Time of day matters for breast cancer treatment says new study from Leicesters Hope Cancer Trials Centre
LEICSTER, UK 29th November 2022 – At least 35,000 women a year in the UK receive radiotherapy as part of treatment for breast cancer. While advances in treatment have doubled survival from this disease in the last 40 years, a substantial proportion suffer lifelong late effects which can affect quality of life. Breast shrinkage (atrophy) results in changes to the size and appearance of the breast and may cause discomfort.
As part of the EU-funded REQUITE project, with UK patients recruited in the Hope Cancer Trials Centre, scientists and clinicians from the University of Leicester and University Hospitals of Leicester NHS Trust have identified three genes linked to circadian rhythms – our internal body clocks – that are associated with increased risk of side-effects following radiotherapy at particular times in the day.
Circadian rhythms, or body clocks, are 24-hour cycles which govern the sleep / wake status and numerous cell functions that can affect the response to cancer treatment.
Dr Adam Webb of the Department of Genetics and Genome Biology at the University of Leicester says: “Radiotherapy is routinely used in the treatment of breast cancer, and atrophy as a side-effect is common. Carefully allocating treatment slots following simple DNA tests could be an effective, simple and low-cost step to improve long-term quality of life for thousands of breast cancer patients every year.
“Our study has shown that time of day of treatment can affect the severity of atrophy, and that the highest and lowest risk times are dependent on variations in key circadian genes.
“For one combination of the three gene variants, representing 14% of the population, atrophy could be reduced from 70% to 30% simply by treating in the morning as opposed to mid-afternoon.”