DISEASE CHARACTERISTICS: Histologically or cytologically confirmed small cell carcinoma of the lung Limited disease (stage I-IIIb but excluding T4 tumor based on malignant pleural effusion or N3 disease based on contralateral hilar or contralateral supraclavicular involvement) No pericardial or pleural effusion on chest x-ray regardless of cytology Measurable or evaluable disease Tumor must be encompassed by limited radiation therapy fields without causing severe symptomatic pulmonary dysfunction