vaginal mets

[CUBuffsgrad98]

Hello everyone, a case for opinions:
66 y.o. healthy woman, dx ovarian CA 2 years ago --> sx --> chemo (had a hard time with chemo)
Since then has had waxing and waning PET pos LN in PAN, abdomen, inguinal, etc. Not huge amount of dz

Has bx + recurrent dz in the mid vaginal area, anterior wall. 3 small areas, not much depth to them (not detected on MRI) Discussed with med onc/gyn onc who only want vaginal areas treated (works for me because the patient is terrified of any possible side effects).

How would you treat? Recurrent radiation naive endometrial is recommended whole pelvis 45 Gy then brachy boost. Im leaning 40 Gy/20 fx then 6 Gy x3 HDR to the surface. Its a lot of tx for a palliative case, but progressive dz there could be a mess, esp when systemic burden is low. I think the local control it affords would be worth it........anyone?

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[Palex80]

Why not do only brachy? It's palliative, right?
You could probably also boost the anterior wall of the vagina if you have a shielded applicator (or a fancy multi-channel applicator)...
4 x 5 Gy for all of the vagina at 5mm depth, then boost the affected areas with 2 x 5 Gy?

 

[CUBuffsgrad98]

I agree it is palliative, so I dont want to go overboard, but its also gross disease. Not sure brachy alone is good enough to control gross disease without being too aggressive? If it progresses/recurs in this area, it could be a big mess.....

For what its worth, some other colleagues have suggested EBRT alone 50Gy/20 fx or 39 Gy in 13 fx. I think the vulvar irritation from this would be severe, not not mention there would be at least some bowel exposed to this high dose?

 

[CUBuffsgrad98]

btw, I like the idea of a shielded boost, but I dont have the capability, and would worry about the precision as the lesion can be seen on PET, but not seen on MRI. I can visually see it on exam, but in planning I would need a wide area to make sure I didnt miss

 

[medgator]

If it is <5 mm of depth to the lesions, you could try brachy first, and always save your external for later....

 

[Palex80]

btw, I like the idea of a shielded boost, but I dont have the capability, and would worry about the precision as the lesion can be seen on PET, but not seen on MRI. I can visually see it on exam, but in planning I would need a wide area to make sure I didnt miss

My CTV for the boost would be lesions plus 1 cm along the mucosal tissue and I would add another 5mm for CTV-PTV margin since the applicator is never 100% at the same spot.
You said it was the anterior wall, so blocking the dorsal 90 degrees of the applicator could spare the rectum from excessive dose.
I'd treat 2-3 times/week, so she would basically be done in 2-3 weeks if you are doing 6 fractions (4x all of vagina + 2x boost).

 

[seper]

it's hard to outline vaginal mets on HDR planning CT
would also do 40 Gy EBRT + cylinder boost

 

[Palex80]

You don't need to outline them. You don't even need a planning CT.
I've never outlined them on a planning CT.

All you have to do is make certain where they are located, draw a nice figure. Then measure the distance they are from fixed anatomical points like the urethra, the vaginal dome, etc.
Then make a plan accordingly.

If you can see that the lowest one is 2 cm cranial to the urethra for example, the highest one being 4 cm away from the vaginal dome and the vagina (urethra-dome) is 9 cm long, then you can do the math:
2 cm is lowest GTV, 9-4=5 cm is the highest GTV measured from the urethra. Your GTV is thus 5-2=3 cm long. Add to that 1 cm PTV margin and you have to treat 5 cm of vagina, with the first source position 2 cm from the applicator tip. Are all lesions located anteriorly? Block out the rectum.

Done.

You need to "stretch" the vagina properly when performing these measurements, to make certain they are the same when the applicator is in. A female colleague of mine used to insert a "dummy" cylinder, left it in for 10 min, then took it out, then measured immediately. She said it helps to bring the vagina to a state similar to that during treatment before measuring. It may sound weird or even nasty, but it actually makes some sense I guess.

 

[seper]

without fiducials, all that stretching and measurement is a bit voodoo in my opinion, sorry
also, clinically visible lesion is just tip of the iceberg, considering mode of cancer dissemination into vagina

 

[thesauce]

If no plans for chemo in the near future, I'd go ahead and give WPRT to 45/1.8 and vaginal cylinder boost (6 x 3 or whatever your preference)