In our secondary data analysis, we found evidence that both fall-prevention exercise training approaches from the GET FIT trial may effectively address frailty in older postmenopausal women treated with chemotherapy. Strength training benefited the most, leading to an 86% higher chance of reducing overall frailty levels and two-fold better odds of improving at least one frailty component than a seated stretching control group. Tai ji quan also showed a positive trend toward reducing frailty and was twice as likely to improve at least one criterion compared to controls. The benefits of strength training and tai ji quan were consistently better than stretching at any baseline level of frailty, except for the most frail, who were likely to improve from any study program. Women were more likely to benefit from the study programs had a higher BMI, comorbidity score, and frailty status before starting the study exercise programs compared to other women.
Our analysis is the first to show that supervised, group exercise training can reduce frailty in women cancer survivors experiencing accelerated aging most likely associated with prior chemotherapy treatment. Frailty is a dynamic state, and over 6 months, we observed movement within our sample where women could move from pre-frail or frail to less frail states. Strength training reduced overall frailty more than other groups, which is consistent with the established benefits of this modality on multiple frailty constructs (i.e., muscle strength, fatigue, and physical activity) in people with cancer.[18, 27, 28] Our program targeted the lower body and focused on functional movement patterns because the original aim was to decrease falls, thus this specific type of strength training was also specific enough to target physical frailty criteria. Tai ji quan targets neuromuscular function differently than strength training emphasizing postural control through slow choreographed movements that challenge balance and stability. Though frailty levels improved among women in tai ji quan, changes did not reach statistical significance. In studies of tai ji quan in people with and without cancer, this modality can reduce fatigue, slowness, and weakness and increase overall activity levels.[20, 21] A higher frequency or longer duration of tai ji quan may be needed to improve frailty components enough to shift the overall phenotype.
Women engaged in strength training or tai ji quan were twice as likely to improve in at least one frailty criterion as compared to women who participated in seated stretching. However, the modalities changed individual criteria differently. Women in the strength training group were 3.5 times more likely to increase their self-report physical activity enough to no longer meet the frailty criteria of inactivity. Participation in strength training can improve self-efficacy for exercise and exercise self-confidence thus, women may have felt more capable of engaging in more physical activity in their daily lives.[29, 30] Since we focused our strength training program on functional movements it is also possible that women had more muscular strength and endurance to engage in more frequent and/or longer periods of physical activity. Conversely, women in tai ji quan were twice as likely to report levels of fatigue that no longer met the criterion for frailty. Our tai ji quan program consisted of eight movement forms and additional therapeutic movements all done continuously in a standing position for up to 60 minutes, likely leading to improvements in muscular endurance and work capacity that can reduce fatigue.[20, 21, 31] Neither strength training nor tai ji quan significantly improved the other physical frailty criteria enough to significantly improve frailty status for these outcomes. This finding was a bit surprising since strength training significantly increased maximal muscle strength in the primary analysis of GET FIT, while tai ji quan improved postural stability. In this subsample, fewer women within each study group may have met these frailty criteria at baseline and thus had less room for improvement, thereby making it less likely to see group differences. However, since some women did improve in two or more frailty criteria, we suspect that there was some improvement in these physical frailty criteria among those with lower functioning at baseline. Future studies that aim to reduce frailty should carefully consider whether or how the target sample is defined based on initial frailty so that ceiling effects are limited.
We also took the opportunity to identify characteristics of women most likely to improve in the frailty criteria in response to the experimental exercise programs. We found that women with higher BMI, more comorbidities and more frailty were more likely to improve in one or more frailty criteria compared to women who were generally healthier. Other than receipt of chemotherapy, we did not specifically identify a target sample with known frailty or frailty risk for the original study. Yet, our sample had rates of frailty on par or higher than other studies in cancer survivors, because it included all women who are known to be at higher risk of frailty for a given age.[4, 6, 14] Obesity and comorbidities are associated with frailty in people with cancer,[4, 5, 32] and our “responder” group also had higher levels of frailty at baseline. Hence, this group may inadvertently have become a reasonable target sample, who according to the principle of initial values, had the greatest room and need for improvement. Notably, the higher BMI consistent with obesity, higher comorbidities, and more frailty did not adversely impact the ability of these women to participate and respond to regular, structured group exercise training. Future studies may wish to consider these characteristics when identifying an appropriate target sample to study frailty.
Our study is among the first to determine whether exercise can reduce frailty in people with cancer and begins to contribute to the developing exercise prescriptions for frailty for future exercise guidelines for cancer survivors. There are some additional strengths. One advantage of conducting a secondary data analysis on a large, well-powered, and complex behavioral intervention is that additional outcomes of interest can be examined more quickly and with substantial cost savings than performing a new trial. Since GET FIT was aimed at falls as a primary outcome and frailty is a precursor to falls, the methods used in the original study are well aligned with an analysis to examine frailty. The experimental interventions in GET FIT were selected because they were well-established fall prevention approaches in non-cancer populations and were potentially accessible in community settings. Accordingly, the same advantages of testing these programs apply in this analysis focused on frailty. The GET FIT study was sufficiently powered for falls, and adherence and compliance to all study exercise programs were high; consequently, the study fidelity for this analysis was strong.
Our study also has limitations. GET FIT was not designed a priori to address frailty, a multi-component syndrome, and it is possible that a more targeted and/or multi-component intervention would have greater effects on frailty than a single modality. The choice of our stretching control group for GET FIT was selected because a seated flexibility program was expected to have little effect on falls and reduce unequal attention and/or attrition with a usual care control. As seen in the probability analysis, even low-intensity activity such as seated stretching may have some benefit in women who are more frail; thus, we may have underestimated the benefit of strength training and tai ji quan compared to no exercise. Our sample was limited to women under 75 years of age since we set the original inclusion criteria for GET FIT to minimize the influence of other comorbidities and advanced age on fall. Therefore, we cannot be certain our findings generalize to much older women, who may have the highest prevalence of frailty. Nonetheless, three-quarters of our sample between the ages of 50–75 years met criteria for pre-frailty and frailty which corroborates our prior findings of early onset frailty in women breast cancer survivors, and reinforces the concept of accelerated aging in this population. Clinicians should be aware that even their non-elderly patients may be at risk for frailty or have frailty and could benefit from regular structured exercise programs. Finally, we did not include a measure of unintended weight loss or sarcopenia in our frailty measure. Still, given the high levels of overweight and obesity in our sample, we suspect this criterion had little influence on our findings.
This analysis furthers our understanding of whether and how two well-established exercise modalities could reduce frailty related to chemotherapy. By 2040, the proportion of cancer survivors over 65 years old will rise to 73%, with most surviving 5 years or longer.[1] Within just 5 years the number of older survivors in the U.S. alone will reach 14 million. Thus, there remains an urgent need to develop low-cost, accessible, efficacious, and appropriate interventions to reduce frailty and its adverse consequences in older cancer survivors.[33] Our analysis suggests that two types of exercise that target neuromuscular functioning in different ways can address the problem of frailty, and in turn offer different exercise options for older cancer survivors. By reducing frailty, exercise may interrupt the downward trajectory toward disability and dependence and, in turn, potentially delay or avoid hospitalization and premature death. Future studies designed to reduce frailty in people with cancer can build on these promising findings to refine the optimal modalities or combinations thereof, and the dose, timing and at-risk populations in order to reduce frailty associated with the combined effects of aging and cancer.