Clinical implications of the serum CA19-9 level in "biological borderline resectability" and "biological downstaging" in the setting of preoperative chemoradiation therapy for pancreatic cancer.

BACKGROUND

Biological factors are emphasized in borderline resectable pancreatic cancer (BRPC), and CA19-9 is an important factor for biological borderline resectability (b-BR). The aim of this study was to investigate the cut-off value of CA19-9 for biological borderline resectability and "biological downstaging" in chemoradiation therapy (CRT) for pancreatic cancer (PC).

METHODS

A total of 407 patients with anatomically resectable PC (a-R) and BRPC (a-BR) received preoperative gemcitabine-based CRT. The b-BR was determined, according to the CA19-9 value prior to preoperative CRT (pre-CA19-9), as the subgroup of a-R cases in which the survival was comparable with that in a-BR cases. "Biological downstaging" was determined based on prognostic analyses regarding the CA19-9 value after preoperative CRT (post-CA19-9) in association with the survival of R cases (a-R cases without the b-BR factor).

RESULTS

The 5-year survival of a-R patients with pre-CA19-9 > 120 U/mL was comparable with that of a-BR patients (44% vs 34%, p = 0.082). The survival of b-BR patients with post-CRT CA19-9 ≤ 37 U/mL (normalized) was comparably favorable with that of R patients (56% vs 65%, p = 0.369). The incidence of distant recurrence was higher in b-BR patients without post-CA19-9 normalization than in those with post-CA19-9 normalization (70% vs 50%, p = 0.003), while the incidence of local recurrence was comparable between these two groups (12% vs 13%, p = 0.986).

CONCLUSIONS

Biological BRPC was determined to be an anatomically resectable disease with pre-CA19-9 > 120 U/mL, and post-CA19-9 normalization indicated "biological downstaging" in b-BR in the preoperative CRT strategy.