Inclusion Criteria:

- Registered patient at MSKCC

- Histologically proven breast cancer. It is not necessary that pathology be reviewed
at MSKCC

- Age ≥18 years Group 1 (A and B)

- Diagnosed with metastatic breast cancer on biopsy or imaging study.

- Patients will be considered to have lung metastases, and will be assigned to group 1A
if any of the following criteria are met, otherwise patients will be assigned to
group 1B "No known Lung Metastases," Biopsy-proven lung metastasis.

- Pleural effusion with cytologic evidence of malignancy.

- Pleural effusion, exudative in character, without alternative explanation and
attributed, in the opinion of the clinician to metastatic disease.

- Symptoms attributable to lung metastases and a radiological pattern interpreted by a
radiologist as suspicious for metastatic disease.

- Any pulmonary nodule on chest radiograph, CT scan, PET-CT or MRI, which is
interpreted by the clinician and radiologist to be metastatic in etiology, whether or
not a biopsy was performed, and regardless of symptoms.

- A radiographic pattern interpreted by a radiologist as consistent with lymphangitic
carcinomatosis.

Group 2 (Controls)

- History of early breast cancer and currently no evidence of disease

Exclusion Criteria:

- Inability to provide written informed consent.

- Inability to complete smoking and NSAID questionnaire.

- Steroid use within the previous 4 weeks.

- Radiotherapy to the breast, chest wall or axilla within the previous 3 months.

- Men with breast cancer.