What rectal dose constraints do you use for definitive chemoradiation for vulvar/vaginal cancer?

The anorectum can be difficult to constrain when treating vulvar cancer definitively, as the reason we are often treating with chemoRT as opposed to upfront surgery is because the tumor is located in or near the anal sphincter. For definitive treatment, I cover the primary tumor to 64Gy in 32 fractions and I follow the contouring recommendations and constraints primarily from the most recent GOG protocol, GOG 279.

Following the protocol and standard contouring guidelines, the anorectum is contou...