Point in the light/dark cycle of the day when cytotoxic chemotherapy is administered influences inflammatory responses that can give rise to harmful treatment side-effects, suggest study findings published in Scientific Reports.1

A team of researchers from The Ohio State University, Columbus, Ohio, conducted a study using female mice to compare how cyclophosphamide and doxorubicin injections affected inflammatory responses in the spleen and the brain at 2 hours into daylight (an inactive period for mice) and at 2 hours into darkness.

Daylight exposure increased expression of inflammation-pathway genes in the spleen. Higher levels of toxic chemotherapy agent metabolites associated with inflammation were also detected. Nighttime injections, however, increased inflammatory-pathway gene expression in brain tissue.

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The timing of chemotherapy infusions might reduce inflammatory responses and the risk of side effects in human patients, speculated lead study author Jeremy C. Borniger and colleagues.

Borniger’s team was quick to acknowledge that much more research is needed. For one thing, the findings suggest that inflammatory responses to chemotherapy drugs vary differently throughout the light/dark cycle. In addition, tests of peripheral blood may not reveal biomarkers for inflammatory processes in brain tissue.


1. Borniger JC, Walker WH, Guadier-Diaz MM, et al. Time-of-day dictates transcriptional inflammatory responses to cytotoxic chemotherapy. Sci Rep. 2017 Jan 24. doi: 10.1038/srep41220 [epub ahead of print]