Correlation of CEA but not CA 19-9 as serum biomarkers of disease activity in a case of metastatic rectal adenocarcinoma.

We present the case of a 62-year-old-man with moderately differentiated adenocarcinoma of the rectum. This patient underwent neoadjuvant chemoradiation and surgical resection followed by adjuvant chemotherapy. After completing therapy, this patient had 2 instances of CEA elevation, both of which preceded the discovery of recurrent disease. While on treatment for these recurrences, CA 19-9 increased rapidly to 4,405. This CA 19-9 elevation persisted for approximately 4 months in the absence of clinical, radiographic or additional serologic evidence of progressive disease before returning to baseline. Shortly after this tumor marker normalized, a small area of locally recurrent disease was discovered. This case highlights the utility and pitfalls of colorectal cancer disease monitoring with CEA and CA 19-9. The differential diagnosis of CA 19-9 elevation is discussed in this report.