Its a common complaint on other forums as well. My '05 Ram has the cancer as well even with the full well liners.
Line-X or Herculiner has become an interesting idea for the rockers, lower panel and fender areas, and wells for me. Maybe next spring?
I've been seeing a few too. But it's not just the Rams. I was at a body shop where they were replacing the metal above the wheel wells on an F-150! They used foam in there too!!