In patients with T1 anal squamous cell cancer status post local excision with a close margin, would you recommend close observation or adjuvant concurrent chemoradiation?

I would solicit the opinions of my colorectal surgery and GI colleagues to see if re-resection (with TAMIS, for example) is possible. If it is not, I would likely observe. If the margin was positive and not just close, I would do traditional chemoradiation.