Cisplatin and Irinotecan Followed by Carboplatin, Etoposide, and Radiation Therapy in Treating Patients With Limited-Stage Small Cell Lung Cancer

RATIONALE: Drugs used in chemotherapy, such as cisplatin, irinotecan, carboplatin, and etoposide, use different ways to stop tumor cells from dividing so they stop growing or die. Radiation therapy uses high-energy x-rays to damage tumor cells. Combining chemotherapy with radiation therapy may kill more tumor cells. PURPOSE: Phase II trial to study the effectiveness of cisplatin and irinotecan followed by carboplatin, etoposide, and radiation therapy in treating patients who have limited-stage small cell lung cancer.