ESTRO 36 Abstract Book

S139 ESTRO 36 2017 _______________________________________________________________________________________________

= 3a, PSA > 20 ng/ml, GS > or = 8) prostate cancer who underwent HDR brachytherapy as monotherapy (no external beam radiotherapy) using 27 Gy/2 fractions in one day from July 2011 to October 2014 were analyzed prospectively. Patient age ranged 57 to 81 (median 72 ） years old. Fifty-nine patients were received neoadjuvant hormonal therapy, and 10 patients were also adjuvant hormonal therapy. Acute and late toxicities were assessed as per Common Terminology Criteria for Adverse Events (CTCAE), Version 4.03. The dosimetric factors affecting the acute or late grade 2 to 3 GU toxicity were analyzed by univariate analysis. PSA failure was defined as the Phoenix definition of nadir + 2 ng/mL. Biochemical relapse-free survival was analyzed using the Kaplan Meir method. Results The median follow-up period was 52 months (range 21 – 64). The 4-year biochemical relapse-free survival rate was 89.0%. Neither acute nor late grade 2 to 3 rectal toxicities developed. Acute grade 2 genitourinary (GU) toxicity occurred in 12.0% (grade 3 in 0.0%). The predictor of acute grade 2 GU toxicity was urethra D90 (the dose that covers 90% volume of the urethra) > 11.5 Gy (p-value < 0.01). Late grade 2 to 3 GU toxicity occurred in 20.5% (grade 3 in 3.6%). However, any predictors of late grade 2 to 3 GU toxicity weren’t founded. Conclusion HDR brachytherapy as monotherapy in localized prostate cancer is a highly effective treatment with minimal side effects. OC-0272 Long-term rectal toxicity following I-125 prostate brachytherapy in 1,260 patients A. Yorozu 1 , S. Sutani 1 , R. Kota 1 , A. Sunaguchi 1 , K. Toya 1 , S. Saito 2 1 Tokyo Medical Centre- NHO, Department of Radiation Oncology, Tokyo, Japan 2 Tokyo Medical Centre- NHO, Department of Urology, Tokyo, Japan Purpose or Objective To analyze factors associated with long-term rectal toxicity in permanent prostate brachytherapy patients. Material and Methods This retrospective cohort study examined 1,260 patients treated with I-125 brachytherapy without external beam radiotherapy between 2003 and 2013. Neoadjuvant androgen deprivation (NAD) was given to 39% of patients. The patient, treatment, and dosimetry factors were examined for an association with rectal toxicity. Toxicity was graded according to the National Cancer Institute’s Common Terminology Criteria for Adverse Events ver 4.0. Rectal dosimetry was calculated through dose-volume histogram of the rectum using day-1 and day-30 CT-based dosimetry, and expressed as volume of rectum in cc receiving 100% and 150% of the prescription dose (RV100 and RV150, respectively), and as dose to 5% and 30% of rectum (RD5 and RD30 respectively). The Kaplan-Meier method and Cox regression model were used for analysis. Results The median follow-up was 6.6 years. Median RV100 was 0.15 cc at day 1, and 0.56 cc at day 30. Any grade of proctitis, rectal bleeding, fecal incontinence, diarrhea, and anal pain was observed in 22.9%, 22.8%, 15.2%, 10.6%, and 9.9% of patients, respectively. Toxicities were categorized as grade 1 in 28.8% of patients and grade 2 in 1.7%. No Grade 3 toxicity was observed. Actuarial risk of grade 2 rectal toxicity was 2.0%. The majority cases (82%) of grade 2 toxicities were diagnosed by the third year. Upon univariate analysis, the likelihood of G2 toxicity was significantly associated with RV150, RV100, RD30, RD5 at day 1, and NAD. Only RV100 at day 1 and NAD fit a Cox regression model. Actuarial risk of grade 2 was 1.4%, 3.1%, 4.8%, and 6.7% for patients with RV100 <=0.2cc, 0.2-0.5cc, 0.5-1cc, >1cc at day 1, respectively (P=0.029). Actuarial

risk of grade 2 was 1.1 % for patients with NAD, and 2.2% for patients without NAD (p=0.032). Conclusion I-125 prostate brachytherapy is well tolerated. Rectal dosimetry at day 1 is relevant to long-term rectal toxicity. RV100 and NAD are associated with rectal toxicity. OC-0273 Prostate brachytherapy in African-Caribbean patients: A retrospective analysis of 370 cases V. Atallah 1 , N. Leduc 2 , M. Creoff 2 , P. Escarmant 2 , V. Vinh-Hung 2 1 universitary hospital, radiotherapy, Pointe-a-pitre, Guadeloupe 2 Universitary hospital Martinique, Radiotherapy, Fort- de-france, Martinique Purpose or Objective Prostate cancer is the most frequent malignancy in African-Caribbean men, a population sharing common genetic traits with African-American (AA) but presenting also genomic and epidemiologic specificities. Despite socio-economic disparities with French mainland, all patients were treated within the French state-financed equal-access healthcare system. In this study, we report biochemical outcomes of patients treated by brachytherapy in our department from 2005 to 2014 in an African-Caribbean population Material and Methods 370 consecutive patients receiving I125 brachytherapy as a curative treatment for early-stage (localized) disease between 2005 and 2014 were recorded. Selected patients presented with low risk disease: initial PSA (iPSA) < 10 ng/mL, clinical stage <= T2a, Gleason <7. Patients with intermediate risk of recurrence were also included on a case to case basis with PSA <15 or Gleason 7 (3+4). Biochemical failure free-survival (BFFS) was defined according to the ASTRO nadir+2 definition. Results The 3-year and 5-year BFFS for the entire cohort were 98.3% and 91.6% respectively. For patients with low and intermediate-risk disease, the 5-year BBFS rates were 92.1 and 90.8%, respectively. In univariate and multivariate analysis, only Gleason score ( ˂ 7 vs 7; P = 0.030 ˂ 0.05) was a significant predictor of biochemical failure. The overall rate of late and acute grade 2 or higher Genito-urinary toxicity was 12.6% and 10.3 %. Conclusion In this large single-center series, brachytherapy achieved excellent rates of medium-term biochemical control in both low- and selected intermediate-risk localized prostate cancer in African-caribean patients. Brachytherapy seems to be an excellent choice of treatment, with excellent outcomes and limited morbidity for African-Caribbean populations. To our knowledge, our series is the first presenting brachytherapy results in this specific population. OC-0274 Comparison of MRI/CT fusion and CT for prostate post-implant dosimetry using sector analysis N. Katayama 1 , M. Takemoto 2 , A. Takamoto 3 , S. Sugiyama 1 , K. Hisazumi 1 , K. Watanabe 1 , H. Ihara 1 , K. Katsui 1 , Y. Nasu 3 , S. Kanazawa 3 1 Okayama University Graduate School of Health Sciences, Department of Radiology, Okayama, Japan 2 Himeji Red Cross Hospital, Department of Radiotherapy, Himeji, Japan 3 Okayama University Graduate School of Health Sciences, Department of Urology, Okayama, Japan Purpose or Objective Anatomical structures are well defined, so MRI/CT fusion is considered the best method for postimplant dosimetry of permanent prostate brachytherapy. We compared the results obtained from MRI/CT fusion-based dosimetry with those of CT-based dosimetry using sector analysis, and