Ethics and Animal Welfare Rules Outweigh Published Scientific Data

Mice are extensively used in cancer research as recipients of cancer cell growth. Human cancer cells are transplanted into mouse tissues and organs (xenograft) in an effort to simulate cancer growth and test possible treatments. These procedures are normally regulated by the Institutional Animal Care and Use Committees (IACUCs) present in every institution that uses animals for federally funded research. In 2011, a group of researchers at Massachusetts General Hospital and Harvard Medical School published a Nature letter describing the potential anticancer effects of the molecule piperlongumine in a mouse xenograft cancer model of EJ bladder carcinoma. However, their data have been partially retracted both in 2012 and again more recently as some of the animals showed tumors that far exceeded the maximum size of 1.5 centimeter diameter permitted by the IACUC at Massachusetts General Hospital. A Nature editorial commented that this represents a breach of animal welfare rules, as mice could have experienced more suffering than allowed for. As a result, Nature now requires authors to provide clear details regarding tumor size and to observe the rules for ethical experiments.