Except in the case of breast cancer (4.3%), a high percentage of ALDH1 expression (between 75 to 100% of tumor cells) was found in each of the other five cancer types (ovarian: 29.2%, colon: 38.8%, lung: 43.9%, pancreatic 78.9% and liver: 97.0%). Here, ALDH1A1 is linked to breast cancer.