MutL homolog 1 expression in thyroid carcinoma and its clinical significance

Objective: The aim of this study was to evaluate the MutL homolog 1 (MLH1) protein expression in thyroid cancer patients and its association with clinical pathological characteristics. Materials and Methods: Forty thyroid cancer tissues and 22 partial paired normal thyroid tissues from 40 thyroid cancer patients who received surgery were collected in this study. MLH1 protein expression was tested by immunohistochemical method for the 40 cancer tissues and 22 partial paired normal thyroid tissues. The positive expression rate of MLH1 was compared between cancer tissue and normal tissue. The association between clinical pathological features such as gender, age, pathology type, clinical stage, lymph node metastasis, and MLH1 protein expression was calculated. Results: MLH1 protein was mainly expressed in the nucleus with a small amount of expression in cytoplasm. The MLH1-positive expression rates in cancer and normal tissue were 47.5% and 81.8%, respectively, with statistical difference (P = 0.008); MLH1 protein positive expression was correlated with clinical stage (P = 0.04) and cancer lymph node metastasis (P = 0.03). However, its expression was not associated with gender (P = 0.63), age (P = 0.77), and pathology type (P = 0.77). Conclusion: MLH1-negative expression may play an important role in thyroid cancer tissue development and lymph node metastasis.