Particle therapy toxicity outcomes: A systematic review

Abstract

Owing to its physical properties, particle therapy (PT), including proton beam therapy (PBT) and carbon ion therapy (CIT), can enhance the therapeutic ratio in radiation therapy. The major factor driving PT implementation is the reduction in exit and integral dose compared to photon plans, which is expected to translate to reduced toxicity and improved quality of life. This study extends the findings from a recent systematic review by the current authors which concentrated on tumour outcomes for PT, to now examine toxicity as a separate focus. Together, these reviews provide a comprehensive collation of the evidence relating to PT outcomes in clinical practice. Three major databases were searched by two independent researchers, and evidence quality was classified according to the National Health and Medical Research Council evidence hierarchy. One hundred and seventy-nine studies were included. Most demonstrated acceptable and favourable toxicity results. Comparative evidence reported reduced morbidities and improvement in quality of life in head and neck, paediatrics, sarcomas, adult central nervous system, gastrointestinal, ocular and prostate cancers compared to photon radiotherapy. This suggestion for reduced morbidity must be counterbalanced by the overall low quality of evidence. A concerted effort in the design of appropriate comparative clinical trials is needed which takes into account integration of PT's pace of technological advancements, including evolving delivery techniques, image guidance availability and sophistication of planning algorithms.

Survey of clinician opinions on the role of proton beam therapy in Australia and New Zealand

“…A recent systematic review of 136 studies of both proton and carbon ion therapies (two thirds related to PBT alone) showed PBT provided at least equivalent tumour outcomes to conventional photon therapy. 1,2 There was the suggestion of reduced treatment morbidity associated with PBT for a range of tumour sites. 1,2 There are currently numerous trials underway comparing PBT and conventional photon beam RT in the treatment of several adult malignancies, including (but not limited to) breast, prostate, lung, head and neck, oesophagus and liver cancers.…”

“…1,2 There was the suggestion of reduced treatment morbidity associated with PBT for a range of tumour sites. 1,2 There are currently numerous trials underway comparing PBT and conventional photon beam RT in the treatment of several adult malignancies, including (but not limited to) breast, prostate, lung, head and neck, oesophagus and liver cancers. 13,17 Numerous paediatric oncology clinical protocols allow for PBT, and registries have been established to capture prospective clinical and dosimetric data in patients treated with PBT.…”

“…PBT has the advantage of significantly reducing the dose delivered to adjacent normal tissue and therefore reducing the potential sequelae of the treatment, which is particularly relevant in children with cancer. A recent systematic review of 136 studies of both proton and carbon ion therapies (two thirds related to PBT alone) showed PBT provided at least equivalent tumour outcomes to conventional photon therapy 1,2 . There was the suggestion of reduced treatment morbidity associated with PBT for a range of tumour sites 1,2 …”

“…Proton beam therapy (PBT) allows delivery of highly conformal radiation therapy (RT), which has dosimetric advantages over conventional RT and holds the promise of conferring clinical benefits for some patients. [1][2][3][4] PBT can be used in two different clinical scenarios: (1) to reduce dose to normal tissues, whilst maintaining the standard dose to a tumour, or (2) to allow dose escalation to a tumour, whilst respecting dose constraints to critical normal tissue structures. PBT has the greatest potential benefit in paediatric cancer patients and in adults with tumours situated near critical normal structures.…”

“…Proton beam therapy (PBT) allows delivery of highly conformal radiation therapy (RT), which has dosimetric advantages over conventional RT and holds the promise of conferring clinical benefits for some patients 1–4 …”