Do you omit adjuvant radiotherapy in T4a laryngeal SCC with favorable prognostic factors?

I guess one could omit PORT for such a situation. I have never encountered this situation and I don't know what data NCCN is using to support this recommendation. Historically, pT4 is the indication for PORT.

It would be very unlikely that it would be so favorable that RT could be omitted. If that were the case, larynx preservation should have been employed. There would likely be subglottic extension that would increase the risk of positive level 6 nodes and a stomal recurrence.

I agree with Dr. @Dr. First Last, there is little data to support observation, and T4 alone without any other risk factor is a high/high intermediate risk factor (Peters et al., PMID 8482629). It still should remain a classic indication for PORT.

A recent NCDB analysis we did at our institution noted...

It depends upon the histology. For example, a low-grade chondrosarcoma of the larynx can do very well with surgery alone, even if T4a. See Chin et al., PMID 27291822 for more details.