Effects of resistance plus aerobic training on body composition and metabolic markers in older breast cancer survivors undergoing aromatase inhibitor therapy☆
Introduction
Cancer is one of the major public health problems and leading causes of death in the world (National Center for Health Statistics, 2016). With the growth in the world population, the number of new cases is expected to increase considerably, reaching 20.3 million by 2030 (Ferlay et al., 2010). Among all types of cancers, breast cancer is the most common among women (International Agency for Research on Cancer, 2012). According to the National Cancer Institute, in 2017, it is estimated that over 57,960 new cases of breast cancer will occur in Brazilian women (Instituto Nacional do Câncer (INCA), 2016).
In postmenopausal women, 80% of breast cancer cases are hormone receptor positive (Bardia et al., 2012) and aromatase inhibitor therapy (AI) is typically prescribed as standard treatment, which increases survival rates upwards of 40% compared to tamoxifen (Riemsma et al., 2010). However, treatment of breast cancer with aromatase inhibitor therapy can produce alterations in body composition, such as increases in body fat mass as well as decreases in lean body mass and bone mineral density (Napoli et al., 2015; Battisti et al., 2014; Van Londen et al., 2011) and, these alterations can increase the risk of fractures, osteoporosis, and chronic diseases (Akyol et al., 2016; Saarto et al., 2008). In addition, the side effects of AI also include loss of bone mineral density of 2.6% per year and symptoms of arthralgia and myalgia (Limburg, 2007; Peppone et al., 2010). AI decreases circulating estrogens and thus may also may weaken estrogen-mediated protective effects on the cardiovascular system among women on AI (Amir et al., 2011; Foglietta et al., 2017).
A non-pharmacological alternative to reverse or attenuate the side effects of breast cancer treatment on body composition is exercise training. Several studies have shown that exercise is effective for improving body composition (increased lean body mass, decreased fat body mass, and body mineral density at the spine, hip, and whole body), inflammatory and metabolic blood markers, physical fitness, and quality of life of breast cancer survivors (Battaglini et al., 2014; Dieli-Conwright and Orozco, 2015; Almstedt et al., 2016). Thomas et al. (2016) demonstrated an association between 12 months of combined exercise (twice-weekly supervised resistance training program and 150 min of moderate-intensity aerobic exercise at home) with a decrease in percentage body fat and an increase in lean body mass in postmenopausal breast cancer survivors taking AI.
However, there are few studies including exercise programs which combine aerobic and resistance training for women undergoing treatment for breast cancer with aromatase inhibitor therapy. Furthermore, the long term benefits of combining resistance and aerobic training in breast cancer survivors on AI are not clear, and more studies are needed with this population, focusing on responses of combined exercise on body composition and metabolic markers. Thus, the aim of this study was to evaluate the effects of combined aerobic + resistance training on body composition and metabolic markers in older breast cancer survivors undergoing aromatase inhibitor therapy.
Section snippets
Study design
We conducted a 36 week single-blind, parallel group randomized controlled trial from March 2015 to July 2016 in a city in the southeastern region of Brazil (ClinicalTrials.gov NCT02804308). Women were randomized to a resistance + aerobic training group or a low-intensity stretching control group. All testing and exercise training took place at the Sao Paulo State University-Campus of Presidente Prudente, physical education department. This study was approved by the Research Ethics Committee of
Results
On average, women in the exercise group were 63 years old and in the control group 67 years old; the majority of women were homemakers, married, with children, and with at least a high school education. Approximately 52% of the exercise group (EX) and 41% of the control group (CON) had undergone total mastectomies and 66% EX and 69% CON received chemotherapy. The majority of the women were diagnosed with stage I breast cancer and the average time on AI was 19.3 months in the EX and 17.9 months
Discussion
The objective of this study was to evaluate the effects of combined resistance plus aerobic training on body composition and metabolic markers in older breast cancer survivors undergoing AI. Our main finding was that combined training significantly improved the body composition of older breast cancer survivors in the exercise group, mainly through decreased body fat mass, in contrast to increases in the control group. The exercise program did not significantly improve lean mass or bone mineral
Conflicts of interest
The authors declare that they have no conflict of interest.
Acknowledgements
The Amazon Research Foundation - FAPEAM, supported Scholarship.
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Declarations of interest: none.