T. Nishimura,1 H. Yamazaki,2 and H. Okabe1; 1Uji-Takeda Hospital, Uji,. Japan, 2Kyoto Prefectural ... Median follow up time is 32 months (range: 20 - 42 ...
Poster Viewing Abstracts S397
Volume 84 Number 3S Supplement 2012 implanted in the tumor for TT1 and the standard pattern was adjusted to have one catheter in the center of the tumor for TT2. To determine if any observed difference between the geometries was dependent on the number of catheters implanted or the boost dose prescribed, plans using an equivalent total of 12, 14, or 16 catheters were optimized with the Inverse Planning Simulated Annealing (IPSA) algorithm (using class solution optimization parameters) to deliver a minimum peripheral dose to the prostate gland and two alternative boost dose levels (138% and 175%) to the MRI-defined GTV. Results: Plans using the tumor targeted catheter geometries showed improved GTV coverage. The TT1 pattern showed the largest improvement and this was consistent across plans using 12, 14, or 16 catheters. For plans using 14 catheters and optimized to deliver a 138% boost, mean coverage of the GTV by the prescribed boost isodose was 99.0%, 98.3%, and 97.1% for the TT1, TT2, and S geometries respectively (p Z 0.008 on multiple comparison testing between TT1 and S). The absolute improvement in tumor coverage by the boost isodose was greater when plans were optimized to deliver the higher 175% boost level. There was no statistically significant difference in dose to the organs at risk (OAR). As the number of implanted catheters was increased from 12 to 16, there was a trend for reduced dose to the OAR and improved dose conformity to the GTV for all geometries. On subgroup analysis, improved target coverage was greatest in men with small tumors (GTV: prostate volume 0.1). Conclusions: Tumor targeted catheter implantation geometries improve the dosimetry of a boost dose to the tumor in HDR brachytherapy for prostate cancer and this strategy is more important in men with small volume tumors. Accurate MRI-guidance strategies during catheter implantation may assist in this regard. Author Disclosure: B.T. Nguyen: None. A. Albert-Green: None. J. Abed: None. C. Menard: None.
2473 Exceptionally High Incidence of Symptomatic Grade 2-4 Late Rectal Toxicity in Radiation Therapy of Prostate Cancer in 2.2 Gy Hypofractionation Using Image Guided Intensity Modulated Radiation Therapy T. Nishimura,1 H. Yamazaki,2 and H. Okabe1; 1Uji-Takeda Hospital, Uji, Japan, 2Kyoto Prefectural University of Medicine, Kyoto, Japan Purpose/Objectives: To examine the frequency of rectal toxicity in using image-guided intensity modulated radiation therapy (IG-IMRT) for prostate cancer in 2.2 Gy hypofractionation. Materials/Method: We examined 118 consecutive patients with prostate cancer by IG-IMRT from June 2007 to July 2009. Median follow up time is 32 months (range: 20 - 42 months). Clinical target volume (CTV) consisted of prostate and seminal vesicle and planning target volume (PTV) consisted of CTV plus 5 mm expansion, not avoiding rectum. PTV received a dose of 72.6 -74.8 Gy in 33 - 34 fractions (2.2 Gy/fraction). Megavoltage CT (MVCT) scans were performed before each treatment and corrected to registered position to planning CT scans. Results: Late rectal bleeding Grade 1, Grade 2, and Grade 3 were shown in 19 (16%), 5 (4%), and 4 (3%) patients, respectively, according to CTC-AE Ver. 3. We found paradoxical elevated risk of rectal bleeding by correct irradiation delivery to rectum compared to historical control. Conclusions: IGRT using daily MVCT scans warrant exact dose delivery, which resulted in increased rectal dose and exceptionally high incidence of rectal toxicity. Careful PTV contouring and dose schedule setting are important for safety IG-IMRT. Author Disclosure: T. Nishimura: None. H. Yamazaki: None. H. Okabe: None.
2474 Comparison of the Objective and Subjective Assessments of Urinary Condition in Hypofractionated Carbon-ion Radiation Therapy for Localized Prostate Cancer T. Kaminuma,1 H. Katoh,1 H. Ishikawa,2 T. Tamaki,3 K. Shirai,1 H. Matsui,1 K. Itoh,4 T. Ohno,1 K. Suzuki,4 and T. Nakano3; 1Gunma University Heavy Ion Medical Center, Gunma, Japan, 2Department of
Radiation Oncology, University of Tsukuba, Ibaraki, Japan, 3Department of Radiation Oncology, Gunma University, Gunma, Japan, 4Department of Urology, Gunma University, Gunma, Japan Purpose: To analyze the objective and subjective changes of urinary condition before, during, and after hypofractionated carbon-ion radiation therapy (C-ion RT) using questionnaires of quality of life and uroflowmetry (UFM). Methods: Between March 2010 and January 2011, 40 patients, who received C-ion RT for prostate cancer and completed objective and subjective assessments for urinary conditions, were assessed in this study. Patients with the intermediate-risk and high-risk groups were treated with androgen deprivation therapy (ADT) combined with hypofractionated Cion RT. (C-ion RT was delivered once a day, 4 fractions per week.) The total dose was 57.6 GyE in 16 fractions over 4 weeks with a fraction dose of 3.6 GyE. The patients’ urinary conditions were assessed four times, before, and at the completion of treatment, and 90 days and 1 year after Cion RT. Questionnaires of MOS 8-item Short Form Health Survey (SF-8) and Expanded Prostate Cancer Index Composite (EPIC) were used for subjective assessments and UFM for objective assessments. Statistical analysis was performed by Spearman’s rank correlation coefficient using the statistical package SPSS version 20. Results: In UFM, maximum urinary flow rate (MFR) and residual volume (RU) at the completion of C-ion RT (13.1 5.7 mL/s, 30.9 59.3 mL) were significantly worse than those before treatment (15.6 6.1 mL/s, 14.3 25.9 mL) but returned to the initial levels by 90 days after C-ion RT (19.1 8.1 mL/s, 19.0 39.1 mL). Spearman’s rank correlation coefficient analysis showed that scores of Urinary (Summary score), Urinary Irritative/Obstructive and Urinary Bother (Subscales) correlated with MFR (p Z 0.002, 0.001, 0.002) and RU (p < 0.001, < 0.001, Z 0.001). However, the totals of the means plus the standard deviations of these three factors exceeded 100, which is the maximum score, in every data except for those at the completion of C-ion RT. These data suggested that there were ceiling effects in these subjective assessments. Conclusions: The objective and subjective assessments indicate that urinary condition tends to be worse at the completion of C-ion RT but recovered to satisfactory levels at 90 days after C-ion RT. There were ceiling effects in the subjective assessments. The results of this study suggest that, compared to the subjective assessments using questionnaires, UFM may provide more accurate assessment of the urinary condition after C-ion radiation therapy for prostate cancer. Author Disclosure: T. Kaminuma: None. H. Katoh: None. H. Ishikawa: None. T. Tamaki: None. K. Shirai: None. H. Matsui: None. K. Itoh: None. T. Ohno: None. K. Suzuki: None. T. Nakano: None.
2475 Quality of Life Assessment in Patients Receiving a Spacer Between Prostate and Anterior Rectal Wall to Optimize Radiation Therapy of Localized Prostate Cancer E. Castellanos, K. Sjo¨din, M. Djordjevic, and M. Gubanski; Karolinska University Hospital, Stockholm, Sweden Purpose/Objective(s): To explore the effects of using Polyethylene glycol (PEG) based hydrogel spacer on health-related quality of life (HRQOL) among men with localized prostate cancer treated with IMRT. Materials/Methods: The injection of a spacer gel (10mL) was performed under transrectal ultrasound guidance after dissecting the space between prostate and rectum in 11 patients with prostate cancer. Patients were followed up with four self-assessment questionnaires (EORTC QLQ-C30 and -PR25). Questionnaires were completed before the spacer application (baseline), 1 week after the injection of hydrogel at the start of radiation therapy and three months after completion of the treatment. Results: The results from treatment of the eleven first consecutive, patients are included in this report. The procedure was well tolerated. No bleeding, infections or other notable complications occurred. Pain, tenderness, discomfort and flatulence were specifically questioned. Except for a tendency for increased stool frequency during the first week after injection no deterioration of quality of life was observed.
