For patients you treat with LDR prostate brachytherapy, how do you sequence treatment with external beam radiation therapy?

We use EBRT followed by LDR brachytherapy in 3-4 weeks time

To do LDR followed by EBRT you must be mindful that the implant will still be active and delivering low dose rate radiation while EBRT is being delivered. So the prescription must either be modified from the traditional 45Gy + 110Gy or you will need to use a short half life isotope (Cs or Pd) and wait for at least 3 half-lives. There is sparse, robust literature supporting the safety and efficacy of that approach.

With combination brachytherapy and external radiotherapy for prostate cancer, I see the greatest intensity of side effects (primarily urinary) following the brachytherapy procedure. Scheduling the brachytherapy after the external beam would require either a significant gap in treatments to allow resolution of the external beam effects on the prostate, or sequencing the brachytherapy first.

My routine for patients requiring combination therapy is to perform a Pd-103 implant initially to deliver ...

We also sequence LDR implant after EBRT. My exception is small glands (~12-18cc) that will get ADT. Due to cytoreduction, I will implant first to prevent a potentially technically challenging implant.

Having sequenced LDR before and after, I now always do it first. It is easy to start external beam but can be more difficult to schedule a seed implant given operating room availability, anesthesia availability, physics presence sooner rather than later, etc...

I usually wait 2 weeks prior to starting external beam. Trying to keep the total treatment package time shorter and I can monitor my patients closely under beam. The vast majority of toxicity is GU and reduced flow with dysuria, urgency a...