Elevated CEA with negative PET scan on surveillance of colorectal cancers-a role of CEA kinetics.

INTRODUCTION

The management of patients with elevated CEA after curative treatment of colorectal cancers without structural disease is uncertain. The aim was to study the clinical risk factors, CEA thresholds, and kinetics that could predict relapses.

METHODS

Retrospective study of colorectal cancers patients that were detected to have an elevated CEA (> 5 ng/ml on 2 separate occasions) and normal clinical exam, colonoscopy, and positron emission tomography (PET). Receiver operating characteristic (ROC) curves were generated to determine the optimal cutoff for absolute CEA values and proportional rise that could predict recurrences.

RESULTS

162 patients were followed for a median of 42 months. 32 patients (19.7%) relapsed of which 11 (34.4%) had a peritoneal disease. Besides known clinical risk factors, higher CEA at the time of negative PET and rising CEA trend predicted disease recurrence on multivariate logistic regression. CEA threshold of 10.05 ng/ml provided a sensitivity/specificity of 53%/86.2%, while CEA velocity of 1.36 ng/ml over 3 months presented a sensitivity/specificity of 80%/70.6% for subsequent relapse.

CONCLUSIONS

The discriminatory value of CEA kinetics was more than that of a single absolute value. An algorithm for managing these patients based on clinical risk factors, absolute CEA value, and its kinetics is suggested.