A Systematic Review and Meta-analysis of the Effect of Proton Versus Photon in Prostatic Cancer Patients
Authors: Al-Ghubaishi Somayah Ali , Altheebi Sara Mohammad , Alsahwan Zainab Aziz , Althomali Raghad Ahmed , Kadasah Norah Saeed , Banoun Yusra Hassan , Alsubhi Mohammed Ahmed 
Published: January 2025

Abstract

Background:
Prostate cancer (PC) is also a common urologic malignancy and an important contributor to cancer deaths amongst males. For PC treatment, radiation therapy (RT) is used frequently with the use of new technologies such as intensity-modulated RT, which helps to deliver radiation concentrated on the tumour avoiding damage of the healthy tissue. Photon therapy can be compared to a modern type of RT known as proton therapy (PT), that can also deliver anticancer radiation, but with less damage to healthy tissues. Nevertheless, the clinical utility of PT in PC remains questionable because the therapy is expensive and there are few comparative trials. The objectives of this systematic review and meta-analysis are to systematically assess the comparative efficacy and toxicity of proton compared with photon therapy in the treatment of localised PC.

Methods:
Specifically, the methods of these systematic reviews and meta-analyses were identified according to the Cochrane Handbook and the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement. After developing the review protocol, it was published on PROSPERO. The trim-and-fill method was then applied to assess if any additional studies needed to be incorporated in an effort to balance potential source of bias that might have pulled the summary odds ratio towards either end of the distribution. These eight sample cohort studies were sourced from the initial PubMed, Web of Sciences as well as Scopus search under the keywords ‘Proton’, ‘Photon’, ‘Prostatic cancer’ and ‘Radiotherapy’. The Newcastle–Ottawa Scale was used to assess the quality of the included studies. Extraction of data was done by four authors, concerning the aspects of study design, patients’ characteristics and treatment results. Sensitivity analyses as well as other statistical analyses were conducted using Review Manager 5.4 and OpenMetaAnalyst software.

Results:
The meta-analysis consisted of eight researches from different countries including the USA, Austria, Norway and Singapore, which compared proton with photon therapy in patients with PC. Compared with photon therapy, PT decreased radiation of the rectum and bladder by six standardised mean differences on average. The study concluded that proton therapy significantly reduces radiation dose to organs at risk, particularly the rectum and bladder, but no significant differences were observed for intraprostatic lesions or urethra. It was also observed that there were no different levels of tolerance to dose for intraprostatic lesions and the urethra when applying both forms of treatment. Subgroup analyses showed that removing some studies will reduce the heterogeneity and give consistent results.

Conclusions:
A case of PT seems to have benefits in the reduction of dosage amounts delivered to organs at risk such as the rectum and bladder in the treatment of PC patients. However, no enhancement in managing intraprostatic lesions and the urethra was reported as compared with photon therapy. More comparative studies on bigger patient series and those using a common treatment planning algorithm are still required to confirm our findings and investigate the general applicability of PT in PC.