What dose and fractionation would you recommend for anal melanoma that is localized but refusing surgery?

I have treated patients with 30 Gy / 5 fractions with 2 fractions per week. There is some proctitis, for sure; and this is adapted from the adjuvant experience from MDACC. Patients have tolerated it well. We will then start immunotherapy after the radiation.

On the other hand, if the patient has a BRAF mutation, then I would defer radiation and start combination BRAF/MEK inhibitors.

Ballo et al, JCO 2012

I've also treated a patient with metastatic melanoma involving the low rectum, which may have been mucosal subtype, using SBRT 30 Gy in 5 fractions of 6 Gy each, every-other day. Immunotherapy was given concurrently and the patient had a rapid local response and stoppage of her bleeding. This fractionation is not that different from the 5 Gy x 5 fractions used in Europe for pre-op rectal cancers, but the volume is smaller for SBRT.