Circulating tumor cells: A surrogate to predict the effect of treatment and overall survival in gastric adenocarcinoma.

Background: Circulating tumor cells and serum tumor markers have been found significant in predicting outcome for several malignancies. However, their role in gastric cancer is not fully clarified. We conducted a retrospective study to explore the prognostic value of circulating tumor cells and their applicability in assessing the treatment efficacy in gastric cancers.

Methods: From September 2015 to December 2018, 116 patients with newly pathologically diagnosed gastric adenocarcinoma were enrolled. At both baseline and two courses after chemotherapy, the data of circulating tumor cells and serum tumor markers, such as CEA, CA72-4, CA19-9, CA50, and CA242, were collected. The relationships between the change trend of circulating tumor cells and the treatment efficacy were analyzed after chemotherapy, with a paired t-test. Univariate and multivariable analysis were used to find prognostic factors for overall survival (OS).

Results: We found there is a significant difference between the circulating tumor cells-positive and circulating tumor cells-negative before and after therapy (mOS 12.6 vs. 31.6 months, P<0.001; mOS 12.4 vs. 24.2 months, P=0.002), respectively. Also, differentiation, pre-therapeutic circulating tumor cells and therapeutic response were independent predictors of overall survival. Following two courses of chemotherapy, the number of circulating tumor cells increased obviously in the progressive disease group (P=0.002), while they decreased in the non-progressive disease group (P=0.02). Thus, the change in the circulating tumor cells count had a close association with the therapeutic response (P=0.004).

Conclusion: Generally, circulating tumor cells provide a novel tool to evaluate the outcomes of gastric cancer patients. Since the change of circulating tumor cells was highly related to treatment response, it may be an auxiliary to assess the effect of chemotherapy, leading an earlier adjustment of following regimens.