Should we Continue to Monitor or Choose to Ignore the Mild Increase in CA19-9 after Surgery.

Background: Different detection platforms can lead to significant differences in the results of CA19-9. Here, a case of a 38-year-old male colon cancer patient who underwent CA19-9 testing on two platforms after surgery.

Methods: We first inspect the instrument to confirm its normal operation and good indoor quality control. Then, we conduct dilution experiments to eliminate interference from heterophilic antibodies, compare and analyze inherent differences with other platforms, and regularly follow up to dynamically monitor the patient's condition.

Results: During follow-up, the patient's CA19-9 levels rose consistently on both platforms, leading to tumor recurrence two years later, missing optimal treatment.

Conclusions: Dynamic monitoring of tumor markers should be based on a stable platform and combined with imaging examinations. For abnormal elevated results, humanistic care is needed to address the patient's fear and doubts about the test results.