ESTRO 2020 Abstract book

S691 ESTRO 2020

mean dose for BCC was 47.11Gy and for SCC was 53.05Gy. 29 (5.22%) recurrences were observed: 17.2% in OV, 37.9% in EB and 44.8% in HDR (p 0.197). 62.1% of them were SCC. Four patients died due to the NMSC (2.7%), all of them were SCC histology. Complete response was mostly appreciated in all groups. Only 0.5% BCC and 4.2% SCC had partial response, and in 2.4% BCC and 2.1% SCC the disease persisted. Acute toxicity was greater in the OV (57.3% G3) than in EB (47.7% G2) and HDR (42.8% G2) (p 0.0001). Despite most patients did not present chronic toxicity, 7.3% G4 was detected in EB (p=0.0001). There were excellent cosmetic results reported in the patients clinical histories. Conclusion 1. We don’t observe outcome differences between radiotherapy techniques in our retrospective review. OV technique presents major acute toxicity with statistical significance compared with HDR and EB, however, EB present major chronic toxicity and poor cosmetics results. PO-1223 Superficial radiotherapy in epithelial skin cancer S. Blanco Parajon 1 , M.Á. De la Rúa Calderón 1 , C. Prada García 1 , M. Balagué Montes 1 , P. Sánchez Galiano 2 , G. Juan Rijo 1 1 Hospital Universitario Central de Asturias, Radiation Oncology, Oviedo, Spain ; 2 Hospital Universitario Central de Asturias, Radiological Physics, Oviedo, Spain Purpose or Objective To retrospectively review epithelial skin cancer treated with superficial radiation therapy (SRT) in our institution. Material and Methods We analyzed 249 patients with a total of 272 lesions, treated with SRT between February 2005 and November 2018. Results Mean age was 79.57 years (77.18 in BCC and 83.32 in SCC). 51% were women. Histologically, 62.1% were BCC and 37.5% SCC. 70.6% were primary tumors, 28.3% recurrences after surgery and 1.1% recurrences after topic treatment. By location 9.2% were in area L, 36.4% in area M and 54.4% in area H. Staging was 4.8% in situ, 58.8% T1, 25.4% T2, 9.9% T3 and 1.1% T4. Positive perineural invasion was present in 2.6% and not known in 71%. Immunosuppression in 28.1%. Definitive primary SRT was performed in 59.9%, after surgery R0 in 1.1%, after surgery R1 in 29%, after surgery R2 in 3.3% and palliative treatment in 6.6%. The most common radiation dose was 54 Gy in 20 fractions delivered in 74.3% of lesions. Median follow up was 45 months (0.1-168). Globally recurrence free survival (RFS) was 91.2%, being 91.7% for primary tumors and 90% for recurrences. In lesions treated after surgery, primary lesions and palliative treatments, RFS was 87.9%, 92.6% and 94.4% respectively. Recurrences were 8.8% (58.3% BCC, 41.6% SCC), with 66.7% in-field, 16.7% out-field and 16.7% regional recurrences. RFS at 11.5 years was 75.3±7.7% in BCC and 54.2±22.8% in SCC. Multivariate Cox regression analyses showed increased risk of recurrence in SCC ( P =0.042) and T3 stage ( P =0.026). 2.

lymph node metastasis. The median brachytherapy dose 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