After colonoscopy at the 18-week time point, five polarization-gated probe measurements were taken throughout the visually normal distal mucosa of each saline and AOM-treated rat. For each tissue site, an value was extracted from the copolarized and crosspolarized signals according to Eqs. (7) and (8). The median value from these five sites was taken and used to characterize the mucosa of each individual rat. A Welch’s t-test was used to determine statistical significance between groups. The first comparison we made was between saline-treated rats and all rats treated with AOM. Figure 5(a) shows that in rats treated with AOM, there is a statistically significant increase in the parameter from the visually normal mucosa for both the co- and crosspolarized signals ( and 0.003, respectively). The values for saline controls were and from the co- and crosspolarized signals, respectively, while for AOM they were and from the co- and crosspolarized signals, respectively. Figure 5(b) illustrated what the shape of the refractive-index correlation would look like for saline and AOM-treated rats given the values from the crosspolarized signal. Both curves can be represented by stretched exponentials with the AOM curve decaying more slowly, suggesting that the AOM-rat tissue structure has correlations at longer length scales than the saline-rat tissue structure does. We next investigated whether the parameter could be a predictor of both concurrent and future risk of neoplasia. In Fig. 5(c), we compare the m parameter values measured at 18 weeks among saline controls, AOM rats that developed tumors by 18 weeks (tumor presence), and AOM rats that had not developed tumors by 18 weeks (no tumor presence). This figure demonstrates that the parameter mirrors neoplasia risk. For both the copolarized and crosspolarized parameter, there is an increase in for rats that had not developed tumors by the 18-week time point but were still at risk of developing tumors because of the AOM treatment ( and 0.007, respectively). There is a further increase in in rats that harbored neoplasia at the time of measurement as shown in Fig. 5(b). These results demonstrate that the parameter is most sensitive to the presence of neoplasia, but that it is also predictive of the risk of future neoplastic development.