Night Shift Linked to Aggressive Breast Cancer

Working the night shift or frequently crossing time zones can disrupt a woman's natural sleep cycle, potentially increasing her risk for aggressive breast cancer. Researchers have found that these circadian disruptions can alter the structure of mammary glands and weaken the body's immune defenses, thereby promoting cancer development.

The study utilized genetically engineered models, revealing that those with disrupted internal clocks developed aggressive breast cancer earlier than models on a regular day-night schedule. Tumors in the disrupted group were more aggressive and showed a greater tendency to spread, indicating poorer outcomes.

Beyond accelerating tumor growth, the disruption suppressed immune surveillance and changed the makeup of healthy breast tissue, making it more susceptible. These findings highlight the critical role of circadian rhythms in maintaining bodily defenses and suggest new avenues for counteracting cancer's progression.