What is the evidence that there is a benefit to giving doses higher than 3060 cGy-3600 cGy in the elective treatment of uninvolved lymph nodes in the treatment of SCC of anal canal with chemoradiation?  

The published data with dose varying from 30.6 to 45 Gy to uninvolved nodes has not shown any difference in regional control. The studies which did not treat the pelvis to an adequate volume or excluded inguinal region reported higher regional recurrence.  

There is no data. The first studies for anal cancer were 30 Gy with chemo.  These increased in subsequent studies to 40 and 45 Gy.  Some treated the inguinal nodes; some didn't.  There is a study from France looking at the subsequent risk of inguinal nodes - this was related to radia...

An excellent discussion about dose to the elective nodes can also be found in this related question on dose to the primary tumor in anal SCC: What dose do you typically prescribe to the primary tumor for definitive treatment of squamous cell carcinoma of the anal canal (given concurrently with ...