Radiation therapy (RT) is often delivered after lumpectomy for women with breast cancer. A common perceived side effect of RT is fatigue, yet its exact effect on activity levels and sleep is unknown. In this study we analyzed the change in activity levels and sleep using an activity tracking device before, during, and after RT for women with early stage breast cancer and ductal carcinoma in situ who underwent adjuvant RT.

After institutional review board approval, activity levels were quantified before, during, and after RT with measurements of steps, miles walked, calories burned, and sleep metrics in 10 women fitted with activity trackers. All data were uploaded and tabulated on a secure database. Multivariable linear regressions were used to evaluate changes in these variables over time during the RT course.

Median step count was 5047 per day (range, 2741-15,508) and distance traveled was 1.6 miles per day (range, 0.9-5.3). Step count, distance, and calories decreased by an average of 54 steps per day, 0.02 miles per day, and 3 calories per day (median calories 1822; range, 1461-2712) during RT, respectively. These changes were statistically significant (P < .001), but not clinically relevant. There was no significant change in sleep (average 6.8 hours per night; range, 5.5-8.3).

RT has a minimal effect on activity or sleep in women undergoing treatment for breast cancer. Activity levels varied greatly between patients in a population of women undergoing hypofractionated RT. Because increased activity levels correlate with improved outcomes, further studies evaluating attempts to increase physical activity during as well as after treatment with radiation are warranted.