A total of 47 samples of colon cancers (the 27 with marginal tissues included and 20 without marginal tissues) were cut in triplicate and immunostained for Pms2, Ercc1 and Xpf, plus a total of 11 colon cancers (3 with marginal tissues and 8 without marginal tissues) were sectioned and immunostained for Ku86. The gene discussed is ERCC1; the disease is malignant colon neoplasm.