Experimental study design Reference animals did not undergo tumour injection or chemotherapy treatment but were handled similar to experimental groups. Tumour-bearing rats were injected with tumour, received no chemotherapy. Two weeks following implantation of the tumour, when the implants grew to approximately 2.3cm3 (or 1.2% of body weight), rats received CPT-11/ 5-FU combination regimens, for 1 or 2 cycles. The start day of chemotherapy cycle-1 (week 5); the first day of chemotherapy cycle-2 (week 6). ↓ End of each bar represents the day that animals were euthanized.