We sought to determine if carbohydrate antigen 19-9 (CA19-9 ) nadir (nCA19-9), time to nadir (TTN), and doubling time (DT) after radiotherapy (RT) correlate with outcomes in pancreatic ductal adenocarcinoma.We examined the records of 102 patients treated with RT for primary, nonmetastatic pancreatic ductal adenocarcinoma between August 1998 and July 2011. Of these, 33 patients were treated with postoperative chemoradiotherapy (PORT) and 69 patients with definitive chemoradiotherapy (CRT).Among the patients treated with PORT, TTN and DT were associated with both overall survival (OS; P = <0.01 for both) and freedom from progression (FFP; P = <0.01 for both). In patients treated with CRT, nCA19-9 and TTN correlated with both OS (P = <0.01 and P = 0.02, respectively) and FFP (P = 0.01 and <0.01, respectively). On multivariable analysis, in patients treated with PORT, TTN remained independently correlated with OS and FFP (P = 0.01; hazard ratios [HR], 6.43 and P = 0.02; HR, 4.00, respectively), whereas DT remained independently correlated to FFP (P = 0.04; HR, 0.27). In patients treated with CRT, controlling for pretreatment CA19-9, nCA19-9 and TTN independently correlated with OS (P = <0.01; HR, 3.0 and P = 0.03; HR, 2.56, respectively) and FFP (P = 0.04; HR, 2.31 and P = <0.01; HR, 4.0, respectively).CA19-9 kinetics after RT correlate with disease progression and survival and could serve as a prognostic tool to guide treatment decisions.
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