Anemia Drugs May Cause Deadly Blood Clots

ByABC News
November 10, 2009, 4:23 PM

Nov. 11 -- TUESDAY, Nov. 10 (HealthDay News) -- New research on cancer patients adds to the controversy surrounding anemia drugs such as Procrit and Aranesp, concluding that they increase the risk of venous thromboembolism, potentially fatal blood clots.

These drugs, called erythropoiesis-stimulating agents (ESAs), are commonly prescribed to fight anemia associated with chemotherapy and chronic kidney disease. Recent studies have linked them with increased risk of death, stroke and new cancers.

"These drugs hit the market in the mid-1990s, and by 2002, 50 percent of patients on chemotherapy were receiving them," said lead researcher Dr. Dawn Hershman, co-director of the breast program at the Herbert Irving Comprehensive Cancer Center at New York-Presbyterian Hospital/Columbia University Medical Center in New York City.

Initial testing of these drugs was done on only 12 weeks of use, she noted. "Right from the beginning, there was concern that these drugs would cause some side effects, but the initial studies did not find any risk of thrombosis."

Her longer study was more informative. "We confirmed that these agents can increase the risk of thrombosis by twofold," Hershman added.

The report is published in the Nov. 10 online edition of the Journal of the National Cancer Institute in advance of print publication on Dec. 2.

For the study, Hershman's team collected data on 56,210 cancer patients treated with chemotherapy from 1991 through 2002. Of these patients, 15,346 also received ESAs.

The researchers found that 14.3 percent of patients receiving ESAs developed thromboembolism (deep vein thrombosis or pulmonary embolism) compared with 9.8 percent of those who did not receive an ESA.

ESAs stimulate red blood cell production and are intended to reduce the number of blood transfusions needed during chemotherapy. However, the rate of blood transfusions remained the same for both groups (22 percent). Survival in both groups was also similar, the researchers noted.