Routine use of PET scans to follow asymptomatic patients after curative therapy did not affect survival according to the retrospective analysis of a cohort of 97,152 lung cancer and 4,446 esophageal cancer patients. The authors compared high and low level use PET centers, and found no differences in 2-year survival.

http://jnci.oxfordjournals.org/content/108/7/djv429.abstract