These immunohistochemical groups showed a good fit with the known clinicopathological features associated with these subsets of CRC. In particular, the MLH1�\negative group was associated with advanced age, predilection for female gender and proximal selleck chem Dovitinib colon, large tumour size and poor differention. The presumed HNPCC group was young and showed no gender difference, and there was a predilection for the proximal colon compared with the MMR�\proficient group. Although it is possible that a small proportion of presumed sporadic MSI�\H and HNPCC cases were incorrectly assigned, the overall findings are likely to be valid in view of the large numbers of samples and the good fit with clinico�\pathological features. Table 11 summarises the clinicopathological data of the different subsets of CRC.

Any disagreement between the clinicopathological features and the numbers of available tissue punches shown in table 11 is due to missing clinicopathological data. Table 1Clinicopathological characteristics of 1420 patients with colorecteal cancer Normal colon tissue To compare the MUC1 and MUC2 expression in CRC with that in normal colon mucosa, a control group of 57 tissue samples from a normal colon was included in the study. Immunohistochemistry of TMA Sections of TMA blocks 4 ��m thick were transferred to an adhesive�\coated slide system (Instrumedics, Hackensack, New Jersey, USA) to facilitate the transfer of TMA sections to slides and to minimise tissue loss. Standard indirect immunoperoxidase procedures were used for immunohistochemistry (ABC�\Elite, Vector Laboratories, Burlingame, California, USA).

A total of 1420 CRC and 57 normal colonic mucosa samples were immunostained for MUC1 (clone 139H2, dilution 1:100, Monosan), MUC2 (clone Ccp58, dilution 1:100, Monosan, Cedarlane Laboratories, Hornby, Ontario, Canada), MLH1 (clone MLH�\1; dilution 1:100; BD Biosciences Pharmingen), MSH2 (clone MSH�\2; dilution 1:200; BD Biosciences Pharmingen) and MSH6 (clone 44; dilution Batimastat 1:400; BD Biosciences Pharmingen). After dewaxing and rehydration in deionised water, sections for immunostaining were subjected to antigen retrieval by heating in a microwave oven (1200 W, 15 min) in 0.001 mol/l EDTA, pH 8.0, for MLH1 and MSH2 and in 0.01 mol/l citrate buffer, pH 6.0, for MSH6. Endogenous peroxidase activity was blocked using 0.5% H2O2. After transfer to a humidified chamber, the sections were incubated with 10% normal goat serum (Dako Cytomation, Mississauga, Canada) for 20 min and incubated with primary antibody at room temperature for 1 h (MUC1 and MUC2). Subsequently, the sections were incubated with peroxidase�\labelled polymer (K4005, EnVision+System�\HRP (AEC); DakoCytomation) for 30 min at room temperature.