Proton versus photon therapy in locally advanced cervical cancer; a dosimetric study
Abdulwahid, D. Lines, D. Stich, P. Lee, J. Barraclough, Lisa H Hoskin, Peter J
Abdulwahid, D.
Lines, D.
Stich, P.
Lee, J.
Barraclough, Lisa H
Hoskin, Peter J
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Abstract
Purpose or Objective
To investigate whether protons deliver comparable target
dose whilst reducing organs at risk (OAR) doses for the
external beam component of cervical cancer treatment
which could allow dose escalation for the brachytherapy
component and improve toxicities.
Material and Methods
Five patients who received radical chemoradiation with a
Volumetric Modulated Arc Therapy (VMAT) technique using
the EMBRACE II protocol for definition of planning volumes
and constraints. The prescribed dose to the planningtarget
volume primary (cervix, uterus, pelvic ± para-aortic
lymph nodes) was 45 Gy in 25 fractions. The SIB dose for
the involved nodes was 55 Gy in four patients. They were
retrospectively replanned with single field (SFO) and
multi-field (MFO) optimised proton plans. The lower target
constraints were 95% of the prescribed dose in 95% of the
target volume. For every patient, target parameters as
well as V20, V30,V40 to the organs at risk (bladder and
rectum) were evaluated and compared between the two modalities. Results
Both photon and proton plans provided excellent target
volume coverage, homogeneity and conformity. With both
SFO and MFO, there was a reduction of the V20 and V30 to
the organs at risk compared to VMAT Conclusion
Photon and proton plans were dosimetrically adequate in
terms of target coverage, conformity and
homogeneity. Protons offered the best sparing of bladder
and rectum at low dose levels but were similar for dose
volume parameters >V30. This could contribute to a
significant reduction of acute and late toxicity in cervical
cancer treatment. Further validation with clinical
endpoints will determine whether there is a role for proton
therapy instead of photon therapy to improve the side
effect profile of patients with locally advanced cervical
cancer.
Description
Date
2020
Publisher
Collections
Keywords
Type
Meetings and Proceedings
Citation
Abdulwahid D, Lines D, Stich P, Lee J, Barraclough L, Hoskin P. PO-1487: Proton versus photon therapy in locally advanced cervical cancer; a dosimetric study. Radiotherapy and Oncology . 2020 Nov;152:S800.