ESTRO 2023 - Abstract Book

S1970

Digital Posters

ESTRO 2023

fractions in 3 days (range, 20 to 22.5 Gy), and cumulative EQD2 was 77.5Gy (10). Mandibular BT doses were limited to a median of 4.4 Gy (D 0.1 cc) and 3.15 Gy (D 1cc) per fraction. At a median follow up of 16 months (range, 3 to 23 months), 11 out of 14 are alive and disease free. Among the three who had recurrence, one had local recurrence, one had locoregional and one developed local recurrence with lung metastases. No long-term toxicity was observed during the limited follow up, except in one who developed early superficial asymptomatic mandibular radio-necrosis (mandibular dose of 81.1 Gy EQD2 and follow-up of 6;months) and managed conservatively. Early HN Cancers treated with interstitial BT in study interval 21 Tongue 14 Lip 3 Buccal mucosa 2 Tonsil 2

Conclusion Brachytherapy for Head and neck cancers, tongue cancers poses a unique challenge and requires a dedicated multi- disciplinary team approach. Our preliminary experience suggests modest outcome with acceptable toxicities especially in oral tongue cancers.

PO-2188 High dose rate surface brachytherapy in non-melanoma skin cancer

C. F. Pedrero 1 , S. Fernandez Alonso 1 , S. Guardado González 1 , C. Arias Guillén 1 , G. Pozo Rodriguez 2 , E. Capón Saez 1 , A. Ferrando Sanchez 2 , R. D´Ambrosi 1 , J.F. Pérez-Regadera Gómez 1 1 Hospital Universitario 12 de Octubre, Radiation Oncology, Madrid, Spain; 2 Hospital Universitario 12 de Octubre, Medical Physicist, Madrid, Spain Purpose or Objective To study the evolution of patients diagnosed by non-melanoma skin cancer treated by HDR plesiotherapy in our center. Materials and Methods Between 01/01/17 and 08/30/22, 37 patients were treated and we studied retrospectively their characteristics.

All lesions were staged following the 8th TNM-UICC system and to assess toxicity, we used the CTCAE v5.0 scales.

Results Mean age was 76 years (range 67-93). 70% were men and 30% women.

The histology was squamous cell in 49%, basal cell in 43% and others in 7%.

According to the 8th TNM-UICC staging, 11% was T1N0M0, 70% was T2N0M0, 11% was T3N0M0, 3% was T3N1M0, 3% T3N2M0 and 2% was T4N0M0.

51% patients had undergone prior surgery on the lesion.

Lesions were located in the ear in 66% cases, in the nose in 9%, in temporal region in 6%, in frontal region in 6%, in the lip in 6%, in the periorbital region in 3%, in the shell in 2% and in the scrotum in 2%.

Dose were delivered according to the following fractionation schemes: 6x7Gy 63%, 9x4.5Gy 25%, 7x7Gy 3%, 5x7Gy 3%, 5x5Gy 3% 25x2Gy 3%.

G1 skin acute toxicity appeared in 40%, G2 in 25% and G3 in 11%. No G4 acute toxicity was observed.

G1 skin chronic toxicity appeared in 32% (13% hypopigmentation, 8% hyperpigmentation, 5% induration, 3% atrophy and 3% fibrosis).

Median OS was 5 years.