LAUSR

Two measures of host rhythmicity, rest/activity and diurnal cortisol secretion rhythms, have demonstrated prognostic significance across several cancer types. We previously reported a significant correlation between these two parameters among presurgical breast cancer patients. The association between rest/activity and cortisol rhythms has not been reported among patients with lung cancer. Patients diagnosed within the past five years collected salivary cortisol twice a day and wore actigraphy devices for 10 consecutive days. Most of the 65 patients (67%) were female, non-Hispanic white (78%), averaging 23 months post diagnosis and diagnosed with advanced (41%, n = 27) or metastatic (24%, n = 16) disease. Clinical characteristics were not associated with rhythm variables. Spearman correlations tested hypotheses. Rest/activity rhythm was associated with steeper diurnal slope (rho = −0.301, p = 0.024). Nighttime restfulness was associated with lower mean (rho = −0.312, p = 0.018) and bedtime cortisol (rho = −0.347, p = 0.008), while daytime sedentary behavior was associated with higher diurnal mean (rho = 0.368, p = 0.005) and bedtime cortisol (rho = 0.355, p = 0.007). These measures offer insight into distinct host rhythms (behavioral and endocrine). While factors contributing to the disruption of these rhythms have not been identified in human cancer studies, their significant associations imply a shared variance that may reflect endogenous circadian phase. These and other rhythm metrics may have the combined potential to robustly measure host circadian disruption and help determine if it is a cause, correlate or marker of lung cancer progression.