GSTM1 and colorectal carcinoma: Similarly, in Denmark, in a study aimed at finding age-specific and sex-specific f-Hb thresholds that could improve population-based CRC screening, it was concluded that, in an FIT-based CRC screening programme, it is possible to decrease the number of colonoscopies required while at the same time increasing overall sensitivity and specificity, and detect more cancers and adenomas by using different f-Hb thresholds for different female and male age groups.