Endometrial cancer - patterns of local failures?

[seper]

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Greetings,
Is anybody aware of a study classifying local failures based where in vagina they occur? (i.e. lower vagina vs. top of the cuff vs. "suburethral" vs. lateral walls, etc). It is of interest because my group is considering switching to a multi-channel vaginal cylinder, which can produce asymmetrical dose distribution.

 

[deleted4401]

So, the Miami cylinder's advantage isn't for what you're asking. The target is the upper 1/3 to 2/3 of the vagina. You can bill more for it, however 🙂 I use single channel, myself.

The advantage is for actual vaginal recurrences that occur or for vaginal cancer. That's when the asymmetrical planning helps you out.

 

[seper]

I use Nucletron CT/MR compatible mufti-channel vaginal cylinder set. I'm uneasy playing with asymmetrical dose distribution, fearing 1) under-dosing critical areas and 2) creating hotspots in vaginal wall.

 

[deleted4401]

Yeah, not sure what you're asking.

For a post-op endometrial primary that has an indication for vaginal cuff brachytherapy, the multi catheter doesn't offer a benefit, because the target is the whole cuff. I target the upper 3cm, by contouring 3cm of the cylinder and adding 0.5cm margin and subtracting out bowel/bladder. With multichannel, you barely dent the DVH. Nobody at this point is changing the target or shape of the cuff, based on recurrence patterns and what not.

But, for the primary cancers and recurrences you can treat the whole vaginal mucosa, but increase weighting to the areas of gross disease. As far as accuracy, I think no other modality in RT gives you accuracy and conformality of brachytherapy, especially with a cylinder where you can place it right up to the cuff and image it.

 

[seper]

With mulch-channel, you can prescribe to 5 mm depth and decrease rectal dose compared to single channel cylinder. I'd like to know if posterior vaginal wall failures are common before doing it routinely.