**3. Clinical difference between EAC and ESCC**

#### **3.1. Location of ESCC and EAC**

In 50–60% of cases, ESCC is located in the middle third thoracic esophagus in Thailand, Iran, and Japan [3, 12, 13, 14]. About 60% of SCCs is also located in the middle third of the esophagus in Iran. Several studies have found that ESCC was most commonly located in the lower third of the esophagus, such as studies conducted in Ghana [15].

In 80% of cases, EAC is located at the gastroesophageal junction (GEJ) and 20% in the lower third thoracic esophagus. This entity is capable of producing EAC directly or, more commonly, through an intermediate pre-neoplastic lesion or Barrett's esophagus (BE). BE is a pre-malignant lesion that develops in 6–14% of patients with Gastroesohageal reflux disease (GERD), of which approximately 0.5–1% will develop EAC [10, 11]. Increased incidence of BE in the past 30 years correlates with an increased incidence of EAC during the same period.
