Final answer:
Squamous cell carcinoma is the most common type of esophageal cancer worldwide, affecting the squamous cells lining the esophagus.
Step-by-step explanation:
The most common type of esophageal cancer worldwide is squamous cell carcinoma. This cancer affects the squamous cells that line the esophagus and is more prevalent in certain parts of the world. Another common type, particularly in Western countries, is adenocarcinoma, which often arises from a condition called Barrett's esophagus, associated with chronic acid reflux. While not as common as basal cell carcinoma, which is the most common type of skin cancer, squamous cell carcinoma of the esophagus is a significant health concern and can be very serious if not diagnosed and treated early.