Stereotactic Radiosurgery and Erlotinib in Treating Patients With Non-Small Cell Lung Cancer and Brain Metastases

DISEASE CHARACTERISTICS:

* Histologically confirmed non-small cell lung cancer (NSCLC) meeting the following criteria:

  * Fewer than 5 intraparenchymal brain metastases by gadolinium-enhanced MRI meeting the following criteria:

    * Maximum diameter ≤ 4.0 cm

      * If multiple lesions are present and one lesion is \> 3.0 cm, the remaining lesions must be ≤ 3.0 cm in maximum diameter
    * No metastases within 3 mm of the optic nerve or optic chiasm such that some portion of the optic nerve or chiasm would receive \> 9 Gy from radiosurgery
    * No metastases in the brainstem, midbrain, pons, or medulla
* No prior complete resection of a single brain metastasis or of all known brain metastases

  * Subtotal resection allowed provided residual disease is ≤ 4.0 cm in maximum diameter
* No clinical or radiographic evidence of unstable systemic progression (other than the study lesion\[s\]) within the past month

  * Patients with brain metastases at initial presentation do not require 1 month of scans documenting stable disease
* Isolated brain metastases with stable systemic disease allowed
* No leptomeningeal metastases by MRI and/or positive cerebrospinal fluid cytology

PATIENT CHARACTERISTICS:

* Karnofsky performance status 60-100%
* Life expectancy ≥ 3 months
* ANC \> 1,000/mm³
* Platelet count \> 100,000/mm³
* Hemoglobin \> 10 g/dL
* PT and PTT normal
* AST \< 2 times upper limit of normal (ULN)
* Alkaline phosphatase \< 2 times ULN
* Total bilirubin \< 2 times ULN
* Lactic dehydrogenase \< 2 times ULN
* Serum creatinine \< 1.5 times ULN
* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective contraception during and for ≥ 2 weeks after completion of study therapy
* Neurologic function status 0-2
* No history of allergic reactions attributed to compounds of similar chemical or biologic composition to erlotinib hydrochloride
* No contraindication to MRI (e.g., cardiac pacemaker)
* No absolute contraindication to lumbar puncture

PRIOR CONCURRENT THERAPY:

* See Disease Characteristics
* Prior systemic therapy allowed
* No prior cranial radiotherapy

  * Prior radiotherapy to noncranial sites allowed
* More than 1 week since prior intrathecal chemotherapy or prior treatment of leptomeningeal carcinoma
* No concurrent systemic therapy

  * Prior or current erlotinib hydrochloride for treatment of systemic disease allowed provided systemic disease has not progressed while on erlotinib hydrochloride
* No concurrent enzyme-inducing anticonvulsant

  * If patients are on an enzyme-inducing anticonvulsant (e.g., phenytoin, carbamazepine, or phenobarbital), the agent must be converted to a nonenzyme-inducing anticonvulsant before or at the start of erlotinib hydrochloride treatment
* No concurrent CYP3A4 inhibitors or inducers (e.g., Hypericum perforatum \[St. John wort\] or ketoconazole)
* No other concurrent investigational therapy