Radiologic assessment of tumor response in pancreatic cancer is complicated by desmoplastic reactions within or around the tumor. The objective of this study was to evaluate the correlation between a decline in carbohydrate antigen 19-9 (CA 19-9) and survival in patients with advanced pancreatic cancer who received upfront chemotherapy.
CA 19-9 serum basal values were measured in 247 patients with advanced pancreatic cancer who were enrolled in 5 consecutive trials between 1997 and 2007. Survival curves were compared among patients who had a predefined CA 19-9 nadir variation (<50%. Group 1; 50% to 89%, Group 2; or >89%, Group 3). To eliminate guarantee-time bias, survival analysis was repeated using the landmark method.
In both univariate and multivariate analysis, the basal CA 19-9 value significantly predicted survival. The median survival was 15.5 months for 34 patients who had normal basal CA 19-9 values, 11.9 months for 108 patients who had basal values between 38 U/mL and 1167 U/mL, and 8 months for 105 patients who had basal values >1167 U/mL. At least 1 CA 19-9 follow-up value was available for 204 patients who had baseline values greater than normal. A significant difference in overall survival was observed in univariate and multivariate analyses between Groups 1 and 2, between Groups 1 and 3, and between Groups 2 and 3. The results were confirmed using the landmark method.
In this study, baseline CA 19-9 was confirmed as an independent prognostic factor for survival, and it may be considered as a stratification factor in trials in patients with advanced pancreatic cancer. Biochemical response may be used as a complementary measure to radiologic response to provide a better assessment of chemotherapy activity and to drive treatment decisions in clinical practice. Cancer 2009. © 2009 American Cancer Society.