AUTONOMIC CONTROL, FUNCTIONAL CAPACITY AND FATIGUE IN BREAST CANCER: A CASE-CONTROL STUDY

I. Ribeiro¹, A. Zamúner¹, M.I. Arias¹, I. Canales¹, J. Campos¹, N. Yáñez², F. Ortega²

Background: In the postoperative (PO) period of breast cancer, the manifestation of cardiotoxicity induced by cancer treatment is frequent. The evaluation of cardiac autonomic control, through the heart rate variability (HRV), is a prognostic tool related to the risk of cardiac mortality as well as the assessment of functional capacity, that could be effective to monitore changes related to cardiotoxicity induced by cancer treatment. Moreover, it is important to consider fatigue symptoms as a patient reported outcome following PO, but there is a lack of evidence regarding to this symptom at different periods of surgery. Thus, studies on cardiovascular risk factors following breast cancer treatment are still incipient.

Purpose: To assess the autonomic control, functional capacity and fatigue in women after breast cancer surgery, compared to a matched healthy controls.

Methods: The study was approved by the Ethics Committee of Catholic University of Maule, Chile (protocol number: 159/2018). Eighteen female breast cancer survivors (PO group, age: 50.67±9.35 years; body mass index, BMI: 27.26±3.053kg/m2) and 18 control (48.72±7.66 years; BMI: 26.45±4.139kg/m2) were evaluated. The autonomic control was evaluated by the spectral analysis of the HRV. The power spectral density (PSD), the low frequency (LF) and high frequency (HF) bands were quantified by means of a heart rate monitor (Polar®, V800) evaluated in the supine position for 10 minutes and then 10 minutes in the standing position. Fatigue was assessed using the Brief Fatigue Inventory (BFI) survey. The data were analyzed with the Mann-Whitney U test and Student's t test for independent samples according to normality, considering a significant p value <0.05.

Results: There were differences for the autonomic control variables (STDRRSDNN, RMSSD and PSD) expressed in deltas, showing negatively altered for the PO group, in comparison to the control group (p <0.05). Functional capacity and fatigue were similar between groups (p> 0.05).

Conclusion(s): The PO group presented impairments in autonomic control, characterized by lower HRV. These data reveal cardiovascular risk factors in this population. For the other side, the functional capacity and fatigue were similar between groups. Future studies using physical exercise in different stages of the disease focused on cardioprotection, functional capacity and fatigue may minimize the side effects of cancer treatment.

Implications: Early intervention of physical therapy during breast cancer treatment may prevent the impairments of autonomic control in breast cancer survivors.

Funding, acknowledgements: This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

Keywords: Breast neoplasms, Heart rate, Walking

Topic: Oncology, HIV & palliative care

Did this work require ethics approval? Yes

Institution: Catholic University of Maule, Chile

Committee: Ethics Committee of Catholic University of Maule, Chile

Ethics number: 159/2018