Sleep-disordered breathing in patients with newly diagnosed lung cancer

Burden of obstructive sleep apnea in patients with lung cancer and its effect on performance status

The association between lung cancer and obstructive sleep apnea has remained a matter of debate for years. Obstructive sleep apnea is thought to increase the incidence of lung cancer due to intermittent hypoxaemia and sleep fragmentation. The aim of this study is to assess the prevalence of obstructive sleep apnea in patients with lung cancer and its effect on those patients' performance status. This is a prevalence study that was conducted at Chest Diseases Department, Alexandria Main University Hospitals. We enrolled 153 patients with lung cancer. All patients underwent cardiorespiratory monitoring using a home sleep-testing device. Performance status was assessed using Karnofsky performance status scale. The study included 120 (78.4%) males and 33 (21.6%) females newly diagnosed with lung cancer. The mean age was 59.98 ± 11.11 years. Obstructive sleep apnea (apnea-hypopnea index ≥ 5) was present in 134 (87.6%) patients. Eighty-five (63.4%) patients had mild obstructive sleep apnea, 39 (29.1%) patients had moderate obstructive sleep apnea, and 10 (7.46%) patients had severe obstructive sleep apnea. Prolonged nocturnal oxygen desaturation as demonstrated by time of oxygen saturation spent below 90% (T90%) during total sleep time > 30% was present in 25 (16.3%) patients. There was a significant difference in the median value of Karnofsky performance status scale between patients with lung cancer and associated obstructive sleep apnea and those without obstructive sleep apnea. In conclusion, obstructive sleep apnea is highly prevalent among patients with lung cancer. Performance status is worse among patients with lung cancer in the presence of obstructive sleep apnea. Screening patients with lung cancer for obstructive sleep apnea is important regardless of the presence of classical symptoms of obstructive sleep apnea.

Associations among sleep-disordered breathing, sleep quality, and lung cancer in Korean patients

PURPOSE

Intermittent hypoxia and sleep fragmentation, two main features of sleep-disordered breathing (SDB), have been shown to increase the aggressiveness of lung cancer, mainly in animal and in vitro studies. However, the association between SDB and lung cancer has not been well described in human studies. In this study, we investigated the associations among SDB, sleep quality, and lung cancer in Korean patients.

METHODS

Patients with histologically diagnosed lung cancer performed a home sleep apnea test. Sleep questionnaires including the Epworth Sleepiness Scale (ESS), Insomnia Severity Index, and Pittsburgh Sleep Quality Index were also administered. Clinical information related to lung cancer was collected during the study.

RESULTS

Sixty-nine patients were enrolled, 31 of whom were poor sleepers. The overall prevalence of SDB was 57% and that of moderate to severe SDB was 27%. Underlying chronic obstructive pulmonary disease (COPD) and smoking history were significantly more frequent in patients with moderate to severe SDB compared to patients without or with mild SDB. No significant differences were observed in the apnea-hypopnea index (AHI), oxygen desaturation index (ODI), or time with oxygen saturation < 90% (T90) according to cancer cell types, mutations, stages, and survival. However, small-cell lung cancer patients showed a trend toward higher AHI, ODI, and T90 values.

CONCLUSION

The prevalence of SDB and proportion of poor sleepers were high in Korean patients with lung cancer. Paying more attention to sleep status may be helpful for patients with COPD, a smoking history, and small-cell lung cancer.

Incidence disparities of obstructive sleep apnea-associated lung cancer by gender; Korean National Health Insurance data analysis

Introduction

Obstructive sleep apnea (OSA) is known to increase the risk of various cancers. By analyzing the Korea National Health Insurance Service (KNHIS) registry, the impact of OSA on the lung cancer incidence was analyzed in a retrospective cohort group.

Methods

A retrospective cohort of adult patients newly registered with OSA in the KNHIS data from 2007 to 2017 was included and observed until December 2019 (12 years). The main outcome measure was newly diagnosed lung cancer. The control group was set with age and sex that matched those in the OSA group.

Results

The hazard ratio (HR) of OSA for lung cancer incidence showed a significantly reduced HR of 0.87 (95% CI, 0.82-0.93). The observed significance of this finding was limited to male OSA patients [HR, 0.84 (95% CI, 0.78-0.90)], while no significant association was found in female OSA patients [HR, 1.05 (95% CI, 0.91-1.21)], irrespective of their age.

Discussion

OSA patients have a lower risk of developing lung cancer, but this risk reduction is gender-specific, as female OSA patients do not show a reduction in hazard ratio.

The association between obstructive sleep apnea and lung nodule, carcinoembryonic antigen

PURPOSE

The association between obstructive sleep apnea (OSA) and cancer risks gaining more and more attention. Data on the association between OSA and lung cancer risk are limited. This study is to investigate whether a link exists between low-dose computed tomography (LDCT) scanning of the chest findings, carcinoembryonic antigen (CEA) and OSA in patients suspected of OSA.

METHODS

The cross-sectional study included patients aged 18 years or older who underwent continuous nocturnal polysomnography at our sleep center between February 2019 and November 2020. All subjects underwent chest LDCT and CEA. Patients with an apnea-hypopnea index (AHI) of ≥ 15/h were classified as clinically significant OSA group, whereas patients with an AHI < 15/h were classified as control group.

RESULTS

A total of 277 patients were enrolled in the study. 176 patients were categorized into the OSA group, while 101 patients were categorized into the control group. There is no relationship between any OSA-related parameter and presence of lung nodule or presence of ≥ 6 mm lung nodule in the binary logistic regression analysis. OSA group demonstrated a significant higher value of CEA than control group. Stepwise multiple linear regression analysis showed that lowest O₂ saturation (β = - 0.256, p < 0.001), smoking status (β = 0.156, p = 0.007) and age (β = 0.153, p = 0.008) were independent predictors of elevated CEA.

CONCLUSIONS

OSA was independently related to the elevated of serum CEA level, but not with presence of pulmonary nodule or ≥ 6 mm pulmonary nodule in LDCT. Further well-designed longitudinal studies with pathology available are needed to identify the association between OSA and risk of lung cancer.

Cancer-related Fatigue in Lung Cancer: A Research Agenda: An Official American Thoracic Society Research Statement

Background: Fatigue is the most common symptom among cancer survivors. Cancer-related fatigue (CRF) may occur at any point in the cancer care continuum. Multiple factors contribute to CRF development and severity, including cancer type, treatments, presence of other symptoms, comorbidities, and medication side effects. Clinically, increasing physical activity, enhancing sleep quality, and recognizing sleep disorders are integral to managing CRF. Unfortunately, CRF is infrequently recognized, evaluated, or treated in lung cancer survivors despite more frequent and severe symptoms than in other cancers. Therefore, increased awareness and understanding of CRF are needed to improve health-related quality of life in lung cancer survivors. Objectives: 1) To identify and prioritize knowledge and research gaps and 2) to develop and prioritize research questions to evaluate mechanistic, diagnostic, and therapeutic approaches to CRF among lung cancer survivors. Methods: We convened a multidisciplinary panel to review the available literature on CRF, focusing on the impacts of physical activity, rehabilitation, and sleep disturbances in lung cancer. We used a three-round modified Delphi process to prioritize research questions. Results: This statement identifies knowledge gaps in the 1) detection and diagnostic evaluation of CRF in lung cancer survivors; 2) timing, goals, and implementation of physical activity and rehabilitation; and 3) evaluation and treatment of sleep disturbances and disorders to reduce CRF. Finally, we present the panel's initial 32 research questions and seven final prioritized questions. Conclusions: This statement offers a prioritized research agenda to 1) advance clinical and research efforts and 2) increase awareness of CRF in lung cancer survivors.

Sleep-Disordered Breathing in Newly Diagnosed Patients of Lung Cancer

Sleep-disordered breathing (SDB) is highly prevalent in patients with cancer and affects their prognosis. However, data on SDB in lung cancer patients are lacking, and few studies have conducted level I polysomnography (PSG) in this patient population. This study aimed to measure SDB in newly diagnosed lung cancer patients at the sleep clinic of a tertiary respiratory institute in New Delhi, India, for eight months. This study included 30 patients. Participants received a clinical examination, completed a sleep questionnaire, and then underwent overnight PSG. We scored sleep parameters according to the American Academy of Sleep Medicine guidelines. Both descriptive and inferential statistics were used to analyze the data. We used univariate analysis with chi-square testing, and p<0.05 was considered significant. SDB and obstructive sleep apnea (OSA) were found in 66.6% and 56.6% of patients, respectively. Mild, moderate, and severe OSA were seen in 26.6%, 16.6%, and 13.3% of patients, respectively. Nocturnal oxygen desaturation (NOD) or NOD90 (i.e., when >30% of sleep time was spent with oxygen saturation levels <90%) was seen in 13.3% of patients. Adenocarcinoma was the most common histological variant of cancer. Tumor-node-metastasis staging was significantly associated with the presence of OSA (p=0.045). Lung cancer patients should receive routine PSG to identify and manage patients with SDB, especially given that symptoms of SDB such as easy fatigability and non-refreshing sleep are overlooked as symptoms of lung cancer. Proper management of SDB or OSA would help improve patients' quality of life and improve their overall prognosis.

PCAT19 Regulates the Proliferation and Apoptosis of Lung Cancer Cells by Inhibiting miR-25-3p via Targeting the MAP2K4 Signal Axis

Both PCAT19 and miR-25-3p have been reported in lung cancer studies, but whether there is a correlation between the two and whether they jointly regulate the progress of lung cancer have not been reported yet. Therefore, this study carried out a further in-depth research. The expression of PCAT19 was detected in lung cancer (LC) tissues and cells by quantitative real-time polymerase chain reaction (qRT-PCR). The effect of PCAT19 on tumor growth was detected in a tumor-bearing model of nude mice. PCAT19-transfected cells were treated with Honokiol and anisomycin. The effects of PCAT19 on proliferation, apoptosis, and cycle of LC cells were investigated by biomolecule experiments. The effects of PCAT19 on the expressions of mitogen-activated protein kinase- (MAPK-) related proteins were evaluated by western blotting. The expression of PCAT19 was decreased in LC tissues and related to patient survival, tumor size, and pathology. In addition, upregulation of PCAT19 hindered LC cell proliferation, miR-25-3p expression, and the activation of extracellular regulated protein kinases (ERK) 1/2, p38, and c-Jun N-terminal kinase (JNK), while facilitating LC cell apoptosis. Furthermore, upregulation of PCAT19 reversed the effects of Honokiol and anisomycin on promoting cell proliferation and inhibiting cell apoptosis. Collectively, our findings show that upregulated PCAT19 suppresses proliferation yet promotes the apoptosis of LC cells through modulating the miR-25-3p/MAP2K4 signaling axis.

Prevalence of Sleep Disturbance in Patients With Cancer: A Systematic Review and Meta-Analysis

Sleep disturbance is one of the most common and troubling symptoms that harm the quality of life throughout all phases of treatment and stages of the illness among patients with cancer. The aim of this meta-analysis is to examine the present status of sleep disturbance prevalence in patients with cancer. The following databases were searched: PubMed, CINAHL, MEDLINE, EMBASE, PsycINFO, from inception to April 2021. Prevalence rates were pooled with meta-analysis using a random-effects model. A total of 160 studies (N = 46,279) published between 1998 and 2021 met the inclusion criteria. The overall prevalence of sleep disturbance was 60.7% (26,448/46,279 participants, 95% CI 58.1–63.3%) with significant heterogeneity between studies (p < .000, τ² = .0000, I² = 96.4%). This meta-analysis highlights the importance of developing optimal monitoring strategies to reduce sleep disturbance and improve the quality of life of cancer patients.

Development and Validation of a Prognostic Nomogram in Lung Cancer With Obstructive Sleep Apnea Syndrome

To analyze the prognostic factors and survival rate of lung cancer patients with obstructive sleep apnea (OSA) by nomogram. The nomogram was established by a development cohort (n = 90), and the validation cohort included 38 patients. Factors in the nomogram were identified by Cox hazard analysis. We tested the accuracy of the nomograms by discrimination and calibration, and plotted decision curves to assess the benefits of nomogram-assisted decisions. There were significant difference in sex, apnea hypopnea index (AHI), Tumor Node Metastasis (TNM), coronary heart disease, lowest arterial oxygen saturation [LSpO2 (%)], oxygen below 90% of the time [T90% (min)], the percentage of the total recorded time spend below 90% oxygen saturation (TS90%) and oxygen desaturation index (ODI4) between lung cancer subgroup and lung cancer with OSA subgroup (P < 0.05). Lung cancer patients with OSA age, AHI, TNM, cancer types, BMI and ODI4 were independent prognostic factor. Based on these six factors, a nomogram model was established. The c-index of internal verification was 0.802 (95% CI 0.767–0.885). The ROC curve analysis for the nomogram show 1-year survival (AUC = 0.827), 3-year survival (AUC = 0.867), 5-year survival (AUC = 0.801) in the development cohort were good accuracy. The calibration curve shows that this prediction model is in good agreement. Decision curve analysis (DCA) suggests that the net benefit of decision-making with this nomogram is higher, especially in the probability interval of <20% threshold. The nomogram can predict the prognosis of patients and guide individualized treatment.

Cancer and obstructive sleep apnea: An updated meta-analysis

OBJECTIVE

The relationship between cancers and obstructive sleep apnea (OSA) has been discussed for decades. However, the previous meta-analysis led to opposite conclusions. To further investigate this controversial issue, we performed this systematic review and meta-analysis update.

METHODS

PubMed, Embase, and the Cochrane Library were systematically searched and studies on "cancer and OSA" were all included. Two reviewers independently searched articles, extracted data, and assessed the quality of included studies. Moreover, the overall incidence of cancer and OSA in corresponding populations was calculated.

RESULTS

Of the 1434 titles identified, 22 articles involving more than 32.1 million patients were included in this meta-analysis. An overall incidence of OSA positive individuals in cancer was 46 (95%CI, 27-67)%, and the prevalence of cancers in OSA patients reached 1.53 (95%CI, 1.01-2.31) times higher than non-OSA individuals.

CONCLUSION

This meta-analysis indicated that there was a high prevalence of OSA in cancer patients, and individuals with OSA were more likely to develop tumors, and the incidence was related to the severity of OSA.

Effect of Conventional Nursing Combined with Bedtime Oculomotor Training on Sleep Quality and Body Immunity of Advanced Lung Cancer Patients

Objective. The aim of this study is to explore the effect of conventional nursing combined with bedtime oculomotor training on sleep quality and body immune of advanced lung cancer patients. Methods. By means of a retrospective study, 120 advanced lung cancer patients admitted to our hospital from January 2019 to January 2020 were selected as the research subject and divided into the intervention group (PSQI (Pittsburgh Sleep Quality Index) score≥10 points, n = 60) and the control group (PSQI score<10 points, n = 60). Conventional nursing was performed to the control group, and an eye movement exercise before sleep was added additionally in the intervention group, 30 min each time, once a day, and 5 times a week for 3 months, so as to compare their sleep quality, body immunity indexes, negative emotion scores, adverse reaction rate (ARR), quality of life, and satisfaction with nursing. Results. After nursing, the intervention group obtained a significantly lower PSQI score (5.54 ± 1.23 VS 7.98 ± 1.65, $P<0.05$ ), better body immunity indexes ( $P<0.001$ ), lower negative emotion scores ( $P<0.05$ ), lower ARR ( $P<0.05$ ), better quality of life ( $P<0.001$ ), and higher satisfaction with nursing ( $P<0.05$ ) than the control group. Conclusion. Combining conventional nursing with the eye movement exercise before sleep can alleviate negative emotions, improve the sleep quality, promote body immunity, and reduce the ARR, which is more satisfying to patients and should be applied and promoted in practice.

Obstructive Sleep Apnea and Lung Cancer: A Systematic Review and Meta-analysis of 4,885,518 Participants

RATIONALE

In 2020, lung cancer was the leading cause of cancer deaths, and was the most common cancer in men. Though obstructive sleep apnea (OSA) has been postulated to be carcinogenic, epidemiological studies are inconclusive.

OBJECTIVES

We conducted this systematic review and meta-analysis to investigate the associations between OSA and the incidence and mortality of lung cancer.

METHODS

Four electronic databases (PubMed, Embase, Cochrane Library, and Scopus) were searched from inception till 6 June 2021 for randomized controlled trials and observational studies examining the association between sleep apnea and incident lung cancer. Two reviewers selected studies, extracted data, graded the risk of bias using the Newcastle-Ottawa scale and the quality of evidence using GRADE. Random-effects models were used to meta-analyze the maximally covariate-adjusted associations.

RESULTS

Seven studies were included in our systematic review; among which four were suitable for meta-analysis, comprising a combined cohort of 4,885,518 patients. Risk of bias was low to moderate. OSA was associated with a higher incidence of lung cancer (HR 1.25, 95%CI 1.02 to 1.53), with substantial heterogeneity (I²=97%). Heterogeneity was eliminated, with a stable pooled effect size, when including the three studies with at least 5 years of median follow-up (HR 1.32, 95%CI 1.27 to 1.37, I²=0%).

CONCLUSIONS

In this meta-analysis of 4,885,518 patients from four observational studies, patients with OSA had approximately 30% higher risk of lung cancer, compared to those without OSA. We suggest more clinical studies with longer follow-up as well as biological models of lung cancer be performed to further elucidate this relationship.

Insomnia in patients with advanced lung cancer admitted to palliative care services

AIM

To assess the prevalence of insomnia and possible associated factors in patients with advanced lung cancer admitted to different settings of palliative care.

METHODS

Secondary analysis of a consecutive sample of patients with advanced lung cancer receiving palliative care. Epidemiological and clinical data, treatments received in the last month, Karnofsky status, Edmonton Symptom Assessment System (ESAS), Athens Insomnia Scale and the Hospital Anxiety and Depression Scale (HADS), as well as concomitant medical treatment were recorded.

RESULTS

One-hundred-eight-two patients with advanced lung cancer were surveyed. The mean age was 69.9 years (SD 10.8), and 121 patients (66%) were men. The majority of patients showed consistent levels of insomnia. A poor Karnofsky level, pain, nausea, and drowsiness, time from diagnosis (1-3 years), HADS anxiety, and HADS depression, were positively associated with insomnia.

CONCLUSIONS

About 50% of patients with advanced lung cancer admitted to palliative care services had relevant insomnia. Several factors associated with insomnia have been identified and should prompt physicians for a careful examination and subsequent treatment.

Severe OSA associated with higher risk of mortality in stage III and IV lung cancer

STUDY OBJECTIVES

OSA has been associated with increased cancer incidence and mortality. The aim of this study was to investigate cancer-related mortality, overall survival, and progression-free survival in patients with suspected OSA and lung cancer.

METHODS

This was a case series analysis of lung cancer from a sleep cohort with suspected OSA between 2009 and 2014. The AHI, hypoxia index, and survival outcome were recorded. Immunohistochemistry was used to analyze hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor expression in tumor pathology.

RESULTS

In the sleep cohort comprising 8,261 patients, a total of 23 patients had lung cancer. The incidence of lung cancer was significantly higher in the sleep cohort than in the entire adult population in Taiwan (crude incidence rate: 242.1 vs 51.5 per 10⁵ persons, P < .01). The 3-year cancer-related mortality was 25% in AHI < 15 events/h, 50% in AHI 15-29 events/h, and 80% in AHI ≥ 30 events/h (χ² test for trend, P = .03). In Kaplan-Meier survival analysis, patients with stage III-IV lung cancer and AHI < 30 events/h exhibited significantly better overall survival (P = .02) and progression-free survival (P = .02) than patients with severe OSA. Overexpression of HIF-1α and vascular endothelial growth factor was shown in 63% and 45% of lung tumor samples. Overexpression of HIF-1α was positively associated with AHI (P = .04).

CONCLUSIONS

In this preliminary case series, severe OSA is associated with an increased risk of cancer mortality in patients with stage III-IV lung cancer. AHI was significantly associated with HIF-1α overexpression.

Atractylon treatment prevents sleep-disordered breathing-induced cognitive dysfunction by suppression of chronic intermittent hypoxia-induced M1 microglial activation

Chronic intermittent hypoxia (CIH) induced by sleep-disordered breathing (SDB) is a key factor involved in cognitive dysfunction (CD). Increasing evidence has shown that atractylon (ATR) has anti-inflammatory effects. However, it remains unclear if ATR has a protective effect against SDB-induced nerve cell injury and CD. So, in the present study, CIH-exposed mice and CIH-induced BV2 cells were used to mimic SDB. The results showed that ATR treatment decreased CIH-induced CD and the expression of inflammatory factors in the hippocampal region by suppression of M1 microglial activation and promotion of M2 microglial activation. Also, ATR treatment promoted sirtuin 3 (SIRT3) expression. Down-regulation of SIRT3 decreased the protective effect of ATR against CIH-induced microglial cell injury. Furthermore, in vitro detection found that SIRT3 silencing suppressed ATR-induced M2 microglial activation after exposure to CIH conditions. Taken together, these results indicate that ATR treatment prevents SDB-induced CD by inhibiting CIH-induced M1 microglial activation, which is mediated by SIRT3 activation.

Evaluation of Subjective Sleep Disturbances in Cancer Patients: A Cross-Sectional Study in a Radiotherapy Department

Background: The factors associated with sleep disturbances in cancer patients remains unclear. This study aimed to explore the prevalence of sleep disorders and predictors associated with sleep disturbance in cancer patients from a radiotherapy department. Methods: Patients with cancers were recruited before the start of radiotherapy from our institution between January 2019 and February 2020. Pittsburgh Sleep Quality Index (PSQI) scale was used to assess sleep quality. Descriptive statistics, Chi-square test, and multivariate logistic regression analysis were used to conduct statistical analysis. Results: A total of 330 eligible patients were included. Of them, 38.3% (n = 127) had the globe PSQI score >7, indicating that they suffered from sleep disorders. Patients with lung cancer (45.2%) were more likely to suffer from sleep disturbance, followed by cervical cancer (43.8%), nasopharyngeal carcinoma (41.7%), esophageal cancer (41.5%), breast cancer (37.7%), and colorectal cancer (30%). With regard to the PSQI components, the mean sleep duration was 8 h, 20.3% (n = 67) of them reported poor subjective sleep quality, 6.1% (n = 20) needed medication to improve sleep, and 53.6% (n = 177) suffered daytime dysfunction. Multivariate logistic regression models showed body mass index (BMI) ≥ 20 kg/m² [odds ratio (OR) 0.599, 95% confidence interval (CI) 0.329-0.948, P = 0.031] and the receipt of surgery (OR 0.507, 95% CI 0.258-0.996, P = 0.048) were the significant favorable predictors for sleep disturbance, while age, gender, marital status, education level, comorbidity, metastasis status, diagnostic status, and cancer type were not significantly associated with sleep disturbance. Conclusions: Approximately 40% of the cancer patients suffer from sleep disturbance before the start of radiotherapy. Patients with BMI ≥ 20 kg/m² and receiving surgery are less likely to develop sleep disturbance in comparison with others.

Sleep disorders and cancer: State of the art and future perspectives

A bidirectional connection between sleep and cancer exists; however, the specific associations between individual sleep disorders and particular tumors are not very clear. An accurate assessment of sleep disorders in cancer patients is necessary to improve patient health, survival, response to therapy, quality of life, reduction of comorbidities/complications. Indeed, recent scientific evidence shows that knowledge and management of sleep disorders offer interesting therapeutic perspectives for the treatment of cancer. In light of this need, the objective of this review is to assess the evidence highlighted in the research of the last ten years on the correlation between each specific category of sleep disorder according to the International Classification of Sleep Disorders 3rd Ed. and several types of tumor based on their anatomical location (head-neck, including the brain and thyroid; lung; breast; ovary; endometrium; testes; prostate; bladder; kidney; gastrointestinal tract, subdivided into: stomach, liver, colon, pancreas; skin; bone tumors; hematological malignancies: leukemia, lymphoma, multiple myeloma, polycythemia), in order to evaluate what is currently known about: 1) sleep disorders as cancer risk factor; 2) tumors associated with the onset of sleep disorders; 3) targeted therapies of sleep disorders in cancer patients and new oncological perspectives following the evaluation of sleep.

Sleep Apnoea Adverse Effects on Cancer: True, False, or Too Many Confounders?

Obstructive sleep apnoea (OSA) is a prevalent disorder associated with increased cardiovascular, metabolic and neurocognitive morbidity. Recently, an increasing number of basic, clinical and epidemiological reports have suggested that OSA may also increase the risk of cancer, and adversely impact cancer progression and outcomes. This hypothesis is convincingly supported by biological evidence linking certain solid tumours and hypoxia, as well as by experimental studies involving cell and animal models testing the effects of intermittent hypoxia and sleep fragmentation that characterize OSA. However, the clinical and epidemiological studies do not conclusively confirm that OSA adversely affects cancer, even if they hold true for specific cancers such as melanoma. It is likely that the inconclusive studies reflect that they were not specifically designed to test the hypothesis or because of the heterogeneity of the relationship of OSA with different cancer types or even sub-types. This review critically focusses on the extant basic, clinical, and epidemiological evidence while formulating proposed directions on how the field may move forward.

Obstructive sleep apnea and cancer: a complex relationship

PURPOSE OF REVIEW

Obstructive sleep apnea (OSA) has been recognized as a risk factor for cancer mainly through hypoxia, based on studies that did not distinguish among cancer types. The purpose of this review is to discuss the most recent data on epidemiology and pathophysiology of the OSA-cancer association.

RECENT FINDINGS

According to epidemiological studies, OSA may have different influences on each type of cancer, either increasing or decreasing its incidence and aggressiveness. Time spent with oxygen saturation below 90% appears the polysomnographic variable most strongly associated with unfavorable effects on cancer. Experimental studies support the role of hypoxia as an important risk factor for cancer growth and aggressiveness, especially when it shows an intermittent pattern. These effects are largely mediated by the hypoxia-inducible factor, which controls the synthesis of molecules with effects on inflammation, immune surveillance and cell proliferation. Sleep fragmentation participates in increasing cancer risk. Modulating effects of age remain controversial.

SUMMARY

Effects of OSA on cancer may largely vary among neoplastic diseases, both in their magnitude and direction. The worse risk associated with intermittent rather than persistent hypoxia, and the effects of OSA therapy on cancer natural history are still poorly known, and deserve new careful studies.

The Association of Sleep Disorders, Obesity and Sleep-Related Hypoxia with Cancer

BACKGROUND

Sleep disorders have emerged as potential cancer risk factors.

OBJECTIVE

This review discusses the relationships between sleep, obesity, and breathing disorders with concomitant risks of developing cancer.

RESULTS

Sleep disorders result in abnormal expression of clock genes, decreased immunity, and melatonin release disruption. Therefore, these disorders may contribute to cancer development. Moreover, in sleep breathing disorder, which is frequently experienced by obese persons, the sufferer experiences intermittent hypoxia that may stimulate cancer cell proliferation.

DISCUSSION

During short- or long- duration sleep, sleep-wake rhythm disruption may occur. Insomnia and obstructive sleep apnea increase cancer risks. In short sleepers, an increased risk of stomach cancer, esophageal squamous cell cancer, and breast cancer was observed. Among long sleepers (>9 hours), the risk of some hematologic malignancies is elevated.

CONCLUSION

Several factors including insomnia, circadian disruption, obesity, and intermittent hypoxia in obstructive sleep apnea are contributing risk factors for increased risk of several types of cancers. However, further studies are needed to determine the more significant of these risk factors and their interactions.

Associations between objectively assessed physical fitness levels and sleep quality in community-dwelling elderly people in South China

PURPOSE

The aim of this study was to explore associations between objectively assessed physical fitness levels and sleep quality in community-dwelling elderly people in South China.

METHODS

One thousand one hundred thirty-six (504 males and 632 females) community-dwelling adults aged ≥ 50 years old in Dongguan City, South China, were included in the cross-sectional study. All the participants were asked to complete all prepared multi-instrument questionnaire, including the Pittsburgh Sleep Quality Index (Chinese version), for the assessment of the sleep quality and information regarding socio-demographic characteristics, lifestyle, and physical health data. Physical fitness was measured by grip strength, one-leg standing test (OLST) with eyes open, back scratch test, and the forced vital capacity (FVC).

RESULTS

The percentage of poor sleep quality among elderly people (≥ 50 years old) was up to 18.2%. Lower FVC was associated with the poorer sleep quality (adjusted OR = 0.74 per SD increase; P = 0.009), and participants with lower performance in back scratch test were more likely to suffer poor sleep quality (adjusted OR = 1.17 per SD increase; P = 0.035). The independent contribution of physical fitness tests results on the risk of poor sleep quality was 22.1%.

CONCLUSIONS

Our results indicated that sleep quality was strongly associated with physical fitness among community-dwelling elderly people; the lower of the physical fitness predicted poorer sleep quality.

Anti-tumor effect of endostatin in a sleep-apnea mouse model with tumor

BACKGROUND

Obstructive sleep apnea (OSA) is associated with cancer incidence and mortality. The underlying mechanism is unclear. This study aims to evaluate the influence of intermittent hypoxia (IH), a novel hallmark of OSA, on tumor and to access the anti-tumor effect of endostatin on a mouse model with OSA.

METHODS

The C57BL/6 J mice were randomly classified into four groups: control (normoxia) (CTL), control plus endostatin (CTL + ED), IH, and IH plus endostatin (IH + ED). Mice in IH and IH + ED groups were subjected to IH 8 h per day in 5 weeks. Lewis lung cancer cells were injected into the flank of each mouse after 1 week of IH exposure. Endostatin was also intraperitoneally injected after tumor volume reached about 200 mm³. The maximum standard uptake values (SUVmax) were detected by micro-positron emission tomography-computed tomography (micro-PET-CT) imaging prior and post-endostatin administration. Microvessel density (MVD) and vascular endothelial growth factor (VEGF) were determined for evaluating the anti-tumor effect of endostatin among the normoxia and IH conditions.

RESULTS

Mice had higher SUVmax in the IH group than the CTL group (p < 0.01). When compared with mice in the CTL group, those in the IH group had significantly greater MVD values (p < 0.001). The SUVmax can be attenuated by endostatin both in the CTL (p < 0.01) and IH conditions (p < 0.001). When compared with CTL group, mice in the IH group had increased MVD values (p < 0.001) and VEGF expression both at mRNA (p < 0.05) and protein levels (p < 0.001 in western blotting results). Treatment with endostatin attenuated serum and tissue VEGF levels, lowering the MVD values. As compared to normoxia condition, the endostatin-therapeutic effects were more significant under the IH condition (p < 0.05 in western blotting results).

CONCLUSIONS

Micro-PET-CT imaging is a promising non-invasive technique to evaluate the tumor metabolic characteristics under IH condition in vivo. The anti-tumor effect of endostatin under IH condition is superior to that of the normoxia condition.