When do you use a vaginal cuff boost with pelvic RT for stage II endometrial cancer?

Most prospective studies studying the role of external beam in endometrial cancer have treated patients with pelvic radiation (46/2 Gy or 50.4/1.8 Gy) without any brachytherapy. These studies have reported very low rates (2-3%) of in field failure in the radiation arms, so recommending external beam without brachytherapy is a reasonable choice for post-operative treatment. However, many radiation oncologists do combine pelvic radiation and brachytherapy. In our practice, we generally prescribe 45 Gy/1.8 Gy and 2 or 3 HDR treatments of 5 Gy prescribed to the vaginal surface for most cases of endometrial cancer requiring post-operative pelvic radiation. The vaginal cuff boost compensates for the slightly lower dose of pelvic radiation, bringi...

I agree entirely with @Dr. First Last. I will add that the patients receiving external beam RT today tend to have a higher risk profile than those studied in the past, because most intermediate risk patients are now treated with vaginal cuff RT only.

To answer whether stage II patients are ever treated with VBT alone, it's not a boards answer as it's not supported by randomized data, but we have done it based on this multi-institutional analysis out of Loyola: https://www.ncbi.nlm.nih.gov/pubmed/29885996

Requirements are that the patient undergo a thorough pelvic +/- paraaortic dissection (usually our gyn-onc is getting 20-25+ nodes). I'm not sure how I would feel about omitting Pelvic RT in a patient undergoing SLNB.

Additionally, the myometrial invasion have to be <= 50%, and grade has to be 1-2, with negative margins. We generally favor microscopic stromal invasion (barely stage II rather than bulky stage II) I suppose.

It's a relatively rare scenario, but we have offered VBT alone in ...