Risk for infection(s) from fiducial marker placement

Most of us who have gone through any form of image-guided external beam radiotherapy have had TRUS-guided transrectal placement of gold fiducial markers or radio transponders placed in our prostates. Some who have had salvage radiation have had them placed in the prostate bed. Fiducial placement carries a risk for infection, a risk that may be growing because of increased resistance to fluoroquinolone antibiotics. The procedure is similar to a transrectal biopsy, and carries many of the same risks.

Loh et al. reported the results of an Australian study among 359 patients who had fiducials placed between 2012 and 2013. All patients had received standard prophylactic fluoroquinolone antibiotics. The men were all sent a brief questionnaire within 2 years of the procedure. Responses were confirmed based on patient records. They got a very good response rate (79 percent) with the following findings:

  • 27 percent experienced increased urinary frequency and dysuria.
  • 11.6 percent experienced chills and fever.
  • 7.7 percent received subsequent antibiotics for urinary tract infection.
  • 2.8 percent were admitted to the hospital for sepsis.

A similar study by Berglund et al. of Calypso radio transponder placement in 50 men reported that 10 percent had subsequent infections, with 6 percent going on antibiotic therapy. One patient suffered an epidural abscess that required open debridement and lumbar fusion. One patient suffered a prostate abscess with MRSA.

This rate of infection is higher than what is reported by physicians, which is 1.3 percent or less, but is consistent with current infection rates reported after transrectal biopsies. Liss et al. reported biopsy-related resistant infections of 8 percent among men who received only fluoroquinoline prophylaxis and 6 percent were hospitalized. Almost all of them were found to have fluoroquinolone-resistant infections. Rectal culture of all the men in the study revealed fluoroquinoline-resistant bacteria, predominantly Escherichia coli, in 1 in 5 men. The rate of infection has been steadily increasing. Resistant E. coli infections can cause potentially fatal septic shock and intractable chronic prostatitis.

Loh et al. go so far as to recommend that radiation oncologists forgo the use of fiducials for IMRT (but not for SBRT). They point to a dosimetry study that showed that the difference in prostate localization without fiducials was almost always less than 5 mm. However, it also showed differences could be as high as 1 cm. It is the extremes of motion that fiducial image guidance controls for so well, and it is those extremes that account for most of the toxicity.

There are less radical measures that can be taken:

  • Careful screening of patients for previous fluoroquinoline use, major surgeries with antibiotics, hospital workers and their families, diabetes and other co-morbidities that may increase risk of infection. Men with a number of previous biopsies, as may happen with active surveillance, are especially susceptible.
  • Rectal swab culture for resistant bacteria, and selection of more specific antibiotics based on the resulsts of the culture.
  • Use of a different class of prophylactic antibiotic, like aminoglycosides, Flagyl, clindamycin, Bactrim, amoxicillin or carbapenems.
  • Applying povidone-iodine to clean the rectum (as in this study).

Transperineal fiducial placement carries insignificant risk of infection, but may require a spinal block or local anesthesia.

Patients should raise this concern with their doctors prior to fiducial placement. As someone who got a urinary tract infectrion from fiducial placement, I wish, in hindsight, that I had.

Editorial note: This commentary was written for The “”New” Prostate Cancer InfoLink by Allen Edel.

2 Responses

  1. It is questionable whether the 27% of men experiencing urgency and dysuria should attribute this to the fiducials procedure. The questionnaire was sent out anywhere from 3 to 15 months after the fiducials were placed. Given that radiation usually starts within a few days of the procedure, how did these men know whether to attribute this response to the fiducials or the radiation? This is not addressed.

    Interestingly, the other three findings are more likely associated with infection, and are also significantly lower. However, it would be helpful to know if all these men had waited a significant period between biopsy and planting the gold seeds.

  2. I don’t think the authors were implying that the 27 percent were all infections, only the 7.7 percent. As one who got such an infection, it would be hard to forget, even 15 months later. In my case, it was about 8 months after my last biopsy.

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