Among Medicare patients who underwent surgery for colorectal cancer resection during the first 18 months of approved Centers for Medicare and Medicaid Services (CMS) coverage for FDG-PET imaging, there was a substantial growth in utilization of FDG-PET within two years of surgery and the highest rates of utilization occurred within six months of surgery, according to a study in the February issue of Radiology.

Hanna M. Zafar, MD, assistant professor of radiology and colleagues from the Hospital of the University of Pennsylvania in Philadelphia investigated early adoption and potential predictors of postoperative utilization of FDG-PET in patients who underwent colorectal cancer resection between July 2001 and December 2002 (the first 18 months of CMS coverage for FDG-PET) and who were observed for two years from the date of surgery.

“A 41 percent relative increase in utilization of FDG-PET was found among patients who underwent resection early in the study period compared with those who underwent resection late in the study period,” wrote the authors, who found no change in CT utilization between these two groups.

Of the 10,630 patients (mean age, 77.5 years), who underwent resection for colorectal cancer during the study period, 10 percent of patients underwent at least one FDG-PET exam in the two-year period following surgery.

FDG PET was used more frequently during the first six months following surgery compared with 18–24 months following surgery. “The highest utilization of FDG PET was during the first six months following surgery,” according to Zafar and colleagues.

Combined FDG PET/CT scanners were not common during the majority of the study period from July 2001 to December 2004. The study found that FDG-PET was almost never performed without CT, which suggested that, at least initially, FDG-PET did not replace, but was used as an adjunct to CT.

Zafar and colleagues also found a significantly higher use of FDG-PET in rectal over colon cancer. They found that "higher early postoperative utilization of FDG PET may be driven by difficulties in interpreting CT results in the recent postsurgical period, concern for tumor left in the operative bed, and/or more aggressive monitoring of patients for disease recurrence in the early postoperative period compared with subsequent periods."

The authors noted that the study had limitations associated with the use of a large claims database--several Medicare patients were excluded, including those enrolled in health maintenance organizations and those without Part A or B coverage; the findings may not be relevant to patients younger than age 66 and there was no knowledge of the precise clinical indications for FDG-PET.