Chemotherapy Before & After Surgery in Patients With Resectable Gallbladder Cancer

PRIMARY OBJECTIVE: I. To determine the difference in overall survival (OS) at 3 years for patients with incidental gallbladder cancer (IGBC) who receive neoadjuvant gemcitabine hydrochloride (gemcitabine) and cisplatin (gem/cis) prior to reoperation followed by adjuvant capecitabine compared to patients who receive only adjuvant capecitabine after reoperation. SECONDARY OBJECTIVES: I. To determine the difference in recurrence-free survival (RFS) at 1 year for patients with IGBC who receive perioperative chemotherapy prior to and after re-operation compared to patients who receive only adjuvant chemotherapy after reoperation. II. To assess the clinical effect of perioperative chemotherapy compared to only adjuvant chemotherapy after reoperation on resectability among 3 cohorts: all enrolled patients, all patients who undergo staging laparoscopy, and all patients who undergo laparotomy. III. To compare the incidence of residual disease at the time of re-resection between patients who receive perioperative chemotherapy and those who receive only adjuvant chemotherapy. OUTLINE: Participants are randomized to 1 of 2 arms. ARM I: Participants undergo re-resection (including partial liver resection and portal lymph node dissection) after incidental diagnosis of gallbladder cancer. Participants then receive capecitabine orally (PO) twice daily (BID) on days 1-14. Treatment repeats every 21 days for 8 courses in the absence of disease progression or unacceptable toxicity. ARM II: Participants receive cisplatin intravenously (IV) over 1 hour and gemcitabine IV over 30 minutes on days 1 and 8. Treatment repeats every 21 days for 4 courses in the absence of disease progression or unacceptable toxicity. Within 10 weeks of chemotherapy, participants undergo re-resection (including partial liver resection and portal lymph node dissection). Participants then receive capecitabine PO BID on days 1-14. Treatment repeats every 21 days for 8 courses in the absence of disease progression or unacceptable toxicity. After completion of study treatment, participants are followed up periodically for up to 3 years.