ESTRO 2021 Abstract Book

S1156

ESTRO 2021

with data of literature, in fact in most of the 14 reported studies RT was overall well tolerated. The major observed toxicity was G3 skin toxicity in one study. Conclusion To our knowledge, there are no other cases of EPMD re-irradiation in literature. Even if several studies have demonstrated its feasibility in clinical practice, it is still not clear which are the skin dose constraints in re- irradiation setting. Our patient showed an excellent response and tolerated very well the high doses of both the radiation treatments. This suggests that the tolerance of skin to re-irradiation following a long period between the two treatments may be comparable to the normal constraints. PO-1407 Radiotherapy in Gorlin Syndrome: Is it an absolute contraindication? D. Esteban Moreno 1 , G. García Álvarez 2 , D. Rivas Sánchez 3 , D. Gonsalves Pieretti 4 , S. Suarez Casanova 4 , I. Castro Rizos 4 , R. Molina Cruz 4 , L.A. Glaría Enríquez 4 , E. López Ramírez 5 1 GenesisCare Toledo, Radiation Oncology , Toledo, Spain; 2 GenesisCare Madrid, San Francisco de Asis, Radiation Oncology, Madrid, Spain; 3 GenesisCare Malaga, Radiation Oncology, Malaga, Spain; 4 GenesisCare Toledo, Radiation Oncology, Toledo, Spain; 5 GenesisCare Madrid, Arturo Soria, Radiation Oncology, Madrid, Spain Purpose or Objective Medulloblastoma is observed in 5-10% of patients with Gorling Sindrome (GS) and it usually occurs in the first two years of life. Radiotherapy administered for medulloblastoma in GS induces basal cell carcinomas (BCC) in the area of radiation, so radiotherapy has traditionally been contraindicated due to reports of BCC induction in GS. We describe our experience with a patient with GS treated with radiotherapy. We have also performed a comprehensive literature review about the use of radiotherapy in BCC associated to GS. Materials and Methods Our case is a 73-year-old woman diagnosed with GS at the age of 33. She had multiple BCCs on her scalp, face, head and back. Previous therapies included multiple surgeries (Mohs last surgery on complex flap scalp), topical treatments and radiation therapy to the back at the age of 40. The patient presented 8 new lesions on the scalp and she refused surgery. She was treated in october of 2019 with 55 Gy in 25 fractions with volumetric arcotherapy (VMAT) with 6MV photons over all lesions and a sequential boost with 6MeV electrons, 10Gy in 5 fractions in two lesions greater than 3cm in diameter at diagnosis. We describe the flow of information through the different phases of the literature review in Image 1.

Results After 10 months of follow up, our patient had fully regression of the lesions (Image 2). After 17 months follow up, the patient presents vertigos pending study by otorhinolaryngology without secondary malignancy tumors.

In the literature review 5 studies show how the radiotherapy in pediatric age cause BCC, meningiomas and