C.W. DAUM, S.K. COCHRANE, J.D. FITZGERALD, L. JOHNSON, T.W. BUFORD
Department of Agin and Geriatric Research, University of Florida College of Medicine, Gainesville, FL, USA
Corresponding author: Thomas W. Buford, Department of Aging and Geriatric Research, University of Florida, Gainesville, FL 32611, Telephone: 352-273-5918, Fax: 352-273-5920, Email: email@example.com
The purpose of this review was to evaluate randomized controlled trials aiming to preserve the functional status, i.e. physical capabilities, of middle-aged and older cancer survivors through a structured, physical exercise intervention. The study team performed a thorough search of the literature using six online databases. This literature search limited included studies to randomized controlled trials which implemented a structured physical activity intervention for middle- and older-aged adults diagnosed with cancer. Studies were also required include at least one objective measure of physical function as a dependent outcome. This literature search yielded thirty-eight studies. The majority of the literature reviewed was successful in improving several functional outcomes including time needed to rise from a chair or distance covered during the six-minute walk test. A large number of published trials also suggest that exercise is effective in decreasing fatigue. However, a lack of trials investigating outcomes in older populations (≥ 65 years) was noted in this review. The results of this review suggest that a structured exercise program may be physically beneficial for middle-aged to older cancer survivors. Particularly, such interventions could preserve the functional status of cancer patients and, consequently, improve their long-term health outcomes. Future implications include further investigation into strictly older cancer patient populations, as outcomes related to exercise might differ between older and middle-aged adults.
Key words: Exercise, exercise therapy, cancer treatment, physical function, cancer survivor.
Functional status, determined by measures of physical performance, is an important predictor of health outcomes in older adults. The capacity to perform basic physical functions is a central aspect of health-related quality of life (1) and a key predictor of hospitalization, surgical outcomes, and mortality (2, 3). Accordingly, maintenance of independent functioning is a critical factor in preserving the health and well-being of older adults. In the U.S., nearly half of the 37.3 million persons aged ≥ 65 years report having one or more physical limitations in performing essential daily tasks (4). The adverse outcomes associated with these limitations have created a significant burden on healthcare systems, which is likely to become more substantial given that older adults represent the fastest growing segment of the population (5). As a result, the development of methods to maintain the health and independence of older persons is an important public health goal.
Numerous co-morbid conditions contribute to the progression of functional decline among older adults; cancer being among the most prevalent and most debilitating. Over 60% of the 14.5 million cancer survivors in the U.S. are over 65 years of age, and the number of older cancer survivors is expected to increase by nearly 30% in the next decade. The monumental healthcare costs ($37-48 billion) associated with treatment of older cancer survivors are expected to increase similarly. Notably, the financial and human costs of cancer survivorship continue long past diagnoses and initial treatment (6, 7). Yet evidence-based treatments which address the complex long-term medical needs of older cancer survivors are lacking (6, 7). Consequently, the development of efficacious interventions to enhance the long-term health and wellness of older cancer survivors is an important research goal with public health implications.
To date, physical exercise is currently the only intervention consistently demonstrated to attenuate functional decline among older adults. However, many cancer survivors face unique challenges (e.g. depression, fatigue, cognitive decline) which may limit the extent of functional improvement in response to physical exercise. These challenges may be particularly acute among patients who have undergone treatment with radiation and/or chemotherapy. The objective of this manuscript was to therefore review the available literature related to studies of exercise for preservation of functional status in late life. Notably, prior reviews have evaluated the efficacy of exercise for improving quality of life outcomes and the physical function of all-age cancer patients (8, 9). However, to our knowledge, this would be the first review of the literature related to the use of physical exercise in the preservation of functional status among older cancer survivors.
A thorough literature search was conducted using literature available through the University of Florida Online Library, PubMed, MEDLINE, NIH Reporter, the Cochrane Library, and Web of Science. We conducted these searches using the following search keywords: exercise therapy/exercise treatment/physical activity/exercise/cancer treatment/intervention/physical function AND cancer/androgen suppression therapy/chemotherapy/cancer survivor. The goal of this literature search was to collect publications that will improve the understanding of older cancer patients’ responses to physical exercise interventions. Specifically, the efficacy of such interventions in preserving the physical function of these individuals was the main focus of our search. The included literature was limited to randomized controlled trials which involved a structured physical activity intervention – e.g. aerobic training, strength training, etc. – and incorporated at least one objective measure of physical function (e.g. 6-Minute-Walk-Test, timed up and go, etc.). Initial searches focused on older adults (i.e. > 65 years of age), however our search was later broadened to include middle-aged adults (> 45 years) given the relative scarcity of trials for older cancer survivors. The scope of the search was then further narrowed to focus on prostate, breast, and mixed tumor types, as little relevant literature exists outside of these designations. Mixed tumor types were defined as controlled trials in which the study cohorts were composed of patients with varying cancer types. Furthermore, trials addressing exercise treatment in conjunction with palliative care were excluded as palliative care was outside the scope of this review.
A review of the literature provided 38 studies that met our requirements for inclusion (10-47). All studies were controlled trials that lasted between 21 days and 18 months in duration and were published between 1989 and 2015. These studies overwhelmingly included dependent outcomes related to functional fitness, physiologic predictors of function, and exercise behavior. Of those reviewed, 20 studies examined the effectiveness of exercise interventions during treatment for cancer (10, 12, 14, 17-21, 23-27, 30, 31, 43-47) and 18 studies include post-treatment participants or cancer survivors (11, 13, 15, 16, 22, 28, 29, 32-42). The studies were categorized based on type of cancer as well as completion of treatment, and the resultant categories include prostate cancer, breast cancer during treatment, breast cancer after treatment, and mixed tumors. These categories represent the four areas in which the majority of the literature is available.
In total, 3,398 individuals participated in the studies reviewed. A significant portion of these participants came from the RENEW trial (N=641), which makes up nearly 20% of the individuals in this review. The exercise modalities reviewed and deemed safe for aging cancer patients and survivors include aerobic exercise (10-14, 16-24, 26, 28-30, 33-45, 47), resistance exercise (11-14, 17, 19, 21, 22, 24-27, 29, 32-35, 37-42, 45), qigong classes (which include elements of Tai Chi) (15), Nia exercise (a combination of martial arts, yoga, and dance) (31), Greek traditional dance classes (32), and soccer training (46). Aerobic and resistance interventions were either home-based or center-based and were performed at varying levels of intensities across studies. Two studies included separate aerobic and resistance interventions (17, 26). Reference group activities included standard care (10-14, 16-18, 20, 23, 26, 28-33, 35-37, 40, 43-47) stretching classes (15, 21), wait-list controls (19, 25), relaxation (27), physiotherapy (24), psychotherapy (34), delayed exercise (22), or home-based exercise (39). We assessed outcome variables for each study, but we did not evaluate subjective measures such as quality of life and pain given prior reviews on these topics (8, 9).
A total of 738 prostate cancer patients, 598 actively undergoing treatment, participated in nine trials ranging from N= 21 to N = 155 (14, 15, 19, 23, 25, 26, 39, 45, 46).The mean age of participants in these studies was 69.2 years old, with all studies having a mean age > 65 years old. Individuals undergoing treatment had been prescribed androgen suppression/deprivation therapy (14, 19, 25, 45, 46), or radiation therapy (23, 26). Two studies were composed of prostate cancer survivors not actively undergoing treatment, and these individuals were classified as older, fatigued, and sedentary (15, 39). Trial durations ranged from eight weeks to twelve months. All prostate studies are represented in Table 1.
Table 1 Prostate Cancer
*Functional fitness assessed as the maximum number of repetitions of a standardized chair sit-to-stand test; †Muscle strength was measured by an eight repetition maximum of horizontal bench press and leg extension; ‡Denotes resistance intervention outcome §Denotes aerobic intervention outcome; Population values are Mean ± Standard Deviation (SD) or Mean ± SD Exercise Group; SD Control Group in cases which cohort SD was not reported; Median and/or range were included in population values if mean and/or SD were not reported; + indicates a statistically significant increase in the variable in response to the exercise intervention; – indicates a statistically significant decrease in the variable in response to the exercise intervention; 0 indicates no statistically significant relationship found; VO2 max: Peak Oxygen Consumption; BMI: Body Mass Index
Three trials employed combined aerobic and resistance exercise interventions (14, 19, 39). Two of these trials measured aerobic capacity through a 400 meter walk test or a six-minute walk test (19). Intervention groups significantly improved in 400 meter walk test times and in walking distance compared to a home-based exercise control. These trials also reported that the combined intervention did not change fatigue for the exercise group compared to a control. One trial measured lower body performance via a timed chair rise time test, and a twice-weekly supervised aerobic and resistance home-based exercise program significantly decreased chair rise with a mediation effect of 1.7 (0.6 to 4.5) compared to a standard care control (39). A separate study assessed functional fitness as the maximum number of chair sit-to-stand repetitions, and the 12-week aerobic and resistance exercise lifestyle program increased in the exercise group by 3.66 repetitions compared to the standard care control. This intervention also significantly decreased participant fatigue – as measured by Functional Assessment of Cancer Therapy-Fatigue scores – by 3.1 points compared to the control (14).
Two trials implemented strictly aerobic interventions (23, 26). These assessed aerobic capacity by submaximal aerobic capacity measures (23) or peak oxygen consumption (VO2 max) (26). The 24-week aerobic intervention increased exercise group VO2 max by 1.4 ml/kg/min, and the 8-week aerobic intervention increased exercise group submaximal aerobic capacity by 2.8 metabolic equivalents. Both were compared to standard care controls. The 8-week aerobic intervention also measured lower body strength with a timed, five-repetition chair sit-and-stand test. Participants in the tri-weekly aerobic exercise intervention had between-group comparison pre- to post-radiotherapy score decreases of 1.7 ± 0.9 in the time taken to complete the five repetitions compared to the standard care control (23). An additional two trials employed resistance exercise interventions (25, 26). Both trials measured upper- and lower-body strength using eight-repetition maximum tests for bench press and leg press. For lower body muscular fitness, leg press repetitions increased by 11.8 in the intervention group and decreased by 1.6 in the control group (25). Lower- and upper-body strength were superior with resistance training (P<.001 for both) when compared to a control and aerobic training (26). Additionally, both trials decreased fatigue levels compared to controls.
A soccer training intervention for patients undergoing androgen deprivation therapy measured VO2 max, lean body mass, knee-extensor strength, and percent body fat (46). The trial improved lean body mass and improved muscle strength for knee extensors (1RM) in the intervention group (P < 0.001). Sit-to-stand repetitions increased significantly compared to a control with a mean change score of 1.4. However, the intervention was unable to significantly change VO2 max compared to the control. An intervention employing qigong classes (exercise that incorporates meditation and Chinese martial arts) for fatigued and sedentary survivors was able to increase fatigue assessment scores (higher score=less fatigued) – as measured by the Functional Assessment Chronic Illness Therapy-Fatigue Scale (scale 0-52) – for exercise participants by 5 points compared to a stretching class (15). A home-based diet and exercise intervention for prostate cancer patients measured fatigue and aerobic capacity by a six-minute walk test. The intervention increased exercise group six-minute walk test scores by 36.5 meters compared to a standard care control. No significant change was seen with fatigue (45).
Breast Cancer during Treatment
A total of ten exercise intervention studies exist which included individuals with breast cancer actively undergoing chemotherapy or radiation therapy (10, 17, 20, 21, 27, 30, 31, 43, 44, 47). The studies ranged in sample sizes from N=14 to N=242 individuals, and in total the ten studies were comprised of 740 participants. The mean age of individuals in these trials was 50.3 years old, with no studies focusing on older breast cancer survivors (> 65 years). These studies included a combined aerobic-resistance intervention (21), aerobic interventions (10, 17, 20, 30, 43, 44, 47), resistance training (17, 27), and a Nia exercise program (31). All breast cancer during treatment studies are represented in Table 2.
Table 2 Breast Cancer During Treatment
*Denotes resistance intervention outcome; † Denotes aerobic intervention outcome; ‡Muscle strength was measured by an eight repetition maximum of horizontal bench press and leg extension; §Short-Form 36 Health Status Survey Measuring Physical Function; | |Muscle strength was measured for isometric and isokinetic muscle capacity of upper and lower extremity muscle groups; Population values are Mean ± Standard Deviation (SD) or Mean ± SD Exercise Group; SD Control Group in cases which cohort SD was not reported; Median and/or range were included in population values if mean and/or SD were not reported; + indicates a statistically significant increase in the variable in response to the exercise intervention; – indicates a statistically significant decrease in the variable in response to the exercise intervention ; 0 indicates no statistically significant relationship found VO2 max: Peak Oxygen Consumption
One study assigned participants to either an aerobic or resistance intervention and assessed aerobic capacity, fatigue, and muscle strength. Aerobic capacity was measured by peak oxygen consumption, and the intervention increased VO2 max by approximately 8% for the aerobic exercise group compared to a usual care control. For the resistance exercise group, the resistance intervention was able to increase eight repetition maximums for leg and chest press by approximately 30% compared to the usual care control. Fatigue, as measured by the Functional Assessment of Cancer Therapy-Anemia scale, did not change significantly for either exercise group compared to the control (17). A separate trial employed a five-week, combined aerobic and resistance exercise for stage I-III breast cancer patients. Fatigue was assessed via the brief fatigue inventory questionnaire (scale 0-10), and the intervention was able to significantly decrease (p<0.05) scores for the exercise group compared to a stretching control (21).
A total of six studies employed a home-based or center-based aerobic exercise intervention (10, 20, 30, 43, 44, 47).Four of these measured aerobic capacity or physical function through peak oxygen consumption (VO2 max) (10, 20) or submaximal aerobic capacity measures (43, 44). Trials that assessed VO2 max had conflicting results. A 16-week, aerobic intervention was unable to significantly change peak oxygen consumption measurements for the exercise group compared to a control (10). However, a 12-week, aerobic intervention was able to increase VO2 max by 21.9% for the exercise group compared to a standard care control (20). A 26-week, home-based aerobic intervention was able to increase participants measures of submaximal aerobic capacity by 2.4% compared to a standard care control (44). An aerobic interventions also showed success in decreasing the exercise groups’ fatigue levels (30). One trail measured physical function through the Short-Form 36 Health Status Survey, and the 26-week, home-based aerobic intervention was able to increase scores for the exercise group by 9.8 points compared to a standard care control (44).
One study examined the effects of a twelve-week, progressive resistance training intervention (27). Muscle strength was measured through muscle capacity of upper and lower extremities, and the intervention was able to increase isokinetic and isometric muscle strength (p<0.0001) compared to a relaxation control. Aerobic capacity was assessed by peak oxygen consumption, but no significant change was found for the exercise group compared to the control. Numerical group differences and changes were not reported for muscle strength and aerobic capacity. This trial also measured fatigue through the Fatigue Assessment Questionnaire (scale 0-10), and the intervention was able to decrease the exercise group’s scores by 0.5 points compared to the relaxation control.
A Nia exercise program was employed in a group of breast cancer patients undergoing radiation therapy (31). Nia exercise combines forms of yoga, dancing, and martial arts as a comprehensive exercise approach. This trial measured cardiovascular fitness through a six-minute walk test, but the intervention did not significantly change distance walked between the exercise and control group. The trial also assessed fatigue through the Functional Assessment Chronic Illness Therapy-Fatigue Scale (scale 0-160). The Nia exercise intervention increased fatigue scores (higher score=less fatigue) for the intervention group by 7.1% compared to the standard care control.
Breast Cancer after Treatment
Studies in the breast cancer after treatment group included individuals who were assigned to an exercise intervention after completion of treatment for breast cancer. Nine studies (11, 16, 22, 28, 29, 32, 33, 35, 36) totaling 384 participants ranged in length from 6 weeks to 18 months and sample sizes N=14 to N=104. The mean age of these breast cancer patients was 55.6 years old, with no studies focusing on older survivors. Exercise interventions included aerobic exercise, (16, 28) combined aerobic and resistance exercise, (11, 22, 29, 33, 35) a home-based moderate physical activity program, (36) and a combined Greek traditional dance and resistance program (32). Control groups included standard care (11, 16, 28, 29, 32, 33, 35, 36) and a delayed exercise group that completed the exercise intervention after a 12-week waiting period (22). All breast cancer after treatment studies are represented in Table 3.
Table 3 Breast Cancer after Treatment
* Short-Form 36 Health Status Survey Measuring Physical Function; †Muscle Strength measured by recording weight used for bicep curls, leg presses, and chest extensions; Population values are Mean ± Standard Deviation (SD) or Mean ± SD Exercise Group; SD Control Group in cases which cohort SD was not reported; Median and/or range were included in population values if mean and/or SD were not reported; + Indicates a statistically significant increase in the variable in response to the exercise intervention; – Indicates a statistically significant decrease in the variable in response to the exercise intervention; 0 Indicates no statistically significant relationship found; VO2 max: Peak Oxygen Consumption; BMI: Body Mass Index
Studies that employed a combined aerobic and resistance intervention assessed aerobic capacity through a six-minute walk test, (11, 35) VO2 max, (29) and submaximal aerobic capacity measures (22). All four of these combined interventions reported increases in participant’s measurement of aerobic capacity at the commencement of the trials compared to standard care controls. Muscle strength was assessed by either leg extension strength (35) or by recording weight used for bicep curls, leg presses, and chest extensions(22). Measurements of leg extension strength increased by an average of 25.4 newtons in the combined exercise group compared to a standard care control. The recorded weight used for bicep curls, leg presses, and chest extensions increased by an average of 71% for the combined intervention group compared to a standard care control. One study assessed physical function through the Short-Form 36 Health Status Survey, but did not show a significant change in participant’s scores by the end of the intervention compared to a standard care control (33).
Two total studies used strictly aerobic exercise interventions (16, 28). Both assessed aerobic capacity through VO2 max. A fifteen-week aerobic intervention reported a 14.4% increase in peak oxygen consumption for the exercise group compared to a standard care control (28). However, a 12-week, moderate-intensity aerobic intervention reported no significant change in peak oxygen for the exercise group compared to a standard care control (16). A six-week home-based, moderate physical activity intervention reported an increase in six-minute walk test measurements with the exercise group walking an average of 97 feet farther in six minutes compared to a standard care control (36).
An intervention that combined resistance exercise with a Greek traditional dance course measured physical function through a six-minute walk test score, while also assessing handgrip strength (32). Six-minute walk test scores increased by an average of 55.21 meters in the exercise group compared to a standard care control. Handgrip strength was assessed using a baseline handheld dynamometer, and the exercise group averaged a 21% increase in strength compared to the control at the end of the trial.
Ten studies enrolled a total of 1,536 participants with mixed tumor types and ranged from 21 days to 12 weeks in duration.(12, 13, 18, 24, 34, 37, 38, 40-42) The mean age of these participants was 59.8 years old, with four studies having a mean age > 65 years. Sample sizes ranged from N=18 to N=641. The exercise interventions implemented in these studies included aerobic exercise, (18, 40) combined resistance and aerobic exercise, (12, 13, 24, 37) and home-based exercise.(34, 38, 41, 42) Controls were standard care, (12, 13, 18, 37, 40) standard physiotherapy, (24) or psychotherapy (34). All mixed tumor studies are represented in Table 4.
Table 4 Mixed Tumors
*Measured by one repetition maximum of leg press, chest press, and pull down; †Short-Form 36 Health Status Survey Measuring Physical Function/Functional Decline; ‡Type of testing not reported; §Measured via the basic and advanced lower extremity function subscales of the Late Life Function and Disability Index.; | |Functional Assessment of Cancer Therapy-Anemia measuring patient-reported physical function ; Population values are Mean ± Standard Deviation (SD) or Mean ± SD Exercise Group; SD Control Group in cases which cohort SD was not reported; Median and/or range were included in population values if mean and/or SD were not reported; + Indicates a statistically significant increase in the variable in response to the exercise intervention ; – Indicates a statistically significant decrease in the variable in response to the exercise intervention ; 0 Indicates no statistically significant relationship found ; VO2 max: Peak Oxygen Consumption; BMI: Body Mass Index
Two trials implemented aerobic exercise interventions (18, 40). A ten-week, light to moderate aerobic intervention assessed aerobic capacity though submaximal oxygen consumption measures. The intervention increased submaximal aerobic capacity in the intervention by 15.9% compared to a standard care control (40). Additionally, a twelve-week, aerobic exercise intervention increased VO2 max by 43% in the exercise group compared to a usual care control. This trial also assessed physical function and fatigue through FACT-Anemia scores subscales of function and fatigue. The aerobic intervention increased mean intervention group physical function scores by 7.2 points (scale of 0-188) and increased mean fatigue scores by 4 points (scale 0-52; higher score=less fatigue) compared to the standard care control (18).
A total of four studies employed a combined aerobic and resistance exercise program (12, 13, 24, 37). All of these trials measured muscle strength through upper/lower body strength, (12) quad muscle strength, (13) and abdominal muscle strength (24). Exact measurements of muscle strength for the Starting Again trial-a breast, ovarian, testicular, and prostate cancer group rehabilitation program-were not reported (37). A six-week, high intensity resistance and aerobic intervention reported an average 29.6% weight improvement for one-repetition maximums for the exercise group compared to a standard care control (12). A four-week, combined intervention assessed quad muscle strength, but reported no significant change in strength for the intervention compared to a standard care control (13).
Two combined aerobic and resistance interventions assessed aerobic capacity through measures of VO2 max. A three-week, combined intervention reported a 24.4% increase for the intervention group compared to a standard physiotherapy control (24). A six-week, high intensity resistance and aerobic intervention reported an average 10.7% increase in VO2 max for the intervention group compared to a standard care control. This trial also assessed physical function through Short-Form 36 Health Status Surveys (SF-36), and fatigue through the European Organization for Treatment and Research of Cancer Quality of Life Questionnaire. The study reported an average 2.2 SF-36 score increase and an average 6.6 QLQ-C30 score decrease for the intervention compared to the control (12).
Three studies examining the RENEW trial, a large home-based exercise intervention for older, overweight cancer survivors, attempted to assess physical function, functional decline, and lower extremity function (38, 41, 42). All trials measured physical function or rates of functional decline through SF-36 score measures. One intervention assessing the rate of functional decline decreased SF-36 scores by 2.3% for the exercise group. However, SF-36 scores decreased by 7.8% for the control group that did not receive the exercise intervention (41). A separate trial also found similar results, as the intervention decreased SF-36 scores by 2.15 points for the exercise group, but individuals of the control group experienced a decline of 4.84 points at the end of the trial. Lower extremity function scores were assessed via the basic and advanced lower extremity function subscales of the Late Life Function and Disability Index. The intervention increased scores slightly (0.34 points), while control group participants showed a decreased of 1.89 points (42). Lastly, a trial distinguished physical function and lower extremity function between high-to-light physical activity (HLPA), moderate-to-vigorous physical activity (MVPA), and low-to-light physical activity (LLPA) groups. Survivors who increased HLPA and decreased or stabilized MVPA, scored 3.04 points higher on SF-36 scales and 2.28 points higher on basic lower extremity function scales compared to survivors who decreased MVPA or maintained stable MVPA and HLPA (38).
The objective of the present review was to evaluate the extant literature related to the use of physical exercise for improving functional status among middle-aged and older cancer survivors. To our knowledge, this is the first review specifically focused on the use of exercise to maintain physical function among middle-aged and older cancer survivors. The results of this review suggest that these patients may physically benefit from exercise during and after cancer treatment as the majority of published trials demonstrated reasonable efficacy of exercise in improving functional status among these populations. Notably, there are several ongoing trials that should be monitored closely so their results can be compared to the findings of this review (48-50).
Among the various cancer groups highlighted in this review, prostate and mixed tumor groups had by far the highest number of studies focusing on older cancer patients. The majority of these various interventions showed success in lowering rates of functional decline and improving objective measures of physical function for these aging populations. These results are consistent with other trials that have implemented exercise as a form treatment for geriatric patients suffering from other diseases known to accelerate functional decline. For instance, studies examining the effects of physical activity on older individuals suffering from cardiovascular disease have shown that exercise is capable of attenuating age-related decline caused by hypertension or heart failure (51). Similar results have been shown in elderly populations diagnosed with osteoporosis, as exercise has proved successful in increasing bone density and improving other physical outcomes for these patients (52). Overall, it is encouraging that the results of interventions for those suffering from cancer, a separate disease widely known to negatively impact physical function, are comparable with other trials showing improvement for aging populations.
With the benefits of exercise interventions as a form of cancer treatment for middle-aged to older adults becoming more tangible, it is imperative that future trials study populations strictly made up of older adults. As stated previously, this review saw a significant gap in the literature for exercise in only older patient populations (≥ 65 years old). It is paramount that more of these studies examine this population because of the dramatic clinical costs of functional decline and the rapidly growing population of older adults. It may also be important to evaluate the efficacy of creative interventions designed to facilitate adherence among these populations. Examples of such interventions may include the use of dancing, yoga, or interactive video games. For instance, one ongoing study is examining the efficacy of video game exercise interventions on a group of older breast cancer survivors (53). It is possible that cancer patients might perceive these nontraditional exercise interventions as less strenuous, potentially leading to higher motivation and commitment to the regimens. These types of interventions, specifically dancing, may also attenuate cognitive decline- an independent predictor of functional decline among older adults and common side effect of chemotherapy (54-56). Prior studies of the general geriatric population have demonstrated cognitive-motor benefits from both dancing and traditional exercise performed with music (57, 58).
Like any study, there were some limitations to this review. First, not every study in this review used blinding methods (blinding of outcome assessor, blinding of care provider, etc.), and several studies (10, 19, 20, 23, 28, 32, 33, 35, 40, 43, 47) had very small samples sizes. Additionally, the exercise modalities, durations, and disease stages were not all standardized across the reviewed trials, which may have led to variance among outcome measurements. However, all studies did utilize supervised intervention programs and employed parallel comparison control groups. Also, the availability of substantial literature regarding prostate and breast cancer was a positive given that these two forms of cancer are by far the most prevalent among older adults (59).
To conclude, the role of exercise interventions in attenuating functional decline in cancer patients offers some very positive implications. This review found that cancer-related fatigue could be lowered through resistance or aerobic exercise in multiple cancer types. This is likely a very important effect for the patient given that reduced fatigue can greatly influence the functional status of cancer patients (60). Additionally, the ability of interventions to increase the aerobic capacity and muscle strength of individuals can point towards improvements in their diagnoses. Amelioration of all these physical outcomes could lead to lower patient morbidity and mortality rates. However, those implementing exercise in a clinical setting should be wary of patient’s responses to varying intensities and modalities of the interventions. In summary, the results of this review suggest that the use of exercise as a form of cancer treatment may be vital for maintaining and improving the physical health of middle-aged and older cancer survivors.
Funding: No direct funding was used for this manuscript.
Acknowledgements: This work was partially supported by the University of Florida Claude D. Pepper Older Americans Independence Center, funded through the National Institutes of Health (P30AG028740).
Conflicting Interest: None.
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