Inclusion Criteria:

• Histologic or cytologic diagnosis of non-small cell lung cancer (NSCLC) (no component of small cell).
• Patients must have stage IIIB (with malignant pleural effusion), stage IV NSCLC (as staged by the AJCC Cancer Staging Manual. 6th ed, appendix 1) or a recurrence of NSCLC treated over 12 months after they completed prior chemotherapy, chemoradiotheapy or adjuvant therapy who treated with 6 cycles of induction chemotherapy utilizing the following regimens: carboplatin/paclitaxel, carboplatin/gemcitabine, carboplatin/paclitaxel + bevacizumab or carboplatin/gemcitabine + bevacizumab, (see Section 3.2 for acceptable doses and schedules).
• Must be postmenopausal female, as defined by the following criteria:

Prior bilateral oophorectomy or Age greater than 60 years old Age less than 60 years old and amenorrheic for 12 or more months in the absence of chemotherapy or ovarian suppression with FSH and estradiol in the postmenopausal range.

• Registration/randomization should be within 6 weeks of beginning of last cycle of chemotherapy

• Documented evidence of a tumor response of CR, PR, or SD. Tumor assessment must occur between Cycle 6 (Day

  1) of induction therapy and the date of randomization. Tumor assessment will be per RECIST (Appendix 3) by the treating physician. This response does not have to be confirmed in order for the patient to be randomized; however, unconfirmed responses will be stratified in the stable disease strata. Positron emission tomography (PET) scans and ultrasound may not be used for lesion measurements for response determination.

• ECOG performance status 0 or 1.
• At least 18 years of age.
• Adequate organ function, including the following:

Adequate bone marrow reserve: absolute neutrophil (segmented and bands) count (ANC) greater than or equal to 1.0 x109/L, platelets greater than or equal to 75 x109/L, and hemoglobin greater than or equal to 9 g/dL. Hepatic: bilirubin less than or equal to 1.5 times the upper limit of normal (ULN), alkaline phosphatase (ALP), aspartate transaminase (AST), and alanine transaminase (ALT) less than or equal to 2.0 Renal: calculated creatinine clearance (CrCl) ≥45 mL/min based on the standard Cockcroft and Gault formula (Cockcroft and Gault 1976).

• Prior radiotherapy must be completed at least 3 weeks before study enrollment. Patients must have recovered from the acute toxic effects of the treatment prior to study enrollment.
• Signed informed consent document on file.
• Patient compliance and geographic proximity that allow adequate follow up.
• Patient must receive on-study therapy no earlier than 21 days and no later than 42 days from their last cycle (Day 1) of induction therapy.
• Patients must have archival tissue samples. Tumor tissue will be submitted for assessment of ERa, ERb, PR, VEGF and aromatase expression. The patient must also agree to mandatory correlative blood samples at baseline, 5 weeks, 9 weeks, 13 weeks and at the time of progression.

Exclusion Criteria:

• Male gender
• With the exception of those chemotherapies listed as Inclusion criterion No other concomitant biological therapy (e.g. cetuximab) is allowed.
• Have received experimental treatment within the last 30 days at the time of study entry.
• Inability to comply with protocol or study procedures.
• A serious concomitant systemic disorder that, in the opinion of the investigator, would compromise the patient's ability to complete the study.
• Central nervous system (CNS) metastases.
• Concurrent administration of any other antitumor therapy (except arm B, who are allowed to continue with bevacizumab).
• Pregnant or breast feeding.
• Have a prior malignancy other than NSCLC, carcinoma in situ of the cervix, or nonmelanoma skin cancer, unless that prior malignancy was diagnosed and definitively treated at least 5 years previously with no subsequent evidence of recurrence.
• Patients with two or more deep vein thromboses, or an active deep vein thrombosis.
• Patients taking hormone replacement therapy or other hormonal therapies
• The International Normalized Ratio (INR) must be < 1.6 within 28 days prior to registration.
• Patients with bleeding diathesis (i.e., disseminated intravascular coagulation [DIC], clotting factor deficiency) or a history of recent history of hemoptysis (1/2 tsp of red blood). Patients on stable long term anticoagulation prior to starting this trial are allowed.
• History of hypersensitivity to active or inactive excipients of fulvestrant (ie castor oil or Mannitol).
• Treatment of NSCLC with squamous cell histology with bevacizumab.