For early-stage vulvar cancer that is clinically/radiographically node negative with no surgical lymph node evaluation (e.g., patient or surgeon refusal), would elective nodal irradiation be reasonable in the absence of risk factors warranting treatment to the primary site?

With “absence of risk factors” then inherent to that meaning, you probably shouldn’t do something prophylactically that can cause harm (side effects, etc.).

It depends on the a priori risk of nodal involvement based on tumor size, depth of invasion, LVSI, etc.

If the risk is high enough, we can consider vs close observation with ultrasound or PET/CT.

With a negative (reviewed by RadOnc) nodal CT and PET, I would be comfortable avoiding RT to the nodes. However, the dose for microscopic disease without sensitizing chemotherapy would be of low toxicity and fully reasonable.