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diagnosis/treatments, during treatments, posttreatments) and then the researchers compute change scores among the different time periods.1-4 In another approach, cancer survivors are directly asked if their exercise behavior has changed since their diagnosis/treatments.5 In a third approach, cancer survivors are asked to report their exercise behavior at one point in time and their responses are then compared to matched controls without cancer or some other group of interest.6

In two of the earliest studies to quantify the exercise patterns of cancer survivors, Courneya and Friedenreich1,2 surveyed 167 breast cancer survivors and 130 colorectal cancer survivors and asked them to retrospectively report their frequency of light, moderate, and vigorous intensity exercise before their diagnosis, during the time of their adjuvant treatments, and since the completion of their treatments. In both studies, participants reported significantly less moderate and vigorous exercise during their active treatments compared to their prediagnosis time period. Moreover, although participants in both studies reported more moderate and vigorous exercise in the posttreatment time period compared to the active treatment time period, it was still lower than that reported for the prediagnosis time period (Figures

1 and 2). The authors concluded that cancer treatments have a profound negative effect on the exercise behavior of cancer survivors that is not recovered even years after treatments are completed.

In perhaps the largest study to date, Irwin and colleagues3 surveyed over 800 breast cancer survivors 4—12 months postdiagnosis about their physical activity levels in the year before their diagnosis and in the past month since their diagnosis. These researchers found that overall physical activity levels decreased by 2 hours or about 11% after diagnosis. In one of the early prospective studies on exercise patterns, Courneya and colleagues7 followed 66 postsurgical colorectal cancer survivors from

2 to 6 months after their surgery. Results showed that study participants reported a significantly lower frequency of vigorous exercise compared to what they reported for the prediagnosis time period. No changes were reported in light or moderate exercise.

Prediagnosis Active treatment Posttreatment

Figure 1. Changes in Exercise Frequency by Intensity Level Across the Breast Cancer Experience (N = 167). (Data are from Courneya and Friedenreich.2)

Prediagnosis Active treatment Posttreatment

Figure 1. Changes in Exercise Frequency by Intensity Level Across the Breast Cancer Experience (N = 167). (Data are from Courneya and Friedenreich.2)

Prediagnosis Active treatment Posttreatment

Figure 2. Changes in Exercise Frequency by Intensity Level Across the Colorectal Cancer Experience (N = 130). (Data are from Courneya and Friedenreich.1)

Prediagnosis Active treatment Posttreatment

Figure 2. Changes in Exercise Frequency by Intensity Level Across the Colorectal Cancer Experience (N = 130). (Data are from Courneya and Friedenreich.1)

Blanchard et al.h conducted an interview of 352 mixed cancer survivors (44% breast) attending one of four different outpatient clinics in the United States. Participants were asked during the interview if their exercise levels had changed since their diagnosis. Overall, 53% of participants said that their exercise levels had not changed since their diagnosis, 31% reported a decline in exercise levels, and 16% reported an increase (Figure 3). Moreover, of those not currently exercising regularly, 39% reported that their exercise levels had decreased since their diagnosis compared to just 6% reporting an increase. These data suggest that up to twice as many cancer survivors report a decrease, as opposed to an increase, in exercise levels after their diagnosis.

In terms of estimating the prevalence rates of exercise in cancer survivors, most recent research has adopted the public health guidelines recommended by the

I Exercise more Exercise less Exercise same

Figure 3. Changes in Exercise Behavior Since Diagnosis by Current Exercise Status in Mixed Cancer Survivors (N = 352). (Data are from Blanchard et al.5)

Overall >3 times/week <3 times/week

Figure 3. Changes in Exercise Behavior Since Diagnosis by Current Exercise Status in Mixed Cancer Survivors (N = 352). (Data are from Blanchard et al.5)

United States Centers for Disease Control and Prevention and the American College of Sports Medicine.8 These guidelines recommend that adults perform either 20-30 continuous minutes of vigorous exercise 3 days per week (e.g., jogging) or accumulate 30 or more minutes of moderate exercise 5 days per week (e.g., brisk walking). Although these guidelines are likely appropriate for cancer survivors who have completed their primary treatments and are considered disease-free, it is unclear if they are appropriate for cancer survivors currently receiving intensive treatments or having existing disease. Presently, there is no consensus on exercise guidelines for cancer survivors during various treatments.9,10 In the absence of such guidelines, it seems reasonable to use the public health guidelines when estimating prevalence rates both during and after treatments.

In perhaps the most comprehensive prevalence study to date, Coups and Ostroff11 reported data from the National Health Interview Survey conducted in 2000 with over 32,000 adults including over 1600 cancer survivors. The authors reported no differences in exercise participation rates between cancer survivors and non-cancer controls in the younger (18-39 years) and older (65+ years) cohorts but did report a significant difference in the middle-aged (i.e., 40-64 years) cohort (Figure 4). More specifically, approximately 31% of middle-aged non-cancer controls were physically active compared to just 25% of middle-aged cancer survivors. The low rate of exercise participation was consistent across cancer survivor subgroups and ranged between 20 and 30% (Figure 5).

Similar results have been reported by our group across a range of cancer survivors (e.g., non-Hodgkin's lymphoma, multiple myeloma, endometrial) using population-based provincial cancer registry data from Alberta, Canada.12-14 In addition to asking about current exercise rates in these studies, Courneya and colleagues also asked survivors to retrospectively recall their exercise behavior during treatments. The results of these studies have shown that approximately 20-30% of cancer survivors report meeting public health exercise guidelines posttreatment but only 5-10% report meeting the guidelines during treatment (Figure 6).

I Cancer survivors Noncancer

18-39

40-64

Figure 4. Percentage of Cancer Survivors (N = 1646) and Non-Cancer Controls (N = 30, 700) Meeting Public Health Exercise Guidelines by Age Cohort. (Data are from Coups and Ostroff.11)

18-39

40-64

Figure 4. Percentage of Cancer Survivors (N = 1646) and Non-Cancer Controls (N = 30, 700) Meeting Public Health Exercise Guidelines by Age Cohort. (Data are from Coups and Ostroff.11)

Figure 5. Percentage of Various Cancer Survivor Groups (N = 1250) Meeting Public Health Exercise Guidelines. (Data are from Coups and Ostroff.11)

In one of the few studies using the Transtheoretical Model's15 stages of change construct to describe exercise patterns and prevalence rates in cancer survivors, Rhodes, Courneya, and Bobick16 surveyed 175 breast cancer survivors and asked them to report their current stage of change as well as to recall their stage of change during treatment. In recalling the active treatment period, 24% of breast cancer survivors reported being in the precontemplation stage (i.e., they did not exercise and did not even think about exercising), 10% in the contemplation stage (i.e., they did not exercise but they did think about exercising), 47% in the preparation stage

Figure 6. Percentage of Various Cancer Survivor Groups (N = 1310) Meeting Public Health Exercise Guidelines. (Data are from Vallance et al.14; Jones et al13; Courneya etal.12; Peddle, C.J. (2005). Exercise motivation in colorectal cancer survivors: An application of self-determination theory. Unpublished Master's Thesis, Faculty of Physical Education, University of Alberta, Edmonton, AB, Canada.)

Figure 6. Percentage of Various Cancer Survivor Groups (N = 1310) Meeting Public Health Exercise Guidelines. (Data are from Vallance et al.14; Jones et al13; Courneya etal.12; Peddle, C.J. (2005). Exercise motivation in colorectal cancer survivors: An application of self-determination theory. Unpublished Master's Thesis, Faculty of Physical Education, University of Alberta, Edmonton, AB, Canada.)

(i.e., they exercised some but not regularly), and only 19% in the action or maintenance stages (i.e., they exercised regularly). In terms of their current exercise stage of change, 5% reported being in precontemplation, 12% in contemplation, 41% in preparation, and 42% in action or maintenance. These data indicate that about a quarter of all breast cancer survivors report not even thinking about exercising during their treatments.

Other studies have also examined cancer survivors' readiness to change their exercise behavior after a diagnosis. For example, Jones and Courneya17 reported that 84% of cancer survivors preferred to receive exercise counseling at some point during their cancer experience. Similarly, Vallance et al.14 reported that 77% of non-Hodgkin's lymphoma (NHL) survivors were receptive to receiving exercise counseling at some point after their NHL diagnosis. In a larger sample of breast and prostate cancer survivors, Demark-Wahnefried et al.18 reported that 80% were interested in receiving health promotion programs during their cancer experience. Furthermore, 51% indicated a specific interest in receiving exercise programs.

Overall, the data on exercise patterns and prevalence rates suggest that cancer survivors experience a significant decrease in their exercise levels during active treatments. There is some natural recovery of exercise levels after treatments but they do not usually return to prediagnosis levels. Moreover, the actual exercise prevalence rates for posttreatment cancer survivors seems to range from 20 to 30% across a wide range of cancer survivor groups. These prevalence rates appear to be below that reported for matched controls and the general population. The actual prevalence rates of exercise for cancer survivors receiving treatments appear to be much lower, ranging from 5 to 10% across a wide range of cancer survivor groups. These prevalence rates are definitely below that reported for the general population.

Despite the consistencies in these data, there are important limitations in the research on exercise patterns and prevalence rates in cancer survivors. Perhaps the most important limitation is that all studies to date have relied on self-report data. It is well-known that self-report overestimates the exercise levels in most populations, consequently, it is likely that the prevalence rates presented here are higher than the actual rates. Second, many of the studies are transparent in nature, likely resulting in selection biases, which may also lead to overestimates of the exercise rates in the various cancer survivor populations. Third, many of the studies are retrospective which can create problems of memory and recall bias. Fourth, few studies are of a nationally representative sample and few have made comparisons to appropriately matched controls. Finally, it is not clear what the exercise guidelines are for cancer survivors, especially during treatments, and these guidelines may vary by cancer survivor group, symptoms, and prognosis.

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