Fulvestrant With or Without Lapatinib and/or Aromatase Inhibitor Therapy in Treating Postmenopausal Women With Metastatic Breast Cancer That Progressed After Previous Aromatase Inhibitor Therapy

DISEASE CHARACTERISTICS:

* Histologically or cytologically confirmed breast cancer

  * Metastatic disease
* Confirmed disease progression after treatment with an aromatase inhibitor (AI) administered in the adjuvant or metastatic setting

  * Must have demonstrated a prior response to AI therapy (i.e., responded after \> 2 years of treatment in the adjuvant setting OR complete or partial response or stable disease after ≥ 24 weeks of treatment in the metastatic setting) AND have subsequent disease progression after completion of AI therapy
* Meets 1 of the following criteria:

  * Measurable disease, defined as ≥ 1 lesion that can be accurately measured in ≥ 1 dimension (longest diameter to be recorded) as ≥ 20 mm with conventional techniques or ≥ 10 mm with spiral CT scan
  * Evaluable disease, defined as bone lesions, lytic or mixed (lytic and sclerotic), evaluable by plain x-ray, CT scan, or MRI

    * Lesions identified only by radionucleotide bone scan are not allowed
* No HER2/neu-overexpressing tumor (IHC 3+ or FISH+)
* Hormone receptor status:

  * Estrogen receptor- and/or progesterone receptor-positive primary or metastatic tumor

PATIENT CHARACTERISTICS:

* Female
* Postmenopausal, as defined by any of the following criteria:

  * At least 60 years of age
  * 45 to 59 years of age and meets ≥ 1 of the following criteria:

    * Amenorrhea for ≥ 12 months and intact uterus
    * Amenorrhea for \< 12 months and follicle-stimulating hormone within the postmenopausal range (including patients with hysterectomy, prior hormone replacement therapy, or chemotherapy-induced amenorrhea)

      * Patients who received prior luteinizing hormone-releasing hormone (LHRH) analogues must not have restarted their menses after cessation of therapy
  * Over 18 years of age and bilateral oophorectomy
* WHO performance status 0-2
* Life expectancy ≥ 8 months
* Leukocytes ≥ 3,000/μL
* Absolute neutrophil count ≥ 1,500/μL
* Platelet count ≥ 100,000/μL
* Total bilirubin normal
* AST/ALT ≤ 2.5 times upper limit of normal
* Creatinine normal OR creatinine clearance ≥ 60 mL/min
* LVEF normal as measured by ECHO or MUGA
* Able to swallow and retain oral medication
* No ulcerative colitis
* No malabsorption syndrome or disease significantly affecting gastrointestinal function
* No known history of uncontrolled or symptomatic angina, arrhythmias, or congestive heart failure
* No known immediate or delayed hypersensitivity reaction or idiosyncrasy to drugs chemically related to fulvestrant, aromatase inhibitors, lapatinib tosylate, or excipients
* No unresolved or unstable serious toxicity from prior therapy
* No active or uncontrolled infection
* No dementia, altered mental status, or any psychiatric condition that would prohibit the understanding or rendering of informed consent
* No other malignancy within the past 5 years except for adequately treated cervical carcinoma in situ, melanoma in situ, or basal cell or squamous cell carcinoma of the skin
* No other concurrent disease or condition that would make the patient inappropriate for study participation
* No serious medical disorder that would interfere with patient safety

PRIOR CONCURRENT THERAPY:

* See Disease Characteristics
* Prior radiotherapy for the primary or metastatic tumor allowed
* More than 4 months since prior LHRH analogues
* More than 30 days (or 5 half-lives, whichever is longer) since prior investigational agents
* More than 14 days since prior and no concurrent CYP3A4 inducers\*, including any of the following:

  * Rifampin, rifapentine, rifabutin, or other rifamycin class agents
  * Phenytoin, carbamazepine, or barbiturates (e.g., phenobarbital)
  * Efavirenz or nevirapine
  * Oral glucocorticoids (e.g., cortisone \[\> 50 mg\], hydrocortisone \[\> 40 mg\], prednisone \[\> 10 mg\], methylprednisolone \[\> 8 mg\], or dexamethasone \[\> 1.5 mg\])
  * Modafinil
* More than 14 days since prior and no concurrent herbal or dietary supplements\*, including any of the following:

  * St. John's wort
  * Ginkgo biloba
  * Kava
  * Grape seed
  * Valerian
  * Ginseng
  * Echinacea
  * Evening primrose oil
* More than 7 days since prior and no concurrent CYP3A4 inhibitors\*, including any of the following:

  * Clarithromycin, erythromycin, or troleandomycin
  * Itraconazole, ketoconazole, fluconazole (\> 150 mg daily), or voriconazole
  * Delaviridine, nelfinavir, amprenavir, ritonavir, indinavir, saquinavir, or lopinavir
  * Verapamil or diltiazem
  * Nefazodone or fluvoxamine
  * Cimetidine or aprepitant
  * Grapefruit or grapefruit juice
* More than 6 months since prior and no concurrent amiodarone\*
* No prior fulvestrant and/or lapatinib tosylate
* No prior resection of the stomach or small bowel
* No other concurrent anticancer therapy, including chemotherapy, immunotherapy, and biologic therapy

  * Concurrent bisphosphonates allowed
* No other concurrent investigational therapy
* No concurrent participation in another clinical trial NOTE: \*For patients randomized to receive lapatinib