Marked 24-h rest/activity rhythms are associated with better quality of life, better response, and longer survival in patients with metastatic colorectal cancer and good performance status

The rest/activity circadian cycle has been used as a reference for chemothe rapy administration at specific times to improve tolerability and efficacy, Because cancer processes may be associated with alterations of circadian r hythms, the rest/activity cycle was monitored noninvasively to assess its r elationship with tumor response, survival, and quality of life in 200 patie nts with metastatic colorectal cancer. Patients wore an actigraph, a wristw atch that records the number of accelerations per minute, for 3 days before receiving chronomodulated chemotherapy, The circadian rhythms in activity were estimated by two robust parameters: the autocorrelation coefficient at 24 h (r24), and the dichotomy index (I<O) for comparing amounts of activit y when in bed and out of bed. Accurate data for inclusion, quality of life, response, and survival were available for 192 patients. Survival at 2 year s was 5-fold higher (P = 10(-4)) in patients with marked activity rhythm (I <O in upper quartile) than in those with rhythm alteration (I<O in lower qu artile), These results were supported by the multivariate Cox analysis. Mul tivariate regression analysis showed that circadian rhythms in activity (I< O; P = 3 x 10(-4)) and in WBCs (P = 0.03) as well as performance status (P = 0.02) were jointly prognostic of response, Patients with marked rest/acti vity rhythms also had better quality of life and reported significantly les s fatigue. The individual rest/activity cycle provides a novel independent prognostic factor for cancer patients' survival and tumor response as well as a quantitative indicator for quality of life.