The role of early postoperative PET-CT in patients with pathological stage III colon cancer: Results from a large single institution study.

Abstract

562 Background: Current staging of patients (pts) with pathological stage III colon cancer is suboptimal; many pts still recur despite unremarkable preoperative staging work-up. We previously reported that early postoperative PET-CT can alter the stage and management of pts with high risk stage III colon cancer in up to 19% of patients. The aim of the current study was to expand the previous one to a larger cohort and to determine the role of early postoperative PET-CT in the general population of stage III colon cancer pts, regardless of their individual risk. Methods: A retrospective chart review of all consecutive pts with stage III colon cancer who underwent early postoperative PET-CT between 2007 and 2016. Demographic and clinicopathological data were collected. Results: 247 pts, 124 (50%) males, with a median age of 66 years (range, 30-92), were included. Pathological stage was IIIA, IIIB and IIIC in 18 (7.3%), 161 (65.1%) and 72 (29.1%) pts, respectively. The median number of lymph nodes retrieved was 15 (range, 6-64) and that of positive lymph nodes was 2 (range, 0-21). High FDG-uptake was observed in 52 (21.0%) pts, including 6 (2.4%) who had clear postoperative changes, 10 (4.0%) who had a false positive abnormal uptake of whom 6 underwent invasive diagnostic procedures. The PET-CT results modified the management of 36 pts (14.5%) who were found to have true positive findings: 30 (12.1%) were proven to have overt metastatic disease and in 6 (2.4%) a second primary was discovered. With the median follow-up of 39.0 months (range 7.2-98.4 months), of the 30 pts found to be metastatic, 10 (33.3%) underwent curative treatments and are currently with no evidence of disease (NED). Updated data, on more patients and a longer follow-up, will be presented at the meeting. Conclusions: Early postoperative PET-CT changed the staging and treatment of 14.5% of resected stage III pts, and has the potential for early detection of curable metastatic disease. We currently evaluate this strategy and its actual impact in a prospective trial.