Aspirin on CTCs of Advanced Breast and Colorectal Cancer

BACKGROUND: * Invasion and metastasis are the main reason of death in metastatic cancer, and abundant evidence find circulating tumor cells(CTCs) take the core position in breast and colorectal cancer metastasis. * Platelets play multiple role to facilitate the epithelial to mesenchymal transition of tumor cells and protect CTCs to survival in the circulation, which enrolled in the whole process of metastasis. * Several clinical trials and observational study have validate the primary and secondary prevention effect of aspirin to both breast and colorectal cancer. OBJECTIVES: * Determine the effect of aspirin on CTC number of metastatic breast and colorectal cancer; * Determine the effect of aspirin on CTC subtype (epithelial/mesenchymal/mixed type) of metastatic breast and colorectal cancer. ELIGIBILITY: * Adults age from 18-75 years old. * Patients were diagnosed for metastatic breast or colorectal cancer by pathology. * Patients who were not currently receiving intravenous chemotherapy , oral administrated with capecitabine was permitted. Concurrent endocrine therapy ( for at least 2 months before enrollment), bisphosphonate therapy, and/or monoclonal targeted therapy were permitted. * No disease of hemorrhagic tendency or history of non-steroid drug allergy. * CTCs≥5 / 7.5ml blood STUDY DESIGN: * Aspirin will be administered orally once a day in 28-day cycles. * The CTC was evaluated every 28 days for 2 months.