PDPN and neoplasm: Multivariate survival analysis based on the Cox proportional hazards model including all parameters found to be significant on univariate analyses (data not shown), including PDPN positivity, lymphatic invasion, vascular invasion, tumor size ≥3 cm, G3 tumor, UICC grade pT3/4, UICC grade pN1, and stage III/IV (Table 2) [37], found that PDPN positivity (relative risk 2.598, P = 0.0030) and UICC N1 category (P = 0.0302) were independent markers of poor prognosis (Table 2) [37].