The investigators want to develop a gene expression profile for the prediction of immunotherapy response of patients with metastatic breast cancer presenting malignant pleural effusion.

1. The patiets with malignant pleural effusion are randomizned to be treated with cytokins(inteleukin 2) or dendritic cells(DC) plus cytokine induced killer cells(CIK) locally.
2. Malignant pleural effusion from metastatic breast cancer patient is obtained through thoracentesis and is centrifugalized to enrich cancer cells before the therapy.
3. The enriched cancer cells are flash frozen and stored at -80℃ until processing.
4. The gene expression in pleural effusion is detected by microarray to screen gene markers that are differently expressed between groups .
5. Statistical analysis is performed using unsupervised hierarchical cluster.

Inclusion Criteria:

• Patients should be histologically confirmed with metastatic breast cancer and malignant pleural effusion
• an Eastern Cooperative Oncology Group (ECOG) performance status of 0-2;
• At least one measurable lesion;
• Normal cardiac, hepatic, renal and bone marrow functions;
• Life expectancy ≥3 months;
• Discontinuity of previous chemotherapy for a minimum of 4 weeks.
• Not receive chemotherapy in pleural cavity

Exclusion Criteria:

• previous history of other malignancies;
• previous surgery history on the needle biopsy organ;
• Serious or uncontrolled concurrent medical illness.

The breast cancer patiets present with pleural effusion and can receive chemotherapy.