Impact of Sleep Apnea on Cancer Growth: Recent Research Findings

Understanding Sleep Apnea

Sleep apnea is a disorder characterized by periodic interruptions in breathing during sleep. The two primary types include central sleep apnea, where the brain fails to signal the muscles responsible for breathing, and obstructive sleep apnea, which occurs when throat muscles relax, constricting the airways.

Intermittent Hypoxia and Its Consequences

The repeated airway constriction associated with sleep apnea leads to intermittent hypoxia, a condition marked by fluctuating oxygen levels. Recent studies have indicated that this intermittent lack of oxygen, particularly from obstructive sleep apnea, may contribute to cancer development.

Study Design and Methodology

In a study published in the *American Journal of Respiratory and Critical Care Medicine*, researchers investigated the effects of sleep apnea on cancer using mice as subjects. The experiment involved 21 mice aged 20 months and 24 mice aged 2 months, simulating older and younger human populations, respectively. The mice were exposed to either six hours of room air or intermittent hypoxia daily for 10 days before being injected with lung cancer cells. After one month, the researchers euthanized the mice to analyze tumor growth.

Findings on Tumor Growth in Mice

Results indicated that young mice subjected to intermittent hypoxia exhibited increased tumor growth compared to their counterparts exposed to room air. Tumor analysis revealed a higher presence of tumor-associated macrophages in the young mice exposed to intermittent hypoxia, suggesting that these macrophages play a role in promoting tumor development.

Conclusions and Future Research Directions

The study concluded that intermittent hypoxia, as a result of sleep apnea, is a significant risk factor for cancer growth in young mice. The observed differences in immune responses between young and old mice are likely related to variations in immunological pathways involving tumor-associated macrophages. However, the specific mechanisms behind these differences remain unclear. Future research should aim to clarify how intermittent hypoxia influences these immune responses.

References

Torres, M., Campillo, N., Nonaka, P.N., Montserrat, J.M., Gozal, D., Martinez-Garcia, A.,… Almendros, I. (2018). Aging Reduces Intermittent Hypoxia-induced Lung Carcinoma Growth in a Mouse Model of Sleep Apnea. *The Journal of Respiratory and Critical Care Medicine*. https://doi.org/10.1164/rccm.201805-0892LE
Mayo Clinic. (2018, July 25). Sleep Apnea. Retrieved from https://www.mayoclinic.org/diseases-conditions/sleep-apnea/symptoms-causes/syc-20377631