Journal of Clinical Oncology, 2007 ASCO Annual Meeting Proceedings (Post-Meeting Edition).
Vol 25, No 18S (June 20 Supplement), 2007: 4522
© 2007 American Society of Clinical Oncology

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Abstract

Post-resection CA 19–9 predicts overall survival (OS) in patients treated with adjuvant chemoradiation: A secondary endpoint of RTOG 9704

Thomas Jefferson Univ, Philadelphia, PA; Radiation Therapy Oncology Group, Philadelphia, PA; Fox Chase Cancer Center, Philadelphia, PA; University of Maryland Medical Center, Baltimore, MD; Rush University Medical Center, Chicago, IL; Brown University, Providence, RI; Northwestern University, Chicago, IL; St. Vincent’s Cancer Center, Castine, ME; Duke University Medical Center, Durham, NC

4522

Background: CA 19–9 is an important tumor marker in pancreatic adenocarcinoma. Several single institutional studies have demonstrated post-resection CA 19–9 to be an important prognostic factor. A secondary endpoint of RTOG 9704, a phase III adjuvant chemoradiation trial for pancreatic cancer, was to prospectively evaluate the ability of post-resectional CA 19–9 to predict survival. Methods: A total of 538 patients were accrued to this trial, of which 385 had evaluable CA 19–9 levels. These were analyzed using ELISA GI-MA kits provided by Diagnostic Products Corporation, a Siemens Company. CA 19–9 expression was analyzed as a dichotomized variable (<180 vs. =180). Cox proportional hazards models were utilized to characterize the contribution of CA 19–9 expression on OS. The following additional variables were included in the multivariate analysis: treatment, nodal involvement, tumor diameter (< or > 3cm), and margin status. Actuarial estimates for OS were calculated using Kaplan-Meier methods. Results: Most patients had CA 19–9 < 180 (n=220, 57%), while 34% were Lewis Antigen negative (unable to express CA 19–9) and 33 (9%) patients had levels >180. Survival was statistically significantly improved among patients with CA 19–9 <180 compared with those whose CA 19–9 =180 (HR=3.58(95% CI=2.40–5.34), p<0.0001) (table). This corresponds to a 72% reduction in the risk of death. This improvement was observed among patients with pancreas head and non-head tumors when analyzed separately. The multivariate analysis confirms that CA 19–9 is a highly significant predictor of OS in patients with resected pancreatic cancer. Conclusions: This prospective analysis of CA 19–9 in 385 patients treated with adjuvant chemoradiation definitively confirms the importance of post-resectional CA 19–9 in pancreatic cancer patients who have undergone resection. Patients with post-resection CA 19–9 >180 should be considered for additional therapy.

No significant financial relationships to disclose.

Abstract presentation from the 2007 ASCO Annual Meeting