Subcutaneous emphysema associated with laparoscopic or robotic abdominal surgery: a retrospective single-center study.

BACKGROUND: Subcutaneous emphysema (SCE) is a common complication in laparoscopic surgery. However, its precise incidence and impact on the clinical course are partially known. In this study, the incidence and risk factors of SCE were retrospectively analyzed. METHODS: Patients who underwent laparoscopic/robotic abdominal surgery (e.g., gastrointestinal, hepatobiliary, gynecologic, and urologic surgery) between October 2019 and September 2022 were retrospectively analyzed. The presence of SCE was confirmed by either conclusive findings obtained through chest/abdominal X-ray examination immediately after operation, or intraoperative palpation conducted by nurses. X-ray examination was performed in the operation room before extubation. RESULTS: A total of 2503 patients treated with laparoscopic/robotic abdominal surgery between October 2019 and September 2022 were identified and all of them were included in the analysis. SCE was confirmed in 23.1% of the patients (i.e., 577/2503). SCE was identified by X-ray examination in 97.6% of the patients. Extubation failure was observed in 10 patients; however, pneumothorax was not observed. Female sex (odds ratio [OR]: 2.09; 95% confidence interval [95%CI]: 1.69-2.57), age ≥ 80 years (OR 1.63; 95%CI 1.19-2.22), body mass index < 20 (OR 1.32; 95%CI 1.06-1.65), operation time > 360 min (OR 1.97; 95%CI 1.53-2.54), robotic surgery (OR 2.54; 95%CI 1.91-3.38), maximum intraabdominal pressure with CO2 > 15 mmHg (OR 1.79; 95%CI 1.02-3.16), and endo-tidal CO2 > 50 mmHg (OR 1.32; 95%CI 1.08-1.62)were identified as independent factors of SCE. Regarding the extubation failure due to SCE, age (OR 5.84; 95%CI 1.27-26.8) and maximum intraabdominal pressure with CO2 (OR 21.7; 95%CI 4.76-99.3) were identified as risk factors. CONCLUSION: Although the presence of SCE is associated with a low risk of severe complications, monitoring of the perioperative intraabdominal pressure is essential for performing safe laparoscopic/robotic surgery, particularly in elderly patients.

Correlation between recurrence-free survival and overall survival after upfront surgery for resected colorectal liver metastases.

BACKGROUND: The role of recurrence-free survival (RFS) as a valid surrogate endpoint for overall survival (OS) in patients who underwent upfront surgery for colorectal liver metastases remains uncertain. The aim of the study was to compare the two survival measures in a nationwide cohort of upfront resected colorectal liver metastasis. METHODS: Data from patients with colorectal liver metastases without extrahepatic metastases who underwent curative surgery for liver metastases were retrieved from the Japanese nationwide database (data collection 2005-2007 and 2013-2014). RFS, OS, and survival after recurrence were estimated using the Kaplan-Meier method. The correlation (ρ) between RFS and OS was assessed using the rank correlation method combined with iterative multiple imputation, to account for censoring. As a secondary analysis, the correlation was evaluated according to adjuvant chemotherapy regimen. In sensitivity analysis, the pairwise correlation between RFS and OS was calculated. RESULTS: A total of 2385 patients with colorectal liver metastases were included. In the primary analysis, there was a moderately strong correlation between RFS and OS (ρ = 0.73, 95 per cent c.i. 0.70 to 0.76). The strength of the correlation was similar regardless of the adjuvant treatment regimen (oxaliplatin plus 5-fluorouracil: ρ = 0.72, 0.67 to 0.77; 5-fluorouracil alone: ρ = 0.72, 0.66 to 0.76; observation: ρ = 0.74, 0.69 to 0.78). The mean(s.d.) pairwise correlation coefficient between 3-year RFS and 5-year OS was 0.87(0.06). CONCLUSION: In surgically treated patients with colorectal liver metastases, there was a moderately strong correlation between RFS and OS, which was unaffected by the treatment regimen. Further validation using a trial-level analysis is required.

A Case Report of Primary Unresectable Hilar Cholangiocarcinoma Causing Colonic Obstruction Due to Peritoneal Dissemination.

Although surgical resection is the only available treatment to achieve long-term survival in biliary tract cancer, many cases are often identified at an advanced stage at the time of diagnosis. Radiotherapy may be an alternative option to prolong survival in cases with locally advanced unresectable disease. While there are some reports of long-term survival after radiotherapy for unresectable biliary tract cancer, it is rare that clinical symptoms are exhibited by peritoneal dissemination more than 8 years after radiotherapy and that resection can be performed. Our case was a 55-year-old female who had visited with a complaint of jaundice and was diagnosed with primary unresectable hilar cholangiocarcinoma. She received definitve chemoradiotherapy, and repeated receiving maintenance chemotherapy thereafter until clinical manifestation. During follow-up, she was diagnosed with stenosis of the sigmoid colon, which was attributed to peritoneal dissemination of cholangiocarcinoma. We herein report a rare case of primary unresectable hilar cholangiocarcinoma after chemoradiotherapy which was followed by chemotherapy that was controlled for more than 8 years but eventually caused colonic obstruction attributed to peritoneal dissemination.

[A Case of Ascending Colon Cancer with Skull Metastasis].

A 55-year-old woman became aware of a tumor on the left side of the head in July, 2020 and was referred to our hospital in September because of its rapid growth. A head CT showed a neoplastic lesion of the skull. A CT from the neck to the pelvis revealed an ascending colon tumor and multiple lesions in the liver, which was suspected as metastasis. A colonoscopy also showed a type 2 like lesion in the ascending colon, and a biopsy showed adenocarcinoma. A pedunculated polyp had been pointed out in the ascending colon at another hospital four years previously, and the pathological result was an adenoma, but endoscopic mucosal resection was not performed. It is considered that the adenoma became advanced colon cancer with metastasis through the mechanism of multistage carcinogenesis. Metastatic lesions of the ascending colon cancer was suspected with regard to the skull lesion. In addition to the rapid growth, surgical removal was desirable from the viewpoint of cosmetology, and surgery was performed in November. The postoperative pathological diagnosis was a metastatic skull tumor derived from ascending colon cancer. The diagnosis was Stage IVb according to the Japanese Classification of Colorectal, Appendiceal, and Anal Carcinoma (9th Edition). Although chemotherapy was started after surgery, the metastatic liver cancer increased rapidly and the patient passed away in April, 2021.

[A Resected Case of Adeno-Squamous Carcinoma of Gallbladder with Liver Invasions].

A patient was 70-year-old female. Because unknown fever following operation of left knee in December 20XX-1, abdominal simple CT was performed, diagnosed as cholecystitis and liver abscesses. However, her unknown fever did not improve with antibiotics therapy. Abdominal enhanced CT and MRI revealed to gallbladder cancer with liver invasion and metastases. These lesions were relatively localized in liver S4a/S5 and gallbladder, hepatoduodenal mesentery. Because unknown fever was exhausting, cholecystectomy, S4a+S5 hepatectomy with extrahepatic bile duct resection and lymph node dissemination were performed in January 20XX+1. In these pathological findings, there were moderate to poorly differentiated adenocarcinoma with squamous cell differentiation in almost area of gallbladder, diagnosed as adeno-squamous carcinoma with liver invasion and metastasis(pT3a[SI][H-inf], int, INF-ß, ly1, v3, pn1, pN1, pM1, pStage ⅣB). One months after operation, abdominal CT revealed multiple liver metastatic recurrences. She died 7 months after operation. Although gallbladder adeno-squamous carcinoma has a poor prognosis, these many cases had a tendency to local infiltration accompanied with tumor fever. If curative resection might be obtained and the symptoms might be improved, aggressive resection should be performed.

[A Case of Mesh Infection Due to Transverse Colon Cancer].

A 69-year-old female underwent a mesh repair for an abdominal incisional hernia 4 years previously in our hospital. She visited local hospital for abdominal pain and fever. Abdominal CT showed a localizes abscess formation above the mesh, then she was taken to our hospital. We suspected mesh infection and performed emergent mesh removal. After the operation, we examined for her anemia. Her colonoscopy and CT findings pointed to transverse colon cancer. We performed right hemicolectomy, and final diagnosis was transverse colon cancer pT4aN0M0, pStage Ⅱb. She underwent adjuvant chemotherapy, and 9 months after surgery, no recurrence was found.

Genetic and epigenetic aberrations of ABCB1 synergistically boost the acquisition of taxane resistance in esophageal squamous cancer cells.

Taxanes are applied as potent chemotherapeutic agents in the treatment of patients with esophageal cancer, but their usefulness is limited, partly because of acquisition of chemoresistance. In our previous study, we established three taxane resistant esophageal cancer cell lines; significant ABCB1 upregulations were found in all three. However, the responsible mechanism(s) still remains an open question. In this study, we explored possible mechanisms that might contribute to upregulation of ABCB1 in taxane resistant cells. ABCB1 gene amplification was found in taxane resistant cell line RTE-1P, but expressional upregulation cannot be explained only by gene amplification, because gene amplification is one order of magnitude or less whereas gene expression is more than two orders of magnitude. In the parental TE-1, ABCB1 expression was upregulated after treatment with 5-azadeoxycytidine and/or trichostatin A; epigenetic mechanisms may be deeply involved. ABCB1 has two promoters; a downstream promoter was found to play the dominant role in taxane resistant esophageal cancer cell lines. Analyses of CpG islands demonstrated that taxane resistant cells showed unmethylated CGI whereas parental cells were dominantly methylated. In conclusion, we propose that both the ABCB1 gene amplification and aberrations in epigenetic mechanisms are responsible for acquisition of taxane resistance in esophageal cancer cells.

[Bilateral Multiple Liver Metastases after Pancreatoduodenectomy for a Duodenal Neuroendocrine Tumor-A Case Report].

The patient was a 79-year-old woman. In January 20XX, upper gastrointestinal endoscopy revealed a duodenal tumor with bleeding and ulceration. This tumor was diagnosed as a duodenal neuroendocrine tumor(NET)based on biopsy findings. In March 20XX, the patient underwent pancreatoduodenectomy with lymph node dissemination. Based on these pathological findings, the tumor was diagnosed as a duodenal NET(G2)with a lymph node metastasis(T2, N1, M0, Stage Ⅲ). Twenty months after the operation, abdominal CT revealed multiple liver metastases(S4, S7, and S8). After this recurrence, she underwent the subcutaneous somatostatin analogue injection therapy every 28 days, and transarterial chemoembolization( TACE)when these recurrent tumors showed remarkable regrowth, once a year, accounting for her age. She has maintained good disease control for 5 years.

[Resection of the Acinar Cell Carcinoma of the Pancreas with Lymph Node Recurrence along the Lesser Curvature of the Stomach-A Case Report].

A 78-year-old woman had undergone subtotal stomach-preserving pancreatoduodenectomy for acinar cell carcinoma (ACC)of the pancreatic head approximately 2 years before presentation, and the pathological diagnosis had been pT2pN0pM0, fStageⅠB(JPS 7th). Adjuvant chemotherapy was discontinued after 3 months because of side effects. Contrast- enhanced CT and PET-CT 2 years postoperatively revealed a tumor measuring 2 cm with a high concentration of FDG in the minor curvature of the stomach. During laparotomy, a 3 cm large lymph node was palpated in the minor curvature of the stomach, and a small lymph node was found adjacently. We diagnosed the patient with multiple lymph node recurrences and performed gastric lymph node dissection of the minor curvature. The pathological diagnosis was a single 2 cm large ACC lymph node metastasis. The patient did not consent to postoperative adjuvant chemotherapy and showed no recurrence for 1 year and 7 months postoperatively. Pancreatic ACC is a rare pancreatic tumor, and its clinicopathologic features are still largely unknown. In recent years, there have been reports of active resection or long-term survival with anti-cancer drug treatment even in recurrent cases, such as the present case. However, the indication and method of anti-cancer treatment are unclear and might need the accumulation of many more cases.

[A Case of Mature Teratoma in the Hepatoduodenal Ligament].

A 60's woman was admitted to our hospital because of palpitations that occurred with exertion. Coronary angiography computed tomography(CT)of suspected angina detected a tumor in the pancreatic head region. Abdominal CT showed a poorly enhanced 40×32 mm solid tumor in the hepatoduodenal ligament that contained a fatty component and calcification. During surgery, the tumor was located in the hepatoduodenal ligament, adhered to the pancreatic head, common hepatic artery, gastroduodenal artery, portal vein and common bile duct. However, the tumor was resected by preserving them. The tumor contained stratified squamous epithelium, a sebaceous gland, nerve, a pancreatic gland, and an adrenal gland. The histological diagnosis was a mature cystic teratoma. The patient showed no recurrence in 2 years and 10 months post-surgery. Mature teratomas in the hepatoduodenal ligament are extremely rare. Some reports showed that combined resection was performed when the tumor was in contact with the common bile duct, portal vein, and arteries. However, in our case, the tumor was removed relatively safely without combined resection.

[A Case of Appendix Torsion with Low-Grade Appendiceal Mucinous Neoplasm].

An 84-year-old woman with a chief complaint of right lower abdominal pain was admitted to our hospital in November 20XX. Abdominal CT scan revealed a 9.6×4.1 cm diameter low density area proximal to the 13 mm diameter appendix, which led to perforated appendicitis with a huge abscess. The patient underwent an open appendectomy with partial cecum resection. The appendix was found to be twisted by 540°. The pathological diagnosis was low-grade appendiceal mucinous neoplasm(LAMN). Recent research has found that the use of laparoscopic surgery for the treatment of LAMN has been increasing. Appropriate surgical intervention should be considered for LAMN because it is a borderline malignancy. Careful treatment with laparoscopic surgery might be considered as one of the treatment options for LAMN. We hope to accumulate more cases of LAMN to confirm our results.

[A Case of Intestinal Obstruction Caused by Peritoneal Metastatic Recurrence One Year after Radical Operation for Pancreatic Cancer].

In December 20XX-1, abdominal enhanced CT of a 73-year-old female patient showed a 28mm-in-diameter pancreatic tail cancer with splenic venous invasion. She underwent neoadjuvant GEM/TS-1 combination chemotherapy but abandoned this chemotherapy due to melena and exanthema. She underwent a distal pancreatectomy with lymph node dissemination. In these pathological findings, the tumor was diagnosed as a pancreatic tail cancer with splenic venous invasion(T3, N0, M0, Stage ⅡA). She underwent adjuvant GEM chemotherapy, but she abandoned this chemotherapy due to exanthema and was managed with observation. In September 20XX, she had a postoperative bowel obstruction and was treated with natural light. However, she had a postoperative bowel obstruction again in July, 20XX+1. Fluoroscopic images revealed stenosis in the intestine located 170 cm from the nasal cavity. She underwent open surgery to manage the bowel obstruction. There was a peritoneal tumor with adhesion to each intestine serosa in 3 areas located 80 cm, 100 cm, and 150 cm from the Treitz ligament. Therefore, she underwent a small intestine resection and anastomosis 70 cm to 110 cm from the Treitz ligament. Pathological findings showed that there was a 3mm-in-diameter adenocarcinoma in this peritoneal tumor. In these findings, this final diagnosis was an adhesive intestinal obstruction caused by peritoneal metastasis. Curative resection for single peritoneal recurrent metastasis might be useful for prognosis prolongation.

[Long-Term Survival after Palliative Surgery for Advanced Gastric Cancer with Bone Marrow Metastasis-A Case Report].

A 57-year-old woman was diagnosed with advanced gastric cancer with bone marrow metastasis(cT4aN1pM1[MAR], pStage Ⅳ). After 18 courses of S-1 and cisplatin and 18 courses of ramucirumab and paclitaxel, the chemotherapy was stopped because of stenosis. We performed endoscopic metallic stent placement, but stenosis reappeared after a month. Subsequently, distal gastrectomy was performed as a palliative surgery. She had no complications and improved appetite, therefore, she resumed chemotherapy after 3 postoperative months and continued for 4 years and 9 months from the first visit. In general, gastric cancer with bone marrow metastasis has a poor prognosis, however, in this case, long-term survival was achieved with palliative surgery.

Involvement of Transient Receptor Potential Vanilloid Receptor 1, (TRPV1)-Expressing Vagal Nerve in the Inhibitory Effect of Gastric Acidification on Exogenous Motilin-Induced Gastric Phase III Contractions in Suncus murinus.

BACKGROUND: Gastric acidification inhibits motilin-induced gastric phase III contractions. However, the underlying mechanism has not been thoroughly investigated. Here, we studied the inhibitory mechanism by gastric acidification on motilin-induced contraction in Suncus murinus (S. murinus). METHODS: We measured interdigestive gastric phase III contractions in conscious, freely moving S. murinus, and examined the inhibitory effect of gastric acidification on motilin action and the involvement of the vagus nerve and transient receptor potential vanilloid receptor 1 (TRPV1) in the inhibitory mechanism. RESULTS: A bolus injection of motilin evoked phase III-like contractions during intravenous infusion of saline. Intragastric acidification (pH 1.5-2.5) inhibited motilin-induced phase III contractions in a pH-dependent manner and significantly decreased the motility index at a pH below 2.0. In contrast, intraduodenal acidification (pH 2.0) failed to inhibit motilin-induced contractions. Vagotomy significantly alleviated the suppression of motilin-induced gastric contractions under acidic conditions (pH 2.0), suggesting vagus nerve involvement. Moreover, intragastric acidification (pH 2.0) significantly increased the number of c-Fos-positive cells in the nucleus tractus solitarii. In vagotomized S. murinus, the number of c-Fos-positive cells did not change, even under gastric acidification conditions. TRPV1 mRNA was highly expressed in the muscle and mucosal regions of the antrum and the nodose ganglion, whereas was not detected in the upper small intestine. Capsazepin, a TRPV1 antagonist, completely rescued the inhibitory effect of gastric acidification. CONCLUSIONS: Gastric acidification in S. murinus inhibits motilin-induced contractions, a finding similar to results observed in humans, while TRPV1-expressing vagus nerves play a role in the inhibitory mechanism.

Monitoring ctDNA RAS Mutational Status in Metastatic Colorectal Cancer: A Trial Protocol of RAS-trace and RAS-trace-2 Studies.

Background: Spatial and temporal heterogeneities of RAS and other molecular genes should be considered in the treatment of metastatic colorectal cancer (mCRC) treated with anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (mAbs); acquired RAS mutation is sometimes observed at disease progression of treatment with the anti-EGFR mAb. At the same time, discrepancy of RAS status from tissues and circulating tumor DNA (ctDNA) in the same patient is sometimes observed. Based on this, we commenced two observational studies to clarify these heterogeneities of RAS and BRAF in mCRC, using next generation sequencing from liquid biopsy. Methods/Design: RAS-trace study is an observational study to monitor ctDNA RAS/BRAF/PIK3CA status every 4-12 weeks using the Plasma-SeqSensei™ CRC RUO Kit (Sysmex Inostics GmbH) in mCRC with RAS/BRAF wild-type (wt) on tumor tissue. The primary endpoint was the time to the acquired RAS mutations. A total of 42 patients has been accrued. RAS-trace-2 study is also an observational study aimed at comparing the efficacy of the anti-EGFR mAb in ctDNA RAS/BRAF wt with ctDNA RAS or BRAF mutant mCRC patients, whose RAS/BRAF are wt in tumor tissue. The primary endpoint was progression-free survival in patients with ctDNA RAS/BRAF wt and RAS or BRAF mutant. A total of 240 patients will be accrued over 2 years. Discussion: These trials will help us understanding the clinical significance of spatial and temporal heterogeneities of RAS, BRAF and other genes, while optimizing the anti-EGFR mAb treatment strategies in mCRC.

A peptide binding to the tetraspanin CD9 reduces cancer metastasis.

As an organizer of multi-molecular membrane complexes, the tetraspanin CD9 has been implicated in a number of biological processes, including cancer metastasis, and is a candidate therapeutic target. Here, we evaluated the suppressive effects of an eight-mer CD9-binding peptide (CD9-BP) on cancer cell metastasis and its mechanisms of action. CD9-BP impaired CD9-related functions by adversely affecting the formation of tetraspanin webs-networks composed of CD9 and its partner proteins. The anti-cancer metastasis effect of CD9-BP was evidenced by the in vitro inhibition of cancer cell migration and invasion as well as exosome secretion and uptake, which are essential processes during metastasis. Finally, using a mouse model, we showed that CD9-BP reduced lung metastasis in vivo. These findings provide insight into the mechanism by which CD9-BP inhibits CD9-dependent functions and highlight its potential application as an alternative therapeutic nano-biomaterial for metastatic cancers.

Anatomical Validation of Internal Iliac Vessels Assessed by Three-dimensional Angiographic Analysis.

Objectives: Anatomical understanding of the internal iliac vessels is important with the increasing frequency of minimally-invasive pelvic surgery. We aimed to investigate the branch patterns of internal iliac vessels, especially the veins. Methods: This study included 30 patients with 60 half-pelvises who underwent minimally-invasive pelvic surgery. Branch patterns were assessed on surgical videos with a multi-detector computed tomography-based three-dimensional simulation. Branch patterns of the superior gluteal artery and vein (SGA and SGV), inferior gluteal artery and vein (IGA and IGV), internal pudendal artery and vein (IPA and IPV), and obturator artery and vein (ObA and ObV) were investigated. Results: In the most frequent internal iliac vein (IIV) branch pattern, 67% of SGV branched from the IIV, 95% of the IGV branched from the IPV and 82% of the ObV branched from the IPV. According to Adachi's classification, 62% of IIVs were Type I and 33% Type IV. Although IIV branch patterns are heterogeneous, in individual patients with the most frequent branch patterns, good correlation (75-100%) of the branch patterns was observed between the internal iliac artery (IIA) and IIV, and between the right and left IIVs. Conclusions: This study clarified the branch patterns of IIV. In patients with the most frequent branch patterns, good correlation of the branch patterns was observed between the IIA and IIV, and between right and left IIV. We believe this helps secure the safety and standardization of minimally-invasive pelvic surgery.

Short-term administration of diclofenac sodium affects renal function after laparoscopic radical nephrectomy in elderly patients.

OBJECTIVE: Non-steroidal anti-inflammatory drugs decrease the glomerular filtration rate. However, few studies have been conducted on renal function in patients treated with non-steroidal anti-inflammatory drugs during the first week after laparoscopic radical nephrectomy. The purpose of this study is to determine whether short-term administration of non-steroidal anti-inflammatory drugs during the first week after laparoscopic radical nephrectomy is a risk factor for impaired renal function. METHODS: Renal carcinoma patients undergoing laparoscopic radical nephrectomy in Nagoya University Hospital from April 2004 to July 2010 were identified in a retrospective cohort study. The 164 patients were divided into non-non-steroidal anti-inflammatory drug-treated (n=50) and non-steroidal anti-inflammatory drug-treated (n=114) groups. RESULTS: Elderly patients (>60 years old) in the non-steroidal anti-inflammatory drug-treated group showed a significant correlation between the residual renal function ratio and the total dose of diclofenac sodium (r=-0.277, P<0.05). There was no significant correlation between the residual renal function ratio and the total dose of loxoprofen sodium. The time to doubling of the serum creatinine level was significantly shorter in elderly patients treated with diclofenac sodium compared with that in patients treated with non-non-steroidal anti-inflammatory drugs (P=0.034). These results suggest that renal ischemia induced by short-term administration of diclofenac sodium impairs renal function in elderly patients after laparoscopic radical nephrectomy. CONCLUSIONS: In the present study, we found the first evidence that short-term administration of diclofenac sodium is one risk factor for renal impairment after laparoscopic radical nephrectomy in elderly patients. To prevent renal impairment after laparoscopic radical nephrectomy in elderly patients, the use of loxoprofen sodium, which has a negligible effect on renal function compared with diclofenac sodium, is recommended.

Superlattice-Induced Variations in Morphological and Emission Properties of GaInN/GaN Multiquantum Nanowire-Based Micro-LEDs.

Core-shell GaInN/GaN multiquantum shell (MQS) nanowires (NWs) are gaining great attention for high-efficiency micro-light-emitting diodes (micro-LEDs) owing to the minimized etching region on their sidewall, nonpolar or semipolar emission planes, and ultralow density of dislocations. In this study, we evaluated the changes in NW morphologies and the corresponding device properties induced by GaInN/GaN superlattice (SL) structures. The cathodoluminescence intensities of the samples with 20 and 40 pairs of SLs were about 2.2 and 3.4 times higher, respectively, than that of the sample without SLs. The high-resolution scanning transmission electron microscopy (STEM) inspection confirmed that the high growth temperature of SLs prevented growth in the semipolar plane region close to the n-GaN core. A similar phenomenon was also observed for the GaN quantum barriers of the semipolar MQS region under a high growth temperature of 810 °C. This phenomenon was ascribed to the passivation of the semipolar plane surface by hydrogen atoms and the high probability of decomposition through NH3 or N-H-related bonds. Although no clear SL grew on the semipolar plane near the n-core region, the top area of the nonpolar plane SL was expected to adequately suppress the point defects propagating from the n-GaN core to the semipolar plane MQS. The electroluminescence (EL) spectra and light output curves demonstrated a clear enhancement of more than 3-folds compared to the fabricated micro-LEDs without SL structures, which was associated with the improved crystalline quality of the MQS and enlarged area of the semipolar planes. Moreover, by increasing the growth time of GaN quantum barriers, the EL emission intensity of the micro-LED devices exhibited a 4-fold improvement owing to the reduced carrier overflow in the thickened GaN barriers on the semipolar (11̅01) planes. Thus, the results verified the possibility of realizing highly efficient NW-based micro-LEDs by optimizing the NW morphology using SL structures.