Barbui is a professor of hematology and founder of the department of hematology at Bergamo Hospital. He is currently the scientific director of clinical research foundation at Papa Giovanni XXIII Hospital, Bergamo, Italy.

Dr. Tiziano Barbui

Dr. Tiziano Barbui explains how excess blood cell production in certain myeloproliferative neoplasms can impair circulation and why treatments like phlebotomy are used.

How Essential Thrombocythemia and Polycythemia Vera Affect Blood Flow 

Excess blood cell production in two myeloproliferative neoplasms (MPNs) — essential thrombocythemia, or ET, and polycythemia vera, also known as PV — can impair circulation, according to Dr. Tiziano Barbui.

In a video interview with CURE, Barbui explained that both diseases begin in the bone marrow and are marked by abnormal increases in blood cell counts. In polycythemia vera, red blood cells are overproduced, increasing blood viscosity and making it harder for blood to flow through small vessels. In essential thrombocythemia, the problem lies with excess platelet production.

Barbui emphasized that treatment is essential not only to relieve symptoms but also to prevent more serious complications linked to impaired blood circulation in both MPNs.

These two diseases, called essential thrombocythemia and polycythemia vera, are chronic hematologic conditions. Like other tumors, they originate in the bone marrow and cause abnormal overproduction of blood cells. In PV, this overproduction specifically affects erythrocytes (red blood cells), while in ET, the excess production involves platelets.

Both diseases are defined by an overproduction of blood cells in the bone marrow. This increased cell volume can make blood circulation, especially in the small vessels, more difficult. In the case of polycythemia vera, the high number of red blood cells leads to increased blood viscosity, making it harder for blood to flow. As a result, circulation may become obstructed in some blood vessels.

This is why patients with an excess of red blood cells often undergo phlebotomy — to reduce the number of circulating cells and improve blood flow. Without this intervention, blood flow may be impeded or stop altogether. However, the problem isn’t limited to the excess number of blood cells alone.

Transcript has been edited for clarity and conciseness.

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Arterial thrombosis may occur years before cancer diagnosis, suggesting it could be a risk factor, according to Dr. Tiziano Barbui.

Early Arterial Thrombosis May Signal Future Cancer Risk

Arterial thrombosis events like strokes or heart attacks may occur five to seven years before a cancer diagnosis, raising the possibility that they are not a result of the tumor itself but could instead be a risk factor for developing cancer, explained Dr. Tiziano Barbui.

In an interview with CURE, Barbui said his team observed a higher rate of arterial thrombosis in patients years before they were diagnosed with solid tumors, compared with a control group without cancer. This challenges the commonly understood link between cancer and thrombosis, which typically occurs closer to the time of diagnosis.

In a follow-up study, Barbui and colleagues found that this trend was especially pronounced in younger patients. He suggested that genetic mutations such as JAK2, along with chronic inflammation from conditions like polycythemia, may play a role in both thrombosis and cancer development — particularly in individuals with added risks like smoking or diabetes.

By looking at the patient history before their cancer diagnosis, we noticed that these patients had a higher frequency of arterial thrombosis — including strokes and, sometimes, myocardial infarctions — compared with a control group without cancer. Importantly, these events occurred not near the time of cancer diagnosis, but five to seven years before the tumor developed. That suggests the thrombosis wasn’t caused by the tumor itself.

We already know there's a link between cancer and thrombosis, but usually the thrombosis occurs close to the cancer. In this case, it happened years earlier, leading us to hypothesize that thrombosis might actually be a risk factor for developing solid tumors.

In a second paper, we found that this pattern was even more common in younger patients. One possible reason is exposure to JAK2 mutations and systemic chronic inflammation caused by underlying diseases like polycythemia. These factors not only contribute to the blood disorder but may also promote cancer development — especially in patients with additional risk factors like smoking or diabetes.

This finding has generated a lot of interest, particularly in the U.S. For example, the REVEAL study, which you might have heard of, also documented a similar pattern — though it was published after our work and has yet to release a full paper. That study showed that patients with arterial thrombosis may go on to develop myelofibrosis, a progression of the disease.

Dr. Tiziano Barbui

How Essential Thrombocythemia and Polycythemia Vera Affect Blood Flow

Early Arterial Thrombosis May Signal Future Cancer Risk

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