People who survive a type of blood cancer known as Hodgkin lymphoma early in life may be twice as likely to develop heart problems in adulthood as peers without a history of these tumors, a U.S. study suggests.

By age 50, Hodgkin survivors were almost five times as likely to have severe cardiovascular health conditions that can be life threatening, the study found.

While the study didn't look at why these cancer survivors might have heart problems, both chemotherapy and radiation typically used to treat these tumors can cause permanent heart damage, said lead study author Dr. Nickhill Bhakta of St. Jude Children's Research Hospital in Memphis, Tennessee.

"The most obvious and simple option is to just give less medicine and/or radiation," Bhakta said by email. "This is difficult because we want to cure cancer and when we know something works, it's hard to give less of it for fear that we may not cure patients."

To assess the lasting effects of treatment on heart health, Bhakta and colleagues examined data on about 350 adults who survived at least a decade after their Hodgkin diagnosis, as well as about 270 people without a cancer history who were similar in gender and age.

Researchers started following patients in 1971 and continued to monitor them through 2014.

More than 90 percent of the participants with Hodgkin disease received radiation during their treatment, and 36 percent of them took drugs known as anthracyclines, a type of chemotherapy that can damage the heart.

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Researchers looked at a wide range of cardiovascular conditions, from abnormal heart rhythm to high blood pressure and elevated cholesterol, as well as heart attacks, valve disorders and clots that impede blood flow.

They assessed both the number of heart-related problems, and the severity of each one.

At age 50, about 46 percent of the cancer survivors had experienced at least one serious heart problem, compared with about 16 percent in the control group of individuals without a cancer history, researchers report in The Lancet Oncology.

Cancer survivors were also more likely to experience severe complications like heart attacks and structural defects such as valve disorders or damage to the aorta, the vessel that carries blood from the heart to the rest of the body.

Higher radiation doses were associated with higher odds that patients would have severe complications, though higher doses of anthracyclines didn't appear to influence this risk.

One limitation of the study is that it may have underestimated the mortality risk associated with cancer treatment because not enough people died to calculate this, the authors note.

It's also possible that the results could look different for patients who joined the study more recently, when doctors treating them might have been more aware of the heart risks of radiation and chemotherapy and more closely monitored people for heart problems, the authors point out.

Targeted radiation techniques as well as new types of cancer drugs may cause less damage to the heart in the future, but it's too soon to say which of these experimental approaches might pan out, Bhakta said.

"If any of these treatment options mean we can dial down the effect to the heart, substitution could play a role in reducing the burden of heart disease in this population," Bhakta added.

Even without new treatments, there are some things patients can do to help prevent heart problems, noted Marianne Aznar an oncology researcher at Rigshospitalet and the University of Copenhagen in Denmark who wrote an editorial accompanying the study.

"Patients can reduce their risk of heart disease by adopting a healthy lifestyle - giving up smoking, avoiding becoming overweight, and eating a healthy diet with plenty of fruit and vegetables and cutting down on saturated fat and sugar," Aznar said by email.

"Patients could also talk to their general practitioner about monitoring for hypertension and high cholesterol, which can also affect the risk of heart disease," Aznar added.