Many cancer patients and survivors die from heart disease rather than from their tumors, 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% of these patients died from cancer and another 11% 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 tumors 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 tumors - both of which are also examples of cancers with a good prognosis for long-term cancer survival.