Objective        To determine the expression of claudin 3 and claudin 4 in esophageal squamous carcinoma and its precancerous lesion

and investigate the clinicopathological s

ignificance of the expression.       Methods        Tissue microarray technology and immunohistochemical assay (Envision) were used to detect the expression of claudin 3 and 4 in 93 tissue samples of esophageal    squamous   carcinoma

20 samples of dysplasia

20 samples of esophagitis and 15 cases of normal esophageal mucosal tissues.       Results        Claudin 3 was expressed in only 1 case of normal esophageal mucosa (6.7%)

4 cases of esophagitis (20.0%)

6 cases of dysplasia (30.0%) and 40 cases of squamous carcinoma (43.0%). The positive rate was the highest in cancer tissue

and the lowest in normal esophageal tissue

with significant difference between them (

P

0.05). The rate was obviously higher in the cancer tissue than in normal tissue (

P

0.05)

but no difference was seen among the normal tissue

dysplasia and esophagitis tissue (

P

0.05). Claudin 4 expression was found in 5 cases of normal esophageal mucosa (33.3%)

7 cases of esophagitis (35.0%)

8 cases of dysplasia (40.0%) and 42 cases of squamous carcinoma (45.2%)

without significant difference among these groups (

P

0.05). The expression of claudin 3 and 4 was not associated with other clinicopathologic factors

such as sex

age

tumor size

pathological grade and infiltration (

P

0.05)

but obviously negatively associated with   lymphatic metastasis and   patient survival (

P

0.05). The expression of claudin 3 and 4 was significantly correlated with each other (Chi-sqaure=8.520

K=0.302

P

=0.004)

but had no significant difference in esophageal squamous carcinoma (

P

0.05). Kaplan-Meier survival analysis showed that the survival rate in patients with claudin3 and 4 expression was significantly higher than those without (

P

0.05).       Conclusion      Claudin 3 may participate in the occurrence of esophageal squamous carcinoma. Down-regulation of claudin 3 and 4 is associated with   lymphatic metastasis in esophageal squamous carcinoma

and they might serve as potential markers for prognosis of

esophageal squamous  carcinoma.