ESTRO 38 Abstract book

S71 ESTRO 38

168 patients was compared between RTOG and CTCAE scores (Table 1). RTOG classified patients’ genitourinary and gastrointestinal toxicities at higher grade than CTCAE. RTOG and CTCAE scores were associated in all scenarios (p<0.01), even with percentages of ≥ grade 2 toxicities differing. Conclusion There is no significant statistical difference between the scores, even thought RTOG score tends to increase the severity of the described symptoms. While, CTCAE appears to be more complex it is more reliable and reproductible in research, since each symptom is separately described with its corresponding grade. The use of the CTCAE score is preferable for reporting toxicities of HDR brachytherapy as monotherapy for prostate cancer. Detailed methodology and the use of guidelines can improve research quality, guarantee the report quality, and facilitate future research comparisons. PV-0147 MRI-guided salvage HDR brachytherapy for locally recurrent prostate cancer L. Joseph 1 , A. Sundaramurthy 1 , A. Berlin 1 , J. Helou 1 , C. Menard 2 , P. Warde 1 , C. Catton 1 , B. Lao 1 , A. Bayley 1 , A. Rink 1 , A. Beiki-Ardakani 1 , P. Chung 1 1 Princess Margaret Cancer Centre, Radiation Oncology, Toronto, Canada; 2 Centre Hospitalier de L’Universite de Montreal, Radiation Oncology, Montreal, Canada Purpose or Objective Biochemical relapse (BCR) may occur in up to 40% of patients with localized prostate cancer treated with external beam radiotherapy (RT). A proportion of these, the disease recurrence is local alone. Radical salvage treatment options remain limited, and brachytherapy represents an attractive organ-preserving alternative. We report the results of a prospective study of MR-guided This was a phase II prospective cohort study. Eligibility were ECOG performance status 0-1, pathologically proven locally recurrent prostate cancer visible on multi- parametric MRI (mpMRI), > 18 months after primary RT, and PSA-doubling time > 6 months. All patients were treated with HDR brachytherapy under MR guidance alone. In cohort 1, patients were treated to a dose of 16Gy to the whole gland with an integrated 6Gy boost to the MR-visible tumor (GTV) in two fractions 7-14 days apart. Cohort 2 patients were treated to a dose of 26Gy to GTV alone in two fractions 1-2 weeks apart. The GTV was defined using mpMRI (T2-weighted, diffusion-weighted, dynamic contrast-enhanced). CTV margin expansion (5 mm in all directions) was restricted to adjacent organs at risk and 2 mm beyond the prostate boundary where applicable. PTV margins of 2 mm cranio-caudally and 1mm elsewhere were then applied. No patients were given neoadjuvant ADT. Patients were followed up with regular PSA, and mpMRI +/- prostate biopsy were performed after a minimum of 2 years. Toxicity was assessed using CTCAE version 4. BCR was determined using Phoenix definition (nadir+2). Results A total of 43 patients were enrolled, 14 in cohort 1, and 29 in cohort 2. Median age was 70 years (range 62-85). Median PSA pre-salvage was 4.54ng/mL (range 1.68-14). On pre-salvage biopsies, 7%, 72%, 12% and 7% had Gleason Score 6, 7, 8 and 9, respectively and 2% were ungraded. Overall median follow-up was 55 months (range 3-123), 100 in cohort 1, 38.5 in cohort 2. Crude rates of biochemical control at 2 years were 71% in cohort 1 and 82% in cohort 2. 3-year rates were 64% in cohort 1 and 68% in cohort 2. 5-year rates were 50% in cohort 1. Of those eligible and accepting of post-salvage MRI and/or biopsy, 42% (5/12) had localized recurrence confirmed in cohort 1 and 40% (6/15) in cohort 2 (4/15 recurrence within radiation field). Acute GI and GU toxicity was experienced in 13% (

rather than 40 mm as measured previously by trans-rectal ultrasound planning. In response to this finding, the plans of implants on 35 mm long prostates were altered to have less seeds placed in the 40 mm plane and more seeds in the 10 mm plane. Post implant, registered MR-CT images were used to measure the Dose 90 prostate base and Dose 0.1 cc membranous urethra, and these doses made it possible to identify men likely to be at higher risk of BF and urethral stricture. Conclusion Modern imaging has improved our understanding of factors influencing the risks of BF and urethral stricture after low dose-rate prostate brachytherapy, and has guided modifications to implant technique that could mitigate these risks. PV-0146 RTOG versus CTCAE score: reporting toxicity of HDR brachytherapy Monotherapy for prostate cancer M. Jolicoeur 1 , E. Hill 1 1 CICM Hôpital Charles Le Moyne, Radiation Oncology, Greenfield Park, Canada Purpose or Objective Compare the Radiation Therapy Oncology Group (RTOG) score and the Common Terminology Criteria for Adverse Events (CTCAE) score for reporting toxicities of HDR brachytherapy as monotherapy for prostate cancer. Material and Methods Mixed-method methodology was applied. The mixed- method consisted of direct comparison of the scores, a systematic literature review (25 selected articles), and the comparison of the acute toxicity scores classification in a sample of prostatic cancer patients treated by HDR brachytherapy. The patients included in this study were part of the protocol named: HDR Brachytherapy as Monotherapy for Low and Intermediate Risk Prostate Cancer (BRP2) (https://clinicaltrials.gov/ct2/show/NCT03424694). 168 patients were followed up for 3 months after HDR brachytherapy for low and intermediate risk prostate cancer. Patients were evaluated at 1, 3, 6 weeks and 3 months after radiotherapy. Symptoms were classified according to RTOG and CTCAE scores. Descriptive statistics and Fisher Exact test were used to compare RTOG and CTCAE scores. Statistical significance was 0.05.

Results RTOG score unifies several toxicity symptoms in each of the five grades, while CTCAE score classifies each symptom within five grades, according to their severity. RTOG score lacks reproducibility between acute and late toxicities. CTCAE proposes the same score for describing both late and acute toxicities. 64% of the systematic literature review selected studies were prospective. 76% of them used CTCAE, 20% used RTOG, 4% used neither to evaluate early toxicity. There was no standard for the toxicity reporting methodology. 24% of the articles did not report when the toxicity was evaluated. 48% did not inform how the toxicity was evaluated. Only 19% fully reported which symptoms were evaluated. 48% of the studies did not inform if the toxicity was reported per event or worse toxicity per patient. The early toxicity of