Longitudinal Assessment of Colonic Tumor Fate in Mice by Computed Tomography and Optical Colonoscopy

Rationale and Objectives. The purpose of this study was to evaluate the relative merits of micro-computed tomograph colonography (mCTC) and optical colonoscopy (OC) for longitudinal studies of colonic tumors in mice. Materials and Methods. Colonic tumors in mice carrying the Min allele of Apc were followed over several weeks using mCTC and OC. A total of 146 colonic tumors were monitored: 62 in 32 untreated Min mice, 53 in 43 Min mice treated with 5-fluorouracil (5-FU), and 31 in 17 Min mice treated with piroxicam. Results. Colonic tumors in Min mice had three different spontaneous fates: 29 grew, 24 remained static, and 9 regressed. Treating Min mice with 5-FU increased the percentage of regressing tumors from 15% to 58%. The response was dependent in part on the initial size of the tumor. By contrast, treating Min mice with piroxicam did not alter colonic tumor fate. Conclusions. mCTC and OC can be used to determine the spontaneous fates of colonic tumors in mice and to document their individual responses to treatment. The ability to follow individually annotated colonic tumors reduces the number of mice needed for testing.