Infections after fiducial marker implantation for prostate radiotherapy: are we underestimating the risks?

The use of gold fiducial markers (FM) for prostate image-guided radiotherapy (IGRT) is standard practice. Published literature suggests low rates of serious infection following this procedure of 0-1.3%, but this may be an underestimate. We aim to report on the infection incidence and severity associated with the use of transrectally implanted intraprostatic gold FM. Three hundred and fifty-nine patients who underwent transrectal FM insertion between January 2012 and December 2013 were assessed retrospectively via a self-reported questionnaire. All had standard oral fluoroquinolone antibiotic prophylaxis. The patients were asked about infective symptoms and the treatment received including antibiotics and/or related hospital admissions. Potential infective events were confirmed through medical records. 285 patients (79.4%) completed the questionnaire. 77 (27.0%) patients experienced increased urinary frequency and dysuria, and 33 patients (11.6%) reported episodes of chills and fevers after the procedure. 22 patients (7.7%) reported receiving antibiotics for urinary infection and eight patients (2.8%) reported hospital admission for urosepsis related to the procedure. The overall rate of symptomatic infection with FM implantation in this study is 7.7%, with one third requiring hospital admission. This exceeds the reported rates in other FM implantation series, but is in keeping with the larger prostate biopsy literature. Given the higher than expected complication rate, a risk-adaptive approach may be helpful. Where higher accuracy is important such as stereotactic prostate radiotherapy, the benefits of FM may still outweigh the risks. For others, a non-invasive approach for prostate IGRT such as cone-beam CT could be considered.