ESTRO 2023 - Abstract Book

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ESTRO 2023

D2cc to the vaginal mucosa ranged from 124.95 Gy (EQD2) for 4.9mm lesion thickness to 415.36 Gy (EQD2) for 28.1 mm.

Table 1. Dose to the vaginal mucosa for different target thicknesses

Table 2. Dose to OAR after 6x3 BT

Conclusion Limited published data connecting dose to the vaginal mucosa and vaginal morbidities currently exist. A D2cc cut-off at 145 GyEQD2 suggested to be a predictor for vaginal ulcers means that a lateral thickness limit for IMBT would be around 7.5mm. However, even for a patient with a distance between CTV and applicator of 12.8 mm, the total D2cc does not exceed 148 GyEQD2, and is reduced by IMBT to a maximum D2cc of 139.5 GyEQD2.

PO-2148 A retrospective review of vaginal cancer outcomes at a tertiary referral centre in the UK

J. Veeratterapillay 1 , L. Dodd 2 , L. Guttierez 1 , R. Patil 1 , S. Singhal 1 , D. Morgan 3

1 Northern Centre for Cancer Care, Freeman Hospital, Clinical Oncology, Newcastle Upon Tyne, United Kingdom; 2 Northern Centre for Cancer Care, Freeman Hospital, Clinical Oncology, Newcastle Upon Tyne Hospitals , United Kingdom; 3 Northern Centre for Cancer Care, Freeman Hospital, Medical Physics , Newcastle Upon Tyne, United Kingdom Purpose or Objective The aim of this retrospective review is to assess local outcomes following definitive radio(chemo)therapy +/- brachytherapy in patients with vaginal cancer treated at a tertiary referral centre. Materials and Methods Patients with vaginal cancer who received radical intent treatment between October 2008- January 2022 were included. Retrospective data was collected from electronic records including patient demographics, tumour characteristics and treatment details. Kaplan Meier scores were used to estimate local control, progression free and overall survival. 33 patients were included, with a median age of 66 years. 100% had squamous cell carcinoma. 52% of patients had FIGO stage 1/2 disease, 39% had FIGO 3/4a disease and staging was unknown in 9% of patients. All patients received initial external beam radiotherapy (82% received 45Gy/25 fractions, 12% received 50Gy/25 fractions and 6% received other doses); 61% of patients received concurrent chemotherapy with cisplatin. Following this, n=21 (64%) of patients were treated with brachytherapy (n=14 with intracavitary brachytherapy, n=7 with interstitial brachytherapy) and n=10 (30%) of patients received an external beam boost. Results

Median EQD2 doses ( α / β ratio of 10) for patients treated with brachytherapy was 63Gy and with EBRT boost was 54.25Gy.

With a median follow up of 53 months, 3 and 5 year OS were 81 and 76.7% respectively. 3 and 5 year PFS were 78 and 78% respectively and 3 and 5 year local control were 81 and 76.3% respectively.

Conclusion