***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background A simple and accurate survival prediction tool can facilitate decision making processes for hospice patients with advanced cancers . The objectives of this study were to explore the association of cardiac autonomic functions and survival in patients with advanced cancer and to evaluate the prognostic value of heart rate variability ( HRV ) in 7-day survival prediction . Methods A prospect i ve study was conducted on 138 patients with advanced cancer recruited from the hospice ward of a regional hospital in southern Taiwan . Information on functional status and symptom burden of the patients was recorded . Frequency-domain HRV was obtained for the evaluation of cardiac autonomic functions at admission . The end point of the study was defined as the survival status at day 7 after admission to the hospice ward . Multivariate logistic regression analyses were performed to evaluate the independent associations between HRV indices and survival of 7 days or less . Results The median survival time of the patients was 20 days ( 95 % CI , 17–28 days ) . Results from the multivariate logistic regression analysis indicated that the natural logarithm-transformed high-frequency power ( lnHFP ) of a value less than 2 ( OR = 3.8 , p = 0.008 ) and ECOG performance status of 3 or 4 ( OR = 3.4 , p = 0.023 ) were significantly associated with a higher risk of survival of 7 days or less . Receiver operating characteristic ( ROC ) curve analysis revealed that the area under the curve was 0.71 ( 95 % CI , 0.61–0.81 ) . Conclusions In hospice patients with non-lung cancers , an lnHPF value below 2 at hospice admission was significantly associated with survival of 7 days or less . HRV might be used as a non-invasive and objective tool to facilitate medical decision making by improving the accuracy in survival prediction In patients with drug-resistant hypertension , chronic electric stimulation of the carotid baroreflex is an investigational therapy for blood pressure reduction . We hypothesized that changes in cardiac autonomic regulation can be demonstrated in response to chronic baroreceptor stimulation , and we analyzed the correlation with blood pressure changes . Twenty-one patients with drug-resistant hypertension were prospect ively included in a sub study of the Device Based Therapy in Hypertension Trial . Heart rate variability and heart rate turbulence were analyzed using 24-hour ECG . Recordings were obtained 1 month after device implantation with the stimulator off and after 3 months of chronic electric stimulation ( stimulator on ) . Chronic baroreceptor stimulation  decreased office blood pressure from 185±31/109±24 mm Hg to 154±23/95±16 mm Hg ( P<0.0001/P=0.002 ) . Mean heart rate decreased from 81±11 to 76±10 beats per minute−1 ( P=0.001 ) . Heart rate variability frequency-domain parameters assessed using fast Fourier transformation ( FFT ; ratio of low frequency : high frequency : 2.78 versus 2.24 for off versus on ; P<0.001 ) were significantly changed during stimulation of the carotid baroreceptor , and heart rate turbulence onset was significantly decreased ( turbulence onset : −0.002 versus −0.015 for off versus on ; P=0.004 ) . In conclusion , chronic baroreceptor stimulation causes sustained changes in heart rate variability and heart rate turbulence that are consistent with inhibition of sympathetic activity and increase of parasympathetic activity in patients with drug-resistant systemic hypertension ; these changes correlate with blood pressure reduction . Whether the autonomic modulation has favorable cardiovascular effects beyond blood pressure control should be investigated in further studies BACKGROUND Patients with coronary heart disease ( CHD ) who experience depressed mood or psychological stress exhibit decreased vagal control of heart rate ( HR ) , as assessed by spectral analysis of HR variability ( HRV ) . Myocardial infa rct ion and sudden cardiac death are independently associated with depression and stress , as well as impaired vagal HR control . This study examined whether a behavioral neurocardiac intervention to reduce stress or depression can augment cardiovagal modulation in CHD patients . We hypothesized that ( 1 ) cognitive-behavioral training with HRV biofeedback would augment vagal recovery from acute stress , and ( 2 ) vagal regulation of HR would be inversely associated with stress and depression after treatment . METHODS This r and omized controlled trial enrolled 46 CHD patients from 3 clinics of CHD risk reduction in Toronto and Vancouver , Canada . Subjects were r and omized to five 1.5-hour sessions of HRV biofeedback or an active control condition . Outcome was assessed by absolute and normalized high-frequency spectral components ( 0.15 - 0.50 Hz ) of HRV , and by the Perceived Stress Scale and Centre for Epidemiologic Studies in Depression scale . RESULTS Both groups reduced symptoms on the Perceived Stress Scale ( P = .001 ) and Centre for Epidemiologic Studies in Depression scale ( P = .004 ) . Hierarchical linear regression determined that improved psychological adjustment was significantly associated with the high-frequency index of vagal HR modulation only in the HRV biofeedback group . Adjusted R 2 was as follows : HRV biofeedback group , 0.86 for stress ( P = .02 ) and 0.81 for depression ( P = .03 ) ; versus the active control group , 0.04 ( P = .57 ) and 0.13 ( P = .95 ) , respectively . CONCLUSION A novel behavioral neurocardiac intervention , HRV biofeedback , can augment vagal HR regulation while facilitating psychological adjustment to CHD Recent studies suggest that vagal nerve activity , indexed by heart rate variability ( HRV ) , could have a prognostic role in cancer . However , most studies did not control adequately for confounders and included cardiac patients . Furthermore , the validity of this prognostic role needs to be tested in different types of cancer . The present study tested the prognostic role of HRV in prostate cancer ( PC ) and non-small cell lung cancer ( NSCLC ) patients , using a historical prospect i ve design . HRV was derived from brief 10 sec ECGs obtained at approximately the time of diagnosis in 113 PC patients and 133 NSCLC patients . Outcomes included prostate-specific antigen ( PSA ) at 6 and 24 months in PC , and overall survival ( OS ) ( for the full sample ) and survival time ( for the deceased patients ) in NSCLC . Furthermore , the possible mediating role of C-reactive protein ( CRP ) was tested ( in NSCLC ) , as well as whether age and stage moderated the relationship between HRV and prognosis in both types of cancer . In the PC patients , HRV significantly inversely predicted PSA levels at 6 and 24 months , independent of confounders . Furthermore , this was particularly significant in metastatic PC patients , indicating moderation by stage . In NSCLC patients , HRV did not predict OS and survival time , but it did positively predict survival time in patients under the age of 65 , independent of confounders . Additionally , CRP was not found to mediate the relationship between HRV and OS or survival time in NSCLC . The present results partly support previous studies and extend them to two additional common types of cancer , using a more rigorous control over confounders . Together with recent experimental findings , these results propose a modulatory role of vagal nerve activity in cancer . Therefore , routine measurement of HRV in estimating prognosis in cancer may be considered In a historical prospect i ve cohort investigation of 4131 patients undergoing peptic ulcer surgery in 53 hospitals in the western part of Denmark from 1955 through 1960 , the risk of subsequent gastric cancer development was studied . The patients were followed with regard to gastric cancer development until their death or the end of the year 1982 and the incidence of cancer in this cohort was compared to the incidence in the total population in the same region during the same period . A total of 46 gastric cancers were diagnosed versus 47 expected . Up to 15 years after operation the cancer risk was lower than expected . After 15 years the risk was higher than expected with a 2.1-fold higher incidence after 25 years for the total patient population . The highest risk was observed in male subjects undergoing a Billroth II subtotal gastrectomy  with a 3.2 times increase in risk after 25 years . There was no difference between gastric and duodenal ulcer patients ; and patients undergoing simple suture for a perforated ulcer showed no increase in cancer incidence . Patients with long-lasting symptoms had the same incidence as patients with briefer symptoms . These observations indicate that the operation per se and not the ulcer disease may be precancerous The present study was design ed to examine the effect of heart rate variability ( HRV ) biofeedback on the cardiorespiratory resting function during sleep in daily life . Forty-five healthy young adults were r and omly assigned to one of three groups : HRV biofeedback , Autogenic Training ( AT ) , and no-treatment control . Participants in the HRV biofeedback were instructed to use a h and held HRV biofeedback device before their habitual bedtime , those in the AT were asked to listen to an audiotaped instruction before bedtime , and those in the control were asked to engage in their habitual activity before bedtime . Pulse wave signal during sleep at their own residences was measured continuously with a wristwatch-type transdermal photoelectric sensor for three time points . Baseline data were collected on the first night of measurements , followed by two successive nights for HRV biofeedback , AT , or control . Cardiorespiratory resting function was assessed quantitatively as the amplitude of high-frequency ( HF ) component of pulse rate variability , a surrogate measure of respiratory sinus arrhythmia . HF component increased during sleep in the HRV biofeedback group , although it remained unchanged in the AT and control groups . These results suggest that HRV biofeedback before sleep may improve cardiorespiratory resting function during sleep OBJECTIVES The purpose of this study was to test the transcutaneous noninvasive vagus nerve stimulator ( nVNS ) ( gammaCore © ) device to determine if it modulates the peripheral immune system , as has been previously published for implanted vagus nerve stimulators . MATERIAL S AND METHODS A total of 20 healthy males and females were r and omized to receive either nVNS or sham stimulation ( SST ) .  All subjects underwent an initial blood draw at 8:00 am , followed by stimulation with nVNS or SST at 8:30 am . Stimulation was repeated at 12:00 pm and 6:00 pm . Additional blood sample s were withdrawn 90 min and 24 hour after the first stimulation session . After sample s were cultured using the Myriad RBM TruCulture ( Austin , TX ) system ( WBCx ) , levels of cytokines and chemokines were measured by the Luminex assay and statistical analyses within and between groups were performed using the Wilcoxon Signed Ranks Test and Mann-Whitney U with the statistical program R. RESULTS A significant percent decrease in the levels of the cytokine interleukin [IL]-1β , tumor necrosis factor [ TNF ] levels , and chemokine , interleukin [IL]-8 IL-8 , macrophage inflammatory protein [MIP]-1α , and monocyte chemoattractant protein [MCP]-1 levels was observed in the nVNS group non-lipopolysaccharide (LPS)-stimulated whole blood culture ( n-WBCx ) at the 24-hour time point ( p < 0.05 ) . In SST group , there was a significant percent increase in IL-8 at 90 min post-stimulation ( p < 0.05 ) . At 90 min , the nVNS group had a greater percent decrease in IL-8 concentration ( p < 0.05 ) compared to SST group . The nVNS group had a greater percent decrease in cytokines ( TNF , IL-1β ) and chemokines ( MCP-1 and IL-8 ) at 24 hour ( p < 0.05 ) in comparison to SST . LPS-stimulated whole blood cultures ( L-WBCx ) did not show a significant decrease in cytokine levels in either the nVNS or SST group across any time points . The nVNS group showed a significant percent increase in LPS-stimulated IL-10 levels at the 24-hour time point in comparison to SST . CONCLUSIONS nVNS downregulates inflammatory cytokine release suggesting that nVNS may be an effective anti-inflammatory treatment Invasive vagus nerve stimulation has been demonstrated to be an effective treatment in major depressive episodes . Recently , a novel non-invasive method of stimulating the vagus nerve on the outer canal of the ear has been proposed . In healthy subjects , a prominent fMRI BOLD signal deactivation in the limbic system was found . The present pilot study investigates the effects of this novel technique of auricular transcutaneous electric nerve stimulation in depressed patients for the first time . A total of 37 patients suffering from major depression were included in two r and omized sham controlled add-on studies . Patients were stimulated five times a week on a daily basis for the duration of 2 weeks . On days 0 and 14 , the Hamilton Depression Rating Scale ( HAMD ) and the Beck Depression Inventory ( BDI ) were assessed . In contrast to sham-treated patients , electrically stimulated persons showed a significantly better outcome in the BDI . Mean decrease in the active treatment group was 12.6 ( SD 6.0 ) points compared to 4.4 ( SD 9.9 ) points in the sham group . HAMD score did not change significantly in the two groups . An antidepressant effect of a new transcutaneous auricular nerve stimulation technique has been shown 
    Output:
    
These studies show that initially high vagal nerve activity predicts better cancer prognosis , and , in some studies , independent of confounders such as cancer stage and treatments .
The second part of this paper presents a comprehensive review including human and animal cohort and experimental studies showing that vagotomy  accelerates tumor growth , while vagal nerve activation improves cancer prognosis .
Based on all review ed studies , it is concluded that the evidence supports a protective role of the vagus nerve in cancer and specifically in the metastatic stage