Efficacy and safety of camrelizumab plus apatinib in patients with advanced esophageal squamous cell carcinoma previously treated with immune checkpoint inhibitors (CAP 02 Re-challenge): A single-arm, phase II study.

BACKGROUND: With the increasing use of immune checkpoint inhibitors (ICIs) in advanced esophageal squamous cell carcinoma (ESCC), there remains an unmet need for options to address disease progression after prior ICIs. This single-arm phase II study evaluated the efficacy and safety of re-challenge with camrelizumab plus apatinib in patients with advanced ESCC who were previously treated with ICIs. METHODS: This study enrolled patients aged 18-75 years with unresectable locally advanced, locally recurrent, or distant metastatic ESCC who received prior ICIs. Patients received intravenous camrelizumab 200 mg every 2 weeks and oral apatinib 250 mg daily until disease progression, unacceptable toxicity, or consent withdrawal. The primary endpoint was the investigator-assessed confirmed objective response rate (ORR). RESULTS: Between September 1, 2021 and March 29, 2023, 49 eligible patients were enrolled and received treatment. Among the 49 patients, the confirmed ORR was 10.2 % (95 % CI 3.4-22.2), the disease control rate (DCR) was 69.4 % (54.6-81.7), the median progression-free survival (PFS) was 4.6 months (95 % CI 3.8-6.5) and overall survival (OS) was 7.5 months (5.5-13.6). Grade ≥ 3 treatment-related adverse events occurred in 17 patients (34.7 %). No treatment-related deaths occurred. CONCLUSIONS: This study showed that the confirmed ORR was modest and did not reach clinically meaningful improvement for patients with ESCC who were previously treated with ICIs, with a manageable safety profile.

Targeting CircAURKA prevents colorectal cancer progression via enhancing CTNNB1 protein degradation.

Tumor progression of colorectal cancer (CRC) seriously affects patient prognosis. For CRC patients with advanced-stage disease, it is still necessary to continuously explore more effective targeted therapeutic drugs. Circular RNAs (circRNAs) are involved in the regulation of tumor biology. We screened circAURKA, which was significantly highly expressed in CRC by previous high-throughput RNA sequencing. In vitro experiments were performed to investigate the effect of the circRNA on the proliferation and metastasis of HCT116 and SW480 cells. In addition, we used the EdU assay, Transwell assay, nude mouse xenograft tumor model and nude mouse tail vein metastasis model to examine the effect of circAURKA on the proliferation and metastasis of CRC. Mechanistically, fluorescent in situ hybridization (FISH), RNA pull-down, RNA immunoprecipitation (RIP), protein coimmunoprecipitation (co-IP) experiments and animal models were performed to confirm the underlying mechanisms of circAURKA. CircAURKA was significantly highly expressed in CRC tissues and colorectal cells and mainly present in the cytoplasm. The circRNA promoted the proliferation and metastasis of CRC cells in vitro and in vivo. In terms of the molecular mechanism, circAURKA inhibited the degradation of the CTNNB1 protein by promoting the interaction between ACLY and the CTNNB1 protein, thereby promoting the proliferation and metastasis of CRC cells. In addition, circAURKA stability was regulated by m6A methylation modification. This study revealed that circAURKA promoted the proliferation and metastasis of CRC by inhibiting CTNNB1 protein degradation, providing a basis for the development of targeted drugs to control CRC progression.

The metabolism-related lncRNA signature predicts the prognosis of breast cancer patients.

Long non-coding RNAs (lncRNAs) involved in metabolism are recognized as significant factors in breast cancer (BC) progression. We constructed a novel prognostic signature for BC using metabolism-related lncRNAs and investigated their underlying mechanisms. The training and validation cohorts were established from BC patients acquired from two public sources: The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). The prognostic signature of metabolism-related lncRNAs was constructed using the least absolute shrinkage and selection operator (LASSO) cox regression analysis. We developed and validated a new prognostic risk model for BC using the signature of metabolism-related lncRNAs (SIRLNT, SIAH2-AS1, MIR205HG, USP30-AS1, MIR200CHG, TFAP2A-AS1, AP005131.2, AL031316.1, C6orf99). The risk score obtained from this signature was proven to be an independent prognostic factor for BC patients, resulting in a poor overall survival (OS) for individuals in the high-risk group. The area under the curve (AUC) for OS at three and five years were 0.67 and 0.65 in the TCGA cohort, and 0.697 and 0.68 in the GEO validation cohort, respectively. The prognostic signature demonstrated a robust association with the immunological state of BC patients. Conventional chemotherapeutics, such as docetaxel and paclitaxel, showed greater efficacy in BC patients classified as high-risk. A nomogram with a c-index of 0.764 was developed to forecast the survival time of BC patients, considering their risk score and age. The silencing of C6orf99 markedly decreased the proliferation, migration, and invasion capacities in MCF-7 cells. Our study identified a signature of metabolism-related lncRNAs that predicts outcomes in BC patients and could assist in tailoring personalized prevention and treatment plans.

Dominance of plasma-induced modulation in terahertz generation from gas filament.

In this paper, we revisit the fundamental mechanism responsible for terahertz generation from laser-induced plasma filament based on the photocurrent model by employing a blend of analytical calculation and numerical simulation. By using the frequency-decomposed finite-difference time-domain (FD-FDTD) method, the role of two-color field and photocurrent radiation in terahertz generation from plasma filament is visually separated, and the driving effect of photocurrent radiation is confirmed pretty significant within the process. Then, a pair of numerical experiments are taken to further analyze the driving effect of photocurrent radiation, and it is revealed that plasma-induced modulation to photocurrent radiation is actually the underlying physical mechanism of terahertz generation from plasma filament. Furthermore, a three-step diagram is introduced to reillustrate the overall physical process and provides a more comprehensive explanation. In addition, the mechanism of plasma-induced modulation to photocurrent radiation in terahertz generation is substantiated by taking theoretical prediction and numerical simulation of minimal filament length required for achieving stable backward terahertz emission, which directly confirms the validity and significance of plasma-induced modulation to photocurrent radiation in terahertz generation from laser-induced plasma filament.

Breakthrough of solid tumor treatment: CAR-NK immunotherapy.

As the latest and most anticipated method of tumor immunotherapy, CAR-NK therapy has received increasing attention in recent years, and its safety and high efficiency have irreplaceable advantages over CAR-T. Current research focuses on the application of CAR-NK in hematological tumors, while there are fewer studies on solid tumor. This article reviews the process of constructing CAR-NK, the effects of hypoxia and metabolic factors, NK cell surface receptors, cytokines, and exosomes on the efficacy of CAR-NK in solid tumor, and the role of CAR-NK in various solid tumor. The mechanism of action and the research status of the potential of CAR-NK in the treatment of solid tumor in clinical practice, and put forward the advantages, limitations and future problems of CAR-NK in the treatment of solid tumor.

YTHDF2-mediated circYAP1 drives immune escape and cancer progression through activating YAP1/TCF4-PD-L1 axis.

Immune escape is identified as one of the reasons for the poor prognosis of colorectal cancer (CRC) patients. Circular RNAs are considered to promote tumor progression by mediating tumor immune escape. We discovered that higher expression of circYAP1 was associated with a worse prognosis of CRC patients. Functional experiments in vitro and in vivo showed that circYAP1 upregulation inhibited the cytotoxicity of CD8+ T cells by upregulating programmed death ligand-1 (PD-L1). Mechanistically, we found that circYAP1 directly binds to the YAP1 protein to prevent its phosphorylation, enhancing proportion of YAP1 protein in the nucleus, and that YAP1 interacts with TCF4 to target the PD-L1 promoter and initiate PD-L1 transcription in CRC cells. Taken together, circYAP1 promotes CRC immune escape and tumor progression by activating the YAP1/TCF4-PD-L1 axis and may provide a new strategy for combination immunotherapy of CRC patients.

Extracellular vesicles remodel tumor environment for cancer immunotherapy.

Tumor immunotherapy has transformed neoplastic disease management, yet low response rates and immune complications persist as major challenges. Extracellular vesicles including exosomes have emerged as therapeutic agents actively involved in a diverse range of pathological conditions. Mounting evidence suggests that alterations in the quantity and composition of extracellular vesicles (EVs) contribute to the remodeling of the immune-suppressive tumor microenvironment (TME), thereby influencing the efficacy of immunotherapy. This revelation has sparked clinical interest in utilizing EVs for immune sensitization. In this perspective article, we present a comprehensive overview of the origins, generation, and interplay among various components of EVs within the TME. Furthermore, we discuss the pivotal role of EVs in reshaping the TME during tumorigenesis and their specific cargo, such as PD-1 and non-coding RNA, which influence the phenotypes of critical immune cells within the TME. Additionally, we summarize the applications of EVs in different anti-tumor therapies, the latest advancements in engineering EVs for cancer immunotherapy, and the challenges encountered in clinical translation. In light of these findings, we advocate for a broader understanding of the impact of EVs on the TME, as this will unveil overlooked therapeutic vulnerabilities and potentially enhance the efficacy of existing cancer immunotherapies.

Radiotherapy remodels the tumor microenvironment for enhancing immunotherapeutic sensitivity.

Cancer immunotherapy has transformed traditional treatments, with immune checkpoint blockade being particularly prominent. However, immunotherapy has minimal benefit for patients in most types of cancer and is largely ineffective in some cancers (such as pancreatic cancer and glioma). A synergistic anti-tumor response may be produced through the combined application with traditional tumor treatment methods. Radiotherapy (RT) not only kills tumor cells but also triggers the pro-inflammatory molecules' release and immune cell infiltration, which remodel the tumor microenvironment (TME). Therefore, the combination of RT and immunotherapy is expected to achieve improved efficacy. In this review, we summarize the effects of RT on cellular components of the TME, including T cell receptor repertoires, different T cell subsets, metabolism, tumor-associated macrophages and other myeloid cells (dendritic cells, myeloid-derived suppressor cells, neutrophils and eosinophils). Meanwhile, non-cellular components such as lactate and extracellular vesicles are also elaborated. In addition, we discuss the impact of different RT modalities on tumor immunity and issues related to the clinical practice of combination therapy.

An investigation of the flexural behaviour of large-span prestressed and steel-reinforced concrete slabs.

The prestressed and steel-reinforced concrete slab (PSRCS) is an innovative composite structural member offering high load capacity and stiffness and exceptional anti-crack performance, making it a leading trend in composite structures. This paper presents the derived calculation formulas for bearing capacity, section stiffness, mid-span deflection of PSRCS. Additionally, a numerical analysis of PSRCS is conducted using ABAQUS software, with several models created to systematically investigate bearing capacity, section stiffness, anti-crack performance, and failure mode. Concurrently, PSRCS member parameters are analyzed for optimal design, and the results of finite element (FE) calculations are compared with theoretical formula calculations. The results demonstrate that PSRCS exhibits superior load capacity, section stiffness, and anti-crack performance comparing to conventional slabs. The parametric analysis offers optimal design for each parameter and presents the corresponding recommended span-to-depth ratios for various spans in PSRCS applications.

Clinical benefits of PD-1 inhibitors in specific subgroups of patients with advanced esophageal squamous cell carcinoma: a systematic review and meta-analysis of phase 3 randomized clinical trials.

Purpose: In recent years, a number of clinical trials have shown that programmed death 1 (PD-1) inhibitors offer significant survival benefits in patients with esophageal squamous cell carcinoma (ESCC). We conducted a meta-analysis to explore the antitumour efficacy of PD-1 inhibitor-based therapy in specific subgroups of patient with advanced ESCC. Methods: We searched for eligible studies from the PubMed, Embase, Web of Science, Cochrane Library databases and conference abstracts. The indicators related to survival outcomes were extracted. The pooled hazard ratios (HRs) for overall survival (OS), progression-free survival (PFS) and duration of response (DOR) and the pooled odds ratio (OR) for objective response rate (ORR) were calculated to evaluate the efficacy of PD-1 inhibitor-based therapy in ESCC. Data regarding treatment lines, treatment regimens, programmed death ligand 1 (PD-L1) status, baseline demographic and disease characteristics were extracted. Subgroup analyses were conducted in specific populations of ESCC patients. The Cochrane risk of bias tool and sensitivity analysis were used to assess the quality of the meta-analysis. Results: Eleven phase 3 randomized controlled trials (RCTs) involving 6267 patients with ESCC were included in this meta-analysis. Compared with standard chemotherapy, PD-1 inhibitor-based therapy provided benefits in terms of OS, PFS, ORR, and DOR in all populations, the first-line treatment group, the second-line treatment group, the immunotherapy group, and the immunochemotherapy group. Although a limited PFS benefit was observed in second-line treatments and immunotherapy alone, PD-1 inhibitor-based therapy still reduced the risk of disease progression or death. Patients with high PD-L1 expression had a better OS benefit than those with low PD-L1 expression. The HR for OS favoured PD-1 inhibitor-based therapy over standard chemotherapy for all prespecified clinical subgroups. Conclusions: Compared with standard chemotherapy, PD-1 inhibitor-based therapy exhibited clinically meaningful benefits in patients with ESCC. Survival benefits were better in patients with high PD-L1 expression than in those with low PD-L1 expression, suggesting that the PD-L1 expression level can be used as a predictor of survival benefit from PD-1 inhibitor therapy. PD-1 inhibitor-based therapy provided a consistent benefit in reducing the risk of death according to prespecified subgroup analyses of clinical characteristics.

The prognostic value and response to immunotherapy of immunogenic cell death-associated genes in breast cancer.

Breast cancer (BRCA) remains the most prevalent cancer worldwide and the tumor microenvironment (TME) has been discovered to exert a wide influence on the overall survival and therapeutic response. Numerous lines of evidence reported that the effects of immunotherapy of BRCA were manipulated by TME. Immunogenic cell death (ICD) is a form of regulated cell death (RCD) that is capable of fueling adaptive immune responses and aberrant expression of ICD-related genes (ICDRGs) can govern the TME system by emitting danger signals or damage-associated molecular patterns (DAMPs). In the current study, we obtained 34 key ICDRGs in BRCA. Subsequently, using the transcriptome data of BRCA from the TCGA database, we constructed a risk signature based on 6 vital ICDRGs, which had a good performance in predicting the overall survival of BRCA patients. We also examined the efficacy of our risk signature in the validation dataset (GSE20711) in the GEO database and it performed excellently. According to the risk model, patients with BRCA were divided into high-risk and low-risk groups. Also, the unique immune characteristics and TME between the two subgroups and 10 promising small molecule drugs targeting BRCA patients with different ICDRGs risk have been investigated. The low-risk group had good immunity indicated by T cell infiltration and high immune checkpoint expression. Moreover, the BRCA samples could be divided into three immune subtypes according to immune response severity (ISA, ISB, and ISC). ISA and ISB predominated in the low-risk group and patients in the low-risk group exhibited a more vigorous immune response. In conclusion, we developed an ICDRGs-based risk signature that can predict the prognosis of BRCA patients and offer a novel therapeutic strategy for immunotherapy, which would be of great significance in the BRCA clinical setting.

Ultrasound-targeted microbubble destruction remodels tumour microenvironment to improve immunotherapeutic effect.

Cancer immunotherapy (CIT) has gained increasing attention and made promising progress in recent years, especially immune checkpoint inhibitors such as antibodies blocking programmed cell death 1/programmed cell death ligand 1 (PD-1/PD-L1) and cytotoxic T lymphocyte-associated protein 4 (CTLA-4). However, its therapeutic efficacy is only 10-30% in solid tumours and treatment sensitivity needs to be improved. The complex tissue environment in which cancers originate is known as the tumour microenvironment (TME) and the complicated and dynamic TME is correlated with the efficacy of immunotherapy. Ultrasound-targeted microbubble destruction (UTMD) is an emerging technology that integrates diagnosis and therapy, which has garnered much traction due to non-invasive, targeted drug delivery and gene transfection characteristics. UTMD has also been studied to remodel TME and improve the efficacy of CIT. In this review, we analyse the effects of UTMD on various components of TME, including CD8+ T cells, tumour-infiltrating myeloid cells, regulatory T cells, natural killer cells and tumour vasculature. Moreover, UTMD enhances the permeability of the blood-brain barrier to facilitate drug delivery, thus improving CIT efficacy in vivo animal experiments. Based on this, we highlight the potential of immunotherapy against various cancer species and the clinical application prospects of UTMD.

Association of hepatitis B virus DNA levels with overall survival for advanced hepatitis B virus-related hepatocellular carcinoma under immune checkpoint inhibitor therapy.

BACKGROUND: High hepatitis B virus (HBV) DNA level is an independent risk factor for postoperative HBV-associated liver cancer recurrence. We sought to examine whether HBV DNA level and antiviral therapy are associated with survival outcomes in patients with advanced hepatocellular carcinoma (HCC) treated with anti-programmed cell death protein 1 (PD-1)based immunotherapy. METHODS: This single-institution retrospective analysis included 217 patients with advanced HBV-related HCC treated from 1 June 2018, through 30 December 2020. Baseline information was compared between patients with low and high HBV DNA levels. Overall survival (OS) and progression-free survival (PFS) were compared, and univariate and multivariate analyses were applied to identify potential risk factors for oncologic outcomes. RESULTS: The 217 patients included in the analysis had a median survival time of 20.6 months. Of these HBV-associated HCC patients, 165 had known baseline HBV DNA levels. Baseline HBV DNA level was not significantly associated with OS (P = 0.59) or PFS (P = 0.098). Compared to patients who did not receive antiviral therapy, patients who received antiviral therapy had significantly better OS (20.6 vs 11.1 months, P = 0.020), regardless of HBV DNA levels. Moreover, antiviral status (adjusted HR = 0.24, 95% CI 0.094-0.63, P = 0.004) was an independent protective factor for OS in a multivariate analysis of patients with HBV-related HCC. CONCLUSIONS: HBV viral load does not compromise the clinical outcome of patients with HBV-related HCC treated with anti-PD-1-based immunotherapy. The use of antiviral therapy significantly improves survival time of HBV-related HCC patients.

LncRNA profiles from Notch signaling: Implications for clinical management and tumor microenvironment of colorectal cancer.

The interplay between long non-coding RNAs (lncRNAs) and the Notch pathway involves a variety of malignancies. However, Notch-derived lncRNAs and their latent clinical significance remain elusive in colorectal cancer (CRC). In this study, we introduced a framework that could screen Notch-derived lncRNAs (named "NLncer") and ultimately identified 24 NLncers. To further explore the clinical significance of these NLncers, we performed LASSO and Cox regression in TCGA-CRC cohort (n = 584) and then retained six lncRNAs tightly associated with prognosis. The final model (termed "NLncS") was subsequently tested in GSE38832 (n = 122), GSE39582 (n = 573), and an in-house clinical cohort (n = 115). Ultimately, our NLncS model could serve as an independent risk factor and afford a robust performance for assessing the prognosis of CRC patients. Additionally, patients with high NLncS risk scores were characterized by upregulation of immune pathways, strong immunogenicity, abundant CD8 + T-cell infiltration, and potentially higher response rates to CTLA4 blockers, which turned out to be suitable for immunotherapy. Aiming at globally observing the characteristics of high-risk patients, somatic mutation and methylation modification analysis provide us with evidence at the genomic and transcriptomic levels. To facilitate the clinical transformability, we mined deeply into the sensitive compounds targeting high-risk individuals and identified dasatinib as a candidate agent for patients with a high Notch risk score. In conclusion, our NLncS model is a promising biomarker for optimizing the clinical management of CRC patients.

Combination of Low-Dose Gemcitabine and PD-1 Inhibitors for Treatment in Patients With Advanced Malignancies.

Purpose: This study determined the efficacy of low-dose gemcitabine combined with programmed death-1 (PD-1) inhibitors for treating multiple malignancies, providing a cost-effective and safe treatment option. Study Design: This study included 61 patients with advanced solid tumors treated with low-dose gemcitabine combined with PD-1 inhibitors at the Henan Cancer Hospital between January 2018 and February 2022. We retrospectively reviewed medical records to evaluate several clinical factors, including progression-free survival (PFS), overall survival (OS), adverse effects (AEs), and objective response to treatment. Results: Sixty-one patients received treatment with low-dose gemcitabine combined with PD-1 inhibitors. The objective response rate (ORR) was 29.5% and the disease control rate (DCR) was 62.3%. The median PFS was 4.3 months (95% confidence interval, 2.3 to 6.3 months) and the median OS was 15.0 months (95% confidence interval, 8.8 to 21.2 months). Hematological toxicity, mainly leukopenia or thrombocytopenia, was the most common AE, with any-grade and grade 3/4 hematological toxicity reported in 60.7 and 13.1% of patients, respectively. Conclusions: Low-dose gemcitabine combined with PD-1 inhibitors may offer a novel treatment option for patients with advanced malignancies.

Pharmacological Inhibition of Endogenous Hydrogen Sulfide Attenuates Breast Cancer Progression.

Hydrogen sulfide (H2S), a gaseous signaling molecule, is associated with the development of various malignancies via modulating various cellular signaling cascades. Published research has established the fact that inhibition of endogenous H2S production or exposure of H2S donors is an effective approach against cancer progression. However, the effect of pharmacological inhibition of endogenous H2S-producing enzymes (cystathionine-γ-lyase (CSE), cystathionine-ß-synthase (CBS), and 3-mercaptopyruvate sulfurtransferase (3-MPST)) on the growth of breast cancer (BC) remains unknown. In the present study, DL-propargylglycine (PAG, inhibitor of CSE), aminooxyacetic acid (AOAA, inhibitor of CBS), and L-aspartic acid (L-Asp, inhibitor of 3-MPST) were used to determine the role of endogenous H2S in the growth of BC by in vitro and in vivo experiments. An in silico study was also performed to confirm the results. Corresponding to each enzyme in separate groups, we treated BC cells (MCF-7 and MDA-MB-231) with 10 mM of PAG, AOAA, and L-Asp for 24 h. Findings reveal that the combined dose (PAG + AOAA + L-Asp) group showed exclusive inhibitory effects on BC cells' viability, proliferation, migration, and invasion compared to the control group. Further, treated cells exhibited increased apoptosis and a reduced level of phospho (p)-extracellular signal-regulated protein kinases such as p-AKT, p-PI3K, and p-mTOR. Moreover, the combined group exhibited potent inhibitory effects on the growth of BC xenograft tumors in nude mice, without obvious toxicity. The molecular docking results were consistent with the wet lab experiments and enhanced the reliability of the drugs. In conclusion, our results demonstrate that the inhibition of endogenous H2S production can significantly inhibit the growth of human breast cancer cells via the AKT/PI3K/mTOR pathway and suggest that endogenous H2S may act as a promising therapeutic target in human BC cells. Our study also empowers the rationale to design novel H2S-based anti-tumor drugs to cure BC.

Physiological and Pathological Functions of SLC26A6.

Solute Carrier Family 26 (SLC26) is a conserved anion transporter family with 10 members in human (SLC26A1-A11, A10 being a pseudogene). All SLC26 genes except for SLC26A5 (prestin) are versatile anion exchangers with notable ability to transport a variety of anions. SLC26A6 has the most extensive exchange functions in the SLC26 family and is widely expressed in various organs and tissues of mammals. SLC26A6 has some special properties that make it play a particularly important role in ion homeostasis and acid-base balance. In the past few years, the function of SLC26A6 in the diseases has received increasing attention. SLC26A6 not only participates in the development of intestinal and pancreatic diseases but also serves a significant role in mediating nephrolithiasis, fetal skeletal dysplasia and arrhythmia. This review aims to explore the role of SLC26A6 in physiology and pathophysiology of relative mammalian organs to guide in-depth studies about related diseases of human.

Crutchlike Incision Along the Mastoid Groove and Above the Occipital Artery Protects the Lesser Occipital Nerve and Occipital Artery in Microvascular Decompression Surgery.

BACKGROUND: Patients who have had microvascular decompression (MVD) surgery often report sensory discomfort around the surgical area. In most cases, injury of the lesser occipital nerve (LON) is responsible for this postoperative complication. This study aimed to explore an effective method to protect the LON and reduce postoperative discomfort. METHODS: Doppler was used to determine the course of the occipital artery (OA) and the incision. Direct LON identification and a novel crutchlike incision were performed from January 1, 2016, to February 1, 2017, to reduce postoperative sensory disturbance. Postoperative sensory disturbance was evaluated and retrospectively analyzed compared with previous linear incision cases (from January 1, 2015, to December 31, 2015). Anatomic information at the lateral occiput was measured and recorded. RESULTS: The difference in the amount of postoperative sensory disturbance at 3-month follow-up was significant (P = 0.008). Sensory disturbance was significantly lower in patients who had crutchlike incision (P = 0.002) and patients with direct LON identification (P = 0.035) compared with the previous linear incision cases. The distance from OA to the projection of the transverse sinus was 3.2 ± 0.6 cm at the mastoid groove and 2.5 ± 0.4 cm at a site 0.5-1.0 cm from the mastoid groove. CONCLUSIONS: A crutchlike incision at the mastoid groove superior to the OA reduced the incidence of postoperative sensory disturbance and OA injury. The mastoid groove and OA are simple landmarks for determination of the incision in microvascular decompression.