TUMOR-MARKERS IN EVALUATING THE RESPONSE TO RADIOTHERAPY IN UNRESECTABLE PANCREATIC-CANCER

BACKGROUND/AIMS: Serum carbohydrate antigen 19-9 (CA 19-9) and carcino embryonic antigen (CEA) are useful tumor markers in the diagnosis of p ancreatic cancer. However, little research has shown their value for e valuating the response to radiotherapy in patients with advanced pancr eatic cancer. METHODOLOGY: Serial changes of serum CA 19-9 levels were studied in 34 patients with unresectable pancreatic cancer. All patie nts had a CA 19-9 level of 100 U/ml or greater before treatment and re ceived radiotherapy as an initial treatment. A CA 19-9 responder was d efined 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 r elationship between CA 19-9 response and survival. We also studied ser ial changes of serum CEA levels in 20 patients with the level of 5 ng/ ml or greater before radiotherapy, and investigated the relationship b etween CEA response and survival. RESULTS: CA 19-9 response and CEA re sponse were observed in seven (21%) of 34 patients and four (20%) of 2 0 patients, respectively. Median survival times of CA 19-9 responders and non- responders were 318 and 122 days, respectively, and median su rvival times of CEA responders and non- responders were 281 and 151 da ys, 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 analy sis and 0.19 (95% confidence interval, 0.04 to 0.84) in the CEA analys is. CONCLUSION: Serum CA 19-9 may be useful tumor markers for assessin g the effectiveness of radiotherapy for pancreatic cancer. Further inv estigations are necessary to determine the value of CEA.