• Incidence of brain metastases (Phase III patients enrolled before 12/31/05) [ Designated as safety issue: No ]
• Overall survival (Phase III patients enrolled before 12/31/05) [ Designated as safety issue: No ]
• Disease-free survival (Phase III patients enrolled before 12/31/05) [ Designated as safety issue: No ]
• Quality of life (Phase III patients enrolled before 12/31/05) [ Designated as safety issue: No ]
• LENT-SOMA (Phase III patients enrolled before 12/31/05) [ Designated as safety issue: Yes ]
• Incidence of chronic neurotoxicity (Phase II patients enrolled after 12/31/05) [ Designated as safety issue: Yes ]
• Quality of life (Phase II patients enrolled after 12/31/05) [ Designated as safety issue: No ]

• Brain metastases at 2 years after treatment
• Overall survival at 2 years after treatment
• Disease-free survival at 2 years after treatment

• Incidence of chronic neurotoxicity (Phase II patients enrolled before 12/31/05) [ Designated as safety issue: Yes ]
• Quality of life (Phase II patients enrolled before 12/31/05) [ Designated as safety issue: No ]

• Quality of life by EORTC Quality of Life Questionnaire and Brain Cancer Module at 6 and 12 months after treatment and then annually
• Neurotoxicity by LENT-SOMA scale annually after treatment
• Cognitive deficits by Neuropsychological Test Battery at 6 months after treatment and then annually

RATIONALE: Radiation therapy uses high-energy x-rays to damage tumor cells. It is not yet known which radiation therapy regimen is more effective in preventing brain metastases in patients with limited-stage small cell lung cancer.

PURPOSE: This randomized phase II/III trial is studying how well brain irradiation works and compares three different brain irradiation regimens in preventing brain metastases in patients with limited-stage small cell lung cancer.

OBJECTIVES:

• Compare the incidence of brain metastases in patients with limited stage small cell lung cancer treated with different regimens of prophylactic cranial irradiation. (phase III closed to accrual as of 12/31/05)
• Compare the overall and disease-free survival of patients treated with these regimens. (phase III closed to accrual as of 12/31/05)
• Compare the incidence of chronic neurotoxicity in patients treated with these regimens.
• Compare quality of life and late treatment sequelae of patients treated with these regimens. (phase III closed to accrual as of 12/31/05)

OUTLINE: This is a randomized, multicenter study. Patients are stratified according to age (60 and under vs over 60) and time since induction therapy (90 days or less vs 91-180 days vs 181-240 days). Patients are randomized to 1 of 3 treatment arms.

• Arm I: Patients undergo prophylactic cranial irradiation (PCI) once daily 5 days a week. Treatment continues for 2 weeks in the absence of unacceptable toxicity.
• Arm II: Patients undergo PCI once daily 5 days a week. Treatment continues for 2.6 weeks in the absence of unacceptable toxicity.
• Arm III: Patients undergo PCI twice daily 5 days a week. Treatment continues for 3.4 weeks in the absence of unacceptable toxicity.

Quality of life is assessed at baseline, every 6 months for 1 year, and then annually for 3 years.

Patients are followed every 6 months for 1 year and then annually for 3 years.

PROJECTED ACCRUAL: A total of 264 patients will be accrued for this study within 3.5 years.

• Active Comparator: Patients undergo prophylactic cranial irradiation (PCI) once daily 5 days a week for 2 weeks.
• Experimental: Patients undergo PCI once daily 5 days a week for 2.6 weeks.
• Experimental: Patients undergo PCI at a lower dose per fraction than in arm II twice daily 5 days a week for 3.4 weeks.

DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed small cell lung cancer by fine needle aspiration, biopsy, or 2 positive sputa

  • Limited stage (I-IIIB)

    • Confined to 1 hemithorax
    • No T4 or N3 disease
• Complete response after induction chemotherapy (with or without thoracic radiotherapy)
• Consolidative chest radiotherapy may be initiated before study

• No radiographic evidence of any of the following:

  • Brain metastases

    • Normal brain CT scan or MRI less than 1 month before study
  • Ipsilateral lung metastases

  • Malignant pleural effusion

    • Minimal pleural effusion by chest CT scan allowed, but not by chest x-ray

PATIENT CHARACTERISTICS:

Age

• Not specified

Performance status

• Zubrod 0-1

Life expectancy

• Not specified

Hematopoietic

• Absolute granulocyte count at least 1,500/mm^3
• Platelet count at least 75,000/mm^3
• Hemoglobin at least 10.0 g/dL^

Hepatic

• Not specified

Renal

• Not specified

Pulmonary

• See Disease Characteristics

Other

• Not pregnant or nursing
• Fertile patients must use effective contraception
• Neurological function class 1 or 2
• No epilepsy requiring permanent oral medication
• No other malignancy within the past 5 years except nonmelanoma skin cancer or carcinoma in situ of the cervix
• No other serious medical or psychiatric condition that would preclude study participation

PRIOR CONCURRENT THERAPY:

Biologic therapy

• Not specified

Chemotherapy

• See Disease Characteristics
• At least 1 week since prior chemotherapy
• No concurrent chemotherapy

Endocrine therapy

• Not specified

Radiotherapy

• See Disease Characteristics
• No prior external beam radiotherapy to the head or neck, including stereotactic radiotherapy
• Concurrent thoracic radiotherapy allowed

Surgery

• Not specified

Other

• No concurrent antitumor agents