The cancer stem cell (CSC) theory has emerged as an attractive hypothesis for tumor development and progression including metastasis. The theory suggests that tumors consist of subsets of cells with functional heterogeneity in which one small subset has the characteristics of stem cells. These stem cells have the capacity of both self-renewal and heterogeneous differentiation into cancer cells that comprise the tumor. They can also play an important role in invasion, metastasis and, finally, recurrence. Based on the pathgenesis of the cancer metastasis, the recurrences after curative surgery probably develop from the proliferation of occult micro-metastases already established at the time of surgery. The attractive ideas about CSCs hypothesis in metastasis can partially explain the concept of minimal residual disease like occult micro-metastases after curative resections. CSC hypothesis in clinical metastasis is now giving a deep impact on surgical oncology. Efforts to develop diagnostic and therapeutic approach with the successful results from CSC studies would lead to impressive improvement for cancer patients in surgery.
Keywords: Adjuvant chemotherapy, Biomarker, Cancer, Cancer stem cell (CSC), Circulating tumor cells (CTC), Disseminating tumor cells (DTC), Epithelialmesencymal transition (EMT), Mesenchymal-epithelial transition (MET), Metastasis, Micro-metastases, Prognosis, Recurrence, R0 resection, Surgery, Surgical oncology, Target therapy.