Different tumor biology among cancers, and the various regulatory mechanisms upstream of p-STAT3 signaling, for example, endogenous negative regulators such as the suppressor of cytokine signaling (SOCS) family, protein inhibitor of activated STAT (PIAS) proteins and the PTP family, or posttranslational modifications [109] may lead to the difference in prognosis prediction. Here, STAT3 is linked to cancer.