Does walking during chemotherapy impact p16INK4a levels in women with early breast cancer

Background Increased p16(INK4a) (p16) expression is directly related to cellular senescence and is a robust biomarker of aging in humans. Prior studies have shown that levels of p16 dramatically increase in breast cancer patients who have received adjuvant chemotherapy. This study investigated whether moderate physical activity during chemotherapy would attenuate the expected rise in p16 expression. Methods Participants were women with Stage I-III breast cancer enrolled in a walking study for the duration of their chemotherapy (NCT02167932, NCT02328313, NCT03761706). Participants were asked to walk at least 30 min or 6200 steps/day following a structured walking program and to wear an activity tracker. p16 mRNA levels were measured in peripheral blood T-cells before chemotherapy initiation and at approximately 6 months after last chemotherapy treatment (mean 200 days, SD 40 days). Results In total, 141 participants met inclusion criteria and 10% (n = 14) averaged > 6200 steps/day. There was no significant association of daily steps with change in p16 levels pre- to post-chemotherapy (Pearson correlation coefficient = 0.11, p = 0.17). After adjusting for age, stage, anthracycline-based chemotherapy, and baseline p16, the change in log(2) p16 for each 1000 steps was estimated to be 0.03 (p = 0.35). Most participants were sedentary prior to chemotherapy and achieved modest levels of physical activity during treatment. Conclusion A self-guided walking program achieved only modest levels of physical activity and was unable to ameliorate chemotherapy-induced change in p16 levels in women undergoing chemotherapy for early-stage breast cancer. More structured and vigorous exercise programs should be tested for a more definitive exploration of their impact on post-chemotherapy p16 levels.