KRAS and rectal neoplasm: In agreement with previous literature (Smith et al, 2002), a significantly higher proportion of rectal tumours harboured K-Ras mutations (40.0 vs 27.7%, P=0.04), whereas no significant differences in mutation frequencies were found for B-Raf (6.7 vs 13.9%, P=0.07) or PIK3CA (13.9 vs 16.7%, P=0.79).