The purpose of this study is to determine whether Aspirin could affect the number and subtype of circulating tumor cells of metastatic breast cancer 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.

Inclusion Criteria:

• 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.
• PS score ≤ 3
• Anticipated survival time ≥ 3 months
• CTCs≥5 / 7.5ml blood

Exclusion Criteria:

• Allergic to aspirin or other types of non-steroid
• History of hemorrhage of digestive tract or other hemorrhagic disease
• Plan to receive surgery within the time frame of the trial
• Medication history of aspirin or other types of anti-platelets drug within one months before the trial
• Women in pregnant or lactation period
• Any psychological or objective problem may influence the compliance of the patients