Normalization of CEA Levels Post-Neoadjuvant Therapy is a Strong Predictor of Pathologic Complete Response in Rectal Cancer.

ABSTRACT

BACKGROUND: Recent attention has been focused on the relationship between carcinoembryonic antigen (CEA) and pathological complete response (pCR), without consensus regarding its predictive value. This study aims to examine the association between CEA and pCR. METHODS: We conducted a retrospective review of a prospectively maintained database of all patients who underwent primary rectal cancer resection after neo-adjuvant chemoradiotherapy (nCRT). Patients were divided into two groups, pCR or no-pCR, based on final pathology. CEA levels were measured at the initial visit with the surgeon/oncologist and post-completion of nCRT. RESULTS: One hundred and forty-one patients underwent primary rectal cancer resections after nCRT. Nineteen patients (13.5 %) achieved pCR, while 122 (86.5 %) had no-pCR. Pre-nCRT CEA levels were not significantly different between groups (2.75 vs 4.5 µg/L, p = 0.65). However, post-nCRT CEA levels were significantly lower in patients with pCR (1.7 vs 2.4 µg/L, p < 0.01). On multivariate logistic regression analyses, low post-nCRT CEA level was an independent predictor of pCR (OR 1.74, CI 1.06, 3.81) and normalization of CEA from an initially elevated level was a highly significant predictor of pCR (OR 64.8, CI 2.53, 18,371). CONCLUSION: Low post-nCRT CEA is an independent predictor of pCR, and normalization of CEA post-nCRT is a strong predictor of pCR.