Purpose: Preoperative positivity of serum tumor markers has been associated with poor long-term survival among patients with gastric cancer. However, there have been a considerable number of patients who have experienced a normalization of tumor markers (negative conversion) after curative treatment. This study aimed to evaluate the correlation between postoperative tumor marker conversion and survival after gastrectomy among gastric carcinoma patients. Methods: We analyzed the clinical data of 129 patients who underwent curative gastrectomy with elevated preoperative carcinoembryonic antigen or carbohydrate antigen 19-9 between January 2009 and December 2013. Results: Positive tumor markers converted to negative markers 6 months after surgery in 91 patients (70.5%). The patients with a negative conversion of tumor markers had significantly better outcomes than those without negative conversion (overall survival [OS] 63.9 months vs. 41.1 months, P<0.001; disease-free survival [DFS] 59.3 months vs. 33.2 months, P<0.001). Multivariate analyses showed that tumor marker conversion and lymph node metastasis were independent predictors of OS and DFS. During follow-up, tumor markers became elevated again (positive reconversion) in 23 patients (25.3%), with a negative conversion of tumor markers at 6 months after gastrectomy. Among the patients with a positive reconversion of tumor markers, gastric cancer recurred in 18 patients (78.3%). Conclusion Negative tumor marker conversion after curative gastrectomy strongly predicts a better prognosis. Patients without negative tumor marker conversion and those with positive reconversion after normalization should be carefully monitored because of the high possibility of recurrence.

Purpose: Preoperative positivity of serum tumor markers has been associated with poor long-term survival among patients with gastric cancer. However, there have been a considerable number of patients who have experienced a normalization of tumor markers (negative conversion) after curative treatment. This study aimed to evaluate the correlation between postoperative tumor marker conversion and survival after gastrectomy among gastric carcinoma patients. Methods: We analyzed the clinical data of 129 patients who underwent curative gastrectomy with elevated preoperative carcinoembryonic antigen or carbohydrate antigen 19-9 between January 2009 and December 2013. Results: Positive tumor markers converted to negative markers 6 months after surgery in 91 patients (70.5%). The patients with a negative conversion of tumor markers had significantly better outcomes than those without negative conversion (overall survival [OS] 63.9 months vs. 41.1 months, P<0.001; disease-free survival [DFS] 59.3 months vs. 33.2 months, P<0.001). Multivariate analyses showed that tumor marker conversion and lymph node metastasis were independent predictors of OS and DFS. During follow-up, tumor markers became elevated again (positive reconversion) in 23 patients (25.3%), with a negative conversion of tumor markers at 6 months after gastrectomy. Among the patients with a positive reconversion of tumor markers, gastric cancer recurred in 18 patients (78.3%). Conclusion Negative tumor marker conversion after curative gastrectomy strongly predicts a better prognosis. Patients without negative tumor marker conversion and those with positive reconversion after normalization should be carefully monitored because of the high possibility of recurrence.