Phlebotomy in patients with polycythemia vera on cytoreductive treatment

Dr Chris Hillis is an assistant professor in the Division of Oncology at McMaster University and hematologist at the Juravinski Hospital and Cancer Centre.

Do you continue phlebotomy in patients with polycythemia vera (PV) who receive cytoreductive treatment?

Chris Hillis, MD, MSc: Yes, I absolutely do. Certainly, it is nice for patients if they are able to stop phlebotomy once we have started cytoreductive therapy, but there are a number of patients who still require phlebotomy while on cytoreductive therapy. Of course we can increase our dose of hydroxyurea or hydroxycarbamide to try and get the hematocrit to less than 45%, but occasionally you will run into issues with neutropenia or even thrombocytopenia that require that you still phlebotomize the patient to maintain that hematocrit.

A number of patients who are on studies, such as the CYTO-PV (Cytoreductive Therapy in Polycythemia Vera) study, maintain the combination of cytoreductive therapy as well as phlebotomy. The challenge is that there is some retrospective evidence that would suggest that patients who continue on phlebotomy are at an increased risk of vascular events while on cytoreduction compared with those who are on cytoreduction alone. However, there has been more recent evidence that disproves that.

I think we really do not know what the dangers of phlebotomy are as far as cardiovascular risk factors go. However, we do know that it is inconvenient and certainly the symptoms of iron deficiency that develop over time are very uncomfortable for patients.