What might persistent elevation of CEA indicate in a colorectal cancer patient?

Persistent elevation of Carcinoembryonic Antigen (CEA) levels in a colorectal cancer patient is most commonly associated with the possibility of incomplete surgery. CEA is a tumor marker that is often used to monitor treatment response and disease progression in patients with colorectal cancer. When surgery is performed to remove a tumor, a successful outcome would typically result in a decrease in CEA levels, reflecting the removal of cancerous tissue.

If CEA levels remain elevated following surgical treatment, it may suggest that not all of the cancerous tissue was successfully removed, indicating the presence of residual disease. In some cases, high CEA can also imply the potential for recurrence, necessitating further investigation or intervention.

In contrast, while elevated CEA levels can occur due to several reasons such as infection or other non-cancerous conditions, these do not specifically align with the context of monitoring colorectal cancer. Remission signifies a lack of disease activity, which would typically correlate with lowered CEA levels, and successful treatment would also be associated with reduced CEA values. Hence, the correct context for persistent elevated CEA specifically points towards incomplete surgery in a colorectal cancer scenario.