RATIONALE: Drugs used in chemotherapy, such as gemcitabine and cisplatin, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving chemotherapy drugs after surgery may kill any tumor cells that remain after surgery. Sometimes, after surgery, the tumor may not need more treatment until it progresses. In this case, observation may be sufficient.

PURPOSE: This phase II trial is studying how well giving gemcitabine together with cisplatin works in treating patients with stage I non-small cell lung cancer that was removed by surgery.

OBJECTIVES:

Primary

• To assess the feasibility of assigning adjuvant treatment based on tumoral RRM1 and ERCC1 gene expression in patients with complete surgical resection of stage IA (≥ 2 cm) or IB non-small cell lung cancer.

Secondary

• To estimate the collective 2-year disease-free survival of these patients.
• To assess the frequency and severity of toxicities resulting from the administration of cisplatin and gemcitabine hydrochloride.
• To explore, preliminarily, the relationship between RNA and protein expression of RRM1 and ERCC1, and the relationship between RRM1 and ERCC1 expression in the formalin-fixed and paraffin-embedded tumor specimens, and to generate results on in situ protein expression and other assays for genes involved in drug efficacy.
• To assess the analytical performance of the biomarker assay.

OUTLINE: This is a multicenter study.

Patients are assigned to 1 of 2 treatment arms based on RRM1 and ERCC1 gene expression.

• Arm I (RRM1 ≥ 40 and ERCC1 ≥ 65): Patients undergo active monitoring after surgery with disease assessments at 8, 16, and 24 weeks.
• Arm II (RRM1 < 40 and/or ERCC1 < 65): Beginning within 84 days after surgery, patients receive gemcitabine hydrochloride IV over 30 minutes on days 1 and 8 and cisplatin IV over 30-90 minutes on day 1. Treatment repeats every 21 days for 4 courses in the absence of disease progression or unacceptable toxicity.

Tumor samples acquired at the time of surgery are analyzed by immunofluorescence-based automated quantitative analysis for in situ expression of RRM1 and ERCC1. If available, additional samples are assessed using RT-PCR and real-time quantitative PCR for RRM1 and ERCC1 expression levels; polymorphism analysis for RRM1 and ERCC1 expression at the protein level; and tissue microarray analysis of genes associated with DNA synthesis, damage repair, and drug efficacy.

After completion of study therapy, patients are followed every 6 months for up to 2 years.

DISEASE CHARACTERISTICS:

• Histologically confirmed non-small cell lung cancer

  • Stage IA (longest tumor diameter 2-3 cm) or stage IB disease

• Must have undergone preoperative CT scan of the chest (including the entire liver and adrenals) with IV contrast AND a whole body PET scan or a combined PET/CT scan with no evidence of N1, N2, N3, or M1 disease within 42 days prior to surgery

• A whole body PET scan or a combined PET/CT must be performed within 84 days

  • Any finding on PET scan that clinically suggests N1, N2, N3, or M1 disease must have been cleared by further evaluation, including, but not limited to, any of the following:

    • Ultrasonography, X-ray radiology, magnetic resonance imaging, or nuclear medicine imaging

• Completely resected (R0) disease by lobectomy, bilobectomy, or pneumonectomy performed by open thoracotomy or video-assisted thoracoscopic surgery within the past 35 days

  • Completely excised primary lesion with negative gross and microscopic margins
  • At least two mediastinal lymph node stations sampled

• Must have tumor tissue available from the surgical resection specimen AND agree to have treatment assignment determined by a gene expression analysis performed on that tissue

PATIENT CHARACTERISTICS:

• Zubrod performance status 0-1

• ANC ≥ 1,500/mm³

• Platelet count ≥ 100,000/mm³

• Hemoglobin ≥ 10 mg/dL

• Serum bilirubin ≤ 1.5 times upper limit of normal (ULN)

• AST and ALT ≤ 1.5 times ULN

• Serum creatinine ≤ 1.5 times ULN OR creatinine clearance ≥ 60 mL/min

• Not pregnant or nursing

• Fertile patients must use effective contraception

• No other prior malignancy except for the following:

  • Adequately treated basal cell or squamous cell skin cancer
  • In situ cervical cancer
  • Adequately treated stage I-II cancer from which the patient is currently in complete remission
  • Any other cancer from which the patient has been disease-free for 5 years

• Willing to provide prior smoking history

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics

• No prior systemic chemotherapy or biologic therapy for lung cancer

• No prior thoracic radiation therapy (RT) (including RT to the chest wall)

• No other concurrent investigational agents, chemotherapeutic agents, RT, or hormonal therapy

  • Steroids administered for antiemesis, adrenal failure, or septic shock OR hormones administered for non-disease-related conditions (e.g., insulin for diabetes) allowed