Due to gerd i am on long term maint. of protonix (pantoprazole) 40mg/day. does long term use of protonix (pantoprazole) or other ppi's increase risk of gastrointestinal cancers?

Not that we know of: There has been concern that long-term use of ppis could increase the risk of some GI cancers. However, there is no solid evidence for this. A recent meta-analysis (gut 2013, nov 12) showed that esophageal cancer risk decreases with use of ppis. There are other risks associated with long-term use of ppis, but cancer doesn't appear to be one of them..

??: That is currently being studied in a national trial. We don't have an answer yet. We should have one within a year out two. Study nct 01322623.