Inclusion Criteria

DISEASE CHARACTERISTICS: Histologically or cytologically proven small cell lung cancer
Complete response (CR) or partial response (PR) following first line chemotherapy required
Chest x-ray showing CR or PR required. No documented prior brain metastases

PATIENT CHARACTERISTICS: Age: 16 and over Performance status: ECOG 0-2 Life expectancy: At
least 12 weeks Hematopoietic: Not specified Hepatic: Not specified Renal: Not specified
Other: Not pregnant or nursing Effective contraception use by men or women of reproductive
potential No prior malignancies within 5 years except: Adequately treated nonmelanomatous
skin cancer Adequately treated carcinoma in situ of the cervix No other concurrent
malignancies No prior diagnosis of breast cancer, melanoma, or hypernephroma No major
medical illness that would preclude prolonged administration of marimastat or required
follow up No active peptic ulceration or symptoms suggestive of this diagnosis No grade 3
or 4 musculoskeletal disorders

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: One prior
induction combination chemotherapy regimen required Must be completed prior to
randomization Hematologically recovered before randomization Minimum of 4 cycles required
No change in regimen due to progression No chemotherapy within 28 days prior to
randomization if thoracic radiation is given prior to or concurrent with chemotherapy No
prior marimastat Endocrine therapy: Not specified Radiotherapy: Prior radiotherapy allowed
Must be completed prior to randomization Last dose of radiation treatment must be within
7-14 days prior to randomization if thoracic radiation and/or prophylactic cranial
irradiation is given after completion of chemotherapy If severe esophagitis precludes
administration of oral medication, randomization may be within 21 days after radiation
therapy Surgery: No surgery within 2 weeks prior to randomization Prior complete resection
of tumor allowed Other: No other investigational agents within 4 weeks prior to study, and
none planned No concurrent coumarin anticoagulants and no coumarin anticoagulants within 4
weeks prior to randomization No concurrent antitumor treatment