Nelfinavir, Radiation Therapy, Cisplatin, and Etoposide in Treating Patients With Stage III Non-Small Cell Lung Cancer That Cannot Be Removed By Surgery

RATIONALE: Nelfinavir may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Radiation therapy uses high energy x-rays to kill tumor cells. Nelfinavir may make tumor cells more sensitive to radiation therapy. Drugs used in chemotherapy, such as cisplatin and etoposide, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving nelfinavir together with radiation therapy, cisplatin, and etoposide may kill more tumor cells. PURPOSE: This phase I/II trial is studying the side effects and best dose of nelfinavir when given together with radiation therapy, cisplatin, and etoposide and to see how well they work in treating patients with stage III non-small cell lung cancer that cannot be removed by surgery.