Abstract: Applicants have identified a 36-gene signature that is associated with recurrence of stage I and II rectal cancers not treated with chemotherapy or radiation. This signature can be used to identify early stage rectal cancer patients that may need additional therapy beyond surgery to treat their cancer as well as identify patients that will not benefit from therapy other than surgery.

Abstract: A method of identifying differentially-expressed genes includes deriving an analysis of variance (ANOVA) or analysis of covariance (ANCOVA) model for expression data associated with a number of genes; from the ANOVA or ANCOVA model, deriving a linear regression model defined at least in part by an observation vector representative of an observed subset of the gene-expression data, a design matrix of regressor variables, a vector of regression coefficients representing gene contribution to the observation vector, and a measurement error vector; and to the linear regression model, applying a hierarchical selection algorithm to designate a subset of the regression coefficients as significant regression coefficients, the selection algorithm representing at least one of the observation vector, the design matrix, and the measurement error vector as being hierarchically dependent on parameters having predetermined probabilistic properties, wherein the designated subset corresponds to a respective subset of the genes