Cancer treatment has helped more children than ever survive acute lymphoblastic leukemia (ALL), the most common type of childhood cancer. Thanks to advances in medicine, survival rates have soared to 85%. However, researchers are now uncovering long-term health effects that often go undiagnosed—including heart problems.
A new study from Université de Montréal and CHU Sainte-Justine Azrieli Research Centre, published in the International Journal of Cancer, found that some childhood cancer survivors may develop a hidden heart condition called acquired long QT syndrome (aLQTS).
This condition affects the heart’s electrical system, increasing the risk of irregular heartbeats (arrhythmias), fainting, seizures, and even cardiac arrest.
Heart Risks That Go Unnoticed
Unlike some heart diseases, aLQTS doesn’t cause visible structural damage to the heart. Instead, it affects how the heart’s electrical signals work. This means that many children with the condition feel fine in daily life and might not know they have a problem.
However, under stress—such as during intense exercise—their heart could start beating too fast or unevenly, putting them at serious risk.
To better understand these risks, researchers studied about 200 childhood ALL survivors. Each participant did a treadmill stress test, which measured their heart function while exercising. The results were surprising:
- 70% of those who had an abnormal heart response during exercise showed no problems when tested at rest.
- 10% of the participants had a severe form of long QT syndrome, meaning they were at higher risk for dangerous heart complications.
According to Dr. Cecilia Gonzalez Corcia, a cardiologist and study co-author, chemotherapy can change the way heart muscle cells function. These changes might not show up when a person is resting, but they can cause serious heart problems when the heart is working harder, such as during exercise.
Why Exercise Testing Matters
This study is the first to identify potential cases of aLQTS in childhood cancer survivors using exercise tests. The findings highlight the need for better heart screenings as part of long-term follow-ups for children who have survived ALL.
Currently, standard heart check-ups for cancer survivors rely on electrocardiography (ECG) and electroencephalography (EEG), which are done while the patient is at rest. However, these tests might not detect problems that only appear during physical activity.
Audrey Harvey, the study’s first author, believes that exercise stress tests should become a standard part of medical follow-ups for childhood cancer survivors. She suggests that a cardiopulmonary exercise test could provide more accurate results and help identify at-risk individuals early.
Improving Care for Cancer Survivors
The study also stresses the importance of long-term heart monitoring, especially for survivors who:
- Received high doses of chemotherapy
- Underwent treatment for a long period of time
- Want to return to sports or physical activity after remission
Right now, exercise testing is not officially recommended for pediatric cancer survivors. However, the researchers hope that their findings will encourage experts to rethink standard heart screenings and develop better ways to prevent serious heart conditions in young cancer survivors.
By improving diagnosis and monitoring, this research could help protect the heart health of thousands of childhood cancer survivors and ensure they can live long, healthy lives.
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The research findings can be found in the International Journal of Cancer.
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