Differing Serum Cea in Primary and Recurrent Rectal Cancer - A Reflection of Histology?

BACKGROUND: Serum carcinoembryonic antigen (CEA) levels are not universally measured in colorectal cancers. CEA levels have been reported to be usually normal at time of primary rectal cancer diagnosis but elevated in recurrent disease. The aims of the study were to (1) compare serum CEA levels performed at time of primary and recurrent colorectal tumour diagnosis; and (2) to determine serum CEA levels in rectal cancers at primary diagnosis to analyse potential factors influencing differing CEA levels. METHODS: A retrospective analysis of patients treated for colorectal cancers at Modbury Hospital, South Australia was performed. Each admission was reviewed within the electronic database. Serum CEA levels and tumour-related factors were determined in patients who underwent curative surgery for their primary tumour and developed tumour recurrence/metastases within the study period. RESULTS: 438 patients were treated for colorectal cancer in the study period. In patients who underwent curative surgery and developed a recurrence, serum CEA was elevated in 20% patients at primary diagnosis and in 46.6% patients at recurrence. Only 1 of 30 patients with rectal cancer had an elevated CEA at diagnosis of primary tumour. Tumour relationship to the peritoneal reflection did not appear to play a role. CONCLUSIONS: In rectal cancers, serum CEA levels are often normal at the time of initial diagnosis. However, this should not preclude its use in post-operative surveillance. Serum CEA levels noted in primary rectal cancer appear unrelated to the relationship of the tumour to the peritoneal reflection. Stroma-related factors could possibly be involved and merit further investigation.