The FDA issued a health warning 1 regarding the possible cancer risks of tacrolimus ointment, however, British dermatologists2 don't consider this a significant concern and they are increasingly recommending the use of this drug, for example for the treatment of vitiligo.
Is tacrolimus cancerous and if so, what causes it to be?
1. https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/tacrolimus-marketed-protopic-ointment-information
2. https://web.archive.org/web/20131213072822/http://www.bad.org.uk/Portals/_Bad/Guidelines/Position%20Statements%20%26%20Other%20Documents/Advice%20re%20topical%20tacrolimus.pdf