We further classified the cases into negative (<5% n=80) and positive (⩾5% n=12) groups for ALDH1 and found that the ALDH1-positive group contained a higher proportion of CD44+/CD24− tumour cells than the ALDH1-negative group (median (interquartile range), 45% (20–70%) vs 5% (1–30%); P=0.003). This evidence concerns the gene ALDH1A1 and neoplasm.