O critério de positividade para a análise imunoistoquímica da p53 na confirmação da displasia do esôfago de Barrett faz diferença?

Immunohistochemical overexpression of the p53 protein and Ki-67 (MIB-1) antigen in patients with GERD and chronic esophagitis

BACKGROUND AND STUDY AIMS

Patients with gastroesophageal reflux disease and Barrett esophagus have an increased risk of developing adenocarcinoma of the esophagus. It is uncertain whether molecular or proliferative alterations are present in the early stages of disease.

METHODS

One hundred thirty-eight patients with gastroesophageal reflux disease symptoms were subjected to upper gastrointestinal endoscopy with biopsies of the esophageal mucosa. p53 protein expression and the Ki-67 proliferation index were determined by immunohistochemical studies. Patients were divided into 4 groups according to histopathologic diagnosis: G1, normal epithelium (n=58); G2, mild esophagitis (n=42); G3, moderate esophagitis (n=23), and G4, severe esophagitis (n=15).

RESULTS

p53 overexpression was detected in 7% of G1, 21.4% of G2, 52.2% of G3, and 60% of G4 patients. There were significant differences between G1 and G3 or G4 (P<0.001) and between G2 and G4 (P<0.05). The Ki-67 index was 21.3+/-19.5% in G1, 30.8+/-23.4% in G2, 47.1+/-23.2% in G3, and 48.3+/-25.7% in G4. Significant differences in the Ki-67 index were found between groups: G1 x G3 (P<0.001), G1 x G4 (P<0.001), G2 x G3 (P=0.026), and G2 x G4 (P=0.046). p53 and Ki-67 overexpression were correlated with the severity of esophagitis (P<0.001).

CONCLUSIONS

p53 overexpression and the Ki-67 (MIB-1) index were correlated with histologic findings of inflammation in the esophageal mucosa, particularly in the moderate and severe forms of chronic esophagitis.

P53 and Ki-67 overexpression in gastroesophageal reflux disease--Barrett's esophagus and adenocarcinoma sequence

Gastroesophageal reflux disease (GERD) is a major risk factor for the development of esophageal adenocarcinoma (ACE). Many molecular alterations occur in esophageal carcinogenesis, yet the exact mechanism of ACE development remains unknown. This study aims to determine p53 protein and Ki-67 expression in esophageal mucosa of patients with GERD and study the correlation between these markers and the progression from normal squamous epithelium to esophagitis, columnar epithelium with or without intestinal metaplasia and ACE. We analyzed p53 protein and Ki-67 expression in biopsies of 200 patients with GERD and 35 patients with ACE. Those biopsies were classified into five groups: (i) G1 normal squamous epithelium (58); (ii) G2 esophagitis (80); (iii) G3 columnar epitheliums without intestinal metaplasia (30); (iv) G4, columnar epitheliums with intestinal metaplasia (32); and (v) G5 ACEs (35). p53 protein overexpression was found in 7% (4) of G1, 37.5% (30) of G2, 30% (9) of G3, 62.5% (20) of G4, and 71.4% (25) of G5 (p < 0.001). Ki-67 index increased according to the severity of histopathological diagnoses. Ki67 index was 21.3 +/- 19.5% in G1, 38.8 +/- 24.9% in G2, 37.7 +/- 26.3% in G3, 52.8 +/- 24.6% in G4, and 57.1 +/- 25.1% in G5 (P < 0.001). Linear correlation between p53/Ki67 expression and the multistep progression from squamous epithelium to ACE was observed (P < 0.001 and P < 0.05). Our results indicate that overexpression of p53 and increased Ki-67 could be associated with the development and progression to ACE in patients with GERD.