RATIONALE: Vaccines may help the body build an immune response to kill tumor cells.

PURPOSE: Randomized phase III trial to compare the effectiveness of vaccination with monoclonal antibody BEC2 and BCG with that of no further therapy in treating patients who have limited-stage small cell lung cancer.

OBJECTIVES: I. Determine the impact of adjuvant monoclonal antibody BEC2 and BCG on survival of patients with limited stage small cell lung cancer. II. Determine the safety of this regimen in these patients. III. Determine progression-free survival and quality of life of these patients treated with this regimen.

OUTLINE: This is a randomized, multicenter study. Patients are stratified according to center, Karnofsky performance status (60-70% vs 80-100%), and response to first-line combined modality treatment (complete vs partial). Within 3-7 weeks after completion of prior induction chemoradiotherapy, responding patients are randomized to 1 of 2 treatment arms. Arm I: Patients receive best supportive care and are observed until disease progression is documented. Arm II: Patients receive adjuvant monoclonal antibody BEC2 and BCG intradermally on day 1 of weeks 0, 2, 4, 6, and 10. Treatment consists of 5 vaccinations over a period of 10 to 12 weeks in the absence of unacceptable toxicity or disease progression. Quality of life is assessed at baseline, at weeks 6, 12, and 24, and then every 6 months thereafter. Patients are followed every 3 months.

PROJECTED ACCRUAL: Approximately 500 patients will be accrued for this study within 4 years.

DISEASE CHARACTERISTICS: Histologically or cytologically proven limited stage small cell lung cancer (SCLC) Must have completed adequate first-line combined modality treatment comprising at least 4-6 courses of a 2-drug chemotherapy regimen and chest radiotherapy No evidence of disease progression or relapse Disease response (complete or partial) after treatment

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 60-100% Life expectancy: Not specified Hematopoietic: WBC greater that 3,000/mm3 Platelet count greater than 100,000/mm3 Hepatic: AST less than 1.5 times upper limit of normal Hepatitis B negative Renal: Not specified Cardiovascular: Adequate cardiac function Other: HIV negative Not pregnant or nursing Fertile patients must use effective contraception No prior malignancy within 5 years except adequately treated nonmelanomatous skin cancer or carcinoma in situ of the cervix No history of tuberculosis No grade 3 local skin toxicity reaction (ulceration) to 5 IU or greater of PPD test No active infections requiring systemic antibiotics, antiviral, or antifungal treatments No serious unstable chronic illnesses No psychological, familial, sociological, or geographical condition that would preclude study

PRIOR CONCURRENT THERAPY: Biologic therapy: No prior therapy with proteins of murine origin At least one month since prior immunotherapy No other concurrent immunotherapy Chemotherapy: See Disease Characteristics No concurrent chemotherapy Endocrine therapy: No concurrent chronic use of systemic corticosteroids Radiotherapy: See Disease Characteristics No concurrent radiotherapy including prophylactic cranial irradiation No prior spleen radiotherapy Surgery: No prior surgery for SCLC No prior splenectomy Other: No prior second-line therapy for SCLC At least one month since prior investigational agents No concurrent chronic use of systemic antihistamines or nonsteroidal anti-inflammatory drugs No concurrent immunosuppressive therapy