When adenoma were classified as advanced (larger than 9 mm, or with villous or tubulo-villous histological pattern (>20%), or with high-grade dysplasia) or not advanced, Hb content was significantly higher for advanced adenomas (N=669, average 550 ng ml−1, median 356 ng ml−1) as compared with not advanced ones (N=221, average 385 ng ml−1, median 222 ng ml−1). Here, GSTM1 is linked to adenoma.