US Study Links Night Shifts to Increased Risk of Aggressive Breast Cancer
A recent scientific study from Texas A&M University revealed that night shifts or irregular sleep schedules may significantly increase the risk of aggressive breast cancer, providing some of the strongest evidence to date that circadian rhythm disruption is not only linked to cancer but actually contributes to stimulating its development and spread.
According to a report published by “Medical Xpress,” the research, led by Dr. Tapasree Roy Sarkar, explained that chronic circadian disruption alters breast tissue structure and weakens the immune system, creating an environment suitable for cancer to grow and spread at a faster pace.
Sarkar said: “Cancer has its own rhythm, and if your biological clock is disrupted, cancer exploits that, but we have now found a new way to fight it.”
Earlier Onset and Faster Spread
The study, published in the journal Oncogene, compared two groups of genetically modified models prone to aggressive breast cancer; one group followed a natural day-night cycle, while the other was exposed to irregular lighting patterns mimicking night work.
The key results showed that:
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Cancer appeared four weeks earlier in the models suffering from circadian disruption (18 weeks vs. 22 weeks).
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Tumors were more aggressive and showed a greater tendency to spread to the lungs.
- Immune responses were significantly weakened, allowing tumors to grow.
Sarkar explained: “Not only did the tumors grow faster, but the immune system was effectively suppressed.”
Damage to Healthy Breast Tissue
In addition to tumors, researchers found that long-term circadian disruption changes the shape of healthy mammary glands, making them more susceptible to cancer.
Sarkar said: “We observed clear changes in the milk-producing breast tissue.”
The Key to Immune Suppression
The team identified a key molecule known as (LILRB4), an immune checkpoint receptor, as a primary driver of immune suppression in cancers linked to circadian disruption.
When researchers targeted this molecule, immune activity improved, and tumor growth and spread decreased significantly, even with continued sleep cycle disruption.
Sarkar said: “The (LILRB4) molecule acts as an off-switch for the immune system.”
Significance of the Discovery
Estimates indicate that between 12% and 35% of Americans work night or rotating shifts. This study highlights the importance of sleep timing as a critical factor in cancer risk and treatment methods, opening horizons for personalized treatments for the most vulnerable groups, such as night shift workers, nurses, flight attendants, and frequent travelers.
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