Continuous positive airway pressure, or CPAP, therapy is the most common and effective treatment for obstructive sleep apnea (OSA). A CPAP machine uses a motor to generate pressurized air, which travels through a tube and into a mask worn over the nose or mouth during sleep. This continuous stream of air acts as a splint, keeping the upper airway open and preventing the breathing pauses that characterize OSA. In recent years, questions have emerged regarding a possible connection between the use of these devices and the risk of developing lung cancer.
The Relationship Between Sleep Apnea and Cancer Risk
Untreated obstructive sleep apnea itself has become a focus of research regarding cancer risk. The primary mechanism connecting OSA to cancer is intermittent hypoxia, which involves recurrent drops in blood oxygen levels followed by reoxygenation. These fluctuations are believed to promote conditions favorable for tumor development and can trigger oxidative stress, a state where harmful molecules damage DNA.
This intermittent hypoxia can also lead to systemic inflammation, a known factor in the development of various cancers. The repeated oxygen deprivation associated with sleep apnea may also stimulate angiogenesis, the formation of new blood vessels that tumors need to grow and spread.
Sleep fragmentation, the repeated awakenings caused by breathing pauses, is another hallmark of OSA under investigation for its role in cancer. This disruption of normal sleep may impair immune function, particularly the activity of cells responsible for destroying abnormal cells before they become cancerous. Several large observational studies have suggested an association between the severity of OSA and a higher incidence of and mortality from cancer.
Investigating CPAP Machines and Carcinogens
A source of concern linking CPAP machines to cancer stems from a major product recall. In June 2021, Philips Respironics initiated a voluntary recall of millions of its CPAP, BiPAP, and mechanical ventilator devices. The issue centered on the polyester-based polyurethane (PE-PUR) foam used for sound abatement, which could degrade under conditions like high heat and humidity.
The degradation of the PE-PUR foam can lead to two primary hazards. First, it can release black particles of foam that may be inhaled or swallowed by the user. Second, the breakdown process can release certain chemicals known as volatile organic compounds (VOCs). The U.S. Food and Drug Administration (FDA) identified this as a Class I recall, its most serious designation, due to the potential for serious health consequences.
The specific chemicals released during foam degradation raised alarms because some are considered potential carcinogens, including compounds like toluene diisocyanate and toluene diamine. The FDA has been overseeing Philips’ testing and remediation efforts, which involve replacing the PE-PUR foam with a different, silicone-based material. The situation has led to extensive litigation and a consent decree to ensure the company meets regulatory requirements.
Current Research on CPAP Use and Cancer Outcomes
Separate from the device recall, researchers have investigated whether standard CPAP therapy with a properly functioning machine has any association with cancer risk. The scientific literature on this topic has produced mixed results, and a direct causal link has not been established.
Several large-scale studies have examined cancer incidence among long-term CPAP users. One study following nearly 4,500 patients found that adherent use of CPAP therapy was not associated with a reduction in the overall risk of developing any type of cancer. However, the same study noted a trend toward lower cancer incidence in adherent patients who had more severe oxygen desaturation, suggesting treatment might be more impactful in higher-risk individuals.
Another study looked at cancer risk in users of the recalled Philips devices compared to users of devices from other manufacturers. It found that cancer rates, including for lung cancer, were not higher among those using the Philips devices over a median follow-up of 7.5 years. While researchers acknowledge that longer-term follow-up may be necessary, the current balance of evidence does not support the idea that a properly functioning CPAP machine causes lung cancer.
CPAP Therapy for Patients with Lung Cancer
For individuals with lung cancer who also have obstructive sleep apnea, the focus shifts to the safety and benefits of CPAP therapy. A common concern—that the positive air pressure could cause cancer to spread (metastasize)—is considered a myth by medical experts, with no scientific evidence to support it. The pressure delivered by a CPAP machine is gentle and localized to the upper airway, not forceful enough to affect tumor biology in the lungs.
Conversely, using CPAP can offer significant advantages for lung cancer patients undergoing treatment. Cancer and its treatments often cause profound fatigue, and treating co-existing sleep apnea can improve sleep quality, reduce daytime sleepiness, and enhance overall quality of life.
Some research suggests more direct benefits. One study found that using CPAP after lung cancer surgery was associated with better appetite and breathing. Other studies have explored using CPAP during radiation therapy for lung cancer. The continuous pressure can expand the lungs, which may increase the distance between the tumor and healthy organs like the heart, potentially reducing their radiation exposure. This approach has been found to be safe and may help minimize treatment-related side effects.