Nocturnal hypoxemia portends cancer incidence

Nocturnal hypoxemia is predictive of all-cancer incidence in patients suspected of having obstructive sleep apnoea (OSA), a study has found.

The study included a large multicentre cohort of 8,748 individuals (median age, 61 years; 64.5 percent male) who underwent a diagnostic sleep study. Of these, 1,161 (13.0 percent) had no OSA, 1,878 (21.5 percent) had mild OSA, 1,826 (21.0 percent) had moderate OSA, and 3,883 (44.5 percent) had severe OSA.

Patients with increasing OSA severity were of significantly higher age and body mass index and were more commonly male with medical history of diabetes, hypertension, cardiac disease, and alcohol consumption.

Over a median follow-up of 5.8 years, 718 participants (8.2 percent) developed cancer, with the most common sites being colorectal (n=129), lung (n=69), prostate (n=66), and breast (n=62). The incidence increased from 5.7 percent to 9.1 percent (p=0.0005) between the non-OSA group and the severe OSA group (incidence density rates, 10.0–16.6 per 1,000 person-years).

Kaplan-Meier survival analyses showed that cancer incidence was associated with increasing severity of OSA (p<0.0005) and nocturnal hypoxemia (p<0.0001 for both oxygen desaturation index and night-time with oxygen saturation <90 percent [T90]). The latter was associated with lung and breast malignancies specifically.

In adjusted Cox proportional-hazards models, only T90 conferred an increased risk of incident cancer (T90 ≥13 percent vs <0.01 percent: adjusted hazard ratio, 1.33, 95 percent confidence interval, 1.05–1.68; p=0.02). This association was more pronounced in older patients with obesity and no adequate OSA therapy.

Additional investigation is needed to evaluate whether OSA therapy might reduce the risk of cancer.