What is the optimal interval between vaginal cuff brachytherapy sessions?

At MD Anderson, we give 6 Gy x 5 to the surface and we most often treat every other day. However, given the low risk of toxicity, we think it's safe to make adjustments to this schedule. For example, we often do some treatments on sequential days if that's preferred for any reason. We also schedule chemotherapy in between cuff treatments but generally avoid doing both cuff and chemotherapy on the same day.

At UAB, we gave 7 Gy x 3 = 21 Gy at 0.5 cm at the depth, treating every other day but we can vary somewhat the treatment interval according to patient transportation.

PORTEC-2 did 7 Gy x 3 to 0.5cm depth once per week, which is the approach I use for anyone receiving that fractionation scheme, including patients receiving cuff + chemo.

If q3 week CarboTaxol is involved, I shuffle the schedule slightly with the goal of completing VCB between cycles of chemo, but my only hard stop would be in delivering chemo and VCB on the same day. Ideally, I want to give a few days for acute chemo toxicities to resolve, so frequently end up giving the last VCB the day before their next cycle is due.

For 5 Gy x 2 to depth done as boost after EBRT I allow twice per week.

The standard at my current institution follows the PORTEC-2 regimen, delivering 7 Gy x 3 to 0.5 cm depth once weekly. However, I am planning to change our standard to twice weekly. Where I trained, we typically did 5.5 Gy x 4 to 0.5 cm depth twice weekly.

Per the ABS Guidelines (Small Jr et al., PMID 22265439), their statement as far as timing goes is as follows:

“The panel recommends that, when using HDR, the treatment be delivered in multiple fractions per week if tolerance allows. Daily fractions, however, are not encouraged unless a lower daily dose is used. The practice of delivering one fraction/week, especially as a boost after EBRT, is not recommended."

For 10 years, I have been doing VCB at 700 cGy x 3 to 5 mm primarily and at 400 cGy x 3 to 5 mm as a boost on a Tuesday–Friday–Tuesday schedule (3 fractions over 1 week). It has been very well-tolerated and I am not aware of any recurrences at the cuff.