Sedentary Behavior, Health-Related Quality of Life,and Fatigue Among Breast Cancer SurvivorsStephanie M. George, Catherine M. Alfano, Ashley Wilder Smith, Melinda L. Irwin,Anne McTiernan, Leslie Bernstein, Kathy B. Baumgartner, and Rachel Ballard-BarbashBackground: Many cancer survivors experience declines in health-related quality of life (HRQOL) andincreases in fatigue as a result of cancer and its treatment. Exercise is linked to improvements in these outcomes,but little is known about the role of sedentary behavior. In a large, ethnically-diverse cohort of breastcancer survivors, we examined the relationship between sedentary time, HRQOL, and fatigue, and examinedif that relationship differed by recreational moderate-vigorous physical activity (MVPA) level. Methods:Participants were 710 women diagnosed with stage 0-IIIA breast cancer in the Health, Eating, Activity, andLifestyle Study. Women completed questionnaires at approximately 30-months postdiagnosis (sedentary time;recreational MVPA) and 41-months postdiagnosis (HRQOL; fatigue). In multivariate models, we regressedthese outcomes linearly on quartiles of daily sedentary time, and a variable jointly reflecting sedentary timequartiles and MVPA categories (0; >0 to <9; ≥9 MET-hrs/wk). Results: Sedentary time was not independentlyrelated to subscales or summary scores of HRQOL or fatigue. In addition, comparisons of women with highvs. low (Q4:Q1) sedentary time by MVPA level did not result in significant differences in HRQOL or fatigue.Conclusion: In this breast cancer survivor cohort, self-reported sedentary time was not associated with HRQOLor fatigue, 3.5 years postdiagnosis.Keywords: health behavior, survivorship, epidemiologyImproved prognosis based on early detection andnew treatments for breast cancer has resulted in more than2.5 million women living with a personal history of breastcancer in the United States.1,2 As a result of cancer andits treatment, this growing population of cancer survivorsface persistent physical and psychological challenges.3For example, even 5 years after diagnosis, many survivorsstill experience impaired physical functioning,4,5psychosocial distress,6,7 and fatigue,8 the latter of which isoften reported as the most frequent and distressing cancersymptom.9 Cancer diagnoses may prompt survivors toseek lifestyle change to improve long-term physical andpsychological health and reduce dysfunction.10 Thus, itis important to understand modifiable factors that mayimpact these outcomes to develop better interventionsfor survivors.There is strong evidence that exercise after a breastcancer diagnosis can improve survivors’ HRQOL andfatigue.11–13 Less attention has been paid to sedentarytime—prolonged periods of sitting or reclining withoutwhole body movement like television watching. Manylong-term breast cancer survivors not only fail to getenough exercise [eg, recreational moderate-vigorousintensity physical activity (MVPA)]14 but also spend themajority of their time sedentary.15 Being that too muchsitting is increasingly becoming known as a distinct healthbehavior16 with its own negative health effects,17 thereis a need for research in this area to inform behavioralinterventions for survivors.We previously reported that in the Health EatingActivity and Lifestyle (HEAL) study of breast cancerprognosis, 3 years after diagnosis, higher postdiagnosisrecreational aerobic MVPA was associated with betterHRQOL outcomes (including physical functioning,18vitality,19 social functioning19) and less fatigue.18 Thereis little known about the independent role sedentary timemight have in affecting these outcomes among cancersurvivors. The only study to date observed a inverse relationshipbetween television watching time and HRQOLamong colorectal cancer survivors.20Official Journal of ISPAHwww.JPAH-Journal.comORIGINAL RESEARCHSedentary Behavior and Cancer Comorbidities 351To build on our previous research in the HEALstudy18,19 and address this gap in the literature regardingsedentary behavior among breast cancer survivors,we investigated relationships between sedentary time,independently and stratified by recreational MVPA level,and subsequent HRQOL and fatigue among women withearly-stage breast cancer
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