PIERCE2 and esophageal squamous cell carcinoma: As for NK cells, an innate immune cell with potent cytolytic activity against tumors, they have already been reported to be associated with a favorable outcome in ESCC (Baba et al. 2020); however, this is the first time that the expression of C15orf65 is noted to be related to the prognosis of ESCC and the infiltration of NK cells.