Unique site- and time-specific patterns of recurrence following resection of colorectal carcinoma hepatic metastases in patients staged by FDG-PET

Background/Purpose. We recently reported that patients staged by positron emission tomography (PET) with F-18 fluorodeoxyglucose (FDG) prior to liver resection for metastatic colorectal cancer had an excellent 5-year survival. In this study, the site- and time-specific patterns of recurrence were examined in patients staged by FDG-PET and the results compared to historical literature control data. Methods. From March 1995 to June 2002, all patients having hepatic resection for colorectal cancer metastases had preoperative FDG-PET. A prospective database was maintained. Results. One hundred patients were studied; 48 patients had no evidence of recurrence, 30 patients had recurrence within 12 months of resection, and 22 patients had recurrence after 12 months. Seventy percent of patients with recurrence within 1 year of resection had intrahepatic recurrence. Furthermore, 86% of patients with recurrence more than 1 year after resection had extrahepatic recurrence. We reviewed all published case series of conventionally staged patients. This pattern of early recurrence in the liver and later recurrence in extrahepatic sites has not been reported in any of the conventionally staged series. Conclusions. There is an interesting difference in the pattern of recurrence of FDG-PET-staged patients and conventionally staged patients who undergo liver resection. Several explanations seem possible. One potential explanation requiring further study is that the pattern of recurrence is due to the convergence of two factors-that FDG-PET more effectively detects extrahepatic disease than conventional staging and that liver resection gives a growth spurt to hepatic metastases.