Study Evaluating the Addition of Fulvestrant to Erlotinib in Stage IIIB/IV Non-Small Cell Lung Cancer

Inclusion Criteria: * Estrogen or progesterone receptor positive stage IIIb/IV non-small cell lung cancer * Eligible patients will have stable disease on erlotinib monotherapy at FDA- approved doses after a minimum duration of erlotinib therapy of 2 months * 18 years or older * ECOG Performance Status ≤2 * Adequate Organ Function Requirements * Adequate coagulation function * Postmenopausal status in female patients is required and is defined as no menstrual periods for 12 month or surgical menopause * All patients must sign a written informed consent. Exclusion Criteria: * Pregnant or breast-feeding women will not be entered on this study * Patients who are currently receiving another investigational drugs * Patients who are currently receiving other anti-cancer agents. * Hormone replacement therapy will not be allowed and have to be stopped 1 month prior to entry into the study * Patients who have an uncontrolled infection. * Patients receiving less than 100mg/day of erlotinib * Patients with evidence of progression after 2 months of erlotinib monotherapy. * Patients with a history of bleeding diathesis (i.e., disseminated intravascular coagulation \[DIC\], clotting factor deficiency) or long-term anticoagulant therapy (other than antiplatelet therapy). * Patients with a history of hypersensitivity to active or inactive excipients of fulvestrant (i.e. castor oil or Mannitol). * Patients who in the opinion of the investigator may not be able to comply with the safety monitoring requirements of the study.