title: Change in physical activity during active treatment in a prospective study of breast cancer survivors.
abstract: Physical activity offers many benefits to breast cancer survivors, yet research on physical activity during the immediate period following a breast cancer diagnosis is limited. In a prospective cohort study of 1,696 women diagnosed with invasive breast cancer in the Kaiser Permanente Northern California Medical Care Program from 2006-2009, we describe change in self-reported physical activity levels from around diagnosis to 6 months post-diagnosis and determine factors associated with change. Participants completed a comprehensive physical activity questionnaire at baseline (2 months post-diagnosis) and at follow-up (8 months post-diagnosis). Predictors of physical activity change were determined by multivariable linear regression. Reductions in all physical activity levels were observed (P < 0.0001); mean (SD) change (h/week) of moderate-vigorous physical activity (MVPA) was -1.28 (4.48) and sedentary behavior was -0.83 (6.95). In fully-adjusted models, overweight and obesity were associated with greater declines in MVPA of -1.58 h/week (SD = 0.92) and -1.29 h/week (SD = 0.93), respectively (P = 0.0079). Receipt of chemotherapy only was also associated with a greater decrease in MVPA (-2.12 h/week; SD = 0.92; P < 0.0001), specifically for recreational activities (-1.62 h/week; SD = 0.64; P = 0.0001). These data suggest challenges in maintaining physical activity levels during active treatment among women with breast cancer. Interventions to encourage physical activity in breast cancer survivors should be pursued.
authors.affiliation: Division of Research, Kaiser Permanente, 2000 Broadway, Oakland, CA 94612, USA. Marilyn.L.Kwan@kp.org
authors.forename: Marilyn L
authors.initials: ML
authors.lastname: Kwan
authors.forename: Barbara
authors.initials: B
authors.lastname: Sternfeld
authors.forename: Isaac Joshua
authors.initials: IJ
authors.lastname: Ergas
authors.forename: Allegra W
authors.initials: AW
authors.lastname: Timperi
authors.forename: Janise M
authors.initials: JM
authors.lastname: Roh
authors.forename: Chi-Chen
authors.initials: CC
authors.lastname: Hong
authors.forename: Charles P
authors.initials: CP
authors.lastname: Quesenberry
authors.forename: Lawrence H
authors.initials: LH
authors.lastname: Kushi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000453:epidemiology / Q000534:rehabilitation* / Q000628:therapy; D015331:Cohort Studies; D015444:Exercise; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D009043:Motor Activity; D011446:Prospective Studies; D017741:Survivors