CK20 and CK7 protein expression in colorectal cancer: demonstration of the utility of a population-based tissue microarray.

The ability to use archival tissue to test externally valid hypotheses of carcinogenesis is dependent on the availability of population-based samples of cancer tissue. Tissue microarrays (TMAs) provide an efficient format for developing population-based samples of tissue. A TMA was constructed consisting of archival tissue from patients diagnosed with invasive colorectal cancer in the state of Hawaii in 1995.