Testing the Addition of Paclitaxel Administered Into the Abdominal Cavity Combined With Chemotherapy for Patients With Gastric Cancer Spread to the Abdominal Cavity

PRIMARY OBJECTIVES: I. In the phase II portion, to determine the progression free survival (PFS) from randomization. II. In the phase III portion, to determine overall survival (OS) from randomization. SECONDARY OBJECTIVE: I. To compare the safety and tolerability of the intraperitoneal chemotherapy + systemic therapy regimen vs the systemic therapy alone regimen. OUTLINE: STEP 0: Patients undergo diagnostic laparoscopy within 4 weeks of study registration. STEP 1: Patients are randomized to 1 of 2 arms at the time of Step 0 diagnostic laparoscopy. ARM A: Patients receive standard of care systemic therapy per physician's choice. Patients with stable disease or a response after 12 weeks may continue to receive standard of care treatment in the absence of disease progression or unacceptable toxicity. Patients undergo blood sample collection and computed tomography (CT) and/or magnetic resonance imaging (MRI) throughout the study and may undergo additional diagnostic laparoscopies as clinically indicated. ARM B: Patients undergo placement of an intraperitoneal port. Patients receive leucovorin calcium intravenously (IV) over 15-30 minutes, fluorouracil IV push, paclitaxel IV over 1-2 hours and paclitaxel intraperitoneally (IP) on days 1 and 8 of each cycle. Cycles repeat every 21 days for up to 4 cycles in the absence of disease progression or unacceptable toxicity. Patients with stable disease or a response after 12 weeks may continue to receive treatment in the absence of disease progression or unacceptable toxicity. Patients undergo blood sample collection and CT and/or MRI throughout the study and may undergo additional diagnostic laparoscopies as clinically indicated. After completion of study treatment, patients are followed up every 3 months for 2 years then every 6 months for up to 5 years after Step 1 randomization.