One multicenter randomized phase II study found that tumors with high tumor expression of the hypoxic marker CA9 had higher risk of PAN relapse after CRT, and although extended-field radiotherapy improved PAO recurrence-free survival overall, the therapeutic efficacy of extended-field radiotherapy in terms of improved DFS was only observed in CA9-only positive LACC, but not in CA9/HIFs double-positive patients [159,160]. Here, CA9 is linked to neoplasm.