Posted on 02/02/2026 9:12:07 PM PST by ConservativeMind
A team of researchers have identified a fundamental mechanism that links the 24-hour circadian cycle to the precise repair of DNA breaks. This study, focused on the circadian protein Cryptochrome1 (CRY1), suggests that the time of day when radiotherapy is administered can significantly influence the effectiveness of treatment for certain types of cancer.
It is relatively common for cancer cells to be unable to repair their DNA efficiently. Treatments, such as radiotherapy, exploit this by generating DNA breaks that tumor cells are unable to repair.
This study shows DNA break repair in human cells exhibits a circadian oscillation. In a normal human cycle, repair activity peaks in the early morning and then decreases gradually until nightfall, subsequently increasing again during the night.
The research has identified this regulation depends on a central component of the biological clock, namely the CRY1 protein.
When CRY1 levels are low (corresponding to early morning in humans), efficient DNA repair is stimulated. Conversely, when CRY1 levels increase (which occurs naturally in the afternoon/evening), repair is reduced, thereby increasing the sensitivity of cells to DNA-breaking agents such as ionizing radiation.
This circadian regulation has a direct impact on cancer progression and response to radiotherapy in specific tumors. The study findings suggest that the reduction in repair that occurs when CRY1 levels are high can be exploited therapeutically.
Breast cancer patients with tumors expressing higher levels of CRY1 were found to be more sensitive to radiotherapy. In addition, a retrospective analysis of patient data revealed a significant difference in overall survival based on the time of irradiation: treatment in the afternoon/evening, when CRY1 levels are naturally higher, made tumor samples more sensitive to radiotherapy and improved patient prognosis. This effect was also observed in patients with prostate cancer and breast cancer, but not lung cancer or gliomas.
(Excerpt) Read more at medicalxpress.com ...
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Jim
Lung cancer and gliomas did not benefit from radiation timing.
Bkmk
Pinging (just in case).
Pinging (just in case)
Thanks, hand carrying to my oncologist today.
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