Premenopausal Breast Cancer: Exercise and Leukocyte Telomere Length

Leukocyte telomere length (LTL) may function as a marker of health, the immune system and cancer survival. We evaluated whether premenopausal breast cancer survivors (PBCS) that successfully increased exercise levels also increased LTL. This study is the first to describe LTLs in a population-based sample of PBCS before and after an exercise intervention. We analyzed LTL before and after the Exercise for Bone Health Intervention, a randomized, controlled trial of 273 premenopausal women 55 years of age or younger at diagnosis that started the intervention within 2 years of receipt of initial chemotherapy. This pilot analysis included 60 women with the greatest increase in exercise from pre to post intervention. Those with longer LTLs at pre-intervention (PRE) had LTLs that grew shorter during the study, however, they still had longer LTLs at post-intervention (POST) than those who started with shorter LTLs. The group whose LTLs shortened the most during the study were those with longer LTLs and more exercise at PRE, ANOVA across four levels P = 0.030. In multivariable regression models of LTL change adjusted for age and LTL at PRE, factors that were independently associated with LTLs that became shorter were older age ( P = 0.017), longer telomeres at PRE ( P = 0.0004), higher levels of exercise ( P = 0.013), higher income ( P = 0.011), feeling down-hearted and blue ( P = 0.003), higher levels of sociability ( P = 0.015), more chronic medical conditions ( P = 0.018), and higher levels of insulin-like grown factor-1 at POST ( P = 0.003). While this is a pilot sub-study and requires additional confirmation, we postulate that women accustomed to exercising and being highly sociable pre-diagnosis may have experienced a greater impact on their lifestyles post-diagnosis resulting in a more rapid rate of LTL shortening. We hypothesize that time to return to LTL homeostasis for YBCS may be dependent upon a combination of physical health and psychosocial networks pre and post diagnosis and the immune system may be an important modifier. Further studies combining new technology to improve the capture of exercise and psychosocial well-being, and monitor levels of inflammation are needed to determine whether lifestyle interventions can be used to impact biomarkers of health in YBCS.