The characteristics of the study population overall and by quartile of change from baseline to 6-month follow-up (about eight months post-diagnosis) for total non-sedentary activity are given in . The average age at breast cancer diagnosis was 60.4 years, and 75% were postmenopausal at baseline. Participants were primarily white (72%) and highly educated, with 86% having at least some college education or more. Less than half (43%) were employed at the time of the baseline interview. About 56% never smoked, and 41% and 3% were former or current smokers at the baseline interview, respectively. Change in total non-sedentary activity was relatively similar across most sociodemographic variables.
Characteristics of study participants, overall and by quartiles of change in total non-sedentary activity from baseline to 6 month follow-up, Pathways Study (n=1,696), 2006–2010
The majority of women were diagnosed with early stage breast cancer (54% and 34% Stage I and II, respectively), and 83% had hormone receptor positive tumors (ER+ and/or PR+). About 63% of women had breast-conserving surgery only, while 37% had a mastectomy and less than 1% had no breast surgery. Approximately 33% received chemotherapy only and 33% received radiation therapy only, while 72% overall received hormonal therapy. Almost half (48%) of the women who had the greatest decline in total non-sedentary activity (Quartile 1) had chemotherapy only while 22% had an increase (Quartile 4). The opposite trend was observed for women who had radiation therapy only with almost 24% making up the lowest physical activity quartile and 40% the highest. No differences across quartile of change in activity levels were noted for type of breast cancer surgery and hormonal therapy. At the 6-month follow-up, 7% reported having lymphedema, yet no major differences across quartiles of change were apparent.
Overall, levels of physical activity decreased from baseline to 6-month follow-up (). Total non-sedentary activity decreased by a mean (SD) of −9.40 (27.94) MET-hours/week (P < 0.0001). Overall MVPA decreased by a mean (SD) of −1.28 (4.48) hours/week (P < 0.0001), and the individual MVPA domains also had similar patterns of decrease. Participants reported the greatest decrease in recreational activity (−0.74 hours/week, SD=3.09; P < 0.0001), followed by household activity and transportation activity. About 4% and 7% of women reported no MVPA at baseline and follow-up, respectively. At baseline, about 70% of the cohort was meeting the US 2008 Physical Activity Guidelines while only 58% were doing so at follow-up. Sedentary behavior decreased by a mean (SD) of −0.83 (6.95) hours/week (P < 0.0001). Socializing had the largest reduction of −0.28 hours/week (SD=2.52; P < 0.0001), followed by reading, doing crafts, attending group events, and playing games, while television watching increased by 0.32 hours/week (SD=2.25; P < 0.0001). Overall, those who had higher levels of activity at baseline also did at follow-up, and vice versa (not shown).
Physical activity measures at baseline and 6-month follow-up, and associated change, Pathways Study (n=1,696), 2006–2010
Change in MVPA and sedentary behavior levels from baseline to 6-month follow-up by sociodemographic and clinical characteristics were minimally adjusted for age at diagnosis, AJCC stage, and relevant baseline physical activity measure (data not shown). For MVPA, being non-married (−2.24 hours/week for single women, −1.73 hours/week for separated/divorced women, and −1.62 hours/week for widows) was associated with a greater decrease compared to married (−1.35 hours/week). Similarly, being postmenopausal at baseline (−1.78 hours/week) was associated with a greater decrease in MVPA compared to premenopausal (−1.05 hours/week), as well as being overweight and obese at baseline (−1.89 and −1.70 hours/week, respectively) compared to normal weight (−1.09 hours/week). Women of all cancer stages experienced a decline in activity, although the largest declines were observed in women diagnosed with Stage III (−2.01 hours/week) tumors. Women who had chemotherapy and/or radiation therapy also had decreases in activity, yet the greatest reductions were among those who had chemotherapy only (−2.15 hours/week) and both chemotherapy and radiation therapy (−1.63 hours/week).
For sedentary behavior, Asians and Hispanics (−1.59 and −2.11 hours/week, respectively) experienced more of a decrease compared to Whites, Blacks, and Other races/ethnicities (−0.20, −0.34, and −0.19 hours/week, respectively) (data not shown). Being employed was also associated with a larger decline in sedentary behavior (−0.91 hours/week) compared to unemployed (−0.10 hours/week), as well as being postmenopausal at diagnosis (−0.82 hours/week) vs. premenopausal (0.10 hours/week). Women who had breast-conserving surgery had an increase in sedentary behavior (0.17 hours/week) compared to those who had a mastectomy (−0.27 hours/week).
gives multivariate regression models for change in MVPA and sedentary behavior levels, adjusting for all covariates of interest. For MVPA, being overweight and obese at baseline continued to be associated with more of a decrease (−1.58 and −1.29 hours/week, respectively) compared to normal weight (−0.84 hours/week; P = 0.0079). Having chemotherapy only (−2.12 hours/week) and both chemotherapy and radiation therapy (−1.60 hours/week) also continued to be associated with a decrease in MVPA compared to no treatment (−0.60 hours/week; P < 0.0001). Radiation therapy only (−0.62 hours/week) had a similar level of decline as no treatment (−0.60 hours/week). Partner status, menopausal status, and AJCC stage were no longer associated with MVPA change.
Fully-adjusted multivariable linear regression of sociodemographic and clinical characteristics and change in moderate-vigorous physical activity and sedentary behavior from baseline to six month follow-up, Pathways Study (n=1,696), 2006–2010
For sedentary behavior, Asians, Hispanics, and Blacks (−2.12, −2.43, and −1.81 hours/week, respectively) experienced more of a decrease compared to Whites and Other races/ethnicities (−0.77 and −0.76 hours/week, respectively; P = 0.014) (). Being employed continued to be associated with more of a decline in sedentary behavior (−1.97 hours/week) compared to unemployed (−1.19 hours/week; P = 0.031) while being postmenopausal at baseline remained associated with a greater decrease in sedentary behavior (−2.26 hours/week) compared to premenopausal (−0.89 hours/week; P = 0.019). Women who had any breast surgery had an increase in sedentary behavior (1.09 hours/week for conserving and 0.43 hours/week for mastectomy) whereas the small group who had no surgery experienced a decrease (−6.25 hours/week; P = 0.019). While not observed in the minimally-adjusted models, more education (−0.83 hours/week for post-graduate level vs. −2.48 hours/week for high school or less; P = 0.0068) and higher BMI were each associated with less of a decrease in sedentary behavior (−1.36 hours/week for obese women vs. −2.11 hours/week for normal weight women; P = 0.063).
gives change in levels of MVPA by domain, and sedentary behavior by activity, within each treatment group (chemotherapy only, radiation therapy only, both, none) adjusted for all covariates of interest. For each MVPA domain, reductions were observed in each treatment group, yet for recreational activity, the greatest decrease was among women who had chemotherapy only (−1.62 hours week), followed by both chemotherapy and radiation, radiation only, and no treatment (−1.26, −0.71, and −0.68 hours/week, respectively; P = 0.0001). For the sedentary behavior activities, there was a suggestion that women experienced increases in doing crafts and watching television, and decreases in reading (except for chemotherapy only), socializing, attending group events, and playing games.
Fully-adjusted multivariable linear regression of change in physical activity measures from baseline to 6-month follow-up by treatment status, Pathways Study (n=1,696), 2006–2010