Link between obstructive sleep apnea and some cancers?

A recent study looked at possible relationships between obstructive sleep apnea (OSA) and certain cancers. Specifically, the study analyzed severe OSA as well as severe nocturnal hypoxemia.1 Severe OSA was “significantly associated” with a 15 percent increased risk of developing cancer, compared to people who have not been diagnosed with OSA (HR, 1.15; 95% CI, 1.02–1.30; ARD, 1.28%; 95% CI, 0.20%–2.37%; and NNH ¼ 78).1 Severe nocturnal hypoxemia, or abnormally low levels of oxygen in the blood, was associated with a 30 percent greater risk (HR, 1.32; 95% CI, 1.08–1.61; ARD, 2.38%; 95% CI, 0.47–4.31; and NNH ¼ 42).

The study used data accumulated between 1994 and 2017 at four academic hospitals in Ontario (Canada).2 The researchers looked at 33,997 individuals who had taken part in a diagnostic sleep study and were free of cancer at baseline.2 These sleep studies were conducted at hospital-related sleep clinics rather than with home sleep apnea tests. The study concluded “the severity of OSA and nocturnal hypoxemia was independently associated with incident cancer.”2

The study also noted that disruption of circadian rhythm through sleep fragmentation and/or intermittent hypoxia associated with OSA may also influence tumor cell behavior, including DNA repair, regulation of the cell cycle, and apoptosis.3 Finally, an increase in sympathetic nervous system activity associated with the acute and long-term carotid body response to intermittent hypoxia may affect tumors and their microenvironments, causing progression and metastatic activity.3,4

The study’s first author, Tetyana Kendzerska, MD, PhD, said, “I believe our results are conclusive given that they are based on about 30,000 adults free of cancer at baseline, more than 2,000 of whom developed cancer.”1  Dr. Kendzerska added that the study looked at specific cancer subtypes, noting “…we found colorectal, kidney, lung and smoking-related cancer subtypes to be all directionally  consistently associated with increased hazard of incident cancer, adjusting for known risk factors.”1

Dr. Kendzerska did add that while “Chronic hypoxemia and fragmented sleep are mechanisms by which obstructive sleep apnea is proposed to contribute to cancer development, epidemiological evidence linking OSA and cancer is still inconclusive.”1

The study findings support the hypothesis on the association between OSA and cancer incidence through intermittent hypoxemia and/or sleep fragmentation, suggesting the need for more targeted cancer risk awareness in individuals with OSA. It also calls for additional research on the way cancer biology interfaces with sleep apnea pathophysiology, including the role of OSA treatment in decreasing cancer risk. The study’s authors further claim the findings “also assist in advocating for better care and research into new therapies.”1

References:

  1. Press release, “Some cancers may be related to sleep apnea,” thoracic.org, The Journal of the American Thoracic Society, May 6, 2020.
  2. Tetyana Kendzerska, Marcus Povitz, Richard S. Leung, et al. “Obstructive Sleep Apnea and Incident Cancer: A Large Retrospective Multicenter Clinical Cohort Study.” Cancer Epidemiol Biomarkers Prev 2021;30:295-304. Published OnlineFirst December 2, 2020.
  3. Hunyor I, Cook KM. Models of intermittent hypoxia and obstructive sleep apnea: molecular pathways and their contribution to cancer. Am J Physiol Regul Integr Comp Physiol 2018: 315: R669
  4. Cole SW, Nagaraja AS, Lutgendorf SK, Green PA, Sood AK. Sympathetic nervous system regulation of the tumour microenvironment. Nat Rev Cancer 2015: 15: 563-72.