Tumor markers in evaluating the response to radiotherapy in unresectable pancreatic cancer

BACKGROUND/AIMS: Serum carbohydrate antigen 19-9 (CA 19-9) and carcinoembryonic antigen (CEA) are useful tumor markers in the diagnosis of pancreatic cancer. However, little research has shown their value for evaluating the response to radiotherapy in patients with advanced pancreatic cancer. METHODOLOGY: Serial changes of serum CA 19-9 levels were studied in 34 patients with unresectable pancreatic cancer. All patients had a CA 19-9 level of 100 U/ml or greater before treatment and received radiotherapy as an initial treatment. A CA 19-9 responder was defined as a patient whose serum CA 19-9 level was reduced by more than 50% of the pre-treatment level after treatment. We investigated the relationship between CA 19-9 response and survival. We also studied serial changes of serum CEA levels in 20 patients with the level of 5 ng/ml or greater before radiotherapy, and investigated the relationship between CEA response and survival. RESULTS: CA 19-9 response and CEA response were observed in seven (21%) of 34 patients and four (20%) of 20 patients, respectively. Median survival times of CA 19-9 responders and non- responders were 318 and 122 days, respectively, and median survival times of CEA responders and non- responders were 281 and 151 days, respectively. Based on results of the Cox regression analysis, the relative rates of cancer death between responders and non-responders were 0.24 (95% confidence interval, 0.08 to 0.72) in the CA 19-9 analysis and 0.19 (95% confidence interval, 0.04 to 0.84) in the CEA analysis. CONCLUSION: Serum CA 19-9 may be useful tumor markers for assessing the effectiveness of radiotherapy for pancreatic cancer. Further investigations are necessary to determine the value of CEA.