ESTRO 2020 Abstract Book

S643 ESTRO 2020

For overall survival, significant prognostic factors were age, smoking and WHO-PS (table 1). Acute treatment- related toxicity was generally mild with only 2.5 % of patients experiencing grade 3 GU toxicity and 1 % grade 3 GI toxicity. However, grade 2 toxicity was more preponderate with 15 % of patients experiencing grade 2 GI and 33 % of patients experiencing grade 2 GU toxicity. When comparing the different groups, significantly more grade 2 GI toxicity was noted in the CRT-group compared to the RT-only regimens but GU toxicity did not differ.

was 60 Gy (37-65 Gy). The median treated volume was 36 cm 3 (range: 5.4-85.6 cm 3 ). The median reference dose rate and number of pulses were 0.42 Gy/pulse/h (0.4-0.5 Gy/pulse/h) and 150 pulses (87-175 pulses) respectively. With a median follow-up of 37 months (3-120 months), 12 patients (18.4%) relapsed locally with a median time to local failure of 11.2 months (3.1-54.5 months). At last follow-up, 6 patients (9%) underwent partial surgery and 4 patients (6%) total penectomy for relapse. Three-year overall survival (OS) rate and 3-year disease-free survival (DFS) rate were 88.2% (95%CI: 79.7-97.7%) and 74.4% (95%CI: 63.9-86.6%) respectively. Twelve patients (20%) presented grade 2 painful ulceration resolving spontaneously and 13 patients (21.5%) experienced grade 2 meatal stenosis requiring at least one meatal dilatation. Presence of inguinal lymph node metastasis was correlated with a poorer OS (p=0.019) and DFS (p=0.018). Initial tumor diameter was correlated with poorer local control (p=0.03). No clinical or dosimetric factor was correlated with painful ulceration. The risk of meatal stenosis was strongly correlated with distal urethra D0.1cc (p=0.0016) and D0.2cc (p=0.0019) in multivariate analysis. The optimal cutoff for these constraints were 82 Gy (HR=0.12, 95%CI = 0.04-0.38) and 78 Gy (HR=0.19, 95%CI = 0.06-0.56) for D0.1cc and D0.2cc respectively. Five brachytherapy plans were then generated using these constraints showing the feasibility of sparing the distal urethra while maintaining good tumor coverage. Conclusion This large institutional experience confirms that PDR-BT is a valid option for penile preservation. To our knowledge, this is the first study to report dosimetric constraints for distal urethra correlated with late toxicity. PO-1222 Radiotherapy for non-melanoma skin cancer: three different radiation techniques comparison M. Arquez Pianetta 1 , L. Torres Royo 1 , M. Arguís Pinel 1 , D. Gómez Gómez 1 , Y. López Sánchez 1 , F. Castaño Zuleta 1 , J. Acosta Arteaga 1 , J. Gómez Ramos 1 , M. Murcia Mejía 1 , A. Azón 1 , N. Cabré Rubio 1 , M. Arenas Prat 1 1 Hospital Universitari Sant Joan de Reus, Radiotherapy, Reus, Spain Non-melanoma skin cancer (NMSC), which is the commonest cancer, is mainly represented by basal cell carcinoma (BCC) (75%) and squamous cell carcinoma (SCC) (25%). They can be treated with surgery, radiotherapy or both, with cure rates up to 96-99% with good cosmetic result. Purpose NMSC treated with radiotherapy offer an excellent local control with good cosmetic results, regardless of the radiotherapy technique used. Objective To analyse and compare the results, toxicity and cosmesis in patients treated with electrons beam (EB), high dose rate brachytherapy (HDR) and orthovoltage (OV) for NMSC. Material and Methods Between 2008 and 2014, 364 NMSC were treated in our department. 117 with OV, HDR (138) or EB (109), were evaluated. Clinical response, recurrence, acute and chronic toxicity and cosmesis were analysed. Results With a median follow-up of 66.5 months (0-148 months), mean age was 78.36 years (36-103 years). The mean dose delivered was 49.58Gy (27Gy-70Gy) for all techniques, with mean fractionation of 3.25Gy (1.8Gy-4.5Gy). The Purpose or Objective Introduction Poster: Clinical track: Skin cancer / malignant melanoma

Conclusion (Chemo)radiation in elderly and medically less fit patients was associated with high treatment compliance, acceptable toxicity profile and fair local control and survival rates. Even in the radiotherapy only group, an acceptable local control rate was achieved, justifying such a treatment in this patient population. Unfortunately, no predicting factors for acute toxicity could be identified. PO-1221 Dose-volume predictors of distal urethral toxicity after PDR brachytherapy for penile carcinoma S. Achkar 1,2 , R. Bourdais 1 , R. Sun 1 , T. Kumar 1 , M. Kissel 1 , T. Felefly 1 , M.H. Ta 1 , F.A. Pounou Kamga 1 , A. Escande 1 , E. Deutsch 1 , C. Haie-Meder 1 , C. Chargari 1 1 Gustave Roussy, Radiation oncology department, Villejuif, France ; 2 Hôtel-Dieu de France, Radiation Oncology department, Beirut, Lebanon Purpose or Objective Interstitial brachytherapy is a conservative treatment approach for localized penile cancer providing good local control. Dose constraints for distal urethra in this procedure are lacking. The aim of this study is to report our experience with pulse dose rate interstitial brachytherapy (PDR-BT) in the treatment of penile cancer and to evaluate dose-volume predictors of late urethral toxicity for potential use in clinical practice. Material and Methods The medical records of 65 patients treated with PDR-BT for localized squamous cell carcinoma of the glans penis in our institution between July 2008 and February 2019 were retrospectively reviewed. All patients underwent circumcision followed by PDR-BT. Interstitial needles were implanted according to the Paris system rules. Toxicity was graded according to Common Terminology Criteria for Adverse Events (CTCAE) v4.0. Univariate and multivariate analyses were performed to determine predictors of survival and toxicity among clinical and dosimetric characteristics. Results Median age at diagnosis was 64 years (range: 36-85 years). Median initial tumor greatest diameter was 25 mm (10-50 mm). Eight patients (12%) presented initially with inguinal lymph node metastasis. The median brachytherapy dose