Circadian Rhythm in Energy Expenditure in Cancer In-and Out-Patients: A Comparative Study

Abstract

Unlike normal humans, an alteration in circadian pattern in energy expenditure (EE) has been observed in cancer patients. In the current cross sectional study we examined rhythm characteristics of EE in cancer in- (n = 30) and out-patients (n = 26), and healthy controls (n = 30). EE was assessed non-invasively using an electronic device - the Actical, programmed with data sampling epoch of 60 seconds. All patients and control subjects wore instrument on their non-dominant hand for 3- 4 consecutive days. Cosinor rhythmometry was used to determine the rhythm characteristics, such as 24-h average/Mesor, amplitude, and peak/acrophase of EE. Circadian and rhythm quotients were derived from the rhythm characteristics. Two- way ANOVA was employed to determine the effects of factors, ‘group’ and ‘gender’ on rhythm characteristics. A significant circadian rhythm in EE was validated in all groups. However, rhythm detection ratio, at 12 h period, was found to be low in both cancer in- and out-patients as compared to controls. Factor ‘group’ produced significant effect on 24 -h average, amplitude, acrophase, rhythm quotient and circadian quotient of EE rhythm. However, effects of factor ‘gender’ and interaction of both factors was significant on circadian quotient only. At the group level, rhythm characteristics, namely 24-h average, amplitude, and circadian quotient of three groups varied from each other significantly in the following order: in - patient < out-patient < control. In conclusion, EE rhythm deteriorated in both in- and out-patients as compared to control subjects, although the deterioration was more pronounced in cancer in-patients. We suggest that further extensive investigation involving larger sample should be carried out to validate the above findings.