ESTRO 2024 - Abstract Book

S5997

RTT - Treatment planning, OAR and target definitions

ESTRO 2024

ipsilateral lung criteria were fulfilled in all plans, although optimal criteria was met in 239 (62.9%) treatment plans. Target-volume and organ-at-risk dosimetric parameters were significantly better for PBI comparing to WBI [PTV V95: 98.0% (1.89) vs. 97.2% (1.95), p=.005; PTV V105: 2.60% (3.30) vs. 4.30% (1.20), p<.001; heart V5: 1.60% (7.27) vs. 10.82% (15.47), p<.001; heart V25: 0.0% (.17) vs. .39% (2.65), p<.001; heart mean dose: .32Gy (.42) vs. .81Gy (.90), p<.001; ipsilateral lung V30: 3.16% (2.75) vs. 14.33% (4.45), p=.001;], except for PTV V107 (0.0% (0.0) vs. 0.0% (0.0), p=.28). DIBH showed no statistically significant impact on heart or ipsilateral lung dosimetric parameters, either for left or right breast irradiation (p>.05).

Conclusion:

In summary, our hospital's adoption of ultrahypofractionation for early-stage breast cancer adjuvant radiotherapy since March 2020 showcases commendable dosimetric compliance. Among 377 patients, V95 and V105 criteria were predominantly met, along with heart and ipsilateral lung constraints, except in one isolated case. Comparing techniques, PBI consistently outperformed WBI in dosimetric parameters, significantly favoring PBI. DIBH demonstrated no significant impact on heart or ipsilateral lung dosimetry for left or right breast irradiation, this result should be interpreted with caution given that patients that didn’t performed well in free-breathing were either treated with DIBH or with another fractionation schedule. This study reinforces the potential of ultrahypofractionation, offering optimized treatment outcomes, reduced treatment burden, and further research will validate its long-term benefits in the management of early-stage breast cancer.

Keywords: Breast, Radiotherapy, Ultrahypofractionation

References:

Brunt, A. M., Haviland, J. S., Wheatley, D. A., Sydenham, M. A., Alhasso, A., Bloomfield, D. J., & et al. (2020). Hypofractionated breast radiotherapy for 1 week versus 3 weeks (FAST-Forward): 5-year efficacy and late normal tissue effects results from a multicentre, non-inferiority, randomised, phase 3 trial. The Lancet, Open Access. Publicado em 28 de abril de 2020. DOI: 10.1016/S0140-6736(20)30932-6. Meattini, I., Becherini, C., Boersma, L., Kaidar-Person, O., Marta, G. N., Montero, A., Offersen, B. V., Aznar, M. C., Belka, C., Brunt, A. M., Dicuonzo, S., Franco, P., Krause, M., MacKenzie, M., Marinko, T., Marrazzo, L., Ratosa, I., Scholten, A., Senkus, E., Stobart, H., Poortmans, P., & Coles, C. E. (2018). European Society for Radiotherapy and Oncology Advisory Committee in Radiation Oncology Practice consensus recommendations on patient selection and dose and fractionation for external beam radiotherapy in early breast cancer. Radiotherapy and Oncology, 126(1), 1-9. DOI: 10.1016/j.radonc.2017.10.016.

Planning Pack for the FAST-Forward Trial, Version 3: A Guide to Outlining, Planning & Verifying FAST-Forward Patients.

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Proffered Paper