Expression and significance of cytokeratin 20 in lymph node micrometastasis of colorectal cancer in stage I and II patients

Objective To assess the impact of cytokeratin 20 (CK20) in lymph node micrometastasis on clinical staging and prognosis of colorectal cancer (stage Ⅰ and stage Ⅱ) by immunohistochemistry. Methods The original histology of one hundred and thirty-seven patients with stage Ⅰ or stage Ⅱ colorectal cancer who had undergone curative resection from January 2010 to December 2011 in Zhongshan City People's Hospital was reviewed. Immunohistochemical staining was performed using CK20 antibodies on all the 945 lymph nodes. The clinical and follow-up data of those patients were used for survival analysis. Results (1) Micrometastases were observed in 15 lymph nodes (1.6%) of 10 patients (7.3%). (2) The presence of micrometastases was not related to gender, age, tumor size, location, operation methods, CEA expression of the primary lesion, histological type, vascular and nerve invasion. (3) The positive rate of CK20 was 16.7% (4/24) of micrometastasis patients in 5 years, higher than those without recurrence or metastasis 5.3% (6/113, χ2=2.282, P=0.131). (4) COX regression analysis showed that gender (P=0.359), age (P=0.917), tumor size (P=0.547), histological type (P=0.106), CEA expression of the primary lesion (P=0.069), tumor location (P=0.760), stage (P=0.069), and surgeries (P=0.350) were not related to prognosis; but the expression of CK20was closely related with the prognosis of the patients (P=0.033), the risk of death in patients with the presenceof lymph node micrometastasis was 3.224 times higher than those without metastasis (95% CI=1.100-9.451). Conclusion CK20 detection of lymph node micrometastasis in colorectal cancer can improve the clinical stage of colorectal cancer, affect the treatment plan and is related to the prognosis of the patients. Key words: Colorectal neoplasms; Keratin-20; Lymph node; Micrometastasis; Recurrence