Obstructive sleep apnea can increase the risk of cancer

~~Knowledge~~

The pooled analysis of 18 studies with more than 430,000 participants in a meta-analysis found that obstructive sleep apnea (OSA) is associated with a 36% increase in cancer risk.
In the subgroup of patients with moderate to severe OSA, the risk was significantly higher, namely more than twice as high , while there was no increase in mild OSA.
The incidence of many cancers was increased, especially cancers of the central nervous system and kidney cancer, but not lung cancer.

Why this matters

The results of the meta-analysis suggest that GPs and specialists should treat OSA aggressively.Further evidence suggests that the best treatment for OSA, continuous positive pressure ventilation, may reduce the risk of cancer.
The mechanism by which OSA promotes the development of cancer is not known, but cell studies and animal models suggest that intermittent hypoxia, or sleep fragmentation—two hallmarks of OSA—promote tumor development, tumor growth, and tumor invasion or metastasis.
The totality of animal and cellular evidence led the researchers to conclude that the link between OSA and cancer risk is «biologically plausible.»

Study design

Meta-analysis of 18 observational studies with>430,000 participants after a search in the databases PubMed, Embase and Cochrane.
The results were measured as pooled relative risk (RR) for cancer in the exposed (i.e.those with OSA) compared to the risk in the non-exposed (i.e. those without OSA).
Subgroup analyses were performed by gender, severity of OSA, study design, and cancer type.
Funding: China National Science Foundation; Key Project of Guangzhou Scientific Research Project.

Key findings

OSA was associated (compared to no OSA) with a 36% increase in overall cancer risk (RR 1.36; 95% CI 1.18-1.56) when adjustments were made for confounding factors. (Relative risk is a statistical measure of the risk of an event in an exposed versus an unexposed population. The 95% confidence interval [CI] describes the range of values between which the relative risk lies with a probability of error of only 5%.)
Excluding confounding factors, OSA was associated with a 49% increased risk of cancer (RR 1.49; 95% CI 1.32-1.69).
The risk was highest in the moderate to severe OSA subgroup defined by ≥15 events/hour.The risk of cancer was more than twice as high in this subgroup (RR 2.62; 95% CI 1.64-4.19), while there was no increased risk in mild OSA (5-14.9 events/hour). The higher risk with higher exposure lends credibility to the overall results.
The risk of cancer was increased by 27% in the female subgroup with OSA (compared to no OSA; RR 1.27; 95% CI 1.06-1.51), but not in men.
According to subgroup analysis, the risk of the following cancers was increased:
- The risk of breast cancer was increased by 32% (RR 1.32; 95% CI 1.03-1.70).
- The risk of cancer of the central nervous system was increased by 71% (RR 1.71; 95% CI 1.06-2.75).
- The risk of kidney cancer was increased by 81% (RR 1.81; 95% CI 1.20-2.74).
- The risk of liver cancer was increased by 19% (RR 1.19; 95% CI 1.10-1.29).
- The risk of pancreatic cancer was increased by 23% (RR 1.23; 95% CI 1.14-1.33).
The risk of this cancers was not increased:
- lung cancer,
Melanoma,

li>Colorectal cancer,

Prostate cancer,
Tumors of the reproductive organs,
Tumors of the spinal cord, and
Thyroid cancer.

The risk of breast cancer was increased by 32% (RR 1.32; 95% CI 1.03-1.70).
The risk of cancer of the central nervous system was increased by 71% (RR 1.71; 95% CI 1.06-2.75).
The risk of kidney cancer was increased by 81% (RR 1.81; 95% CI 1.20-2.74).
The risk of liver cancer was increased by 19% (RR 1.19; 95% CI 1.10-1.29).
The risk of pancreatic cancer was increased by 23% (RR 1.23; 95% CI 1.14-1.33).