Women with metastatic breast cancer see their tumors activate and spread more during sleep, according to a groundbreaking study published in Nature. Disrupting sleep cycles in mice significantly reduced metastatic cells.
Nicola Aceto and colleagues at ETH Zurich noticed an intriguing pattern: circulating tumor cells (CTCs) varied by time of day in patient blood samples. Mouse studies revealed even higher CTC levels, typically collected during their rest periods.
To investigate this link between cancer and circadian rhythms, the researchers analyzed blood from 30 women with breast cancer—30 early-stage and nine with stage IV metastatic disease. Results showed over 78% of CTCs in samples taken at night.
Injecting human breast cancer cells into mice yielded similar findings: CTCs were significantly higher during rest.
Night-collected cancer cells proved far more likely to metastasize, while daytime CTCs lacked this potential.
Disrupting mice's circadian rhythms via altered light-dark cycles slashed CTC concentrations. Administering wake-like hormones (testosterone, insulin, dexamethasone) during rest also lowered CTCs, indicating hormonal control over spread from primary tumors.
Breast cancer affects about 2.3 million people worldwide annually. Early detection yields good outcomes, but metastases complicate treatment.
Further research is needed to integrate these insights into therapies. Timing of blood/tumor sampling could influence results, a factor future monitoring must consider.
