z. Su: None. Z. Li: None. N.P. Mendenhall: None.
2472 Testicular Doses in Prostate Intensity Modulated and Volumetric Arc Radiation Therapy With Different Energy Levels C. Onal, G. Arslan, C. Parlak, and E. Efe; Baskent University Faculty of Medicine, Adana, Turkey Purpose/Objective(s): To evaluate the incidental doses of testes received during prostate radiation therapy (RT) with intensity-modulated RT (IMRT) and volumetric-arc RT (VMAT) at different energy levels. Materials/Methods: We examined the dosimetric data of 15 intermediaterisk prostate cancer patients with prostate and seminal vesicle irradiation. The prescribed dose was 78 Gy in 39 fractions. The mean (Dmean) and maximum doses (Dmax) were measured for IMRT and VMAT plans with each photon energy levels. The dosimetric comparison of testes was performed between 7-field IMRT plans and VMAT plans with single arc with 6, 10 and 15 MV photon energy levels. Doses to the testes were obtained from the Monaco treatment-planning system using Monte-Carlo algorithm. The doses generated from TPS were verified with MOSFET detectors placed on QA phantom. The MOSFET detectors were placed within the QA phantom, from center of irradiated field to 20 cm with 2 cm distance. The values measured from treatment planning were compared with values measured from MOSFET detectors. Results: The mean distance between the center of prostate and testes was 13.5 cm (range, 11.6-16.8 cm). Dmax values for IMRT and VMAT plans did not differ significantly. However, Dmean values were significantly higher in VMAT plans compared to IMRT plans for each energy level. For a complete course of 39 fractions the total testes doses with VMAT and IMRT plans were 22 13 cGy vs 16 8 cGy (p Z 0.03) for 6MV, 18 12 cGy vs 13 12 cGy (p Z 0.04) for 10 MV, and 14 11 cGy vs 11 10 cGy (p Z 0.02), respectively. With increasing photon energy levels, the testes doses significantly reduced both for IMRT and VMAT plans. The doses generated with TPS at 10, 15 and 20 cm were 97%, 95% and 94% in concordance with doses measured with MOSFET detectors. Conclusions: The incidental doses to testes were significantly higher in VMAT plans and lower energies compared to IMRT plans and higher plans. However neutron contamination with photon energies >10 MV should increase the testicular doses more than expected. The testes doses are not negligible during prostate irradiation, and could lead to potential impairment of the endocrine function of Leydig cells. Author Disclosure: C. Onal: None. G. Arslan: None. C. Parlak: None. E. Efe: None.
2473 Stereotactic Body Radiation Therapy (SBRT) for Low-Risk Prostate Cancer: A 3 Way Comparison Between Modulated Arc, Helical Tomotherapy, and Robotic Radiosurgery Plans A. Sen, D. Lollar, W. Falwell, J. Tremblay, H. Sakhalkar, P. Sourivong, M. Payne, O. Taylor, J. Flynn, and D. Kelly; Cancer Treatment Centers of America, Tulsa, OK Purpose/Objective(s): Hypofractionated treatment of low risk prostate cancer by external beam are planned and delivered using Modulated Arc (MA) treatment planning on a conventional linac. Treatment plans are generated on helical tomotherapy (HT) and robotic radiosurgery (RR) for comparison. Materials/Methods: Ten low risk prostate patients were implanted with transponder beacons. MA plans were generated on a commercial planning system and delivered using CBCT image guidance for localization and real time tracking with beacons. Dose fractionation was 7.25 Gy/fx for 5 fractions. Planning goals were set for 95% of the planning target volume (PTV) to receive the prescription dose. Treatment plans were also generated on HT and RR planning systems using the same constraints. PTV margins were set at 5 mm in all directions except 3 mm posteriorly. Plans were evaluated based on the target coverage measured by minimum, mean
Poster Viewing Abstracts S385 and maximum dose to the target, conformity index (CI) and dose heterogeneity index (DHI). The volumes covering 5, 10, 20, 50 and 70% of the prescription dose for rectum and bladder were compared. Results: The mean age of the patients was 61 years (range, 53-79 years). All patients were staged at T1cN0M0 except for one at T1bN0M0. On the MA plans, the prostate volumes were 26.6 to 77.4 cm3 with a mean of 46.8 cm3. The PTVs were 51.1 to 151.1 cm3 with a mean of 92.8. With HT, these mean values were computed to be a little smaller at 45.7 cm3 and 90.4 cm3, even though the contours were identical. The conformity index was 1.17, 1.33, and 1.12 for MA, HT, and CK (p Z 0.004), with RR having the best conformity. The dose heterogeneity index was 2.9, 3.2, and 15.9% (p Z 0.000000), with RR having far more dose heterogeneity. Mean dose to the PTV was 37.7, 38.8, and 42.2 Gy for MA, HT, RR (p Z 0.000000). Dose minimums in the PTV were 32.1, 32.2, and 30.2 Gy. Dose maximums were 40.3, 41.2, and 49.4 Gy. The rectal mean dosage was 11.8, 11.4, and 15.5 Gy for MA, HT, and RR (p Z 0.000000). The maximum dosage in rectum was 38.5, 39.7 and 43.4 Gy. The bladder mean dosage was 12.0, 12.8, and 15.3 Gy (p Z 0.00001). Conclusions: The Modulated Arc and helical tomotherapy (HT) IMRT arc based therapies offered several advantages over robotic radiosurgery in the plans generated for SBRT of prostate cancer. With MA and HT the doses were more homogenous, dose maxima were reduced, treatment time was substantially reduced, and rectal and bladder dosages were lower compared to RR. The MA treatment is most efficient. This study does not take into account the robotic tracking of RR which could allow smaller margins to be used with RR, thereby offering improvement in some of these measures. Author Disclosure: A. Sen: None. D. Lollar: None. W. Falwell: None. J. Tremblay: None. H. Sakhalkar: None. P. Sourivong: None. M. Payne: None. O. Taylor: None. J. Flynn: None. D. Kelly: None.
2474 Migration Evaluation of Gold Markers Implanted in a Prostate Bed for Salvage Focal Irradiation S.I. Shakir,1 C. Udrescu,1 C. Enachescu,1 P. Jalade,1 O. Rouviere,2 and O. Chapet1; 1Centre Hospitalier Lyon Sud, Pierre Benite, France, 2 Hopital Edouard Herriot, Lyon, France Purpose/Objective(s): MRI often allows detecting the macroscopic visible local recurrence when a biochemical relapse occurs after prostatectomy. In our institution, 3 gold markers are implanted in the prostate bed close to the visible nodule. An image guided focal dose escalation is thereby performed. The objective of the present study was to verify the stability of these gold markers throughout the duration of radiation therapy. Materials/Methods: To date, 7 patients were diagnosed with a macroscopic nodule visible on MRI. At the time of detecting a diagnostic biochemical relapse, PSA level was between 0.34 ng/mL and 1.9 ng/mL. Targeted MRI guided biopsies, were systematically done to confirm the macroscopic relapse. Three gold markers were implanted into the prostatic bed for MRI/CT fusion and for image-guided radiation therapy (IGRT). Using an intensity-modulated radiation therapy a dose of 60 Gy was delivered to the prostate bed followed by an image guided dose escalation to 72 Gy to the macroscopic nodule. Before each fraction, anterior and leftlateral KV images were acquired for repositioning based on bone structures (for doses of 60 Gy) and then on gold makers (for the focal boost of 12 Gy). The coordinates of the center of all markers were measured on the two kV images, on x, y and z axes, considering the center of the third marker as reference (coordinates: 0, 0, 0) for all the fractions. The distances between the markers were extrapolated from the coordinates of the 3 markers by the formula: Dij Z square root of [(xj-xi)2+(yj-yi)2+(zjzi)2]. Thereafter, a serial comparison in the distance variation of the markers between the first session and the subsequent one was calculated. Results: A total number of 1128 coordinates have been taken from all the patients and marker-pairs. From those, a total number of 547 measurements of distance variations were calculated. No gold marker was lost during treatment. The mean distance between two markers was 7.8 mm. The mean distance variation between 2 markers was 0.003 mm. A total of 516 (94%) distance variations were below 2 mm. A variation of distance
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International Journal of Radiation Oncology Biology Physics
superior to 2 mm was observed on 6% of measurements (5% of distance reduction and 1% of distance enlargement). The variation of distance never exceeded 3mm in any directions. Conclusions: Despite the absence of prostate, the implantation of gold markers in the surgical bed remains feasible. In a large majority of measurements, the distance variation between two gold markers was inferior to 2 mm and could be reasonably considered as non-relevant. In our experience, implantation of gold markers in the prostatic bed could be used to develop new reliable approaches of salvage focal dose irradiation on macroscopic relapse after prostatectomy. Author Disclosure: S.I. Shakir: None. C. Udrescu: None. C. Enachescu: None. P. Jalade: None. O. Rouviere: None. O. Chapet: None.
Seattle, WA, 4Providence Radiation Oncology Department, Anchorage, AK, 5Saint Alphosus Regional Medical Center, Boise, ID
2475 Quality of Life After IMRT or IMRT+HDR Brachytherapy for Intermediate- or High-Risk Prostate Cancer: 8-Year Results of a Prospective Trial B. Guix, T. Lacorte, J. Bartrina, J. Tello, I. Guix, G. Galdon, M. Espino, and T. Guix; IMOR Foundation, Barcelona, Spain Purpose/Objective(s): To report long term Health Related Quality of Life (HRQOL) in a prospective series of 629 patients with intermediate or highrisk clinically localized prostate cancer treated with either IMRT or IMRT + HDR. Materials/Methods: Between December 1999 and December 2010, 629 patients (pts) with PSA >10, Gleason score >6 and/or T2b-T3 N0 M0 prostate cancer entered the study. Pts were prospectively assigned to one of the two treatment groups: 76 Gy HD-IMRT to the prostate in 38 fractions (group 1; 315 patients) or 46 Gy LD-3D-IMRT+ 16 Gy HDR-B given in 2 fractions of 8 Gy (group 2, 316 patients), limiting the maximum rectal dose to 85% of the prescribed dose. Both groups were well balanced taking into account patient’s as well as tumors’ characteristics. Toxicities were scored by the EORTC /RTOG morbidity grading scales. Special attention to local, regional or distant recurrence, survival, late effects, PSA and testosterone levels as well as HRQOL was done. Results: All pts completed treatment. None pts included in the group 1 or 2 experienced grade 3 or more rectal toxicity. With a mean follow-up of 84 months, the 8-year free-from-failure survival was 90.7% and 98.3% (p < 0.02) in group 1 and 2, respectively; free-from-metastases survival 96.9% and 97.9% (p < 0.08) for group 1 and 2, respectively; and cause-specific survival 97.4% and 98.3% (p < 0.09). HRQOL was evaluated before treatment, at 3 months interval during the first year of follow-up and in a yearly basis until 10-year. International Prostatic Symptom Score (I-PSS) and EORTC’s QLQ-C30 with PR-25 module questionnaires were used. IPSS scores at 1, 3 and 6 months and at 1, 2, 3, 5 and 8 years follow-up were 6.39, 5.00, 2.52, 2.21, 2.35, 3.65 and 1.43 for group 1 pts and 1.50, 1.10, 1.01, 1.05, 0.89, 0.66, 0.67 for group 2 pts. Global HRQOL scores at 1, 3 and 6 months and at 1, 2, 3 and 5 years follow-up were 5.56, 5.75, 5.33, 6.00, 5.40, 5.58 and 5.11 for group 1 pts and 5.60, 6.40, 5.78, 5.89, 5.83, 6.37, 6.00 for group 2 pts, being found to be statistically significant at 3 and 5 years follow-up (p < 0.001 and p < 0.024). Conclusions: High-dose 3D-IMRT + HDR brachytherapy was found to be a method of escalating the dose to the prostate that not only increased the chances of cure for patients if not increased their long-term Health Related Quality of Life. Author Disclosure: B. Guix: None. T. Lacorte: None. J. Bartrina: None. J. Tello: None. I. Guix: None. G. Galdon: None. M. Espino: None. T. Guix: None.
2476 Differences Between Beacon-Localized and Cone Beam CT (CBCT)Localized Radiation Therapy to the Prostatic Fossa M. Kathpal,1 T. Brand,2 S. Ninneman,2 G. Hughs,2 L. Katz,2 M. Brown,3 J. Halligan,4 J. Brooks,5 D. Macdonald,2 and B. Tinnel2; 1University of Medicine and Dentistry of New Jersey, New Brunswick, NJ, 2Madigan Army Medical Center, Tacoma, WA, 3Seattle Cancer Care Alliance,
Purpose/Objective(s): Either CBCT or electromagnetic beacon transponders can localize the prostatic fossa for adjuvant or salvage radiation therapy. We hypothesize that beacons localize this isocenter differently than CBCT. We sought to test this hypothesis, and to evaluate if the beacon-localized isocenter more closely aligns the clinical target volume (CTV) with daily changes in rectum and bladder position such that planning target volume (PTV) margins may be reduced. Materials/Methods: Twelve patients requiring post-prostatectomy radiation were treated on this IRB-approved prospective study. Each patient had 3 beacons placed in the prostatic fossa; one to the right of the vesicourethral anastomosis and two others in the location of the left and right prostate pedicles adjacent to the removed seminal vesicles. Daily radiation was localized by beacons and a CBCT was taken for analysis. By measuring differences between the CTV and relevant anatomy on 5 equally-spaced axial CT slices we calculated necessary PTV margins for each fraction. We then auto-fused each CBCT scan with the treatment planning scan, recorded the shifts incurred, and repeated our measurements, representing a hypothetical CBCT -localized treatment. We report a PTV margin for each technique that would cover the CTV during 95% of all 379 fractions analyzed. We also used intra-fraction motion data (considering anterior motion to coincide with anterior movement of the posterior bladder wall) to produce a worst-case estimate of required anterior PTV margins. Results: When shifting from the beacon-localized isocenter to the CBCTlocalized isocenter, the mean vertical patient shift for all 379 fractions was 1.3 mm ant (SD 2.9 mm, range 5 mm post to 10 mm ant). The mean longitudinal shift was 2.2 mm sup (SD 3.1 mm, range 7 mm inf to 12 mm sup). The mean lateral shift was 0.3 mm to the left (SD 1.5, range 13 mm left to 4 mm right). For beacon-localized treatment, maximum necessary PTV margins were 10 mm ant, 12 mm post, and 6 mm lat. Incorporating measured intra-fraction motion, the anterior margin would be increased to 11 mm. For CBCT-localized treatment, maximum necessary PTV margins were 18 mm ant, 8 mm post, and 6 mm lateral. Inclusion of intra-fraction motion did not change the necessary anterior margin for CBCT-localized treatment. Intra-fraction motion exceeded tracking limits of 5 mm (corrected with treatment pause or reposition) in 13% of fractions. Conclusions: In our cohort, beacon localization placed the isocenter (on average) anterior and superior to the CBCT isocenter, with significant variation over the entire group. The beacon-localized isocenter accounts for some changes in bladder position, thus allowing a decreased anterior PTV margin, or decreased amount of the posterior bladder included in the CTV. Author Disclosure: M. Kathpal: None. T. Brand: None. S. Ninneman: None. G. Hughs: None. L. Katz: None. M. Brown: None. J. Halligan: None. J. Brooks: None. D. Macdonald: None. B. Tinnel: None.
2477 Does Postprostatectomy Radiation Therapy Expose Patients to Higher Complications?: A Large Medicare Patient Cohort Study S.E. Hegarty,1 T. Hyslop,1 D.Z. Louis,1 V. Maio,1 C. Rabinowitz,1 A.P. Dicker,1 and T.N. Showalter2; 1Thomas Jefferson University, Philadelphia, PA, 2University of Virginia, Charlottesville, VA Purpose/Objective(s): Controversy exists regarding the delivery and timing of radiation therapy (RT) after radical prostatectomy (RP) for prostate cancer (PC). In the absence of clinical trial data, decisions for adjuvant RT (ART) or salvage RT (SRT) are influenced by perceived rates of RT-related toxicity. Data on toxicity are limited. Therefore, we evaluated the genitourinary (GU), gastrointestinal (GI) and sexual complications of post-RP RT, androgen deprivation therapy (ADT) use, and the influence of RT timing. Materials/Methods: The SEER-Medicare database was queried to identify male subjects aged 66 years and older who received RP for PC during 1995-2007 and who had one or more pathological features: seminal vesicle invasion, extracapsular extension and/or positive surgical margin.
2472 Testicular Doses in Prostate Intensity Modulated and Volumetric Arc Radiation Therapy With Different Energy Levels C. Onal, G. Arslan, C. Parlak, and E. Efe; Baskent University Faculty of Medicine, Adana, Turkey Purpose/Objective(s): To evaluate the incidental doses of testes received during prostate radiation therapy (RT) with intensity-modulated RT (IMRT) and volumetric-arc RT (VMAT) at different energy levels. Materials/Methods: We examined the dosimetric data of 15 intermediaterisk prostate cancer patients with prostate and seminal vesicle irradiation. The prescribed dose was 78 Gy in 39 fractions. The mean (Dmean) and maximum doses (Dmax) were measured for IMRT and VMAT plans with each photon energy levels. The dosimetric comparison of testes was performed between 7-field IMRT plans and VMAT plans with single arc with 6, 10 and 15 MV photon energy levels. Doses to the testes were obtained from the Monaco treatment-planning system using Monte-Carlo algorithm. The doses generated from TPS were verified with MOSFET detectors placed on QA phantom. The MOSFET detectors were placed within the QA phantom, from center of irradiated field to 20 cm with 2 cm distance. The values measured from treatment planning were compared with values measured from MOSFET detectors. Results: The mean distance between the center of prostate and testes was 13.5 cm (range, 11.6-16.8 cm). Dmax values for IMRT and VMAT plans did not differ significantly. However, Dmean values were significantly higher in VMAT plans compared to IMRT plans for each energy level. For a complete course of 39 fractions the total testes doses with VMAT and IMRT plans were 22 13 cGy vs 16 8 cGy (p Z 0.03) for 6MV, 18 12 cGy vs 13 12 cGy (p Z 0.04) for 10 MV, and 14 11 cGy vs 11 10 cGy (p Z 0.02), respectively. With increasing photon energy levels, the testes doses significantly reduced both for IMRT and VMAT plans. The doses generated with TPS at 10, 15 and 20 cm were 97%, 95% and 94% in concordance with doses measured with MOSFET detectors. Conclusions: The incidental doses to testes were significantly higher in VMAT plans and lower energies compared to IMRT plans and higher plans. However neutron contamination with photon energies >10 MV should increase the testicular doses more than expected. The testes doses are not negligible during prostate irradiation, and could lead to potential impairment of the endocrine function of Leydig cells. Author Disclosure: C. Onal: None. G. Arslan: None. C. Parlak: None. E. Efe: None.
2473 Stereotactic Body Radiation Therapy (SBRT) for Low-Risk Prostate Cancer: A 3 Way Comparison Between Modulated Arc, Helical Tomotherapy, and Robotic Radiosurgery Plans A. Sen, D. Lollar, W. Falwell, J. Tremblay, H. Sakhalkar, P. Sourivong, M. Payne, O. Taylor, J. Flynn, and D. Kelly; Cancer Treatment Centers of America, Tulsa, OK Purpose/Objective(s): Hypofractionated treatment of low risk prostate cancer by external beam are planned and delivered using Modulated Arc (MA) treatment planning on a conventional linac. Treatment plans are generated on helical tomotherapy (HT) and robotic radiosurgery (RR) for comparison. Materials/Methods: Ten low risk prostate patients were implanted with transponder beacons. MA plans were generated on a commercial planning system and delivered using CBCT image guidance for localization and real time tracking with beacons. Dose fractionation was 7.25 Gy/fx for 5 fractions. Planning goals were set for 95% of the planning target volume (PTV) to receive the prescription dose. Treatment plans were also generated on HT and RR planning systems using the same constraints. PTV margins were set at 5 mm in all directions except 3 mm posteriorly. Plans were evaluated based on the target coverage measured by minimum, mean
Poster Viewing Abstracts S385 and maximum dose to the target, conformity index (CI) and dose heterogeneity index (DHI). The volumes covering 5, 10, 20, 50 and 70% of the prescription dose for rectum and bladder were compared. Results: The mean age of the patients was 61 years (range, 53-79 years). All patients were staged at T1cN0M0 except for one at T1bN0M0. On the MA plans, the prostate volumes were 26.6 to 77.4 cm3 with a mean of 46.8 cm3. The PTVs were 51.1 to 151.1 cm3 with a mean of 92.8. With HT, these mean values were computed to be a little smaller at 45.7 cm3 and 90.4 cm3, even though the contours were identical. The conformity index was 1.17, 1.33, and 1.12 for MA, HT, and CK (p Z 0.004), with RR having the best conformity. The dose heterogeneity index was 2.9, 3.2, and 15.9% (p Z 0.000000), with RR having far more dose heterogeneity. Mean dose to the PTV was 37.7, 38.8, and 42.2 Gy for MA, HT, RR (p Z 0.000000). Dose minimums in the PTV were 32.1, 32.2, and 30.2 Gy. Dose maximums were 40.3, 41.2, and 49.4 Gy. The rectal mean dosage was 11.8, 11.4, and 15.5 Gy for MA, HT, and RR (p Z 0.000000). The maximum dosage in rectum was 38.5, 39.7 and 43.4 Gy. The bladder mean dosage was 12.0, 12.8, and 15.3 Gy (p Z 0.00001). Conclusions: The Modulated Arc and helical tomotherapy (HT) IMRT arc based therapies offered several advantages over robotic radiosurgery in the plans generated for SBRT of prostate cancer. With MA and HT the doses were more homogenous, dose maxima were reduced, treatment time was substantially reduced, and rectal and bladder dosages were lower compared to RR. The MA treatment is most efficient. This study does not take into account the robotic tracking of RR which could allow smaller margins to be used with RR, thereby offering improvement in some of these measures. Author Disclosure: A. Sen: None. D. Lollar: None. W. Falwell: None. J. Tremblay: None. H. Sakhalkar: None. P. Sourivong: None. M. Payne: None. O. Taylor: None. J. Flynn: None. D. Kelly: None.
2474 Migration Evaluation of Gold Markers Implanted in a Prostate Bed for Salvage Focal Irradiation S.I. Shakir,1 C. Udrescu,1 C. Enachescu,1 P. Jalade,1 O. Rouviere,2 and O. Chapet1; 1Centre Hospitalier Lyon Sud, Pierre Benite, France, 2 Hopital Edouard Herriot, Lyon, France Purpose/Objective(s): MRI often allows detecting the macroscopic visible local recurrence when a biochemical relapse occurs after prostatectomy. In our institution, 3 gold markers are implanted in the prostate bed close to the visible nodule. An image guided focal dose escalation is thereby performed. The objective of the present study was to verify the stability of these gold markers throughout the duration of radiation therapy. Materials/Methods: To date, 7 patients were diagnosed with a macroscopic nodule visible on MRI. At the time of detecting a diagnostic biochemical relapse, PSA level was between 0.34 ng/mL and 1.9 ng/mL. Targeted MRI guided biopsies, were systematically done to confirm the macroscopic relapse. Three gold markers were implanted into the prostatic bed for MRI/CT fusion and for image-guided radiation therapy (IGRT). Using an intensity-modulated radiation therapy a dose of 60 Gy was delivered to the prostate bed followed by an image guided dose escalation to 72 Gy to the macroscopic nodule. Before each fraction, anterior and leftlateral KV images were acquired for repositioning based on bone structures (for doses of 60 Gy) and then on gold makers (for the focal boost of 12 Gy). The coordinates of the center of all markers were measured on the two kV images, on x, y and z axes, considering the center of the third marker as reference (coordinates: 0, 0, 0) for all the fractions. The distances between the markers were extrapolated from the coordinates of the 3 markers by the formula: Dij Z square root of [(xj-xi)2+(yj-yi)2+(zjzi)2]. Thereafter, a serial comparison in the distance variation of the markers between the first session and the subsequent one was calculated. Results: A total number of 1128 coordinates have been taken from all the patients and marker-pairs. From those, a total number of 547 measurements of distance variations were calculated. No gold marker was lost during treatment. The mean distance between two markers was 7.8 mm. The mean distance variation between 2 markers was 0.003 mm. A total of 516 (94%) distance variations were below 2 mm. A variation of distance
S386
International Journal of Radiation Oncology Biology Physics
superior to 2 mm was observed on 6% of measurements (5% of distance reduction and 1% of distance enlargement). The variation of distance never exceeded 3mm in any directions. Conclusions: Despite the absence of prostate, the implantation of gold markers in the surgical bed remains feasible. In a large majority of measurements, the distance variation between two gold markers was inferior to 2 mm and could be reasonably considered as non-relevant. In our experience, implantation of gold markers in the prostatic bed could be used to develop new reliable approaches of salvage focal dose irradiation on macroscopic relapse after prostatectomy. Author Disclosure: S.I. Shakir: None. C. Udrescu: None. C. Enachescu: None. P. Jalade: None. O. Rouviere: None. O. Chapet: None.
Seattle, WA, 4Providence Radiation Oncology Department, Anchorage, AK, 5Saint Alphosus Regional Medical Center, Boise, ID
2475 Quality of Life After IMRT or IMRT+HDR Brachytherapy for Intermediate- or High-Risk Prostate Cancer: 8-Year Results of a Prospective Trial B. Guix, T. Lacorte, J. Bartrina, J. Tello, I. Guix, G. Galdon, M. Espino, and T. Guix; IMOR Foundation, Barcelona, Spain Purpose/Objective(s): To report long term Health Related Quality of Life (HRQOL) in a prospective series of 629 patients with intermediate or highrisk clinically localized prostate cancer treated with either IMRT or IMRT + HDR. Materials/Methods: Between December 1999 and December 2010, 629 patients (pts) with PSA >10, Gleason score >6 and/or T2b-T3 N0 M0 prostate cancer entered the study. Pts were prospectively assigned to one of the two treatment groups: 76 Gy HD-IMRT to the prostate in 38 fractions (group 1; 315 patients) or 46 Gy LD-3D-IMRT+ 16 Gy HDR-B given in 2 fractions of 8 Gy (group 2, 316 patients), limiting the maximum rectal dose to 85% of the prescribed dose. Both groups were well balanced taking into account patient’s as well as tumors’ characteristics. Toxicities were scored by the EORTC /RTOG morbidity grading scales. Special attention to local, regional or distant recurrence, survival, late effects, PSA and testosterone levels as well as HRQOL was done. Results: All pts completed treatment. None pts included in the group 1 or 2 experienced grade 3 or more rectal toxicity. With a mean follow-up of 84 months, the 8-year free-from-failure survival was 90.7% and 98.3% (p < 0.02) in group 1 and 2, respectively; free-from-metastases survival 96.9% and 97.9% (p < 0.08) for group 1 and 2, respectively; and cause-specific survival 97.4% and 98.3% (p < 0.09). HRQOL was evaluated before treatment, at 3 months interval during the first year of follow-up and in a yearly basis until 10-year. International Prostatic Symptom Score (I-PSS) and EORTC’s QLQ-C30 with PR-25 module questionnaires were used. IPSS scores at 1, 3 and 6 months and at 1, 2, 3, 5 and 8 years follow-up were 6.39, 5.00, 2.52, 2.21, 2.35, 3.65 and 1.43 for group 1 pts and 1.50, 1.10, 1.01, 1.05, 0.89, 0.66, 0.67 for group 2 pts. Global HRQOL scores at 1, 3 and 6 months and at 1, 2, 3 and 5 years follow-up were 5.56, 5.75, 5.33, 6.00, 5.40, 5.58 and 5.11 for group 1 pts and 5.60, 6.40, 5.78, 5.89, 5.83, 6.37, 6.00 for group 2 pts, being found to be statistically significant at 3 and 5 years follow-up (p < 0.001 and p < 0.024). Conclusions: High-dose 3D-IMRT + HDR brachytherapy was found to be a method of escalating the dose to the prostate that not only increased the chances of cure for patients if not increased their long-term Health Related Quality of Life. Author Disclosure: B. Guix: None. T. Lacorte: None. J. Bartrina: None. J. Tello: None. I. Guix: None. G. Galdon: None. M. Espino: None. T. Guix: None.
2476 Differences Between Beacon-Localized and Cone Beam CT (CBCT)Localized Radiation Therapy to the Prostatic Fossa M. Kathpal,1 T. Brand,2 S. Ninneman,2 G. Hughs,2 L. Katz,2 M. Brown,3 J. Halligan,4 J. Brooks,5 D. Macdonald,2 and B. Tinnel2; 1University of Medicine and Dentistry of New Jersey, New Brunswick, NJ, 2Madigan Army Medical Center, Tacoma, WA, 3Seattle Cancer Care Alliance,
Purpose/Objective(s): Either CBCT or electromagnetic beacon transponders can localize the prostatic fossa for adjuvant or salvage radiation therapy. We hypothesize that beacons localize this isocenter differently than CBCT. We sought to test this hypothesis, and to evaluate if the beacon-localized isocenter more closely aligns the clinical target volume (CTV) with daily changes in rectum and bladder position such that planning target volume (PTV) margins may be reduced. Materials/Methods: Twelve patients requiring post-prostatectomy radiation were treated on this IRB-approved prospective study. Each patient had 3 beacons placed in the prostatic fossa; one to the right of the vesicourethral anastomosis and two others in the location of the left and right prostate pedicles adjacent to the removed seminal vesicles. Daily radiation was localized by beacons and a CBCT was taken for analysis. By measuring differences between the CTV and relevant anatomy on 5 equally-spaced axial CT slices we calculated necessary PTV margins for each fraction. We then auto-fused each CBCT scan with the treatment planning scan, recorded the shifts incurred, and repeated our measurements, representing a hypothetical CBCT -localized treatment. We report a PTV margin for each technique that would cover the CTV during 95% of all 379 fractions analyzed. We also used intra-fraction motion data (considering anterior motion to coincide with anterior movement of the posterior bladder wall) to produce a worst-case estimate of required anterior PTV margins. Results: When shifting from the beacon-localized isocenter to the CBCTlocalized isocenter, the mean vertical patient shift for all 379 fractions was 1.3 mm ant (SD 2.9 mm, range 5 mm post to 10 mm ant). The mean longitudinal shift was 2.2 mm sup (SD 3.1 mm, range 7 mm inf to 12 mm sup). The mean lateral shift was 0.3 mm to the left (SD 1.5, range 13 mm left to 4 mm right). For beacon-localized treatment, maximum necessary PTV margins were 10 mm ant, 12 mm post, and 6 mm lat. Incorporating measured intra-fraction motion, the anterior margin would be increased to 11 mm. For CBCT-localized treatment, maximum necessary PTV margins were 18 mm ant, 8 mm post, and 6 mm lateral. Inclusion of intra-fraction motion did not change the necessary anterior margin for CBCT-localized treatment. Intra-fraction motion exceeded tracking limits of 5 mm (corrected with treatment pause or reposition) in 13% of fractions. Conclusions: In our cohort, beacon localization placed the isocenter (on average) anterior and superior to the CBCT isocenter, with significant variation over the entire group. The beacon-localized isocenter accounts for some changes in bladder position, thus allowing a decreased anterior PTV margin, or decreased amount of the posterior bladder included in the CTV. Author Disclosure: M. Kathpal: None. T. Brand: None. S. Ninneman: None. G. Hughs: None. L. Katz: None. M. Brown: None. J. Halligan: None. J. Brooks: None. D. Macdonald: None. B. Tinnel: None.
2477 Does Postprostatectomy Radiation Therapy Expose Patients to Higher Complications?: A Large Medicare Patient Cohort Study S.E. Hegarty,1 T. Hyslop,1 D.Z. Louis,1 V. Maio,1 C. Rabinowitz,1 A.P. Dicker,1 and T.N. Showalter2; 1Thomas Jefferson University, Philadelphia, PA, 2University of Virginia, Charlottesville, VA Purpose/Objective(s): Controversy exists regarding the delivery and timing of radiation therapy (RT) after radical prostatectomy (RP) for prostate cancer (PC). In the absence of clinical trial data, decisions for adjuvant RT (ART) or salvage RT (SRT) are influenced by perceived rates of RT-related toxicity. Data on toxicity are limited. Therefore, we evaluated the genitourinary (GU), gastrointestinal (GI) and sexual complications of post-RP RT, androgen deprivation therapy (ADT) use, and the influence of RT timing. Materials/Methods: The SEER-Medicare database was queried to identify male subjects aged 66 years and older who received RP for PC during 1995-2007 and who had one or more pathological features: seminal vesicle invasion, extracapsular extension and/or positive surgical margin.