As reported in a recent issue of the Journal of the National Cancer Institute Healy and colleagues from the University of Michigan Medical School have looked at practice patterns based on Medicare Claims data regarding the use of PET scans to follow people who have undergone treatment for either lung cancer or esophageal cancer. See link for the abstract; Dr. Stark can send you the full article. They examined over 97,000 charts of paople with lung cancer and over 4000 charts of people with esophageal cancer. They looked at frequency with which PET scans were ordered as part of routine follow-up surveillance. People who had PET scans as part of initial staging only, or people who had PET scans to follow up on a suspicious finding, were excluded from analysis. They asked two questions: how much variation is there among institutions, and does the frequency of PET scanning have any impact on patient outcome (i.e., survival)?
Here is what they found. There was a huge variation in PET scan ordering. The range for lung cancer was 0.05 to 0.70 PET scans per year; for esophageal cancer it was 0.12 to 0.97 scans per year. Despite this wide variation in the ordering of PET scans there was absolutely no difference in two-year survival statistics. Because patients did not necessarily undergo treatment with curative intent (rather some were merely treated to ameliorate symptoms or prolong life, with no hope of cure) the survival statistics were predictably dismal: about 29% for each disease at two years.
So what is the take-home message? Unless there are outcomes data that show that picking up early recurrence with frequent imaging studies results in an enhanced outcome there is no point is getting these scans in asymptomatic people. For some cancers — most notably testicular cancer — there are robust time-tested data that show that early pickup of recurrence is crucial; but not for these two cancers. Dr. Stark comments, “For reasons of cost, patient anxiety and radiation exposure, there is no reason to scan the average asymptomatic cancer patient repeatedly for evidence of recurrence. Most oncologists know this, but other doctors sadly seem not to. Robust education is necessary. As treatments improve, this paradigm will change.”