I have just finished reading a good book on the subject. It was published in 2010 and is quite up to date. It is a medical book and I did not understand a lot of the terminology but I found it very informative. It covers the increased prevalence,diagnosis,treatment, types of operations,post op treatment, radiotheropy and even molecular structure plus lots lots more. It is expensive to buy, around £140. Your local library can get you a copy for a small charge, but I would suggest this note will lead to a rush, so expect a delay. But remember it is a medical book and is not easy reading. It is a series of articles by numerous learned people in the subject.
Tital - Adenocarcinoma of the Esophagogastric Junction by Paul M.Schneider published by Springer.
Paul Schneider is a professor in the University of Zurich Hospital.