ESTRO 2024 - Abstract Book

S272

Brachytherapy - Gynaecology

ESTRO 2024

of 6 to 8 Gy in 4-6 fractions to achieve total dose of ≥ 85Gy (D90 HR-CTV) in EQD2. Implantation, tumor size, lateral extension from MRI or CT scan before brachytherapy and HR-CTV volume were selected for analysis.

Results:

There were 86.8% of patients who achieved total dose of ≥ 85Gy of D90 HR-CTV) in EQD2. IC/IS brachytherapy was used 77.4%. Median tumor size, HR-CTV volume and lateral extension were 5 cm,23.06 mm3 and 26.5 mm, respectively. Median doses of D90 HR-CTV, D90 IR-CTV, D2cc bladder, D2cc rectum, D2cc sigmoid and D2cc bowel were 89.8 Gy, 65.2 Gy, 76.3 Gy, 67.5 Gy, 62.7 Gy and 60.8 Gy in EQD2, respectively. Implantation and HR-CTV volume were statistically significant with D90 HR-CTV ≥ 85Gy in EQD2 (p=0.012 OR=0.283 and p=0.00 OR=6.143, respectively). When subgroup analysis, we found HR-CTV volumes ≤ 35 ml was the significant factor but lateral extension and tumor size were not statistically significant factors. At the median follow-up time of 24 months (range 1 -107), IC/IS group had significantly local control when compared to IC group (31 months VS 16 months, p=0.00). In addition, tumor size also had significantly local control for tumor < 2 cm, 2-5 cm and > 5 cm (32 months, 30 months and 24 months, p=0.014). Cervix, pelvic and paraaortic recurrent were 5.2%, 3.3% and 6.1%, respectively but distant metastasis was 18.2%. Late grade 3 proctitis, cystitis and vaginal stenosis were 7.1%, 1.9% and 2.4%, respectively. No grade 4 or 5 toxicities were found in our study.

Conclusion:

Intracavitary brachytherapy alone may be used for small tumor which is HR-CTV volumes ≤ 35 ml and IC/IS brachytherapy may be helpful to achieve total dose of D90 HR-CTV ≥ 85Gy in EQD2 which provide good local control and low toxicities. MRI should be done before brachytherapy to select needle insertion.

Keywords: brachytherapy, cervical cancer

2534

Digital Poster

Variation of T-score determination in Locally Advanced Cervical Cancer

Laura Motisi 1 , Jacob Lindegaard 2 , Sabrina Reichl 1 , Willmann Jonas 1 , Allex Laura 1 , Marta Gimeno Morales 3 , Luca Tagliaferri 4 , Maria Concetta La Milia 4 , Alessandra Salvati 4 , Lena Kretzschmar 1 , Ricarda Stella Guninski 1 , Sandeep Kamal 1 , Tiuri Kroese 1 , Maria Belen Navarro-rubio Coello de Portugal 3 , Adriana Martinez-Iage Goni 3 , Maite Echeveste Ucar 3 , Primoz Petric 1 1 Universital Hospital Zürich, Radiation Oncology, Zürich, Switzerland. 2 University Hospital Aarhus, Oncology, Aarhus, Denmark. 3 Cancer Center Clinica Universidad de Navarra, Radiation Oncology, Pamplona, Spain. 4 Fondazione Policlinico Universitario A. Gemelli IRCCS, UOC di Radioterapia, Radiation Oncology, Rome, Italy

Purpose/Objective: