Flere kontrollerede kliniske forsøg, hvor epoetiner blev givet til patienter med en række forskellige almindelige tumorer, herunder planocellulær cancer i hoved og hals, lungecancer og brystcancer, har vist en uforklarlig overdødelighed.
Several controlled clinical studies in which epoetins were administered to patients with a variety of common tumours including squamous head and neck cancer, lung cancer, and breast cancer, have shown an unexplained excess mortality.