Radiation Therapy in Treating Patients With Extensive Stage Small Cell Lung Cancer

DISEASE CHARACTERISTICS:

   - Histologically or cytologically confirmed extensive stage small cell lung cancer
   (SCLC) diagnosed within the past 6 months*

      - Has 1-4 extracranial metastatic lesions NOTE: *Diagnosis made before treatment
      with chemotherapy

   - Has completed 4-6 courses of platinum-based chemotherapy within the past 8 weeks AND
   meets the following criteria:

      - Radiographic partial or complete response to chemotherapy in ≥ 1 site of disease
      according to Response Evaluation Criteria in Solid Tumors (RECIST) criteria (if
      radiotherapy has been delivered to primary disease with chemotherapy, there must
      be complete or partial response in ≥ 1 of the sites that has not been treated
      with radiotherapy)

      - No progression in any site

   - No limited stage SCLC, even if disease progressed

   - No brain or central nervous system (CNS) metastases

PATIENT CHARACTERISTICS:

   - Zubrod performance status 0-2

   - Absolute neutrophil count (ANC) ≥ 1,000/mm^3

   - Platelets ≥ 75,000/mm^3

   - Hemoglobin ≥ 8.0 g/dL (the use of transfusion or other intervention is allowed)

   - Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 2.5 times
   upper limit of normal (ULN) (for patients who will receive radiotherapy to the liver)

   - Serum bilirubin < 1.5 times ULN (for patients who will receive radiotherapy to the
   liver)

   - Serum creatinine < 1.5 times ULN (for patients who will receive radiotherapy to the
   kidneys)

   - Not pregnant or nursing

   - Negative pregnancy test

   - Fertile patients must use effective contraception

   - No severe, active co-morbidity, defined as any of the following:

      - Acute bacterial or fungal infection requiring IV antibiotics at the time of study
      registration

      - Chronic obstructive pulmonary disease exacerbation or other respiratory illness
      requiring hospitalization or precluding study therapy at the time of study
      registration

PRIOR CONCURRENT THERAPY:

   - See Disease Characteristics

   - Recovered from prior chemotherapy (i.e., toxicities ≤ grade 1 [except for neuropathy
   and alopecia])

   - Thoracic radiotherapy administered concurrently with or before chemotherapy for the
   current diagnosis allowed (these patients will not receive mediastinal radiotherapy
   per protocol)

   - No prior radiotherapy to the region of this cancer that would result in overlap of
   radiotherapy fields

   - No concurrent chemotherapy