Antimetastatic efficacy of adjuvant gemcitabine in a pancreatic cancer orthotopic model.

Gemcitabine is a promising new agent that has been recently studied for palliation of advanced (stage IV) unresectable pancreatic cancer. We hypothesized that adjuvant gemcitabine would reduce recurrence and metastases following surgical resection of pancreatic cancer. To test this hypothesis, we evaluated gemcitabine on a green fluorescent protein (GFP) transductant of the human pancreatic cancer cell line BxPC-3 (BxPC-3-GFP) using surgical orthotopic implantation (SOI) in nude mice. GFP enabled high resolution fluorescent visualization of primary and metastatic growth. Five weeks after SOI, the mice were randomized into three groups: Group I received exploratory laparotomy only. Group II underwent surgical resection of the pancreatic tumor without further treatment. Group III underwent tumor resection followed by adjuvant treatment with gemcitabine, 100 mg/kg every three days for a total of four doses, starting two days after resection. The mice were sacrificed at thirteen weeks following implantation and the presence and location of recurrent tumor was recorded. Gemcitabine reduced the recurrence rate to 28.6% compared to 70.6% with resection only (P = 0.02) and reduced metastatic events 58% in the adjuvant group compared to resection only. This study, demonstrating that gemcitabine is effective as adjuvant chemotherapy post-pancreatectomy, suggests this new indication of the drug clinically.