OBJECTIVES: I. Determine the maximum tolerated dose of intraperitoneal interleukin-12 in patients with Mullerian carcinoma (closed to accrual as of 8/23/01), gastrointestinal carcinoma, or peritoneal mesothelioma (closed to accrual as of 8/23/01). II. Determine the qualitative and quantitative toxicity and reversibility of toxicity of this regimen in these patients.