RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. Combining chemotherapy and radiation therapy may kill more tumor cells.

PURPOSE: Phase I trial to study the effectiveness of radiation therapy plus topotecan in treating patients who have non-small cell lung cancer.

OBJECTIVES: I. Determine the maximum tolerated dose of topotecan and chest irradiation in patients with non-small cell lung cancer. II. Determine the qualitative and quantitative toxic effects of this regimen in these patients. III. Determine the degree of antitumor activity of this regimen in these patients.

OUTLINE: This is a dose escalation study of topotecan and thoracic radiotherapy. Beginning on day 1, patients receive topotecan IV continuously for 3-6 weeks and thoracic radiotherapy 5 days a week for 2, 3, or 6 weeks. Cohorts of 4-6 patients receive escalating doses of topotecan and thoracic radiotherapy until the maximum tolerated dose (MTD) of each therapy is determined. The MTD is defined as the dose preceding that at which 2 of 4 or 6 patients experience dose-limiting toxicity. Six additional patients are treated at the MTD. Patients who fail to achieve complete remission (CR) and continue to have measurable disease at 4-6 weeks after completion of radiotherapy receive topotecan IV continuously on days 1-21 at 1 dose level preceding the MTD as determined by the ongoing Protocol NYU-9123. Treatment continues every 4 weeks in the absence of unacceptable toxicity.

PROJECTED ACCRUAL: Approximately 10-20 patients will be accrued within 8-12 months.

• Drug: topotecan hydrochloride
• Radiation: radiation therapy

DISEASE CHARACTERISTICS: Histologically proven non-small cell lung cancer Eligible for chest irradiation with 3,000 to 6,000 cGy (based upon standard radiotherapy indications) Measurable or evaluable disease Measurable disease defined as bidimensionally measurable lesion on physical exam or radiograph (CT or MRI acceptable)

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: 0-2 Life expectancy: At least 12 weeks Hematopoietic: WBC at least 4,000/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.5 mg/dL AST less than 3 times normal Alkaline phosphatase less than 3 times normal Renal: Creatinine no greater than 1.5 mg/dL Other: Not pregnant or nursing

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No more than 1 prior chemotherapy regimen allowed At least 4 weeks since prior chemotherapy and recovered Endocrine therapy: Not specified Radiotherapy: No prior radiotherapy Surgery: Not specified Other: Recovered from toxic effects of any prior therapy