Physical Activity

On average, breast cancer survivors were below the national guideline of at least 150 minutes per week of PA at all assessment points from pre-diagnosis through ten years post- diagnosis. The shape of the mean PA trajectory began with a decrease of 34 minutes per week between pre-diagnosis and six months post-diagnosis, rebounded to pre-diagnosis levels by two years post-diagnosis, increased to a peak of 142 minutes/week at five years post-diagnosis, and then decreased by over an hour to 78 minutes/week at ten years post-diagnosis.

This trajectory shape is consistent with Emery et al. (2009) where breast cancer survivors also reported an inverted-U shape, of increasing and then decreasing PA, from the time of

surgery through five years post-treatment (Emery et al., 2009). In both studies, breast cancer survivors reported approximately 80-90 minutes/week of PA during early survivorship (after surgery in Emery [2009] and approximately six months post-diagnosis in the current study). Both studies also found similar PA levels at 18-24 months post-diagnosis (Emery: approximately 125 minutes/week at 18 months post-diagnosis vs. 129 minutes/week at 24 months post-diagnosis in the current study). After the two-year mark, the two studies started to diverge in patterns,

however. The Emery (2009) survivors declined in PA from two to five years post-diagnosis, and the five-year PA was lower than at the time of treatment. However, in the current study, breast cancer survivors continued to increase their PA from two to five years post-diagnosis, to a peak of 142 minutes per week. At ten years post-diagnosis, a considerable drop in PA was reported.

There are demographic and clinical differences between between the two samples that may explain the diverging patterns after two years post-diagnosis. Demographically, the samples were similar with the exception of race/ethnicity (Emery: 10% non-white vs. 51% in the current sample) and age range (Emery: ages 28-84 with a mean of 50.9 vs. ages 35-64 with a mean of 51

stages (Emery: II-III vs. 0-IIIa in the current study) and a greater proportion receiving

chemotherapy (Emery: over 80% vs. 36% in the current sample). The breast cancer survivors in the Emery (2009) study may have been experiencing a higher long-term symptom burden from more invasive therapy, or perhaps had more comorbid conditions, and therefore were unable to maintain PA levels as long as the survivors in the current study who had a lower disease stage and less invasive therapy.

Pre-diagnosis PA data was not collected in the Emery et al. (2009) study so no information is available about whether the breast cancer survivors decreased PA from pre- to post-diagnosis like the breast cancer survivors in the current study did. However, several cohort studies have also shown a decrease in PA from pre- to post-diagnosis for breast cancer survivors (Andrykowski et al., 2007; Devoogdt et al., 2010; Hair et al., 2014; Irwin et al., 2003; Littman et al., 2000). For example, Hair et al. (2014) found that 59% of breast cancer survivors reported decreasing their PA from pre- to post-diagnosis, but the magnitude of change varied by race. After adjustment for potential confounders, African American women were less likely to meet PA guidelines after diagnosis than Caucasian women.

Breast cancer survivors may be reducing their PA from pre- to post-diagnosis because they are undergoing active treatment, such as breast-conserving surgery and radiation, and experiencing symptoms such as fatigue and breast sensitivity. During active treatment, and through approximately 18 months post-diagnosis, over 80% of breast cancer survivors report fatigue, 70% report breast sensitivity, and over 50% report sleep disturbance (Janz et al., 2007; Montazeri, 2008; Mortimer et al., 2010; Nihal Guleser et al., 2012), all of which are known to affect PA after diagnosis (Alfano et al., 2007; Charlier et al., 2013; Fong et al., 2012; McNeely et

In the current study, PA rebounded at two years post-diagnosis to nearly pre-diagnosis levels. This rebound is consistent with the timing of recovery from active treatment. In general, younger and middle-age breast cancer survivors need approximately 12-18 months to recover from treatment and return to their usual activities (Hsu, Ennis, Hood, Graham, & Goodwin, 2013; Mols, Vingerhoets, Coebergh, van de Poll-Franse, 2005; Montazeri, 2008). This timing of symptom recovery is consistent with longitudinal studies in breast cancer survivors showing PA increases after completion of active treatment (Emery et al., 2009; Harrison et al., 2009; Littman et al., 2000).

Finally, the current study observed a decline in PA from five to ten years post-diagnosis. This result may be due to PA decreasing with age. PA declines as individuals age have been observed for both the general population (Fan, Kowaleski-Jones, & Wen, 2013; Kim et al., 2013; Sun, Norman, & While, 2013) and cancer survivors (Bellury et al., 2012; Hong et al., 2007; Kim et al., 2013; Lynch et al., 2010). Fan et al. (2013) examined PA across 17 activity types for 3,952 women ages 25 years and older participating in the 2003-2006 National Health and Nutrition Examination Surveys (NHANES). Significant decline in leisure PA participation started at ages 35-44 years (e.g., running, dancing, treadmill, and team sports). Total PA also declined with age but significant declines did not occur until ages 55-64 years (e.g., participation in household PA and walking).