A Population-Based Study of the Determinants of Physical Activity in Ovarian Cancer Survivors

Transcription

1 Journal of Physical Activity and Health, 2009, 6, Human Kinetics, Inc. A Population-Based Study of the Determinants of Physical Activity in Ovarian Cancer Survivors Clare Stevinson, Katia Tonkin, Valerie Capstick, Alexandra Schepansky, Aliya B. Ladha, Jeffrey K. Vallance, Wylam Faught, Helen Steed, and Kerry S. Courneya Background: Regular physical activity is associated with quality of life and other healthrelated outcomes in ovarian cancer survivors, but participation rates are low. This study investigated the determinants of physical activity in ovarian cancer survivors. Methods: A population-based, cross-sectional, mailed survey of ovarian cancer survivors in Alberta, Canada, was conducted. Measures included self-reported physical activity, medical and demographic factors, and social-cognitive variables from the theory of planned behavior (TPB). Results: A total of 359 women participated (51.4% response rate), of whom 112 (31.1%) were meeting physical activity guidelines. Variables associated with meeting guidelines were younger age, higher education and income, being employed, lower body-mass index, absence of arthritis, longer time since diagnosis, earlier disease stage, and being disease free. Analysis of the TPB variables indicated that 36% of the variance in physical activity guidelines was explained, with intention being the sole independent correlate ( =.56; P <.001). Conclusion: Various demographic and medical factors can help identify ovarian cancer survivors at risk for physical inactivity. Interventions should attempt to increase physical activity intentions in this population by focusing on instrumental and affective attitudes, as well as perceptions of control. Keywords: exercise, motivation, theory of planned behavior, neoplasm Stevinson, Ladha, Vallance, and Courneya are with the Faculty of Physical Education and Recreation; Tonkin, the Dept of Oncology; and Capstick, Schepansky, Faught, and Steed, the Dept of Obstetrics and Gynecology, University of Alberta, Edmonton, Canada. The American Cancer Society recommends a physically active lifestyle for cancer survivors to reduce risk of secondary cancers and other chronic diseases and to improve quality of life. 1 Physical activity has been associated with lower risk of disease recurrence and longer survival in breast 2 and colorectal 3,4 cancers. Furthermore, there is increasing evidence from meta-analyses 5,6 and more recent large randomized trials of breast cancer survivors 7 9 that engaging in programs of regular exercise leads to improvements in functional and quality-of-life outcomes after a cancer diagnosis. Despite this favorable evidence, studies of various cancer survivor populations consistently show that less than one third of survivors report meeting public health physical activity guidelines The corresponding figures for the general population are over 45% for both men and women. 18 Understanding the factors that influence physical activity behavior is important for enhancing health-promotion strategies. For cancer survivors, additional disease and treatment-related factors may influence ability and motivation for physical activity. Furthermore, since many of these factors differ between survivors of diverse cancer types, it is essential to collect data on individual cancer groups, rather than attempt to generalize the results from other cancer populations. In addition, there is evidence that beliefs, motives, and barriers regarding activity may vary across cancer survivor groups. 19 For ovarian cancer, there are no published data on the determinants of physical activity. An estimated 24,830 new cases of ovarian cancer were diagnosed in the United States and Canada in 2007, 20,21 and the improved survival rate has increased the importance of maintaining a healthy lifestyle in this population. Although the direct impact of physical activity on ovarian cancer survival is unknown, it may play a role via weight control, since obesity is negatively associated with survival. 22 Furthermore, we have previously reported a positive association between physical activity and quality of life in ovarian cancer survivors. 23 However, these data also indicated the prevalence of physical 339

2 340 Stevinson et al activity among ovarian cancer survivors to be low, with only 31.1% meeting the public health guidelines. 23 The identification of key factors that determine physical activity in ovarian cancer survivors can be used to inform the design of health-promotion strategies aimed at increasing physical activity in this understudied population. The purpose of the current study was to examine medical (eg, time since diagnosis, disease stage, disease status), demographic (eg, age, education, employment status), and social-cognitive determinants of physical activity among ovarian cancer survivors using the theory of planned behavior (TPB). The TPB is a social-cognitive theory of behavior 24 that has proven useful in understanding physical activity behavior in cancer survivors. 19 According to the TPB, intention is the immediate determinant of behavior. Intention, in turn, is determined by attitude (positive or negative evaluation of the behavior), subjective norm (perceived social pressure to perform the behavior), and perceived behavioral control (confidence and control over performing the behavior). The constructs of attitude, subjective norm, and perceived behavioral control are thought to represent higher- order structures that each comprise 2 lower-order components. 25 Attitude consists of affective (enjoyment of exercise) and instrumental (perceived benefits of exercise) components, subjective norm is composed of descriptive (perception that important others exercise) and injunctive (perception that important others approve of exercise) components, and perceived behavioral control consists of self-efficacy (confidence in ability to exercise) and perceived control (perceived control over exercise) components. The specific objectives of the current study were to (1) characterize the intentions of ovarian cancer survivors with respect to the current public health physical activity guidelines, (2) identify the demographic and medical variables that are associated with meeting the guidelines, (3) determine the most important socialcognitive correlates of physical activity behavior and intention, and (4) identify the most common behavioral, control, and normative beliefs held by ovarian cancer survivors with regard to physical activity. Methods A full description of the study procedures has been provided elsewhere. 23 Briefly, ethical approval was granted by the Alberta Cancer Board Research Ethics Board and the University of Alberta Research Health Ethics Board to perform a postal survey of ovarian cancer survivors identified through the Alberta Cancer Registry. Eligibility criteria were age 18 years or over, diagnosis of histologically confirmed ovarian cancer between 1985 and 2005, approval of the treating oncologist or general physician, and ability to understand English. Participants were asked to complete and return a consent form and questionnaire. Nonresponders were sent a reminder postcard after 2 weeks and a second questionnaire after 4 weeks. Data collection was performed between May and October Measurements Medical information (ie, date of diagnosis, histologic subtype, disease stage, grade, borderline vs invasive, and treatments received) was obtained from the cancer registry when available. Additional medical and demographic data (ie, age, marital status, employment status, education level, family income, height, weight, smoking and drinking behavior, medical comorbidities, current disease status, and current treatments) were obtained by self-report. Physical activity was assessed by the Leisure Score Index of the Leisure Time Exercise Questionnaire, 26 which requires participants to recall their average weekly frequency of mild-, moderate-, and strenuousintensity activity during the past month. Participants were also asked to indicate the average duration of activities. From these data, we calculated the percentage of participants meeting physical activity guidelines based on the American Cancer Society s 1 recommended physical activity levels for cancer survivors as follows: (1) completely sedentary (no moderate or strenuous physical activity), (2) insufficiently active (<150 minutes of moderate/strenuous activity and <60 minutes of strenuous activity), (3) within guidelines (150 to 300 minutes of moderate/strenuous or 60 to 120 minutes of strenuous activity), and (4) above guidelines ( 300 minutes of moderate/strenuous or 120 minutes of strenuous activity). We also calculated the standard dichotomized guideline by combining the completely sedentary and insufficiently active categories (not meeting guidelines) versus the within and above guidelines categories (meeting guidelines). Reliability and validity of the Leisure Score Index have been shown to compare favorably to other measures of physical activity and fitness. 27 TPB constructs were assessed based on the guidelines of Ajzen. 24,28 Physical activity intention was assessed by 2 items asking respondents to indicate the frequency (ie, days per week) and duration (ie, minutes per day) of vigorous and moderate-intensity physical activity they intended to perform over the next month. From these data, we calculated the percentage of participants intending to meet the physical activity guidelines based on the same cut points as for our behavioral variable. Attitude, subjective norm, and perceived behavioral control were all assessed using 7-point bipolar adjective scales. Six items assessed either the instrumental (useless-useful, harmful-beneficial, unimportant-important) or affective (unenjoyable-enjoyable, painful- pleasurable, boring-fun) component of attitude toward regular exercise. Internal consistencies ( ) for the instrumental and affective scales were.92 and.85, respectively. For subjective norm, 5 items measured either injunctive norm (disapproving-approving, discouragingencouraging, unsupportive-supportive) or descriptive norm (inactive-active, disagree-agree that important

3 Table 1 Percentage of Ovarian Cancer Survivors Meeting Physical Activity Guidelines Based on Demographic and Medical Variables (N = 359) Variable Meeting guidelines, n = 112 (31.2%) 2 P Age 14.6 <.001 <60 y (n = 177) 72 (40.7%) 60 y (n = 182) 40 (22.0%) Marital status married or commonlaw (n = 264) 85 (32.2%) single, divorced, or widowed (n = 95) 27 (28.4%) Education level 27.4 <.001 completed high school or less (n = 153) 25 (16.3%) at least some postsecondary (n = 206) 87 (42.3%) Annual family income 16.7 <.001 <$60,000 (n = 176) 39 (22.2%) $60,000 (n = 124) 55 (44.4%) missing data (n = 59) a 18 (30.5%) Employment status 12.3 <.001 working full or part time (n = 147) 61 (41.5%) retired or on disability leave (n = 212) 51 (24.1%) Body-mass index healthy weight (n = 139) 58 (41.7%) overweight/obese (n = 220) 54 (24.5%) Number of comorbidities (n = 180) 60 (33.3%) 2 (n = 179) 52 (29.1%) Arthritis yes (n = 152) 38 (25.0%) no (n = 207) 74 (35.7%) Smoking status smoker (n = 58) 13 (22.4%) nonsmoker (n = 301) 99 (32.9%) Time since diagnosis <60 months (n = 172) 43 (25.0%) 60 months (n = 187) 69 (36.9%) Disease status disease-free (n = 297) 102 (34.3%) current disease (n = 62) 10 (16.1%) Borderline vs invasive disease borderline (n = 41) 17 (33.3%) invasive (n = 308) 95 (30.8%) Table 1 (continued) Variable Meeting guidelines, n = 112 (31.2%) 2 P Disease stage stage I or II (n = 163) 62 (38.0%) stage III or IV (n = 138) 36 (26.1%) missing data (n = 58) a 14 (24.1%) Received chemotherapy yes (n = 253) 75 (29.6%) no (n = 106) 37 (34.9%) NB. Physical activity based on 2 categories of meeting or not meeting guidelines. a Missing-data category not analyzed. others will be active). Internal consistencies ( ) for the injunctive and descriptive scales were.93 and.84, respectively. Perceived behavioral control was assessed by 2 items (uncontrollable-controllable, unconfident-confident). Although these items can be used separately as measures of perceived control and self-efficacy, respectively, 29 recent data suggest that they should be combined into a single component measure of perceived behavioral control. 30 Internal consistency ( ) was.90. Underlying beliefs were assessed using open-ended questions. Participants were asked to list up to 3 advantages of exercise (behavioral beliefs), barriers to exercise (control beliefs), and people who would approve of exercise (normative beliefs). Data Analysis For the preliminary analyses of the univariate associations between the demographic/medical variables and physical activity, we used the standard dichotomized physical activity guideline to eliminate the skewness of the continuous data and to conserve power. The medical and demographic variables were also dichotomized to conserve power, and missing data were excluded from these analyses. The associations were analyzed using chi-square tests. For the univariate and multivariate associations of the TPB constructs with intention and physical activity behavior, we used the 4 categories of physical activity and intention to increase the variability of these measures and to eliminate the skewness of the continuous data. Univariate associations were analyzed using Pearson correlation coefficients. Hierarchical multiple-regression analyses were used to examine the multivariate associations between demographic, medical, and social-cognitive variables and the physical activity and intention categories. 341

4 342 Stevinson et al Results A total of 359 ovarian cancer survivors returned completed questionnaires, resulting in a 51.4% response rate. A detailed flow diagram of the study and full description of participant characteristics have been presented elsewhere. 23 Based on reported physical activity behavior, 112 (31.1%) survivors were meeting public health guidelines (63 within and 49 above guidelines). A summary of the sample characteristics is available in Table 1, which displays the proportion of participants meeting physical activity guidelines based on demographic and medical variables. Briefly, participants were more likely to be meeting guidelines if they were younger (P <.001), more highly educated (P <.001), wealthier (P <.001), employed (P <.001), free of arthritis (P =.030), and more than 5 years since diagnosis (P =.010); had a healthy body-mass index (BMI; P <.001), had early-stage disease (P =.037), and were currently disease free (P =.005). Categorizing participants according to their physical activity intentions resulted in 80 (22.3%) intending to be completely sedentary, 89 (24.8%) insufficiently active, 123 (34.2%) within guidelines, and 67 (18.7%) above guidelines. Collapsing categories resulted in 190 (52.9%) reporting intentions to meet the physical activity guidelines and 169 (47.1%) not intending to meet them. Table 2 displays the descriptive statistics and bivariate correlations for the TPB constructs and physical activity behavior. The strongest association was between physical activity intention and behavior (r =.60; P <.001). Physical activity intention had the strongest correlations with affective (r =.51; P <.001) and instrumental (r =.54; P <.001) attitudes and perceived behavioral control (r =.51; P <.001). Table 3 presents the results of the hierarchical multiple-regression analysis, indicating that 36% of the variance in physical activity behavior was explained with intention being the sole independent correlate ( = 0.56; P <.001). The medical and demographic variables significant in univariate analyses (Table 1) were added to the model, with the exception of income and disease stage, which were excluded from these multivariate analyses due to substantial missing data (16.4% and 16.2% respectively, a total of 107 participants). This explained an additional significant 6% of the variance in physical activity behavior, with being disease-free ( = 0.09; P =.03), having a healthy BMI ( = 0.12; P =.005), and being better educated ( = 0.14; P =.001) achieving independent associations with behavior, although intention remained the most important correlate ( = 0.51; P <.001). For physical activity intentions, 39% of the variance was explained Table 4), with instrumental ( = 0.21; P =.001) and affective ( = 0.29, P <.001) attitude and perceived control ( = 0.28, P <.001) providing independent associations. Table 5 displays the salient beliefs held by ovarian cancer survivors about physical activity. Beliefs cited by at least 10 participants are reported. Improving health and controlling body weight were the most salient advantages of physical activity reported by ovarian cancer survivors. Lack of time and motivation were the most salient barriers. Finally, family and friends were the most salient people who would approve of physical activity. Discussion The purpose of this study was to identify the demographic, medical, and social-cognitive determinants of physical activity behavior and intentions among ovarian cancer survivors. The intention data indicated that 53.9% of the sample intended to meet physical activity guidelines in the next month. This contrasts with the 31.1% who were currently meeting guidelines. A previous study of non- Hodgkin lymphoma survivors had similar findings, with 51% intending to meet guidelines but only 24% reporting that they did so in the past month. 31 These data are compatible with other evidence that about half of cancer survivors have good intentions regarding healthy lifestyle changes (eg, diet, smoking, physical activity) 32 but that there are various impediments (eg, medical, demographic, environmental) that may prevent these intentions from being realized. Interventions are therefore needed to strengthen intentions in ovarian cancer survi- Table 2 Descriptive Statistics and Correlations for the Theory-of-Planned-Behavior Variables in Ovarian Cancer Survivors (N = 359) Variable Mean SD 1. Physical activity guidelines.60***.33***.36***.15***.06.35*** Intention.51***.54***.32***.21***.51*** Instrumental attitude.65***.61***.19***.53*** Affective attitude.48***.29***.49*** Injunctive norm.40***.43*** Descriptive norm.32*** Perceived behavioral control NB. Physical activity and intention based on 4 categories: completely sedentary, insufficiently active, within guidelines, and above guidelines. ***P <.001.

5 Physical Activity in Ovarian Cancer Survivors 343 Table 3 Hierarchical Forced-Entry Multiple-Regression Analyses of Physical Activity Guidelines on Theory-of-Planned-Behavior Variables for Ovarian Cancer Survivors (N = 359) F change df R 2 change β 1 β 2 (Block #1) , intention 0.56*** 0.51*** instrumental attitude affective attitude injunctive norm descriptive norm perceived behavioral control (Block #2) , age 0.08 education 0.14*** full/part-time employment 0.01 months since diagnosis 0.08 current disease 0.09* body-mass index 0.12** current arthritis 0.04 Abbreviations: F = F ratio; df = degrees of freedom; R 2 = coefficient of determination; ß 1 ß 2 = standardized regression coefficients for equations #1, #2. NB. Physical activity and intention based on 4 categories: completely sedentary, insufficiently active, within guidelines, and above guidelines. *P <.05. ** P <.01. *** P <.001. Table 4 Hierarchical Forced-Entry Multiple- Regression Analyses of Physical Activity Intention on Theory-of-Planned-Behavior Variables in Ovarian Cancer Survivors (N = 359) F change df R 2 change β , Instrumental attitude 0.21** Affective attitude 0.29*** Injunctive norm 0.08 Descriptive norm 0.03 Perceived behavioral 0.28*** control Abbreviations: F, F ratio; df, degrees of freedom; R 2, coefficient of determination. NB. Intention based on 4 categories: completely sedentary, insufficiently active, within guidelines, and above guidelines. *P <.05. ** P <.01. *** P <.001. vors not currently intending to exercise and to facilitate the successful translation of intentions into behavior in those with positive intentions but inadequate behavioral follow-through. Several demographic factors distinguished ovarian cancer survivors who were meeting physical activity guidelines from those who were not. Specifically, younger age, higher education and income, full- or parttime employment, and healthy BMI were associated with meeting physical activity guidelines. These factors are consistent with data from a large sample of Canadian older adults, 33 with the exception that marital status was not associated with physical activity in our study. Furthermore, surveys of colorectal 34 and endometrial 35 cancer survivors have reported physical activity to be associated with similar demographic variables. Efforts to promote physical activity among ovarian cancer survivors must consider these factors. In support of the uniqueness of cancer survivors, specific medical characteristics were also associated with physical activity in our sample. Meeting guidelines was more common among women who had early-stage disease, those who were at least 5 years since diagnosis, and those currently disease free. It is not surprising that participants with more advanced disease, a more recent diagnosis, or current disease are less active, since they are likely to be in poorer state of health, with physical activity seeming less of a priority than disease- or treatment-related concerns. Nonetheless, studies in other cancer survivor populations have indicated benefits of physical activity during cancer treatments 7,9,35 or for individuals with advanced disease, 36,37 and surveys of cancer survivors indicate considerable interest in receiving exercise advice and interventions during or soon after treatments. 38,39 Therefore, physical-activity-promotion efforts among ovarian cancer survivors should not necessarily exclude women based on medical characteristics but may need to modify activities according to the health and treatment status of these individuals. Demographic and medical characteristics provide important information on nonmodifiable factors that identify those at risk for low physical activity. This study also examined modifiable social-cognitive factors (ie, beliefs about physical activity) using the TPB. The TPB explained 36% of the variance in reported physical

6 344 Stevinson et al Table 5 Most Common Behavioral, Control, and Normative Beliefs of Ovarian Cancer Survivors Regarding Regular Physical Activity (N = 359) Beliefs activity behavior and 39% of the variance in physical activity intentions of participants. These findings are consistent with those from previous studies using the TPB in cancer survivors in which 14% to 37% of the variance in exercise behavior and 23% to 68% of the variance in exercise intention was explained. 19 Intention n % of tot al sample % of question respondents (n = 269) Behavioral beliefs (advantages) improve physical health control body weight increase energy increase aerobic fitness feel better increase muscle tone/ strength improve psychological well-being improve cardiovascular health improve mental health relieve stress improve flexibility/balance get out of house/fresh air improve sleep Control beliefs (barriers) lack of time lack of motivation fatigue arthritis/bad joints health problems lack of facilities/equipment too sick pain no partner support Normative beliefs (approving others) family friends spouse/partner medical staff children everyone coworkers was found to be the only significant independent correlate of physical activity behavior, which is also consistent with previous studies of cancer survivors 19 and with the tenets of the TPB. 24 When the demographic and medical variables were included in the analysis, the results indicated that education, BMI, and disease status were still associated with physical activity independently of any social-cognitive variables; however, intention remained the most important correlate of behavior. Not surprisingly, intentions to exercise are strongest in those who are already most active. The challenge for health promotion is in trying to develop strong intentions among the inactive population to bring about positive behavior change. The most important correlates of intention in this population were affective and instrumental attitudes and perceived behavioral control. Interventions for fostering positive intentions should therefore focus on developing favorable attitudes by encouraging the notion that physical activity is enjoyable (eg, by choosing an activity they like, exercising with a friend, selecting moderateintensity activities) and ensuring awareness of the benefits of being physically active. A range of physical and psychological health benefits were identified by ovarian cancer survivors in this study (Table 5), with improvements to general physical health, weight control, and increasing energy being particularly important. To promote a sense of behavioral control, it is necessary to identify, and seek solutions to, perceived barriers to physical activity for individuals. The control beliefs (Table 5) indicate that the most common barriers perceived by ovarian cancer survivors include lack of time, lack of motivation, and lack of energy/fatigue. Interestingly, fatigue is perceived as both a benefit and a barrier to physical activity. This reflects the complexity of the fatigue/physical activity relationship. Although excessive activity may exacerbate fatigue, too much rest leads to physical deconditioning that contributes to increased fatigue during usual daily function. There is encouraging evidence that a moderate volume of physical activity helps reverse declines in fitness and function, contributing to reductions in fatigue This study is the first to examine the determinants of physical activity in ovarian cancer survivors. The large, population-based sample is also a strength of this study, as is the use of a validated theoretical model and validated question items to examine motivation for physical activity. The main weaknesses are the crosssectional design of the study, along with the transparent nature of the physical activity focus, which likely attracted more active survivors and may have encouraged participants to provide more favorable responses due to social-desirability biases. Other limitations are the 51% response rate, the failure to collect data on racial or ethnic characteristics, and the 16% missing data for disease stage and annual income.

7 Physical Activity in Ovarian Cancer Survivors 345 Conclusion In summary, demographic and medical variables can help identify ovarian cancer survivors at risk for physical inactivity, for example, older age, higher BMI, shorter time since diagnosis, and current disease. Behavior-change interventions in this population should focus on developing strong intentions for physical activity by fostering positive instrumental and affective attitudes and strong perceptions of control. Acknowledgments This study was funded by the University of Alberta and a Research Team Grant from the National Cancer Institute of Canada, with funds from the Canadian Cancer Society and the NCIC/CCS Sociobehavioral Cancer Research Network. Kerry S. Courneya is supported by the Canada Research Chairs Program. References 1. Doyle C, Kushi LH, Byers T, et al. Nutrition and physical activity during and after cancer treatment: an American cancer society guide for informed choices. CA Cancer J Clin. 2006;56: Holmes MD, Chen WY, Feskanich D, Kroenke CH, Colditz GA. Physical activity and survival after breast cancer diagnosis. JAMA. 2005;293(20): Meyerhardt JA, Heseltine D, Niedzwiecki D, et al. Impact of physical activity on cancer recurrence and survival in patients with stage III colon cancer: findings from CALGB J Clin Oncol. 2006;24(22): Meyerhardt JA, Giovannucci EL, Holmes MD, et al. Physical activity and survival after colorectal cancer diagnosis. J Clin Oncol. 2006;24(22): McNeely ML, Campbell KL, Rowe BH, Klassen TP, Mackey JR, Courneya KS. Exercise interventions in breast cancer patients: a systematic review and metaanalysis of randomized controlled trials. Can Med Assoc J. 2006;175: Schmitz KH, Holtzman J, Courneya KS, Mâsse LC, Duval S, Kane R. Controlled physical activity trials in cancer survivors: a systematic review and meta-analysis. Cancer Epidemiol Biomarkers Prev. 2005;14: Courneya KS, Segal RJ, Mackey JR, et al. Effects of aerobic and resistance exercise in breast cancer patients receiving adjuvant chemotherapy: a multicenter randomized controlled trial. J Clin Oncol. 2007;25: Daley AJ, Crank H, Saxton JM, Mutrie N, Coleman R, Roalfe A. Randomized trial of exercise therapy in women treated for breast cancer. J Clin Oncol. 2007;25: Mutrie N, Campbell AM, Whyte F, et al. Benefits of supervised group exercise programme for women being treated for early stage breast cancer: pragmatic randomised controlled trial. BMJ. 2007;334: Bellizzi KM, Rowland JH, Jeffery DD, McNeel T. Health behaviors of cancer survivors: examining opportunities for cancer control intervention. J Clin Oncol. 2005;23: Coups EJ, Ostroff JS. A population-based estimate of the prevalence of behavioral risk factors among adult cancer survivors and noncancer controls. Prev Med. 2005;40: Courneya KS, Karvinen KH, Campbell KL, et al. Associations among exercise, body weight, and quality of life in a population-based sample of endometrial cancer survivors. Gynecol Oncol. 2006;97: Irwin ML, McTiernan A, Bernstein L, et al. Physical activity levels among breast cancer survivors. Med Sci Sports Exerc. 2004;36: Jones LW, Courneya KS, Vallance JK, et al. Association between exercise and quality of life in multiple myeloma cancer survivors. Support Care Cancer. 2005;12: Karvinen KH, Courneya KS, North S, Venner P. Associations between exercise and quality of life in bladder cancer survivors: a population-based study. Cancer Epidemiol Biomarkers Prev. 2007;16: Rogers LQ, Courneya KS, Robbins KT, et al. Physical activity and quality of life in head and neck cancer survivors. Support Care Cancer. 2006;14: Vallance JKH, Courneya KS, Jones LW, Reiman T. Differences in quality of life between non-hodgkin s lymphoma survivors meeting and not meeting public health exercise guidelines. Psychooncology. 2005;14: Centers for Disease Control and Prevention. Prevalence of regular physical activity among adults United States, 2001 and Morbidity and Mortality Weekly Report. 2007;56(46): Courneya KS, Karvinen KH, Vallance JKH. Exercise motivation and behavior change. In: Feuerstein M, ed. Handbook of Cancer Survivorship. New York, NY: Springer; 2007: American Cancer Society. Cancer Facts and Figures Atlanta, GA: Author; Canadian Cancer Society/National Cancer Institute of Canada. Canadian Cancer Statistics Toronto, ON: Canadian Cancer Society/National Cancer Institute of Canada; Pavelka JC, Brown RS, Karlan BY, et al. Effect of obesity on survival in epithelial ovarian cancer. Cancer. 2006;107: Stevinson C, Faught W, Steed H, et al. Associations between physical activity and quality of life in ovarian cancer survivors. Gynecol Oncol. 2007;106: Ajzen I. The theory of planned behavior. Organ Behav Hum Decis Process. 1991;50:

8 346 Stevinson et al 25. Conner M, Sparks P. The theory of planned behaviour. In: Conner M, Norman P, eds. Predicting Health Behaviours: Research and Practice With Social Cognitive Models. Maidenhead, UK: Open University Press; Godin G, Jobin J, Bouillon J. Assessment of leisure time exercise behavior by self-report: a concurrent validity study. Can J Public Health. 1986;77: Jacobs DRJ, Ainsworth BE, Hartman TJ, Leon AS. A simultaneous evaluation of 10 commonly used physical activity questionnaires. Med Sci Sports Exerc. 1993;25: Ajzen I. Constructing a TpB questionnaire: conceptual and methodological considerations. umass.edu/aizen/pdf/tpb.measurement.pdf. Accessed June 25, Ajzen I. Perceived behavioural control, self-efficacy, locus of control, and the theory of planned behaviour. J Appl Sport Psychol. 2002;32: Courneya KS, Rhodes RE, Conner M. Effects of different measurement scales on the variability and predictive validity of the two-component model of the theory of planned behaviour in the exercise domain. Psychol Health. 2006;21: Courneya KS, Vallance JKH, Jones LW, Rieman T. Correlates of exercise intentions in non-hodgkin s lymphoma survivors: an application of the theory of planned behavior. J Sport Exerc Psychol. 2005;27: Demark-Wahnefried W, Peterson B, McBride C, Lipkus I, Clipp E. Current health behaviours and readiness to pursue life-style changes among men and women diagnosed with early stage prostate and breast carcinomas. Cancer. 2000;88: Kaplan MS, Newsom JT, McFarland BH, Lu L. Demographic and psychosocial correlates of physical activity in late life. Am J Prev Med. 2001;21: Peddle CJ, Plotnikoff RC, Wild TC, Au HJ, Courneya KS. Medical, demographic, and psychosocial correlates of exercise in colorectal cancer survivors: an application of self-determination theory [published online ahead of print 2007]. Support Care Cancer. 35. Karvinen KH, Courneya KS, Campbell KL, et al. Correlates of exercise motivation and behavior in a populationbased sample of endometrial cancer survivors: an application of the theory of planned behavior. Int J Behav Nutr Phys Act. 2007;4: Headley JA, Ownby KK, John LD. The effect of seated exercise on fatigue and quality of life in women with advanced breast cancer. Oncol Nurs Forum. 2004;31: Oldervoll LM, Loge JH, Paltiel H, et al. The effect of a physical exercise program in palliative care: A phase II study. J Pain Symptom Manage. 2006;31: Jones LW, Courneya KS. Exercise counseling and programming preferences of cancer survivors. Cancer Pract. 2002;10: Karvinen KH, Courneya KS, Campbell KL, et al. Exercise preferences of endometrial cancer survivors: a population-based study. Cancer Nurs. 2006;29: Courneya KS, Friedenreich CM, Sela RA, Quinney A, Rhodes RE, Handman M. The group psychotherapy and home-based physical exercise (GROUP-HOPE) trial in cancer survivors: physical fitness and quality of life outcomes. Psychooncology. 2003;12: Pinto BM, Frierson GM, Rabin C, Trunzo JJ, Marcus BH. Home-based physical activity intervention for breast cancer patients. J Clin Oncol. 2005;23: Segal RJ, Reid RD, Courneya KS, et al. Resistance exercise in men receiving androgen deprivation therapy for prostate cancer. J Clin Oncol. 2003;21: