How would you treat a recurrent endometrial cancer at the vaginal cuff that was initially FIGO 1A with no adj treatment, in a patient with actively treated scleroderma?

I would favor brachytherapy alone using MRI based planning with either a multichannel or hybrid applicator. Dose 6 Gy x 6 to CTV and higher dose (hot spots) to GTV.

I think there is not much data in the gyn space to delineate potential toxicities. Radiation for patients with scleroderma raises the risks of skin fibrosis, as well as hardening of the other tissues in the radiation field. Radiation may also cause a flare of scleroderma symptoms.

One study described 153 breast cancer patients with scleroderma (Shah et al., PMID 29316366) 69 of whom underwent radiation. For those undergoing radiation, about 50% experienced local tissue fibrosis, though no systemic flare. Based on these data, the authors concluded that radiation should be an option for breast cancer patients with scleroderma with informed consent, and based on shared decision-making.

I suppose it might be reasonable to extrapolate to vaginal b...

I agree with Dr. @Dr. First Last that it depends on size and extent. If reasonably small, e.g. <3 cm in size, I would favor brachy alone. My preferred approach is a permanent interstitial implant with Cs-131 to a dose of 55-60 Gy in this patient with no prior RT. I recognize permanent seed implantation (other than prostate) that this is not a common skill set in the radiation oncology community, but it is by far the best way to localize dose/limit volume, deliver dose at depth in a more uniform manner (more conformal) than with cylinder/intracavitary treatment, and there are, in my opinion, significant radiobiologic advantages of low dose-rate continuous radiation.

If the lesion is larger, I would consider limited external beam (limited in ...