Obstructive sleep apnea and cancer: effects of intermittent hypoxia?

Does CPAP increase or protect against cancer risk in OSA: a systematic review and meta-analysis

BACKGROUND

Obstructive sleep apnea (OSA) is a prevalent sleep disorder associated with intermittent hypoxia, sleep fragmentation, and systemic inflammation, all of which may influence cancer development. Continuous positive airway pressure (CPAP) therapy is the primary treatment for OSA, yet its impact on cancer risk remains uncertain. We conducted a systematic review and meta-analysis to evaluate the association between CPAP therapy and the incidence of newly diagnosed cancer in patients with OSA.

METHODS

From inception to March 2025, a comprehensive literature search of MEDLINE, EMBASE, Cochrane databases, and reference lists was conducted. Observational studies assessing the risk of new cancer diagnoses in OSA patients treated with CPAP compared to non-CPAP users were included. Data extraction and quality assessment followed PRISMA guidelines, and meta-analysis was performed using a random-effects model.

RESULTS

Three cohort studies from France, Spain, and Canada, including 72,498 participants, met the inclusion criteria. CPAP compliance varied, defined as > 4 h/night in two studies, while one study lacked specific usage criteria. Cancer diagnoses were ascertained via national registries, hospital databases, or electronic medical records. Meta-analysis revealed a pooled hazard ratio (HR) of 0.81 (95% CI: 0.60-1.09), suggesting a potential reduction in cancer risk among CPAP users. Sensitivity analysis reduced heterogeneity (I² = 0%) and revised the HR to 0.93 (95% CI: 0.81-1.08).

CONCLUSIONS

CPAP therapy does not appear to increase cancer risk in OSA patients, but the evidence is limited and inconclusive. Further research, including randomized controlled trials, is needed to confirm these observations and explore underlying mechanisms.

The role of obstructive sleep apnea and nocturnal hypoxia as predictors of mortality in cancer patients

BACKGROUND

Obstructive sleep apnea (OSA), due to its high prevalence, has been associated with a number of comorbidities, frequently impacting the overall course of these other diseases if left untreated. Recent studies highlight a potential association between OSA and cancer. This study investigates how OSA severity and hypoxia affect cancer prognosis, aiming to elucidate how they interplay.

METHODS

Retrospective study including patients with a diagnosis of OSA after any cancer type followed up in a tertiary center during a 10-year period. OSA was mainly diagnosed after level III polysomnographic studies.

RESULTS

Nocturnal hypoxia was significantly more prevalent in patients presenting lung cancer versus other malignancies and was associated with higher rates of oncologic disease progression. Overall survival was significantly lower in severe OSA patients and also in patients presenting nocturnal hypoxia. A composite hypoxia score considering both OSA severity and significant hypoxia was an independent predictor of mortality regardless of clinical cancer staging and treatment. Shorter time between cancer and OSA diagnosis was also associated with worse prognosis.

CONCLUSION

This study suggests an association between OSA severity and nocturnal hypoxia and increased cancer mortality independently from possible confounding factors such as age, cancer clinical staging at diagnosis, treatment modality and also progression. Neoplastic patients with severe OSA and/or complex hypoxia seem to have lower overall survival rates than those with less severe OSA and nocturnal hypoxia.

Intermittent Hypoxia Mediates Cancer Development and Progression Through HIF-1 and miRNA Regulation

INTRODUCTION

There is still a debate for the link between obstructive sleep apnoea (OSA) and cancer. The mechanisms underlying this causality are poorly understood. Several miRNAs are involved in cancer development and progression with expression being influenced by hypoxia. The aims of this work were (i) to compare miRNAs expression in controls versus patients affected by OSA without or with cancer (ONCO-OSA) and (ii) in colorectal cancer cells exposed to intermittent hypoxia (IH), to evaluate miRNAs impact on tumor progression in vitro.

METHODS

We detected miRNAs by qRT-PCR in patients' sera and in CaCo2 cells exposed to 2-32h of IH with or without acriflavine (ACF), a HIF-1 inhibitor. Viability and transwell invasion test were applied to investigate the proliferation and migration of CaCo2 exposed to IH and treated with miRNA inhibitors or acriflavine. HIF-1α activity was evaluated in CaCo2 cells after IH.

RESULTS

The levels of miR-21, miR-26a and miR-210 increased in OSA and ONCO-OSA patients compared to controls. MiR-23b increased in ONCO-OSA patients, and miR-27b and miR-145 increased in OSA but not ONCO-OSA patients. MiR-21, miR-26a, miR-23b and miR-210 increased in cells after IH. IH stimulated cell proliferation and migration. This effect was reduced after either miRNA inhibition or acriflavine treatment. MiRNA inhibition reduces HIF-1α gene expression. Conversely, acriflavine reduced the expression of these miRNAs.

CONCLUSIONS

We identified a signature of miRNAs, induced by the IH environment. They could be implicated in cancer development and progression through a regulatory loop involving HIF-1.

Leveraging genetic discoveries for sleep to determine causal relationships with common complex traits

Sleep occurs universally and is a biological necessity for human functioning. The consequences of diminished sleep quality impact physical and physiological systems such as neurological, cardiovascular, and metabolic processes. In fact, people impacted by common complex diseases experience a wide range of sleep disturbances. It is challenging to uncover the underlying molecular mechanisms responsible for decreased sleep quality in many disease systems owing to the lack of suitable sleep biomarkers. However, the discovery of a genetic component to sleep patterns has opened a new opportunity to examine and understand the involvement of sleep in many disease states. It is now possible to use major genomic resources and technologies to uncover genetic contributions to many common diseases. Large scale prospective studies such as the genome wide association studies (GWAS) have successfully revealed many robust genetic signals associated with sleep-related traits. With the discovery of these genetic variants, a major objective of the community has been to investigate whether sleep-related traits are associated with disease pathogenesis and other health complications. Mendelian Randomization (MR) represents an analytical method that leverages genetic loci as proxy indicators to establish causal effect between sleep traits and disease outcomes. Given such variants are randomly inherited at birth, confounding bias is eliminated with MR analysis, thus demonstrating evidence of causal relationships that can be used for drug development and to prioritize clinical trials. In this review, we outline the results of MR analyses performed to date on sleep traits in relation to a multitude of common complex diseases.

Obstructive sleep apnoea after radiotherapy for head and neck cancer

Objective

The aim of this study is to focus attention on obstructive sleep apnoea hypopnoea syndrome (OSHAS) as a sequela of non-surgical treatments of selected head and neck cancer (HNca), sharing our experience in drug-induced sleep endoscopy (DISE). To the best of our knowledge, this is the first study that documents dynamic anatomical and functional alterations during sleep in irradiated OSAHS patients by DISE.

Methods

A retrospective study of patients affected by OSAHS referring to our department from January 2018 to December 2019 was carried out. Inclusion criteria were: patients who underwent radiation or chemo-radiation for HNca affecting upper airways that presented sleep-related breathing disorders after treatment.

Results

6 patients with moderate to severe OSAHS and a clinical story of previous non-surgical treatment for an HNca were enrolled. DISE showed in all patients typical anatomical alterations observed in irradiated individuals. Four patients were treated with continuous positive airway pressure, while 2 subjects were treated with tailored minimal invasive surgery without post-operative complications.

Conclusions

Our results suggest that minimal invasive surgical treatments can be a good therapeutic option in very selected patients with post-irradiation iatrogenic OSAHS.

Intermittent hypoxia induces tumor immune escape in murine S180 solid tumors via the upregulation of TGF-β1 in mice

PURPOSE

Studies have shown that intermittent hypoxia (IH) alters host immune functions and promotes tumor growth. However, the relevant mechanisms of these effects have not been completely elucidated. We hypothesized that IH promotes the growth of tumors by changing cytokine levels in the tumor microenvironment and inducing immune escape.

METHODS

Sarcoma-180 (S180) solid tumor cells were injected into the right flank of Kunming mice. The mice were then randomly divided into the IH and room air (RA) groups. The mice were euthanized 2 weeks after IH exposure, and the weight of tumor tissues was measured. Next, IL-6, IL-17, IL-10, and TNF-α levels in tumor tissues were measured via enzyme linked immunosorbent assay (ELISA), and hypoxia inducible factor-1α (HIF-1α) and transforming growth factor β1 (TGF-β1) expressions were examined through Western blot analysis.

RESULTS

Two weeks of IH exposure significantly accelerated the growth of S180 solid tumors. Western blot analysis results showed that the expression levels of HIF-1α and TGF-β1 in S180 tumors in the IH group were significantly upregulated compared with those in the RA group. ELISA results showed that compared with the RA group, the IH group had significantly increased TNF-α and IL-10 (P < 0.05) and significantly decreased IL-17 (P < 0.05).

CONCLUSION

IH might promote the growth of S180 solid tumors by inhibiting the antitumor immune response and inducing tumor immune escape via the upregulation of TGF-β1.

Cyclic Hypoxia: An Update on Its Characteristics, Methods to Measure It and Biological Implications in Cancer

Regions of hypoxia occur in most if not all solid cancers. Although the presence of tumor hypoxia is a common occurrence, the levels of hypoxia and proportion of the tumor that are hypoxic vary significantly. Importantly, even within tumors, oxygen levels fluctuate due to changes in red blood cell flux, vascular remodeling and thermoregulation. Together, this leads to cyclic or intermittent hypoxia. Tumor hypoxia predicts for poor patient outcome, in part due to increased resistance to all standard therapies. However, it is less clear how cyclic hypoxia impacts therapy response. Here, we discuss the causes of cyclic hypoxia and, importantly, which imaging modalities are best suited to detecting cyclic vs. chronic hypoxia. In addition, we provide a comparison of the biological response to chronic and cyclic hypoxia, including how the levels of reactive oxygen species and HIF-1 are likely impacted. Together, we highlight the importance of remembering that tumor hypoxia is not a static condition and that the fluctuations in oxygen levels have significant biological consequences.

Obstructive sleep apnea syndrome and causal relationship with female breast cancer: a mendelian randomization study

Although observational studies have reported a positive association between obstructive sleep apnea syndrome (OSAS) and breast cancer (BC) risk, causality remains inconclusive. We aim to explore whether OSAS is associated with etiology of BC by conducting a two-sample Mendelian randomization (MR) study in a Chinese population and Asian population from the Breast Cancer Association Consortium (BCAC). We found a detrimental causal effect of OSAS on BC risk in the primary analysis of our samples (IVW OR, 2.47 for BC risk per log-odds increment in OSAS risk, 95% CI = 1.86-3.27; P = 3.6×10^-10). This was very similar to results of the direct observational case-control study between OSAS and BC risk (OR = 2.80; 95% CI = 2.24-3.50; P =1.4×10^-19). Replication in the Asian population of the BCAC study also supported our results (IVW OR, 1.33 for BC risk per log-odds increment in OSAS risk, 95% CI = 1.13-1.56; P = 0.0006). Sensitivity analyses confirmed the robustness of our findings. We provide novel evidence that genetically determined higher risk of OSAS has a causal effect on higher risk of BC. Further studies focused on the mechanisms of the relationship between OSAS and breast carcinogenesis are needed.

Hypoxia and aging

Eukaryotic cells require sufficient oxygen (O₂) for biological activity and survival. When the oxygen demand exceeds its supply, the oxygen levels in local tissues or the whole body decrease (termed hypoxia), leading to a metabolic crisis, threatening physiological functions and viability. Therefore, eukaryotes have developed an efficient and rapid oxygen sensing system: hypoxia-inducible factors (HIFs). The hypoxic responses are controlled by HIFs, which induce the expression of several adaptive genes to increase the oxygen supply and support anaerobic ATP generation in eukaryotic cells. Hypoxia also contributes to a functional decline during the aging process. In this review, we focus on the molecular mechanisms regulating HIF-1α and aging-associated signaling proteins, such as sirtuins, AMP-activated protein kinase, mechanistic target of rapamycin complex 1, UNC-51-like kinase 1, and nuclear factor κB, and their roles in aging and aging-related diseases. In addition, the effects of prenatal hypoxia and obstructive sleep apnea (OSA)-induced intermittent hypoxia have been reviewed due to their involvement in the progression and severity of many diseases, including cancer and other aging-related diseases. The pathophysiological consequences and clinical manifestations of prenatal hypoxia and OSA-induced chronic intermittent hypoxia are discussed in detail.

Moderate-to-severe obstructive sleep apnea is associated with telomere lengthening

Obstructive sleep apnea (OSA) is associated with cardiometabolic diseases. Telomere shortening is linked to hypertension, diabetes mellitus, and cardiovascular diseases. Because these conditions are highly prevalent in OSA, we hypothesized that telomere length (TL) would be reduced in OSA patients. We identified 106 OSA and 104 non-OSA subjects who underwent polysomnography evaluation. Quantitative PCR was used to measure telomere length in genomic DNA isolated from peripheral blood samples. The association between OSA and TL was determined using unadjusted and adjusted linear models. There was no difference in TL between the OSA and non-OSA (control) group. However, we observed a J-shaped relationship between TL and OSA severity: the longest TL in moderate-to-severe OSA [4,918 ± 230 (SD) bp] and the shortest TL in mild OSA (4,735 ± 145 bp). Mean TL in moderate-to-severe OSA was significantly longer than in the control group after adjustment for age, sex, body mass index, hypertension, dyslipidemia, and depression (β = 96.0, 95% confidence interval: 15.4-176.6, P = 0.020). In conclusion, moderate-to-severe OSA is associated with telomere lengthening. Our findings support the idea that changes in TL are not unidirectional processes, such that telomere shortening occurs with age and disease but may be prolonged in moderate-to-severe OSA.NEW & NOTEWORTHY Here, we show that moderate-to-severe obstructive sleep apnea is associated with longer telomeres, independent of age and cardiovascular risk factors, challenging the hypothesis that telomere shortening is a unidirectional process related to age/disease. A better understanding of the mechanisms underlying telomere dynamics may identify targets for therapeutic intervention in cardiovascular aging/other chronic diseases.

Accelerated tumor growth under intermittent hypoxia is associated with hypoxia-inducible factor-1-dependent adaptive responses to hypoxia

Mounting evidence has revealed a causative role of intermittent hypoxia (IH) in cancer progression in mouse models of obstructive sleep apnea (OSA), but most studies have focused on the effects of IH following tumor implantation using an exposure to single IH frequency. Thus, we aimed to investigate 1) the potential effect of IH on the initial tumor growth in patients with OSA without an interaction with other mechanisms induced by IH in mice and 2) the influence of the IH frequency on tumor growth, which were tested using pre-conditioning with IH (Pre-IH) and 2 different IH frequencies, respectively. Pre-IH was achieved by alternatively maintaining melanoma cells between normoxia (10 min, 21% O₂) and hypoxia (50 min, 1% O₂) for 7 days (12 cycles per day) before administering them to mice. The conditions for IH-1 and IH-2 were 90 s of 12% FiO₂ followed by 270s of 21% FiO₂ (10 cycles/h), and 90 s of 12% FiO₂ and 90 s of 21% FiO₂ (20 cycles/h), respectively, for 8 h per day. Tumor growth was significantly higher in the Pre-IH group than in the normoxia group. In addition, the IH-2 group showed more accelerated tumor growth compared to the normoxia and IH-1 groups. Immunohistochemistry and gene-expression results consistently showed the up-regulation of molecules associated with HIF-1α-dependent hypoxic adaptation in tumors of the Pre-IH and IH-2 groups. Our findings reveal that IH increased tumor progression in a frequency-dependent manner, regardless of whether it was introduced before or after in vivo tumor cell implantation.