St. Jude Children's Research Hospital investigators found evidence that chest irradiation may leave some adult survivors of childhood cancer in danger of developing pulmonary hypertension in middle age.
Childhood cancer survivors treated with chest irradiation or certain chemotherapy drugs are known to be at risk for a variety of treatment-related heart problems. But the study published recently in the Journal of Clinical Oncology is the first report suggesting survivors might also face higher odds of developing pulmonary hypertension. Pulmonary hypertension is a serious, progressive form of increased pressure in the arteries in the lungs. Untreated, the problem is associated with a significant risk for heart failure and death.
The study involved 498 adult survivors who underwent echocardiography, a recommended heart screening test, which included an estimate of their pulmonary artery pressure. The test found that pulmonary artery pressure was elevated in 25 percent of survivors treated with chest irradiation. The findings suggested the survivors, whose average age was 38 years old, might be at higher risk of pulmonary hypertension. Researchers also found that the risk climbed with increasing radiation dose and was associated with decreased exercise endurance.
The findings will likely lead to revised heart screening recommendations for adult survivors of childhood cancer, as well as research to understand and effectively manage pulmonary hypertension in this newly identified high-risk group.
First author Gregory Armstrong, M.D., an associate member in the St. Jude Epidemiology and Cancer Control department, said the risk might have gone unnoticed in previous studies because survivors were younger and the screening involved a less detailed assessment of pulmonary artery pressure. "One of the keys to this study is that half the survivors are almost 30 years down the road from their diagnosis, but no one expected to see evidence of pulmonary hypertension," he said.
The risk surfaced in St. Jude Lifetime Cohort Study participants undergoing recommended Doppler echocardiography to check for premature heart disease, heart valve abnormalities and other treatment-related cardiovascular problems. The effort, known as St. Jude LIFE, is an ongoing study of St. Jude cancer survivors.
Study co-author Vijaya Joshi, M.D., St. Jude echocardiography laboratory medical director, noticed that some survivors had unexpectedly high pulmonary artery pressures.
That clinical observation led to this larger study, which linked the risk to chest irradiation and found elevated pressure occurred most often in survivors who received a radiation dose of 30 gray or more. Those survivors were almost five times more likely to have elevated pulmonary artery pressure than survivors treated without chest irradiation. They were also likely to be survivors of pediatric Hodgkin lymphoma.
Survivors with higher estimated pulmonary pressure were also less likely to complete a 300-meter walk, which is less than one-quarter mile. "This suggests survivors with this echocardiographic finding do not function as well in their daily lives," Armstrong said.
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