Many cancer patients and survivors die from heart disease rather than from their tumours, especially if they have certain malignancies like breast and prostate cancer, a US study suggests.

Researchers examined data on more than 3.2 million cancer patients diagnosed between 1973 and 2012. During the study period, 38 per cent of these patients died from cancer and another 11 per cent died from cardiovascular disease.

Three of four people with a cardiovascular cause of death died of heart disease.

The risk of dying from cardiovascular diseases was highest in the first year after a cancer diagnosis and among patients who were diagnosed with tumours before age 35.

"These findings show that a large proportion of certain cancer patients will die of cardiovascular disease, including heart disease, stroke, aneurysm, high blood pressure and damage to blood vessels," lead study author Dr. Kathleen Sturgeon of Penn State College of Medicine in Hershey said in a statement.

"We also found that among survivors with any type of cancer diagnosed before the age of 55 years, the risk of cardiovascular death was more than 10-fold greater than in the general population," Sturgeon said.

Fatalities from cardiovascular diseases included deaths related to heart disease, high blood pressure, cerebrovascular disease, blocked arteries and damage to the smaller blood vessels.

The analysis looked at 28 types of cancer and found that the majority of cardiovascular disease deaths occurred in commonly diagnosed malignancies like breast and prostate tumours - both of which are also examples of cancers with a good prognosis for long-term cancer survival.

Read Also

lifestyle

5 affordable ways to reduce your risk of cardiovascular disease

Patients with the most aggressive and hard-to-treat cancers - including malignancies of the lung, liver, brain, stomach, gallbladder, pancreas, esophagus and ovaries - were more likely to die from their tumours than from cardiovascular causes, the study found.

As newer treatments help more cancer patients survive longer, the proportion who die of heart disease and other causes is likely to keep rising, the study authors note in the European Heart Journal.

Side effects of cancer treatments can make survivors vulnerable to heart problems, especially in the first year or two after cancer diagnosis.

Older chemotherapy regimens can weaken the heart muscle, and some newer targeted therapies can lead to heart failure, for example. Radiation may cause heart rhythm disorders or damage arteries and heart valves.

Cancer patients could also have a higher risk of dying from cardiovascular disease within the first year of diagnosis because when they enter the hospital system, other illnesses and problems, such as heart disease, lung dysfunction and kidney failure are also detected, said Dr. Nicholas G. Zaorsky, also of Penn State College of Medicine, the study's senior author.

"We hope these findings will increase awareness in patients, primary care physicians, oncologists and cardiologists as to the risk of cardiovascular disease among cancer patients and the need for earlier, more aggressive and better-coordinated cardiovascular care," Zaorsky said in a statement.

The study wasn't designed to determine whether or how particular cancers or tumour treatments might directly cause potentially fatal heart problems.

One limitation of the analysis is that researchers lacked data on the type of treatments cancer patients received, including whether they had interventions that are known to cause heart problems, the study team notes.

Researchers also lacked data on some individual patient characteristics, such as whether people had other risk factors for heart disease like obesity, smoking or heavy drinking.

Even so, the findings underscore that cancer patients have on average a two to six times higher risk of dying from cardiovascular disease than people in the general population who don't have tumours, Dr. Jorg Herrmann, a cardiologist at the Mayo Clinic in Rochester, Minnesota, writes in an editorial accompanying the study.

"This is a key message that every cardiologist needs to hear," Hermann writes.