What is the theme in The Drowned and the Saved by Primo Levi?

One major theme in the novel, The Drowned and the Saved, is that of shame, a subject we don't often read about in accounts of the Holocaust. The shame the "victims" feel as a result of the atrocities enacted against them is eye opening and difficult to read. I've often read about survivor's guilt.... but never this enlightening look at shame.