Overexpression of fatty acid synthase in oesophageal squamous cell dysplasia and carcinoma.

OBJECTIVE: The expression of fatty acid synthase (FAS), an enzyme necessary for de novo fatty acid synthesis, has been examined in several types of tumours so far, but not in oesophageal cancer and dysplasia. METHODS: We examined the immunohistochemical reactivity of FAS in 4 normal adult oesophagi, 14 dysplastic oesophageal lesions, and 80 squamous cell carcinomas and 6 cases with 4 special types of malignancies of the oesophagus. We also analysed the correlation between FAS expression and various clinicopathological features and long-term survival in patients with oesophageal cancer. RESULTS: In the normal oesophagus, only faint cytoplasmic FAS expression was observed in cells of the basal layer. In contrast, FAS-positive cells were found in 92.9% of cases of dysplasia and 96.5% of cases of carcinoma including 6 cases with a specific histological subtype. However, high expression of FAS did not correlate with either clinicopathological features or prognosis of patients with oesophageal cancer. CONCLUSION: Our results demonstrate that FAS is expressed in almost all oesophageal carcinomas of both usual and special types and dysplastic lesions, suggesting that FAS may be upregulated continuously from the early stage of oesophageal squamous cell carcinogenesis to established carcinoma.