Abstract Book

S148

ESTRO 37

OC-0288 Outcomes of MRI-guided focal salvage high- dose-rate brachytherapy for recurrent prostate cancer. M.J. Van Son 1 , M. Peters 1 , J.L. Noteboom 1 , W.E.P. Eppinga 1 , R. Davila Fajardo 1 , M.A. Moerland 1 , J.R.N. Van der Voort van Zyp 1 1 UMC Utrecht, Radiotherapy, Utrecht, The Netherlands Purpose or Objective Treatment of locally recurring prostate cancer after primary radiotherapy is challenging. Both androgen deprivation therapy (ADT) and whole-gland salvage treatments are associated with toxicity and quality of life (QoL) deterioration. Focal salvage high-dose-rate brachytherapy (HDR-BT) potentially reduces toxicity and may prevent or postpone the need for ADT. Material and Methods We included 68 patients with locally recurrent, non- metastatic prostate cancer after primary radiotherapy (July 2013–August 2017). Disease status was evaluated by multiparametric-MRI (3T) and PSMA- or Choline-PET/CT. Dose planning and delivery of single-fraction (19 Gy) focal salvage HDR-BT was performed after contour adaptation on 1.5T intraoperative MR images with brachytherapy catheters in situ. Before treatment and during follow-up, genitourinary (GU) toxicity, gastro-intestinal (GI) toxicity and erectile dysfunction (ED) were graded according to the Common Toxicity Criteria for Adverse Events (CTCAE) 4.0. In addition, International Prostate Symptoms Score (IPSS) and International Index of Erectile Function score (IIEF-5) were obtained. QoL was measured with validated questionnaires (RAND-36, EORTC QLQ-C30 and EORTC QLQ-PR25). PSA was monitored, with biochemical recurrence defined as nadir+2 (Phoenix definition).

which 6 patients had metastatic disease on diagnostic imaging. A total of 3 patients started ADT. At 18 months, biochemical disease-free survival was 80% (95%CI 66-98%) and metastases-free survival was 89% (95% CI 79-100%). Conclusion In terms of toxicity, MRI-guided focal salvage HD R-BT seems favorable as compared to other salvage treatment modalities. There was no grade 3 acute toxicity, no severe GI toxicity and late severe GU toxicity was limited (1.5%). Long-term patient-reported QoL did not decrease over time. Preliminary results on the level of biochemical control are promising, though longer follow-up is warranted. In the future, further analysis on patient selection will yield more knowledge on the type of patient that benefits most from this treatment. OC-0289 Cancer of the nasal vestibule: excellent outcomes with sole image guided brachytherapy M. Czerwinski 1 , R. Van Leeuwen 1 , J. Kaanders 1 , E. Zwijnenburg 1 , D. Lipman 2 , R. Takes 3 , C. Verhoef 1 1 UMC St Radboud Nijmegen, Radiation Oncology, Nijmegen, The Netherlands 2 AMC Amsterdam, Radiation Oncology, Amsterdam, The Netherlands 3 UMC St Radboud Nijmegen, Otorhinolaryngology, Nijmegen, The Netherlands Purpose or Objective To evaluate the efficacy of modern image guided brachytherapy for squamous cell carcinoma of the nasal vestibule and to explore tumor volume as prognostic factor for regional recurrence. Furthermore, to assess patient satisfaction with nasal function and appearance post-treatment. Material and Methods In a retrospective analysis, we reviewed the medical records of 102 patients with Wang T1-T2 nasal vestibule cancer treated with brachytherapy as the sole treatment at a single institution. Median follow-up time was 42 months (range 3-210 months). A questionnaire study using the validated Nasal Appearance and Function Evaluation Questionnaire was conducted among 42 patients >1 year after treatment. A statistically significant cutoff point for tumor volume was established using Youden’s index method.

Results At baseline, median PSA was 5 ng/ml (range 0.9-39) and median PSA doubling time was 18 months (range 3.2-73). Tumor stages were rT2 (66%), rT3 (31%) and rT4 (3%). Median follow-up was 9.5 months (range 0-47). No acute grade 3 GU or GI toxicity occurred. One patient (1.5%) presented with late grade 3 GU toxicity (urethral stricture) at 24 months. There was no grade 3 GI toxicity. ED remained relatively stable throughout follow-up. Mean IIEF-5 showed a downward trend, with scores of 10.9 at baseline to 7.9 at 18 months (moderate ED, p=0.03). Mean IPSS showed a relative increase in the first year from 8.3 to 12.0 at 9 months (moderate symptoms, p=0.03), returning to baseline-level at 18 months. There were no significant differences in QoL, except for a significant increase in urinary complaints in the first month. Biochemical recurrence occurred in 8 patients, of

Figure 1: example of brachytherapy technique in a very voluminous tumor.