DISEASE CHARACTERISTICS: Histologically or cytologically confirmed non-small cell lung cancer (NSCLC) Stage IIIA (T1-2, N2, M0 or T3, N1-2, M0) if not medically operable Stage IIIB (any T, N3, M0 or T4, any N, M0) Radiographic evidence of mediastinal lymph nodes at least 2.0 cm in the largest diameter sufficient to stage N2 or N3 disease If largest mediastinal node is less than 2.0 cm in diameter and is the basis for stage III disease, then at least one node must be histologically or cytologically confirmed positive Any of the following histologies allowed: Squamous cell carcinoma Adenocarcinoma (including bronchoalveolar cell) Large cell anaplastic carcinoma (including giant and clear cell carcinomas) Poorly differentiated NSCLC No metastatic disease Patients with tumors adjacent to a vertebral body allowed if all gross disease can be encompassed in the radiation boost field (boost volume must be limited to less than 50% of the ipsilateral lung volume) Pleural effusions that are a transudate, cytologically negative, and non-bloody are allowed if tumor can be encompassed within reasonable field of radiotherapy Pleural effusions that can be seen on chest CT but not on chest x-ray and are too small to tap are allowed No brain metastases by MRI or CT scan No prior total surgical resection