The effect of aspirin on circulating tumor cells in metastatic colorectal and breast cancer patients: a phase II trial study

Aspirin could reduce the risk of cancer metastasis. Circulating tumor cells (CTCs) are a key factor of cancer metastasis, but no evidence has revealed how aspirin affects CTCs and its epithelial-mesenchymal transition (EMT). Here, we conducted a clinical trial to investigate how aspirin affects CTCs in metastatic colorectal cancer (MCC) and breast cancer patients (MBC). The trial is retrospective registered at clinicaltrials.gov (NCT02602938). The eligible patients are given 100 mg aspirin q.d. for 8 weeks, and CTCs are evaluated at baseline, 4 and 8 weeks for absolute number, phenotype (epithelial type, E+, mesenchymal type, M+, and biophenotypic type, B+), and vimentin expression. Data on 21 MCC and 19 MBC patients are analyzed, and it revealed that the CTC numbers decreased with aspirin treatment in MCC (p < 0.001) but not MBC (p = 0.0532); besides, ratio of E+ CTCs increased (p = 0.037) and M+ CTCs decreased at 2 months in MCC (p = 0.013), but neither the ratio of E+ or M+ CTCs changes significantly in MBC; vimentin expression of M+ CTCs is higher than E+ and B+ CTCs either in MBC or MCC patients at baseline (p < 0.01); and aspirin suppresses the vimentin expression in M+ (p = 0.002)and B+ (p = 0.006) CTCs of MCC and M+ CTCs of MBC (p = 0.004); besides it find vimentin expression in B+ (p = 0.004) or M+ (p < 0.001), CTCs are markedly decreased in patients with total CTC numbers declined. Aspirin could decrease CTCs numbers and block EMT transition in MCC patients and part of MBC patients.