Anemia drugs may raise blood cancer risk: study

Anemia drugs may raise blood cancer risk: study
CHICAGO (Reuters) - Widely used anemia drugs may increasethe risk that people with the rare blood disorder known asmyelofibrosis will develop leukemia, U.S. researchers said onMonday.
The findings may heighten safety concerns overerythropoiesis-stimulating drugs or ESAs, which include AmgenInc's Aranesp and an older version, Epogen, and Johnson &Johnson's Procrit.
U.S. regulators last month strengthened safety warnings onthe drugs amid concerns that they increase the risk of death,heart attack, stroke and the progression of other cancers.
Researchers at the Mayo Clinic in Rochester, Minnesota,have now found these drugs may be associated with a higher riskof leukemia for people with myelofibrosis.
Myelofibrosis is a bone marrow disorder that interrupts thebody's normal production of blood cells, leading to severeanemia and enlargement of the spleen.
On its own, myelofibrosis becomes progressively worse. Butit can also progress to acute lymphycytic leukemia or lymphoma.
Mayo Clinic researchers examined the records of 311patients with primary myelofibrosis from 1976 to 2006 to seewhat factors led some of them to advance to acute leukemia.
"We found an association with erythropoietin anderythropoietin like-drugs," said Dr. Ayalew Tefferi, whopresented the study at American Society of Hematology's annualmeeting in Atlanta.
Erythropoiesis-stimulating drugs are genetically engineeredforms of the naturally occurring human protein, erythropoietin.Natural erythropoietin is made by the kidney and increases thenumber of red blood cells.
Tefferi said they also found a higher risk with the drugDanazol, a hormone with properties that treat anemia.
"The patients in the study who took the anemia drugs tendedto be sicker. Their leukemia could have been caused by otherfactors," said Amgen spokeswoman Ashleigh Koss.
"It is important to remember that this is a retrospectivestudy, not a prospective study," Koss said. That means itlooked back at the patients after they developed the leukemia,an approach less powerful than the prospective approach, whichinvolves studying patients from the beginning of treatment.
A J&J spokesman was not immediately available.
Tefferi agreed that a prospective study was needed. Butuntil such studies could be performed, he said, patients takingthe drugs should be carefully evaluated.
"The safety has to be proven," he said in a telephoneinterview.
Tefferi also said treatment with the drugs could causefurther enlargement of the spleen, a known complication of thedisease.