Cathepsin D expression as a possible predictor of lymph node metastasis in submucosal colorectal cancer.

The aim of this study was to clarify the usefulness of cathepsin D expression as a predictor of lymph node metastasis in submucosal colorectal cancer (CRC). Cathepsin D expression was examined immunohistochemically in cancer and stromal cells located at the deepest portion of 254 invasive tumours that had been resected from patients with submucosal CRC. In cancer cells, the expression was classified according to differences in intracellular localisation: polarity positive, apical type (PA); polarity positive, basal type (PB); polarity negative (PN); or no expression (NE). Lesions with PN or NE expression showed a significantly higher incidence of lymph node metastasis than those with PA or PB expression. Alternatively, lesions with positive expression in stromal cells showed a significantly higher incidence of lymph node metastasis than that of those with negative expression. None of the lesions with PA or PB expression and negative expression in stromal cells had metastasised to the lymph node. In conclusion, analysis combining cathepsin D expression in cancer and stromal cells may be a quite useful predictor for lymph node metastasis and may broaden the indications for curative endoscopic treatment of submucosal CRC.