The potential of proton therapy to reduce acute haematological toxicity in concurrent chemoradiotherapy for oesophageal cancer

Publication date: Available online 29 July 2017
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Samantha Warren, Christopher N. Hurt, Thomas Crosby, Mike Partridge, Maria A. Hawkins
Radiotherapy dose escalation using a simultaneous integrated boost (SIB) is predicted to improve local tumour control in oesophageal cancer, yet any increase in acute haematological toxicity (HT) could limit the predicted improvement in patient outcome. Proton therapy has been shown to significantly reduce HT in lung cancer patients receiving concurrent chemotherapy, we therefore investigated the potential of bone marrow sparing with protons for oesophageal tumours.21 mid-oesophageal cancer patients treated with conformal radiotherapy (3D50) were selected. Two surrogates for bone marrow were created by outlining thoracic bones (bone) and only the body of the thoracic vertebrae (TV) in Eclipse (Varian). The % overlap of TV with the PTV was recorded for each patient. Additional plans were created retrospectively: a volumetric modulated arctherapy plan (VMAT50) with the same dose as 3D50; a VMAT SIB plan with a dose prescription of 62.5 Gy to the high risk sub-region within the planning treatment volume (VMAT62.5); a re-optimised TV sparing VMAT plan (VMAT62.5bm) and a proton therapy plan (SFO62.5) with the same SIB dose prescription. Bone and TV dose-metrics were recorded and compared across all plans and variation with respect to PTV size and % overlap for each patient was studied.3D50 plans show the highest bone mean dose and TV V30Gy values for each patient. VMAT plans irradiate a larger bone V10Gy volume than 3D50 plans. Re-optimised VMAT62.5bm plans showed improved sparing of the TV volume, but only proton plans showed significant sparing for bone V10Gy and bone mean dose, especially for patients with larger PTV size.

Teaser

Radiotherapy dose escalation is predicted to improve local tumour control in oesophageal cancer, yet any increase in acute haematological toxicity (HT) could limit the predicted improvement in patient outcome. We investigated the bone marrow dose of VMAT, proton plans, and marrow-sparing VMAT plans for oesophageal tumours. Improved marrow sparing was possible with VMAT, but only protons showed significant sparing for bone V10Gy and bone mean dose, especially for patients with larger PTV size.


http://ift.tt/2v9mNkg