While AOM-DSS–induced colorectal tumor formation has been widely discussed as a model of inflammation-induced tumorigenesis, our data showing tumor progression ex vivo in the absence of a humoral immune system (and the above data relating tumor progression through adenoma transition and selection of early APC mutations) suggest that the AOM-DSS model should be considered more as a model of sporadic carcinogenesis. Here, APC is linked to infectious otitis media.