How would you treat a locally advanced rectal squamous cell cancer with vaginal invasion?

I would get p16/HPV status and pDL1 testing. It could be vaginal cancer invading the rectum. I would treat with concurrent chemoRT with cisplatin-based chemo, with EBRT and a boost to 70+ Gy, then reassess for any salvage based on response.

If the anterior wall of the vagina is free (i.e. the 5 cm refers to the cephalo-caudad length of the tumor), and this proves to be a case of a high grade but potentially resectable (assuming adequate response to preoperative tx) T4 rectal cancer. I've treated cases with exactly this histology and pr...