Early decline of CA125 to chemotherapy in advanced gastric cancer with peritoneal effusion.

Abstract

97 Background: Serum cancer antigen 125 (CA125) has been shown to be elevated in gastric cancer with peritoneal effusion, and to be a biomarker for monitoring the efficacy of chemotherapy in ovarian cancer. Therefore, we retrospectively evaluated the hypotheses that an early decline of CA125 to chemotherapy predicted the response of peritoneal effusion and survival in advanced gastric cancer with peritoneal effusion. Methods: CA125 concentration was measured at baseline and 4 to 7 weeks after induction of chemotherapy. The patients whose CA125 decreased at least 25% after chemotherapy were categorized as a decline group, and the other patients were defined as non-decline group. Baseline peritoneal effusion was classified in three levels with CT scan: none; mild; severe. Mild effusion was localized in the pelvic cavity or surface of the liver, and severe effusion was extended throughout the abdominal cavity. CT scan was followed every 2 months after chemotherapy, and the response in peritoneal effusion was defined to decrease at least one level. The median PFS and OS were also evaluated in two groups. Results: 121 advanced gastric cancer patients were assessable for analysis of CA125 concentration between April 2006 and April 2012. In 59 patients with a baseline CA125 below the upper limit of normal (ULN), 16 patients (27%) had peritoneal effusion, and in 75 patients with a baseline CA125 equal to above ULN, 54 patients (73%) had peritoneal effusion (P < 0.0001). Baseline characteristics of 54 patients with effusion and elevated CA125 were as follows: median age = 63 years (range 38-81), male : female = 38 : 16, PS 0-1 : 2-3 = 35 : 19, diffuse: intestinal = 40 : 14, mild effusion : severe effusion = 41 : 13. In 26 patients of the decline group, the response of effusion was 45%, the median PFS was 146 days, and the OS was 308 days. In 28 patients of the non-decline group, the response of effusion was 4%, the median PFS was 67 days, and the OS was 192 days. There were significant differences in response of peritoneal effusion (P = 0.001), PFS (P = 0.0002), and OS (P = 0.005). Conclusions: Early decline of CA125 has potential clinical utility in predicting favorable response and survival to chemotherapy in advanced gastric cancer patients with peritoneal effusion.