A number of different scoring methods and threshold levels have been reported for the assessment of immunohistochemical TS expression in colorectal cancer: (1) The intensity of TS staining of tumors was arbitrarily graded from 0 to 3 (or 0 to 4) and dichotomized (grades 0 to 1 defined as low level, and 3 to 4 as high level of TS expression) – a review of 13 studies [22] and [24, 26, 40, 41], (2) TS expression was dichotomized using arbitrary thresholds of 10 %, 15 %, 20 % [22] or ≥30 % [42] of stained cells per field, (3) Histoscores were calculated [18, 43]. The gene discussed is TYMS; the disease is colorectal cancer.