The study used data for nearly 200,000 patients with stage IV breast, colorectal, lung, or prostate cancer collected by the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database, which includes 28% of the U.S. population.
Between January, 2002 and December, 2006, 95.9% of these patients underwent an advanced imaging test with a mean of 9.79 scans per patient, or 1.38 scans each per month of survival. After the diagnostic phase of their disease, 75.3% were scanned again, and 34.3% were scanned in the last month of life, the researchers found.
Between January, 1995 and December 2006, the proportion of stage IV cancer patients who received an advanced imaging test increased 4.6%.
Additionally, between 1995 and 2006, the mean number of times per month that a stage IV patient received an advanced imaging test went from 1 to 1.57.
However, for patients with much earlier cancers of stage I and II, "frequency and intensity of imaging outside of the diagnostic period declined over time."
The researchers postulated that clinicians are performing these studies in the absence of evidence that they prolong survival, even though there are an increasing number of treatments.