Key Points
• Source: International Journal of Particle Therapy
• Conclusion/Relevance: “Early clinical outcomes of patients treated with PBS–PBT using Monte Carlo–based planning, fiducial placement, and rectal spacers sans endorectal balloons demonstrate minimal treatment-related toxicity with good oncologic outcomes. Rectal spacer stabilization without the use of endorectal balloons is feasible for the use of PBS–PBT [pencil-beam scanning-pencil beam radiotherapy].”
• Investigators at Georgetown University Hospital reviewed records of 33 patients with localized prostate cancer who received placement of fiducials in the prostate and the insertion of a hydrogel rectal spacer.
• During 18 months of follow-up, the most frequent complaint was urinary frequency. No high-grade late genitourinary toxicities occurred, although one grade 3 gastrointestinal toxicity did. One treatment failure was found in a man with high-risk prostate cancer.
• Hydrogel spacers are polyethylene glycol-based gels that form a geometrical expansion of the potential space situated at the posterior prostate and the anterior rectum. These spacers separate the prostate and rectum to a large degree and improve rectal dosimetric across nearly all dose–volume parameters.
• The author write, “These dosimetric improvements have translated into particularly low rates of clinical GI toxicity and excellent patient-reported quality of life for intensity-modulated radiation treatments.”
• Limitations of the current study include its short follow-up period and retrospective nature.