DISEASE CHARACTERISTICS: Histologically proven non-small cell lung cancer of the following histologic types: Squamous cell carcinoma Adenocarcinoma Undifferentiated large cell carcinoma Not otherwise specified (i.e., diagnosis by cytology alone) Unresectable stage I, II, or III disease Measurable lesion Primary and nodal lesions encompassable within radiotherapy fields No positive supraclavicular lymph nodes (stage N3) No massive atelectasis No complete remission if treated with chemotherapy Prior cisplatin, vinblastine, etoposide, paclitaxel, carboplatin, or vinorelbine allowed All chemotherapy delivered within 4 months of entry No pleural effusion with positive cytology Other pleural effusions eligible with following requirements: Present prior to mediastinoscopy or exploratory thoracotomy Transudate cytologically negative on 2 separate thoracenteses OR Present after mediastinoscopy or exploratory thoracotomy Either transudate or exudate with negative cytology on thoracentesis OR Present only on CT and not on chest x-ray Too small to tap under CT or ultrasound guidance Ineligible for treatment on RTOG phase III studies

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 70-100% Hematopoietic: Not specified Hepatic: Not specified Renal: Not specified Other: No second malignancy within the past 5 years except nonmelanomatous skin cancer

PRIOR CONCURRENT THERAPY: Biologic therapy: No prior biologic response modifier therapy Chemotherapy: See Disease Characteristics At least 6 months since prior bleomycin, mitomycin, doxorubicin, or cyclophosphamide No concurrent chemotherapy Endocrine therapy: Not specified Radiotherapy: No prior thoracic irradiation Surgery: Ineligible for definitive surgery