<prompt> In classic Barrets, the length of columnar epithelium in distal oesophagus is1cm2cm3cm4cm  <response>: Classic Barretts 3cm columnar epithelium;Sho-segment Barretts 3 cm of columnar epithelium;Cardia metaplasia intestinal metaplasia at the oesophagogastric junction without any macroscopic change at endoscopy.The relative risk of cancer rises with increasing length of abnormal mucosa. 