Immunohistochemistry performed on local recurrent disease demonstrated that the cytokeratin positive cancer cell fraction was decreased in the gemcitabine treated tumours compared to controls (p = 0.032), while Ki67 positive cells per cancer cell area was significantly increased by gemcitabine treatment, suggesting G treatment may select out a subset of cells with higher proliferative potential (Figure 2a,b). Here, MKI67 is linked to cancer.