Many cancer survivors face increased risk of heart disease

Many adult cancer survivors face an increased risk of heart disease, worsening their long-term survival odds beyond the effect of tumors alone, a U.S. study suggests.

In a study of about 110,000 people, survivors of certain cancers – including tumors in the lung, ovaries, bone marrow and lymph system – had a significantly higher risk of cardiovascular disease than individuals with no history of malignancies, the study found.

Among the 36,000 cancer survivors in the study, just 60 percent of the those who developed cardiovascular disease survived after eight years, compared with 81 percent of cancer patients without heart problems.

“The findings from the current study speak to the growing long-term morbidity associated with cardiovascular disease in cancer survivors, and to the critical importance of strategies to improve cardiovascular health in at-risk survivors long after completion of cancer therapy,” said lead study author Dr. Saro Armenian of City of Hope Comprehensive Cancer Center in Duarte, California.

Previous research has linked cancer chemotherapies known as anthracyclines to weakening of the heart muscle. Research has also tied some radiation therapy to cardiac rhythm disorders and structural damage in arteries and heart valves.

While much of this research has focused on childhood cancer survivors, the current findings reinforce that these risks apply to adults, too, and also suggest that millions of aging cancer survivors need to pay closer attention to lifestyle choices that could help avert cardiovascular disease, Armenian added by email.

“For cancer survivors with modifiable risk factors such as hypertension, diabetes, and dyslipidemia, aggressive management of these conditions may be integral to efforts for long-term cardiovascular disease risk reduction,” Armenian said.

To explore the connection between cardiovascular disease and cancer, Armenian and colleagues analyzed medical records for patients diagnosed with cancer between 2000 and 2007 when they were at least 40 years old and who had survived at least two years since diagnosis. The researchers followed patients until they developed cardiovascular disease, died, or until 2012, when the study ended.

Half of the patients were at least 60 years old at the time of their cancer diagnosis. The most common cancers were breast and prostate malignancies, which each affected about 30 percent of the survivors in the study, followed by colon tumors and melanoma.

The cancer survivors were significantly more likely to have many risk factors for cardiovascular disease than similar people without a history of cancer in the comparison group, according to the report in the Journal of Clinical Oncology.

About 66 percent of the cancer survivors had high blood pressure, compared to 60 percent of their non-cancer peers. Cancer survivors were also slightly more prone to diabetes (23 percent versus 22 percent of non-cancer peers), high cholesterol (58 percent versus 56 percent), excess weight (43 percent versus 35 percent) and a history of smoking (33 percent versus 21 percent).

Cardiovascular disease risk varied by tumor type, however. Survivors of multiple myeloma, a cancer of the plasma cells in bone marrow, were 70 percent more likely to develop cardiovascular disease than people who didn’t get cancer. Lung cancer survivors had a 58 percent increased risk, while non-Hodgkin lymphoma and ovarian cancer both came with a 41 percent higher risk.

For prostate cancer survivors, though, the cardiovascular disease risk was 11 percent lower than it was for people who didn’t have a history of malignancies.

It’s possible some side effects of prostate cancer treatment only temporarily increase the risk of cardiovascular disease and weren’t seen in this study of people who had already survived two years since their cancer diagnosis, the authors speculate.

Because the study is based on looking back at medical records, it cannot say for certain whether cancer itself or tumor treatments cause heart disease, the authors note.

Still, the findings suggest that cardiovascular disease may be a “blind spot” for many adult cancer patients, said Dr. Daniel Lenihan, a cardiovascular disease researcher at Vanderbilt University in Nashville, Tennessee, who wasn’t involved in the study.

“The biggest worry is of course the cancer diagnosis, but the cardiac disease issues can really sneak up and be a bigger problem,” Lenihan said by email.