Hypertension higher in childhood cancer survivors

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Todd M Gibson, PhD

Childhood cancer is not a disease that can be prevented with lifestyle changes, but cardiovascular disease is. As more children with cancer are living to adulthood, this is, fortunately in a way, a problem many will have to face, but unfortunately one they have to face at a higher rate than the rest of society.

A new study, published in Cancer Epidemiology, Biomarkers and Prevention, found that 1 in 12 adults who defeated childhood cancer have undiagnosed hypertension.¹

The study examined more than 3000 adults who had survived a childhood cancer by 10 years or more. Resting blood pressure (BP) measurements were taken, and the research team found that hypertension rates among childhood cancer survivors increased significantly with age and were higher than expected for their specific age, race, gender, age, and body mass index (BMI). The study didn't connect hypertension to any specific type of childhood cancer or treatment, except for nephrectomy, according to the report. 

Over the course of the study, 8% of childhood cancer survivors studied were found to have previously undiagnosed hypertension, and 22% with a previous diagnosis of hypertension were uncontrolled. The research team also looked at BP measurements going back nearly 4 years in a subset of the study group and found that 5% of participants with previously normal BP developed hypertension in that period and another 21% had prehypertension BP measurements.

Examining the study population by age, researchers found that 13% of childhood cancer survivors developed hypertension by age 30 years, 37% by age 40 years, and 70% by age 50 years. These rates increased more sharply with age than in the general population, according to the report, with rates of hypertension in childhood cancer matching those of individuals aged about 10 years older in the general population.

Although rates of developing hypertension or not generally were not affected by the type of childhood cancer diagnosis, researchers did note that survivors of Wilms tumors generally had the highest age-specific prevalence. Other factors associated with increased risk of hypertension outside cancer diagnosis and care included male gender, black race, and increased age and weight-much like the rest of the general population.

Why the higher rate of hypertension?

The study wasn't able to pinpoint a cause for the increased rates of hypertension in childhood cancer survivors, nor were researchers able to correlate their findings to any specific cancer diagnosis or treatment. However, cardiovascular disease is already recognized as a major concern for cancer survivors, earning recognition as the top noncancer cause of mortality and morbidity in survivors, according to the report. In fact, childhood cancer survivors are 8 times more likely to die from a cardiovascular-related death than the general population, and 5 times more likely to face a serious cardiac event, the study notes.

Researchers suspect that frequent exposure to chest-directed radiation and/or high-dose anthracyclines may play a role in the development of cardiovascular disease in childhood cancer survivors, but they also note that these survivors are highly susceptible to the same risk factors everyone else faces-high BP, high cholesterol, and obesity. There is some evidence that chemotherapies and other cardiotoxic treatments, in addition to increased radiation exposure, may be partly to blame for this increased risk in cardiovascular disease, but there is also concern that hypertension can exacerbate these effects.

"A report from the Childhood Cancer Survivor Study (CCSS) found that although both cardiotoxic treatments and hypertension were independently associated with increased risk of coronary artery disease or heart failure, the combination of these factors resulted in a greater than additive increase in risk that yielded an 86-fold increased risk of heart failure in survivors exposed to both anthracyclines and hypertension compared with neither factor," the study notes. "This suggests that development of hypertension can exacerbate the damage caused by cardiotoxic cancer treatments."

How to modify risk factors

The researchers concluded that childhood cancer survivors should be monitored for hypertension more closely into adulthood, and more education may be required about their increased risks and what to do about it.

"The good news is that, unlike prior cancer therapy, high BP is a modifiable risk factor," says Todd M. Gibson, PhD, assistant member of epidemiology and cancer control at St. Jude Children's Research Hospital, Memphis, Tennessee, and lead author of the study. "Research is needed to identify effective interventions to prevent hypertension in survivors, which could include lifestyle behaviors such as diet and exercise, as well as medical interventions such as BP medications. The key point is that our results emphasize the importance of BP surveillance and management in all adult survivors of childhood cancer."

The study reveals that even when patients knew about their condition, they did little to change it, finding that 1 in 5 childhood cancer survivors who knew he/she had hypertension didn't take the medication or make the lifestyle changes necessary to fight it.

Because of the retrospective nature of the study and its examination of individuals long after their childhood cancer and treatment, Gibson says the team is not able to make any statements about preventive measures that might be used during or soon after treatment that might change these results.

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"In general, our results support known hypertension prevention measures such as maintaining a healthy body weight," Gibson says. "Hopefully these results will further emphasize the importance of BP surveillance and management to both childhood cancer survivors and clinicians."

References:

1. Gibson TM, LI Z, Green DM, et al. Blood pressure status in adult survivors of childhood cancer: a report from the St. Jude Lifetime Cohort Study. Cancer Epidemiol Biomarkers Prev. 2017;26(12):1705-1713.