The effect of aging on the growth of colon cancer

Reports on the effect of patient age on the prognosis for colon cancer vary. We have tested the effect of aging using a model of murine colon adenocarcinoma in groups of mice of different ages. In experiment A, Balb/c mice of age groups 3-4 weeks, 10-12 weeks, 24-32 weeks and 40-48 weeks (13 mice/group) were injected with 5 X 10(4) MC-26 cells subcutaneously in the right flank. Tumors were measured twice weekly, and the rate of occurrence of tumor, mortality rate, and growth rate were calculated. In experiment B, the same plan as experiment A was used, except mice of age groups I (14 days), II (3-4 weeks), and III (20-22 months) were used with tumor doses of 1 X 10(4) cells and 5 X 10(5) cells (9-15 mice/group). In both experiments, the rate of growth of tumor, mortality rate, and sizes of tumors obtained were the same. In experiment A, the rate of occurrence of the tumors was the same in all groups, but in experiment B the occurrence of the tumor varied. A palpable tumor appeared earliest in the weanling mice (14 days), next in old mice (20-22 months), and last in the young adult group (3-4 weeks). Tumor doubling time was longest in the young adult mice (7 days), intermediate in the old mice (6.1 days), and shortest in the weanling mice (5.5 days). Established tumors grew at similar rates (as assessed by doubling time), independent of host age. Mortality rates were similar.(ABSTRACT TRUNCATED AT 250 WORDS)