Climate gradient and leaf carbon investment influence the effects of climate change on water use efficiency of forests: A meta-analysis.

Forest ecosystems cover a large area of the global land surface and are important carbon sinks. The water-carbon cycles of forests are prone to climate change, but uncertainties remain regarding the magnitude of water use efficiency (WUE) response to climate change and the underpinning mechanism driving WUE variation. We conducted a meta-analysis of the effects of elevated CO2 concentration (eCO2 ), drought and elevated temperature (eT) on the leaf- to plant-level WUE, covering 80 field studies and 95 tree species. The results showed that eCO2 increased leaf intrinsic and instantaneous WUE (WUEi, WUEt), whereas drought enhanced both leaf- and plant-level WUEs. eT increased WUEi but decreased carbon isotope-based WUE, possibly due to the influence of mesophyll conductance. Stimulated leaf-level WUE by drought showed a progressing trend with increasing latitude, while eCO2 -induced WUE enhancement showed decreasing trends after >40° N. These latitudinal gradients might influence the spatial pattern of climate and further drove WUE variation. Moreover, high leaf-level WUE under eCO2 and drought was accompanied by low leaf carbon contents. Such a trade-off between growth efficiency and defence suggests a potentially compromised tolerance to diseases and pests. These findings add important ecophysiological parameters into climate models to predict carbon-water cycles of forests.

Leaf water relations determine the trade-off between ozone resistance and stomatal functionality in urban tree species.

Urban trees possess different capacities to mitigate ozone (O3) pollution through stomatal uptake. Stomatal closure protects trees from oxidative damage but limits their growth. To date, it is unclear how plant hydraulic function affect stomatal behaviour and determine O3 resistance. We assessed gas exchange and hydraulic traits in three subtropical urban tree species, Celtis sinensis, Quercus acutissima, and Q. nuttallii, under nonfiltered ambient air (NF) and elevated O3 (NF60). NF60 decreased photosynthetic rate (An) and stomatal conductance (gs) only in Q. acutissima and Q. nuttallii. Maintained An in C. sinensis suggested high O3 resistance and was attributed to higher leaf capacitance at the full turgor. However, this species exhibited a reduced stomatal sensitivity to vapour pressure deficit and an increased minimal gs under NF60. Such stomatal dysfunction did not decrease intrinsic water use efficiency (WUE) due to a tight coupling of An and gs. Conversely, Q. acutissima and Q. nuttallii showed maintained stomatal sensitivity and increased WUE, primarily correlated with gs and leaf water relations, including relative water content and osmotic potential at turgor loss point. Our findings highlight a trade-off between O3 resistance and stomatal functionality, with efficient stomatal control reducing the risk of hydraulic failure under combined stresses.

Drought mitigates the adverse effects of O3 on plant photosynthesis rather than growth: A global meta-analysis considering plant functional types.

Tropospheric ozone (O3 ) is a phytotoxic air pollutant adversely affecting plant growth. High O3 exposures are often concurrent with summer drought. The effects of both stresses on plants are complex, and their interactions are not yet well understood. Here, we investigate whether drought can mitigate the negative effects of O3 on plant physiology and growth based on a meta-analysis. We found that drought mitigated the negative effects of O3 on plant photosynthesis, but the modification of the O3 effect on the whole-plant biomass by drought was not significant. This is explained by a compensatory response of water-deficient plants that leads to increased metabolic costs. Relative to water control condition, reduced water treatment decreased the effects of O3 on photosynthetic traits, and leaf and root biomass in deciduous broadleaf species, while all traits in evergreen coniferous species showed no significant response. This suggested that the mitigating effects of drought on the negative impacts of O3 on the deciduous broadleaf species were more extensive than on the evergreen coniferous ones. Therefore, to avoid over- or underestimations when assessing the impact of O3 on vegetation growth, soil moisture should be considered. These results contribute to a better understanding of terrestrial ecosystem responses under global change.

Mechanism Study on the Immobilization of Cu2+/Pb2+ in Aqueous Phase by Mineral Co-Milling-Modified Biochar.

A large number of studies have shown that the modification of biochar can greatly improve its adsorption capacity. This study adopts a one-step ball milling technology without solvent medium, using sawdust biochar (600 °C) and attapulgite/diatomaceous earth to prepare MABC10%/MDBC10% (mass ratio: 10% attapulgite/diatomite +90% biochar coabrasive). Characterization experiments show that attapulgite/diatomite was successfully loaded on biochar and has more C/O functional groups and wider adsorption pore sizes. Adsorption kinetics and isotherm experiments show that the adsorption process of MABC10% and MDBC10% on Cu2+/Pb2+ was mainly multilayer chemical adsorption. The adsorption capacities of MABC10% and MDBC10% for Cu2+ were 40.85 and 65.20 mg·L-1, respectively. The adsorption amounts of Pb2+ were 82.63 and 71.32 mg·L-1, respectively. The particle diffusion model shows that the adsorption process was controlled by both the surface adsorption rate limitation and boundary layer diffusion. The higher acidity in the solution will cause part of the negative charges on the surface of attapulgite/diatomite to be neutralized, thereby hindering its adsorption of Cu2+/Pb2+. The presence of coexisting ions did not significantly affect the adsorption performance. Mechanistic studies have shown that pore diffusion, active sites provided by C/O functional groups, electrostatic interactions, and cation exchange are the main mechanisms of MABC10% adsorption of Cu2+/Pb2+. In summary, MABC10% has a significant adsorption synergistic effect compared to MBC. It was an economical and effective adsorbent, and the higher the pH value of the wastewater, the more significant the adsorption effect.

A Novel Prognostic Score Based on Multiple Quantitative Parameters of Chest CT for Patients with Synchronous Multiple Primary Lung Cancer: Is Solid Component Size a Better Prognostic Indicator?

BACKGROUND: There is no simple and definitive way to predict the prognosis of synchronous multiple primary lung cancer (SMPLC). In this study, we developed a clinical prognostic score for predicting the survival of patients with SMPLC. PATIENTS AND METHODS: This study included 206 patients with SMPLC between 2011 and 2020 at three hospitals. Kaplan-Meier analysis was used to determine the optimal cutoff values for the quantitative chest computed tomography (CT) parameters. Multivariable Cox proportional hazards regression was carried out to identify independent prognostic factors for predicting overall survival (OS) and disease-free survival (DFS). The time-dependent receiver operating characteristic curve was analyzed to evaluate the prognostic performance. RESULTS: A CT-based prognostic score (CTPS) comprising six chest CT parameters was developed. Compared with T stage, CTPS had a higher prediction accuracy for OS and DFS. All C-indices of the model reached a satisfactory level in both the development and validation cohorts. Significant differences in the OS and DFS curves were observed when the patients were stratified into different risk groups. The high-risk group (CTPS of 5-6) had poorer survival than the low-risk group (CTPS of 0-4). CONCLUSIONS: The developed CTPS and the corresponding risk stratification system are valid for predicting the survival of patients with SMPLC.

Elevated ozone inhibits isoprene emission of a diploid and a triploid genotype of Populus tomentosa by different mechanisms.

Ozone (O3) pollution affects plant growth and isoprene (ISO) emission. However, the response mechanism of isoprene emission rate (ISOrate) to elevated O3 (EO3) remains poorly understood. ISOrate was investigated in two genotypes (diploid and triploid) of Chinese white poplar (Populus tomentosa Carr.) exposed to EO3 in an open top chamber system. The triploid genotype had higher photosynthetic rate (A) and stomatal conductance (gs) than the diploid one. EO3 significantly decreased A, gs, and ISOrate of middle and lower leaves in both genotypes. In the diploid genotype, the reduction of ISOrate was caused by a systematic decrease related to ISO synthesis capacity, as indicated by decreased contents of the isoprene precursor dimethylallyl diphosphate and decreased isoprene synthase protein and activity. On the other hand, the negative effect of O3 on ISOrate of the triploid genotype did not result from inhibited ISO synthesis capacity, but from increased ISO oxidative loss within the leaf. Our findings will be useful for breeding poplar genotypes with high yield and lower ISOrate, depending on local atmospheric volatile organic compound/NOx ratio, to cope with both the rising O3 concentrations and increasing biomass demand. They can also inform the incorporation of O3 effects into process-based models of isoprene emission.

Naples Prognostic Score as a novel prognostic prediction tool in video-assisted thoracoscopic surgery for early-stage lung cancer: a propensity score matching study.

BACKGROUNDS: The Naples Prognostic Score (NPS) emerges as a novel prognostic scoring system in surgical oncology. We aim to assess the prognostic significance of preoperative NPS in patients undergoing completely video-assisted thoracoscopic surgery (VATS) lobectomy for early-stage non-small cell lung cancer (NSCLC) by propensity score matching (PSM) analysis. METHODS: The present study was conducted on our single-center prospectively maintained database between January 2014 and December 2015. A Kaplan-Meier survival analysis using the log-rank test was used to distinguish differences in both overall survival (OS) and disease-free survival (DFS) between the patients stratified by preoperative NPS. Finally, multivariable Cox-proportional hazards regression analysis and PSM analysis were carried out to determine the independent prognostic factors for both OS and DFS. RESULTS: There were 457 patients with operable primary stage I-II NSCLC included. Per 1-point increase in NPS was found to be significantly associated with unfavorable OS and DFS of NSCLC. Both OS and DFS were significantly shortened along with each number increase in the NPS group, showing a step-wise fashion. Such strong correlations between preoperative NPS and survival outcomes still remained validated after PSM analysis. In addition, NPS held the best discriminatory power for predicting both OS and DFS when compared to the other peripheral biomarkers. Multivariable analyses on the entire cohort and the PSM cohort demonstrated that preoperative NPS could be an independent prognostic indicator for both OS and DFS. CONCLUSIONS: The NPS scoring system can serve as a novel risk stratification tool to refine prognostic prediction after VATS lobectomy for surgically resected NSCLC.

Biogenic volatile organic compound emissions from leaves and fruits of apple and peach trees during fruit development.

Biogenic volatile organic compounds (BVOCs) are widely involved in a variety of atmospheric chemical processes due to their high reactivity and species diversity. To date, however, research on BVOCs in agroecosystems, particularly fruit trees, remains scarce despite their large cultivation area and economic interest. BVOC emissions from different organs (leaf or fruit) of apple and peach trees were investigated throughout the stages of fruit development (FS, fruit swelling; FC, fruit coloration; FM, fruit maturity; and FP, fruit postharvest) using a proton-transfer-reaction mass spectrometer. Results indicated that methanol was the most abundant compound emitted by the leaf (apple tree leaf 492.5 ± 47.9 ng/(g·hr), peach tree leaf 938.8 ±  154.5 ng/(g·hr)), followed by acetic acid and green leaf volatiles. Beside the above three compounds, acetaldehyde had an important contribution to the emissions from the fruit. Overall, the total BVOCs (sum of eight compounds studied in this paper) emitted by both leaf and fruit gradually decreased along the fruit development, although the effect was significant only for the leaf. The leaf (2020.8 ±  258.8 ng/(g·hr)) was a stronger BVOC emitter than the fruit (146.0 ± 45.7 ng/(g·hr)) (P = 0.006), and there were no significant differences in total BVOC emission rates between apple and peach trees. These findings contribute to our understanding on BVOC emissions from different plant organs and provide important insights into the variation of BVOC emissions across different fruit developmental stages.

PE_PGRS62 promotes the survival of Mycobacterium smegmatis within macrophages via disrupting ER stress-mediated apoptosis.

Mycobacterium tuberculosis, the leading causative agent of tuberculosis, remains one of the most deadly infectious pathogens. PE_PGRS proteins become a new focus as their species specificity in mycobacteria, especially in pathogenic mycobacteria. Despite intensive research, PE_PGRS proteins are still a mysterious aspect of mycobacterial pathogenesis with unknown mechanism. Herein, we focused on a PE_PGRS member from M. tuberculosis, PE_PGRS62, characterized by a surface-exposed protein function in disrupting phagolysosome maturation. Expression of PE_PGRS62 in Mycobacterium smegmatis, a nonpathogenic species naturally deficient in PE_PGRS genes, resulted in enhanced resistance to various in vitro stresses and cellular survival in macrophage. As a consequence, the cytokine profiles of macrophage were disturbed and cell apoptosis were inhibited via decreasing endoplasmic reticulum stress response.

Synthesis of a Macrocycle Bearing a Carbon Framework of [16]Cyclophenacene as a Carbon Nanobelt.

A synthetic pathway to a functionalized tetrahydro[5]phenacene was developed, which served as a precursor, leading to a dehydrobenzo[32]annulene macrocycle containing four carbon-carbon triple bonds. The high efficiency of the macrocyclization step can be attributed to the structural rigidity of its immediate precursor. Hydrogenation of the four carbon-carbon triple bonds produced a macrocycle bearing a carbon framework of [16]cyclophenacene as the shortest macrocyclic belt-like structure of an (8,8)armchair carbon nanotube.

Identification of cis-regulatory regions responsible for developmental and hormonal regulation of HbHMGS1 in transgenic Arabidopsis thaliana.

OBJECTIVES: 3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) synthase (HMGS) is an important enzyme in mevalonate (MVA) pathway of isoprenoid biosynthesis, which regulates the rubber biosynthetic pathway in rubber tree (Hevea brasiliensis) in coordination with HMG-CoA reductase (HMGR). However, little information is available about the regulation of HMGS gene expression. To understand the mechanism controlling the HbHMGS1 gene expression, we characterized the HbHMGS1 promoter sequence in transgenic plants with the ß-glucuronidase (GUS) reporter gene. RESULTS: GUS activity analysis of the transgenic plants showed that the HbHMGS1 promoter is active in all organs of the transgenic Arabidopsis plants during various developmental stages (from 6 to 45-day-old). Deletion of different portions of the upstream HbHMGS1 promoter identified sequences responsible for either positive or negative regulation of the GUS expression. Particularly, the - 454 bp HbHMGS1 promoter resulted in a 2.19-fold increase in promoter activity compared with the CaMV 35S promoter, suggesting that the - 454 bp HbHMGS1 promoter is a super-strong near-constitutive promoter. In addition, a number of promoter regions important for the responsiveness to ethylene, methyl jasmonate (MeJA) and gibberellic acid (GA) were identified. CONCLUSION: The - 454 bp HbHMGS1 promoter has great application potential in plant transformation studies as an alternative to the CaMV 35S promoter. The HbHMGS1 promoter may play important roles in regulating ethylene-, MeJA- and GA-mediated gene expression. The functional complexity of cis-elements revealed by this study remains to be elucidated.

Synthesis of a Cyclophane Bearing Two Benz[a]anthracene Units Connected at the 5 and 7 Positions with Two Naphth-1,4-diyl Groups.

A synthetic pathway to a cyclophane bearing two benz[a]anthracene units connected at the 5 and 7 positions through two naphth-1,4-diyl groups was developed, and its structure was confirmed by X-ray structure analysis. Because of structural constraints, the two naphthyl groups are distorted from planarity and the bonds connecting them to the benz[a]anthracene units are bent significantly. The UV-vis and fluorescence spectra of the cyclophane are red-shifted from those of 7-(1-naphthalenyl)benz[a]anthracene, which is the corresponding monomeric polycyclic aromatic hydrocarbon.

Estimated intraoperative blood loss correlates with postoperative cardiopulmonary complications and length of stay in patients undergoing video-assisted thoracoscopic lung cancer lobectomy: a retrospective cohort study.

BACKGROUND: The purpose of our study was to estimate the influence of estimated intraoperative blood loss (EIBL) on postoperative cardiopulmonary complications (PCCs) in patients undergoing video-assisted thoracoscopic surgery (VATS) lobectomy for non-small-cell lung cancer (NSCLC). METHODS: We conducted a single-center retrospective analysis on the clinical data of consecutive patients in our institution between April 2015 and February 2016. Demographic differences between PCC group and non-PCC group were initially assessed. Receiver operating characteristic (ROC) analysis was performed to determine the threshold value of EIBL for the prediction of PCCs. Demographic differences in the PCC rates and length of stay between two groups of patients divided by this cutoff were further evaluated. A multivariable logistic-regression model involving the clinicopathological parameters with P-value< 0.05 was finally established to identify independent risk factors for PCCs. RESULTS: A total of 429 patients with operable NSCLC were included and 80 of them developed PCCs (rate = 18.6%). The mean EIBL in PCC group was significantly higher than that in non-PCC group (133.3 ± 191.3 vs. 79.1 ± 107.1 mL; P < 0.001). The ROC analysis showed an EIBL of 100 mL as the threshold value at which the joint sensitivity (50.0%) and specificity (73.4%) was maximal. The PCC rate in patients with EIBL≥100 mL was significantly higher than that in patients with EIBL< 100 mL (30.1 vs. 13.5%; P < 0.001). Both the length of stay and chest tube duration were significantly prolonged in the patients with EIBL≥100 mL. Finally, EIBL≥100 mL was identified to be predictive of PCCs by multivariable logistic-regression analysis (odds ratio = 3.01; 95% confidence interval = 1.47-6.16; P = 0.003). CONCLUSIONS: EIBL serves as a significant categorical predictor for cardiopulmonary complications following VATS lobectomy for NSCLC. Thoracic surgeons should minimize the EIBL and strive for the 'bloodless' goal to optimize surgical outcomes.

Synthesis and Characterization of Functionalized [12]Cycloparaphenylenes Containing Four Alternating Biphenyl and Naphthyl Units.

Functionalized [12]cycloparaphenylenes ([12]CPPs) containing four alternating biphenyl and naphthyl units were synthesized. A macrocyclic furan-containing CPP precursor was used for the Diels-Alder reaction with the parent benzyne or 3,6-dimethoxybenzyne to form the corresponding macrocyclic carbon frameworks. The subsequent reductive deoxygenation of the Diels-Alder adducts with Fe2(CO)9 followed by oxidative aromatization with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone produced the functionalized [12]CPPs. The effect of macrocyclic ring size on the reaction rate of oxidative aromatization was investigated.

Synthesis of Partially Hydrogenated Cycloparaphenylenes with Bent and Fused Structures Bearing Armchair Carbon Nanotube-like Connections.

The Diels-Alder reactions between 2 equiv of (E,E)-1,4-bis(4-bromophenyl)-1,3-butadiene and 1,4-benzoquinone led to the formation of a key intermediate with all four 4-bromophenyl substituents cis to one another. The subsequent nickel-mediated homocoupling reactions then produced partially hydrogenated cycloparaphenylenes, including a molecule bearing two units of tetrahydro[6]cycloparaphenylene (4H[6]CPP) fused together through two 1,4-dimethoxybenzene units in an armchair (6,6)carbon nanotube-like connection. Similarly, two 6H[9]CPPs were connected through three 1,4-dimethoxybenzene units in an armchair (9,9)carbon nanotube-like arrangement. A bent 8H[12]CPP and a bent 12H[18]CPP, which were fused intramolecularly with two and three 1,4-dimethoxybenzene units, respectively, to create the bent structures, were likewise synthesized. A molecule containing a bent 8H[12]CPP fused to a 4H[6]CPP was likewise constructed. The structures of these partially hydrogenated CPPs were established by X-ray structure analysis, NMR spectroscopy, and additional independent synthetic pathways.

Body surface area is a novel predictor for surgical complications following video-assisted thoracoscopic surgery for lung adenocarcinoma: a retrospective cohort study.

BACKGROUND: Body surface area (BSA) is a biometric unit to measure the body size. Its clinical significance in video-assisted thoracoscopic surgery (VATS) was rarely understood. We aimed to estimate the predictive value of BSA for surgical complications following VATS anatomical resections for lung adenocarcinoma (LAC). METHODS: A single-center retrospective analysis was performed on the consecutive patients between July 2014 and January 2016 in our institution. The differences in mean BSA values were evaluated between groups of patients classified by the development of postoperative surgical complications (PSCs), overall morbidity and cardiopulmonary complications, respectively. Receiver operating characteristic (ROC) analysis was performed to determine a threshold value of BSA on prediction of PSC occurrence. A multivariate logistic-regression model involving this optimal cut-off value and other significant parameters was established to identify the predictors for PSCs. RESULTS: During the study period, a total of 442 patients undergoing VATS anatomical resections for LAC were enrolled in this study. There were 135 patients developed with one or more complications (rate = 30.5%). PSCs occupied the largest percentages of all these complications (n = 81, rate = 18.3%). The mean BSA in PSC group was significantly higher than that in non-PSC group (1.76 ± 0.15 m2 vs 1.71 ± 0.16 m2; P = 0.016). No difference was found in mean BSA values between groups classified by any other complication. The ROC analysis determined a BSA value of 1.68 m2 to be the threshold value with the maximum joint sensitivity of 72.8% and specificity of 48.5%. Compared to patients with BSA ≤ 1.68 m2, patients with BSA > 1.68 m2 had significantly higher incidences of prolonged air leak (P = 0.006) and chylothorax (P = 0.004). Further multivariate logistic-regression analysis indicated that BSA > 1.68 m2 could be an independent risk factor for PSCs (odds ratio: 2.03; P = 0.025). CONCLUSIONS: BSA is an excellent categorical predictor for surgical complications following VATS anatomical resections for LAC. It may be considered when informing patients about surgical risks and selecting cases in the early learning curve. Large-scale and multi-institutional studies are expected to confirm and modify our findings in the future.

Synthesis of Cycloparaphenylenes Bearing Furan-2,5-diyl or 2,2'-Bifuran-5,5'-diyl Units in the Macrocyclic Structures.

Synthetic pathways to furan-containing cycloparaphenylenes (CPPs) as molecular nanohoops bearing 10, 12, and 15 aromatic units including furan-2,5-diyl or 2,2'-bifuran-5,5'-diyl units have been developed. The X-ray structures of a partially hydrogenated bifuran-containing CPP precursor and the corresponding fully aromatized bifuran-containing CPP were obtained to allow the determination of their conformational arrangements in the crystal lattice. The optical and electrochemical properties of the furan-containing CPPs were investigated.

Clinicopathological and prognostic significance of mTOR and phosphorylated mTOR expression in patients with esophageal squamous cell carcinoma: a systematic review and meta-analysis.

BACKGROUND: Mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase responsible for regulating ribosomal biogenesis and protein synthesis. Dysregulation of mTOR contributes to tumorigenesis, angiogenesis, cellular growth and metastasis but its roles in esophageal squamous cell carcinoma (ESCC) are controversial. Therefore, the objective of this study is to evaluate the prognostic and clinicopathological significance of mTOR/p-mTOR expression in ESCC. METHODS: Literature retrieval was conducted by searching PubMed, EMBASE and the Web of Science for full-text papers that met our eligibility criteria. Odds ratio (OR) and hazard ratio (HR) with 95 % confidence interval (CI) served as the appropriate summarized statistics for assessments of clinicopathological and prognostic significance, respectively. Cochrane Q-test and I2-statistic were adopted to estimate the heterogeneity level between studies. Potential publication bias was detected by Begg's test and Egger's test. RESULTS: A total of 915 ESCC patients from nine original articles were included into this meta-analysis. The pooled analyses suggested that mTOR/p-mTOR expression was significantly correlated with the unfavorable outcomes of differentiation degree (OR: 2.63; 95 % CI: 1.71-4.05; P = 0.001), tumor invasion (OR: 1.48; 95 % CI: 1.02-2.13; P = 0.037), TNM stage (OR: 2.25; 95 % CI: 1.05-4.82; P = 0.037) and lymph node metastasis (OR: 1.82; 95 % CI: 1.06-3.11; P = 0.029), but had no significant relationship to the genders (OR: 0.81; 95 % CI: 0.50-1.32; P = 0.396). Moreover, mTOR/p-mTOR expression could independently predict the worse overall survival (HR: 2.04; 95 % CI: 1.58-2.62; P < 0.001), disease-free survival (HR: 2.39; 95 % CI: 1.64-3.49; P < 0.001) and cancer-specific survival (HR: 1.62; 95 % CI: 1.18-2.23; P = 0.003) of patients with ESCC. Such prognostic value of mTOR was not substantially altered by further subgroup analyses. CONCLUSIONS: Positive expression of mTOR and p-mTOR was significantly associated with the unfavorable conditions on the depth of tumor invasion, TNM stage, differentiation degree and lymph node metastasis. mTOR and p-mTOR could serve as a valuable predictor for the poor prognosis of ESCC. More high-quality worldwide studies performing a multivariate analysis based on larger sample size are urgently required for further verifying and modifying our findings in the future.

Neoadjuvant therapy and risk of bronchopleural fistula after lung cancer surgery: a systematic meta-analysis of 14 912 patients.

OBJECTIVE: Neoadjuvant therapy has been extensively analyzed in studies addressing the risk factors of bronchopleural fistula, but their results vary hugely. Therefore, we conducted this meta-analysis to determine the association between neoadjuvant therapy and risk of bronchopleural fistula in patients undergoing lung cancer surgery. METHODS: We searched PubMed and EMBASE to identify the full-text literatures that met our eligibility criteria. Odds ratio with 95% confidence interval served as the summarized statistics. Heterogeneity within this meta-analysis was evaluated by Q-test and I (2) statistic. Sensitivity analysis was performed for further assessments of robustness. Publication bias was detected by Begg's test and Egger's test. RESULTS: Thirty studies enrolling 14 912 lung cancer cases were included into this meta-analysis. The incidence of bronchopleural fistula was 2.4% (354/14 912) in the large scale. Overall, neoadjuvant therapy significantly increased the risk of bronchopleural fistula after pulmonary resections (odds ratio: 2.166; 95% confidence interval: 1.398-3.357; P = 0.001). In subgroup analysis, neoadjuvant radiotherapy (odds ratio: 3.914; 95% confidence interval: 1.401-10.935; P = 0.009) and chemo-radiation (odds ratio: 2.533; 95% confidence interval: 1.353-4.741; P = 0.004) were significantly associated with the bronchopleural fistula risk but neoadjuvant chemotherapy was not (odds ratio: 1.857; 95% confidence interval: 0.881-3.911; P = 0.104). The impact of neoadjuvant therapy on bronchopleural fistula occurrence remains statistically prominent in the other subgroups. CONCLUSIONS: Neoadjuvant therapy is significantly associated with the occurrence of bronchopleural fistula after lung cancer surgery. Both neoadjuvant radiotherapy and chemo-radiation significantly increase the bronchopleural fistula risk but neoadjuvant chemotherapy does not. Some limitations still exist in this meta-analysis. The updated high-quality studies can help to further confirm and enrich our discoveries in the future.