This study looks at how well chemotherapy works when given before and after surgery compared to after surgery only for treating gallbladder cancer. Chemotherapy is a treatment that uses strong medicines, such as gemcitabine and cisplatin, to stop cancer cells from growing. **Stage II-III gallbladder cancer** means the cancer is bigger but hasn't spread to far parts of the body. Some patients will have chemotherapy both before and after surgery, while others will have it only after surgery. The study will see if having chemotherapy before surgery helps patients live longer and delays cancer from returning.

• **Study Duration**: Up to 5 years of follow-up visits every 3 to 6 months.
• **Participation**: Up to 8 cycles of chemotherapy; surgery and follow-up.
• **Eligibility**: Patients with stage II-III gallbladder cancer who recently had gallbladder removal.