Obstructive sleep apnea (OSA) is already a well-established cardiovascular risk factor in the general population. A new retrospective cohort study, drawn from a multicenter electronic health records database, shows that risk carries over — and in some cases intensifies — among people who also have cancer.
A 4.8 Million-Patient Analysis
Researchers used the TriNetX US Collaborative Network to identify adults aged 40 and older diagnosed with cancer between 2012 and 2023. Of 4,801,487 cancer patients in the database, 643,143 also had a diagnosis of obstructive sleep apnea. After propensity score matching on demographics and comorbidities, the researchers compared 629,114 patients per group for cardiovascular outcomes over the follow-up period.
The primary outcome was a composite of heart failure, atrial fibrillation or flutter, myocardial infarction, coronary revascularization, ischemic stroke, and all-cause mortality, analyzed using Cox proportional hazards models.
Heart Failure Drove the Signal
Cancer patients with OSA had a 27% higher risk of the composite cardiovascular outcome compared with matched cancer patients without OSA (hazard ratio, 1.27). But the risk wasn't evenly distributed across outcome types. Heart failure carried the strongest association, with an 80% higher risk in the OSA group (hazard ratio, 1.80), followed by atrial fibrillation or flutter (hazard ratio, 1.71), myocardial infarction (hazard ratio, 1.42), and ischemic stroke.
The sex-based subgroup analysis produced the most striking finding: among women with cancer, those who also had OSA faced nearly double the risk of heart failure compared with women with cancer alone (hazard ratio, 1.94). That association held regardless of body mass index, suggesting obesity alone does not explain the elevated risk in women.
Why Cancer and Sleep Apnea Might Compound Cardiovascular Risk
The mechanisms linking OSA to cardiovascular disease are already established in the general population: intermittent nighttime oxygen drops trigger sympathetic nervous system activation, oxidative stress, and systemic inflammation, all of which strain the cardiovascular system over years of repeated exposure. Cancer and many of its treatments — including certain chemotherapy regimens, radiation to the chest, and some targeted therapies — independently stress the heart, through mechanisms ranging from direct cardiotoxicity to accelerated atherosclerosis.
The authors' hypothesis is that these two burdens do not simply add together but may compound each other, since cancer treatment can leave the cardiovascular system with reduced reserve capacity precisely when OSA is placing additional strain on it through recurrent hypoxia. That would help explain why the excess heart failure risk in this cohort is considerably larger than the roughly 30-80% increases typically seen in general-population OSA studies.
Why women showed a substantially larger heart failure signal than men is not fully explained by the data, though the researchers note that women with OSA are more likely to be underdiagnosed and go longer without treatment, potentially extending the duration of untreated exposure to intermittent hypoxia during a period when they are also undergoing cancer treatment.
What This Means for Patients
For people undergoing or who have completed cancer treatment, this study adds weight to the case for taking sleep apnea symptoms — loud snoring, witnessed breathing pauses, gasping awakenings, or unexplained daytime fatigue — seriously rather than attributing them entirely to cancer or its treatment. Oncology visits often focus tightly on cancer-specific concerns, and sleep-disordered breathing can go unmentioned or unscreened in that context.
Given the specific finding in women, clinicians managing female cancer patients may want to lower their threshold for sleep apnea screening, particularly since OSA symptoms in women more often present atypically — as fatigue, insomnia, or mood changes rather than classic snoring — and are more prone to being overlooked. Patients with cancer who also have known or suspected OSA should discuss with both their oncology and sleep medicine teams whether treatment, such as CPAP therapy, might reduce their cardiovascular risk during and after cancer care.
