By random in silico designation and analysis of 2 mm2 sections of tumor area to simulate biopsy sampling, we found that (1) one biopsy sample can approximate CD8 prevalence to within one standard deviation of the block mean in greater than 75% of all analyzed cases, (2) using multiple cores improves performance up to three cores (best), and (3) the mean CD8+ cell percentage for multiple biopsies was a less variable and less biased predictor of CD8 status for a given tumor sample than the maximum value. Here, CD8A is linked to neoplasm.