Re: “Dysautonomia in Childhood Cancer Survivors: A Widely Underestimated Risk” by Berger et al. ( J Adolesc Young Adult Oncol. 2019;8(1):9–17)

Dear Editor:

Dr. Berger and colleagues recently published an article in the Journal of Adolescent and Young Adult Oncology on the autonomic nervous system (ANS) activity in childhood cancer survivors. ¹ They should be congratulated for focusing on the relatively neglected field of long-term adverse effects. Indeed, their study provides interesting findings on the ANS dysfunction in survivors, which is a widely underestimated risk. With this letter to the editor, we would like to comment on the importance of physical activity in the management of long-term adverse effects of cancer treatments and further perspectives of the study.

We agree with the researchers' point of view on the role of physical activity and on the need to increase regular physical activity in these patients. As it is developed, physical activity is a positive regulator and modulator of ANS activity in cancer patients. Thus, we believe that physical activity is the most efficient way to improve ANS activity. However, during cancer, children face many challenges. Nearly half do not meet the physical activity recommendations and some drop out of school because of disease and treatments. It appears essential to help them to reinstate the academic system where they are active in a variety of sports activities. This allows them to improve the regulation of their sympathetic and parasympathetic nervous systems, provided that they adhere to regular physical activity. Therefore, it is recommended to promote collective sports activities in school to stimulate the development of pleasure related to physical activity. Nevertheless, although we share the same opinion regarding the beneficial effects of physical activity as described in the article, we see other major effects that deserve to be discussed.

Indeed, the authors indicated that the effect of cancer treatments was not taken into account in their analyses due to the small cohort. However, it has been shown that cancer treatment, such as anthracyclines, can induce long-term cardiotoxicity. ² In the long term, this cardiotoxicity may have terrible consequences in survivors and the effects of cancer treatments in the ANS dysfunction should not be underestimated. It has been reported that survivors have a considerably increased risk for premature cardiovascular diseases such as congestive heart failure. ³ The ANS seems to be activated excessively in these patients, described by an imbalance in the sympathetic and parasympathetic nervous systems. This is one of the precursor signs of heart failure since it has the effect of promoting inappropriate remodeling of the myocardium and deterioration of the cardiac function. ⁴ Thus, in addition to participating in the ANS restoration, physical activity encourages cardiac remodeling, which are important issues in cancer survivors. ² It should also be noted that to reduce the ANS imbalance in survivors, any antiadrenergic strategies should be considered. In this sense, pharmacological options such as early beta-blockers could be a possible option, as well as antiadrenergic auricular electrical stimulation. However, we agree with the authors that lifestyle modifications, such as physical activity, should be prioritized to address the long-term effects of ANS dysfunction and cardiotoxicity. Studies such as this are necessary to develop our understanding and recognition of the ANS dysfunction in survivors and to purpose remediation strategies.