Tissue-specific cancer paradox and mutation rates

Some genes have ubiquitous expression patterns in an individual’s cells, thus a paradox exists whereby mutations in such genes are only strongly associated with cancers of specific tissues. As these genes are ubiquitously expressed in the body’s cells and thereby have functions in -potentially- all tissue types, then surely their resulting defects would manifest as cancers in all tissues? We hypothesize that the different susceptibility to mutations could explain the ‘tissue-specific’ paradox for cancer.