Apnea and Hypopnea Sleep Syndrome and cancer risk
For Dr. Francisco Campos Rodríguez, lung specialist and one of the investigators of this study, "confirming that Obstructive Sleep Apnea predisposes cancer can have a big impact on preventive health policies of cancer as early diagnosis and proper treatment of SAHS could prevent the development of cancer," he says.
Thus he explains that the study, conducted in 7 Spanish university hospitals, confirms a trend already studied in animal models with this sleep disease characterized by obstruction of the upper airway, which occurs during sleep causing hypoxia (lack of oxygen) and alterations in sleep structure.
"Up to now we have recognized the implication of apnea as a risk factor for cardiovascular diseases, but little had been studied about their relationship with other diseases such as cancer, especially the effects lack of oxygen and intermittent hypoxia may have on the formation and progression of tumors," says Dr. Campos.
Another author of this finding, Dr. Isaac Almendros, had already conducted studies on mice which demonstrated that intermittent hypoxia favored tumor growth and metastasis.
Now, a human study has analyzed a series of nearly 5,000 people evaluated for suspected sleep apnea between 2003 and 2007 with a monitering mean of 4.5 years.
At the end of the study period, of the 4,910 patients included 261 of them (5.3%) had developed cancer during the monitering period, and the severity indicator of sleep apnea syndrome which was related with the higher risk of cancer was nocturnal hypoxia, say the experts.
Thus, patients who spent more than 12% of the night with oxygen saturation below 90% had a risk of developing cancer that was almost two and a half times higher than patients without nocturnal hypoxia, although this association was limited to male patients who were under 65, the authors state.
These results, according to experts, "suggest that intermittent hypoxia associated with episodes of apnea may be the link between sleep apnea and cancer."