Should a laryngectomy be performed if pet scan is still showing activity in larynx after chemoradiation for t3n1mo scc of supraglottic larynx?

Laryngectomy. Only if you have biopsy proven cancer at that site. The pet scan will be positive even with inflammation. Wait until there is a biopsy that shows cancer. Suspicion is raised if the suv counts are rising and not falling. I hope this helped. Good health to you!
Biopsy. Ideally you would want a positive biopsy before committing to a total laryngectomy. If there is high clinical suspicion, thin-cut neck CT with contrast may be helpful to compare with the PET scan. As others have said, it could be inflammation, so you could repeat the PET in 3 months.