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Treating hypertension has tended to be a low priority when managing patients with cancer, but a new study in the suggested that untreated hypertension puts these patients at risk for heart failure and other cardiovascular events.

Researchers led by Hidehiro Kaneko, MD, of the University of Tokyo, retrospectively analyzed data on 33,991 cancer patients from a large claims database. These patients did not have a history of cardiovascular disease (CVD) and were not receiving blood-pressure medication. Half of the cohort had a history of breast cancer.

At baseline, just 51% of these patients had normal blood pressure. A total of 14% had elevated blood pressure, 22% had stage I hypertension, and 13% had stage II hypertension. Over a follow-up of 2.6 years, there were 779 heart failure events, the study's primary outcome.

Patients with stage I hypertension had a 24% risk increase for heart failure (HR 1.24, 95% CI 1.03-1.49) and patients with stage II hypertension had nearly double the risk (HR 1.99, 95% CI 1.63-2.43) compared with those with normal blood pressure. Risk was also higher for other cardiovascular events such as atrial fibrillation and stroke.

"The treatment for hypertension was prone to be withheld for patients with cancer because the life expectancy of patients with cancer was estimated to be short and the benefit of preventive efforts for CVD was underestimated in patients with cancer," Kaneko's group wrote.

New treatments, however, have prolonged survival. "Therefore, CVD prevention and management of hypertension from the perspective of long-term clinical outcomes have become more important for patients with cancer," the team said. "Our results suggest the importance of multidisciplinary collaboration (e.g., oncologists and cardiologists) to establish the optimal management strategy for hypertension in patients with cancer."

In the following interview, Kaneko, of the Department of Cardiovascular Medicine, elaborated on the findings.

What do you see as the main clinical implications of this study?

Kaneko: Most important in this study is that hypertension should not be underestimated even in cancer patients (including those under active treatment).

Further studies are needed to determine whether therapeutic intervention for hypertension in cancer patients could improve outcomes of cancer patients, but our study using large-scale epidemiological data suggests that hypertension is associated with an increased risk of cardiovascular events, including heart failure, even in cancer patients.

What are the specific factors that can lead to elevated blood pressure in patients with cancer?

Kaneko: Various factors could lead to the elevation in BP [blood pressure]. For example, cancer treatments -- e.g., angiogenesis inhibitors -- can lead to the development or exacerbation of hypertension. Pain, anxiety, and temporary medications -- e.g., nonsteroidal anti-inflammatory drugs, corticosteroids, and erythropoietin -- also trigger hypertension. Therefore, careful assessment is required for the elevation in BP among cancer patients.

Does elevated blood pressure increase the risk of heart failure more in patients with cancer compared with healthy individuals or the general population?

Kaneko: This is an important point, indeed. Unfortunately, the present study cannot conclude this point. However, cancer patients are known to have an excess risk of cardiovascular events. From this viewpoint, hypertension should not be underestimated even in cancer patients.

Can you tell us more about what your study found about hypertension and risk of cardiovascular events other than heart failure?

Kaneko: Similar to the relationship of increasing BP with the risk of developing heart failure, the risk of coronary artery disease, stroke, and atrial fibrillation increased with increasing BP in a dose-dependent manner.

What did you find in your other subgroup analyses? Was there anything unique about patients with breast cancer?

Kaneko: We conducted subgroup analyses stratified by age, sex, active cancer treatment, or cancer sites, and found that our primary findings were consistent across each subgroup. Particularly, the association between BP and the risk for heart failure was observed even in patients undergoing active cancer treatment. Further, the risk of heart failure also increased with BP in patients having breast cancer as well.

Our analyses underscore the importance of BP management in cancer patients. Multidisciplinary collaboration is undoubtedly required to improve the clinical outcomes of patients living with cancer.

Read the study here.