CDKL2 and neoplasm: Loss of CDKL2 (P = .007), Lauren classification (P = .022), invasive depth of tumor (P = .001), regional lymph node metastasis (P < .001), distant metastasis (P < .001), pathologic staging (P < .001), histologic type and grade (P = .002), lymphovascular permeation (P < .001), and adjuvant chemotherapy (P < .001) were significantly correlated with disease‐free survival.