Pre-treatment carbohydrate antigen 19-9 does not predict the response to neoadjuvant therapy in patients with localized pancreatic cancer

Abstract

Background The prognostic value of CA19-9 in patients with pancreatic cancer (PC) treated with neoadjuvant therapy has not been well described. Methods Pre-treatment CA19-9 levels (with concomitant normal bilirubin level) in patients with localized PC were categorized as normal (≤35), low (36-200), moderate (201-1000), or high (>1000). Post-treatment CA19-9 was measured after neoadjuvant therapy, prior to surgery. Results Pre-treatment CA19-9 levels were evaluable in 235 patients, levels were normal in 60 (25%) patients, low in 78 (33%) patients, moderate in 69 (29%) and high in 28 (12%). After neoadjuvant therapy, post-treatment CA19-9 normalized (≤ 35) in 40 (51%) of the patients in the low group, 14 (21%) of the moderate and 5 (19%) of the high group (P < 0.001). Of the 235 patients, 168 (71%) completed all intended therapy including a pancreatectomy; 44 (73%), 62 (79%), 46 (67%) and 16 (57%) of the normal, low, moderate and high groups (P = 0.10). Among these 168 patients, the median overall survival was 38.4, 43.6, 44.7, 27.2 and 26.4 months for normal, low, moderate and high CA19-9 groups (log rank P = 0.72). Among resected patients, an elevated pre-treatment CA19-9 was of little prognostic value; instead, it was the CA19-9 response to neoadjuvant therapy that was prognostic [hazard ratio (HR): 1.80, P = 0.02]. Conclusions Among patients who completed neoadjuvant therapy and surgery, pre-treatment CA19-9 obtained at the time of diagnosis was not predictive of overall survival, but normalization of post-treatment CA19-9 in response to neoadjuvant therapy was highly prognostic.