In the early stage, 2 weeks and 4 weeks after cancer cell transplantation, plasma IL-6 concentration was comparable to that of control mice, while at 5 and 6 weeks after cancer cell transplantation, there was a significant, 3- to 4-fold elevation in plasma IL-6 concentration compared to control (14.5 ± 4.5 pg/ml and 19.8 ± 2 pg/ml vs. 5.8 ± 1.4 pg/ml, respectively; Fig. 5a). Here, IL6 is linked to cancer.