biostudies-literatureWebb AJCancer Research UKNational Institute for Health Research (NIHR)104269https://www.ebi.ac.uk/biostudies/studies/S-EPMC9486558biostudies-literatureUnknown84<h4>Background</h4>Circadian rhythm impacts broad biological processes, including response to cancer treatment. Evidence conflicts on whether treatment time affects risk of radiotherapy side-effects, likely because of differing time analyses and target tissues. We previously showed interactive effects of time and genotypes of circadian genes on late toxicity after breast radiotherapy and aimed to validate those results in a multi-centre cohort.<h4>Methods</h4>Clinical and genotype data from 1690 REQUITE breast cancer patients were used with erythema (acute; n=340) and breast atrophy (two years post-radiotherapy; n=514) as primary endpoints. Local datetimes per fraction were converted into solar times as predictors. Genetic chronotype markers were included in logistic regressions to identifEBioMedicineTreatment time and circadian genotype interact to influence radiotherapy side-effects. A prospective European validation study using the REQUITE cohort.PMC9486558DRF-2014-07-079CL-2017-11-00218504Johnson KKerns SLElliott RMVega AREQUITE ConsortiumRosenstein BSWard TSeibold PGutierrez-Enriquez SBultijnck RSeoane AHarper EReyes VChoudhury ARancati TRattay TChang-Claude JVeldeman LDe Ruysscher DGomez-Caamano ATalbot CJAzria DSperk EDe Santis MCSymonds RPWebb AJAguado-Barrera MEBrengues MFachal LPost GSosa-Fajardo PBriers ECicchetti ABourgier CDunning AMTaboada-Valladares BWest CMLobato-Busto RValdagni RfalseTreatment time and circadian genotype interact to influence radiotherapy side-effects. A prospective European validation study using the REQUITE cohort.<h4>Background</h4>Circadian rhythm impacts broad biological processes, including response to cancer treatment. Evidence conflicts on whether treatment time affects risk of radiotherapy side-effects, likely because of differing time analyses and target tissues. We previously showed interactive effects of time and genotypes of circadian genes on late toxicity after breast radiotherapy and aimed to validate those results in a multi-centre cohort.<h4>Methods</h4>Clinical and genotype data from 1690 REQUITE breast cancer patients were used with erythema (acute; n=340) and breast atrophy (two years post-radiotherapy; n=514) as primary endpoints. Local datetimes per fraction were converted into solar times as predictors. Genetic chronotype markers were included in logistic regressions to identif2022-01-01T00:00:00Z2022 Oct2026-05-31T16:54:54.757Z2024-11-09T06:04:51.027ZS-EPMC94865583613047410.1016/j.ebiom.2022.104269