The controversy surrounding anaemia drugs, such as, Procrit and Aranesp deepens, as new research on cancer patients concludes, the drugs increase the risk of venous thrombo-embolism i. e. potentially fatal blood clots.

Commonly prescribed for fighting anaemia associated with chemotherapy and chronic kidney disease, recent studies have linked these erythropoiesis-stimulating agents (ESAs) or drugs with increased risk of death, stroke and new cancers.

Hitting the market in the mid-1990s, 50% of patients receiving chemotherapy treatment were taking them.

Dr. Dawn Hershman, lead researcher notes, initial testing of these drugs was only done for 12-weeks, and though there were concerns about drug side-effects, initial studies failed to find any risk of thrombosis.

However, Hershman’s longer study was more informative, confirming these agents could increase the risk of thrombosis twofold.

The report has been published in the 10th November online edition of the Journal of the National Cancer Institute.

For the study, data on 56,210 cancer patients given chemotherapy treatment from 1991 through 2002 was collection, while 15,346 of these patients also received ESAs.

Of those patients receiving ESAs, 14.3% of them developed thrombo-embolism (deep vein thrombosis or pulmonary embolism) compared with 9.8% of those who did not.

ESAs are given to chemotherapy patients to stimulate their red blood cell production, so as to reduce the number of blood transfusions required during treatment. However, the blood transfusion rate for both groups remained the same at 22%, as did survival rates.

In 2007, due to concerns raised by earlier studies, the U. S. Food and Drug Administration (FDA) required ESAs to carry a black box warning label stating the risk for venous thrombo-embolism, tumour promotion and death. The warning suggests restricting ESA use to specific tumour types, including addressing dosage, duration and targeted haemoglobin levels.