A case of complete pathological response after comprehensive treatment in a patient with pulmonary adenocarcinoma with synchronous solitary brain metastasis.

Systemic chemotherapy is the standard treatment for non-small cell lung cancer with distant metastases. However, additional local treatment for brain and thoracic lesions is recommended for patients with synchronous solitary brain metastases (SSBM). We report the case of a 71-year-old male diagnosed with pulmonary adenocarcinoma and SSBM. Pathological examination of the brain metastasis showed positive immunostaining for programmed cell death ligand 1 expression. After four cycles of chemotherapy with immune checkpoint inhibitors, right upper lobectomy with ND2a-1 was performed. Pathological examination revealed complete pathological response, and this patient is expected to experience long-term survival.

Impact of smoking on resected lung cancer depends on epidermal growth factor receptor mutation.

OBJECTIVES: Smokers comprise the majority of surgical patients with primary lung cancer. Epidermal growth factor receptor (EGFR) mutation-negative status impacts the treatment of recurrence. However, the prognostic impact of cigarette smoking stratified by EGFR mutation status has not been reported. Therefore, we assessed its impact on patients with resected lung cancer. METHODS: We retrospectively analysed 362 consecutive patients who underwent complete resection for stage 1 primary lung cancer at our institution between 2012 and 2021. The EGFR mutation status was evaluated using the real-time polymerase chain reaction. We compared the overall survival (OS) and disease-free survival (DFS) between patients with and without a history of smoking. RESULTS: The EGFR mutation-negative group included 194 patients, of whom 160 (83%) had a history of smoking. Male sex (P < 0.01), forced expiratory volume in 1 s (P < 0.01) and adenocarcinoma (P < 0.01) showed significant differences between the groups. In the EGFR mutation-positive group, the 5-year OS and DFS were similar regardless of smoking status (OS: 86% vs 75%; DFS: 73% vs 73%). In the EGFR mutation-negative group, the 5-year OS and DFS were significantly poorer in the smoking group (OS: 87% vs 65%, P = 0.05; DFS: 84% vs 54%, P = 0.01). Deaths from other diseases were relatively high (n = 19, 53%). CONCLUSIONS: Cigarette smoking may be associated with a poor prognosis in EGFR mutation-negative lung cancer but had no impact on the prognosis of the EGFR mutation-positive group. This finding underscores the potential influence of smoking on the treatment of lung cancer recurrence but also highlights its significance in contributing to death from other diseases.

Prognostic potential of lipid profiling in cancer patients: a systematic review of mass spectrometry-based studies.

Cancer prognosis remains a critical clinical challenge. Lipidomic analysis via mass spectrometry (MS) offers the potential for objective prognostic prediction, leveraging the distinct lipid profiles of cancer patient-derived specimens. This review aims to systematically summarize the application of MS-based lipidomic analysis in prognostic prediction for cancer patients. Our systematic review summarized 38 studies from the past decade that attempted prognostic prediction of cancer patients through lipidomics. Commonly analyzed cancers included colorectal, prostate, and breast cancers. Liquid (serum and urine) and tissue samples were equally used, with liquid chromatography-tandem MS being the most common analytical platform. The most frequently evaluated prognostic outcomes were overall survival, stage, and recurrence. Thirty-eight lipid markers (including phosphatidylcholine, ceramide, triglyceride, lysophosphatidylcholine, sphingomyelin, phosphatidylethanolamine, diacylglycerol, phosphatidic acid, phosphatidylserine, lysophosphatidylethanolamine, lysophosphatidic acid, dihydroceramide, prostaglandin, sphingosine-1-phosphate, phosphatidylinosito, fatty acid, glucosylceramide and lactosylceramide) were identified as prognostic factors, demonstrating potential for clinical application. In conclusion, the potential for developing lipidomics in cancer prognostic prediction was demonstrated. However, the field is still nascent, necessitating future studies for validating and establishing lipid markers as reliable prognostic tools in clinical practice.

Intrapulmonary solitary fibrous tumor with malignant potential: A case report.

Intrapulmonary solitary fibrous tumor is rare, and its clinical course has not been sufficiently reported. We presented a case of an 80-year-old male non-smoker and discussed the surgical procedure selection and the recurrence risk assessment. A solid nodule, 1.1 cm in diameter, was identified in the left lower lobe on chest computed tomography and showed no accumulation on positron emission tomography. A wedge resection with a sufficient surgical margin under video-assisted thoracoscopic surgery was performed. Based on histological morphology and immunohistochemical examination, this case was considered an intrapulmonary solitary fibrous tumor with malignancy potential, requiring cautious follow-up observation.

Impact of central nervous system metastasis after complete resection of lung adenocarcinomas harboring common EGFR mutation - A real-world database study in Japan: The CReGYT-01 EGFR study.

OBJECTIVES: To clarify the impact of central nervous system (CNS) metastasis on performance status (PS) at relapse, on subsequent treatment(s), and on survival of patients with lung adenocarcinoma harboring common epidermal growth factor receptor (EGFR) mutation. METHODS: We conducted the multicenter real-world database study for patients with radical resections for lung adenocarcinomas between 2015 and 2018 at 21 centers in Japan. EGFR mutational status was examined at each center. RESULTS: Of 4181 patients enrolled, 1431 underwent complete anatomical resection for lung adenocarcinoma harboring common EGFR mutations. Three-hundred-and-twenty patients experienced disease relapse, and 78 (24%) had CNS metastasis. CNS metastasis was significantly more frequent in patients with conventional adjuvant chemotherapy than those without (30% vs. 20%, P = 0.036). Adjuvant chemotherapy did not significantly improve relapse-free survival at any pathological stage (adjusted hazard ratio for stage IA2-3, IB, and II-III was 1.363, 1.287, and 1.004, respectively). CNS metastasis did not affect PS at relapse. Subsequent treatment, mainly consisting of EGFR-tyrosine kinase inhibitors (TKIs), could be equally given in patients with or without CNS metastasis (96% vs. 94%). Overall survival after relapse was equivalent between patients with and without CNS metastasis. CONCLUSION: The efficacy of conventional adjuvant chemotherapy may be limited in patients with lung adenocarcinoma harboring EGFR mutations. CNS metastasis is likely to be found in practice before deterioration in PS, and may have little negative impact on compliance with subsequent EGFR-TKIs and survival after relapse. In this era of adjuvant TKI therapy, further prospective observational studies are desirable to elucidate the optimal management of CNS metastasis.

Lung adenocarcinoma and squamous cell carcinoma difficult for immunohistochemical diagnosis can be distinguished by lipid profile.

In patients with unresectable non-small cell lung cancer, histological diagnosis is frequently based on small biopsy specimens unsuitable for histological diagnosis when they are severely crushed and do not retain their morphology. Therefore, establishing a novel diagnostic method independent of tissue morphology or conventional immunohistochemistry (IHC) markers is required. We analyzed the lipid profiles of resected primary lung adenocarcinoma (ADC) and squamous cell carcinoma (SQCC) specimens using liquid chromatography-tandem mass spectrometry. The specimens of 26 ADC and 18 SQCC cases were evenly assigned to the discovery and validation cohorts. Non-target screening on the discovery cohort identified 96 and 13 lipid peaks abundant in ADC and SQCC, respectively. Among these 109 lipid peaks, six and six lipid peaks in ADC and SQCC showed reproducibility in target screening on the validation cohort. Finally, we selected three and four positive lipid markers for ADC and SQCC, demonstrating high discrimination abilities. In cases difficult to diagnose by IHC staining, [cardiolipin(18:2_18:2_18:2_18:2)-H]- and [triglyceride(18:1_17:1_18:1) + NH4]+ showed the excellent diagnostic ability for ADC (sensitivity: 1.00, specificity: 0.89, accuracy: 0.93) and SQCC (sensitivity: 0.89, specificity: 0.83, accuracy: 0.87), respectively. These novel candidate lipid markers may contribute to a more accurate diagnosis and subsequent treatment strategy for unresectable NSCLC.

Prospective exosome-focused translational research for afatinib (EXTRA) study of patients with nonsmall cell lung cancer harboring EGFR mutation: an observational clinical study.

Background: The exosome-focused translational research for afatinib (EXTRA) study is the first trial to identify novel predictive biomarkers for longer treatment efficacy of afatinib in patients with epidermal growth factor receptor (EGFR) mutation-positive nonsmall cell lung cancer (NSCLC) via a comprehensive association study using genomic, proteomic, epigenomic, and metabolomic analyses. Objectives: We report details of the clinical portion prior to omics analyses. Design: A prospective, single-arm, observational study was conducted using afatinib 40 mg/day as an initial dose in untreated patients with EGFR mutation-positive NSCLC. Dose reduction to 20 mg every other day was allowed. Methods: Progression-free survival (PFS), overall survival (OS), and adverse events (AEs) were evaluated. Results: A total of 103 patients (median age 70 years, range 42-88 years) were enrolled from 21 institutions in Japan between February 2017 and March 2018. After a median follow-up of 35.0 months, 21% remained on afatinib treatment, whereas 9% had discontinued treatment because of AEs. The median PFS was 18.4 months, with a 3-year PFS rate of 23.3%. The median afatinib treatment duration in patients with final doses of 40 (n = 27), 30 (n = 23), and 20 mg/day (n = 35), and 20 mg every other day (n = 18) were 13.4, 15.4, 18.8, and 18.3 months, respectively. The median OS was not reached, with a 3-year OS rate of 58.5%. The median OS in patients who did (n = 25) and did not (n = 78) receive osimertinib during the entire course of treatment were 42.4 months and not reached, respectively (p = 0.654). Conclusions: As the largest prospective study in Japan, this study confirmed favorable OS following first-line afatinib in patients with EGFR mutation-positive NSCLC in a real-world setting. Further analysis of the EXTRA study is expected to identify novel predictive biomarkers for afatinib. Trial registration: UMIN-CTR identifier (UMIN000024935, https://center6.umin.ac.jp/cgi-open-bin/ctr/ctr_his_list.cgi?recptno=R000028688.

Improved complete portal 4-port robotic lobectomy for lung cancer: Hamamatsu Method KAI.

Robot-assisted thoracoscopic surgery (RATS) has been widely used in lung cancer surgery. We previously devised a new port arrangement for RATS for lung cancer, the "Hamamatsu Method", to provide good cranial field of view using the da Vinci Xi surgical system. Our method utilizes four robot ports and one assist port, while our video-assisted thoracoscopic lobectomy technique is performed with four ports. We believe the number of ports in robotic lobectomy should not exceed those in video-assisted thoracoscopic lobectomy to preserve the advantage of minimal invasiveness. Furthermore, patients are generally more sensitive to wound size and number than surgeons assume. Thus, by combining the access and camera ports of the "Hamamatsu Method", we devised the 4-port "Hamamatsu Method KAI", which is equivalent to the conventional 5-port method, while maintaining full functionality of all four robotic arms and the assistant. "Hamamatsu Method KAI" showed comparable safety as the conventional 5- or 6-port method. Our improved 4-port method ensures minimal invasiveness while maintaining the same feasibility as the original method. The novelty of this operative method is the combined camera/assistant/access incision, and this technique is an option for RATS for lung cancer. "KAI" is a Japanese suffix indicating a sequel or successor.

Primary Cilia Are Frequently Present in Small Cell Lung Carcinomas but Not in Non-Small Cell Lung Carcinomas or Lung Carcinoids.

Most human malignant neoplasms show loss of primary cilia (PC). However, PC are known to be retained and involved in tumorigenesis in some types of neoplasms. The PC status in lung carcinomas remains largely uninvestigated. In this study, we comprehensively assessed the PC status in lung carcinomas. A total of 492 lung carcinomas, consisting of adenocarcinomas (ACs) (n = 319), squamous cell carcinomas (SCCs) (n = 152), and small cell lung carcinomas (SCLCs) (n = 21), were examined by immunohistochemical analysis using an antibody against ARL13B, a marker of PC. The PC-positive rate was markedly higher in SCLCs (81.0%) than in ACs (1.6%) and SCCs (7.9%). We subsequently performed analyses to characterize the PC-positive lung carcinomas further. PC-positive lung carcinomas were more numerous and had longer PC than normal cells. The presence of PC in these cells was not associated with the phase of the cell cycle. We also found that the PC were retained even in metastases from PC-positive lung carcinomas. Furthermore, the hedgehog signaling pathway was activated in PC-positive lung carcinomas. Because ARL13B immunohistochemistry of lung carcinoids (n = 10) also showed a statistically significantly lower rate (10.0%) of PC positivity than SCLCs, we searched for a gene(s) that might be upregulated in PC-positive SCLCs compared with lung carcinoids, but not in PC-negative carcinomas. This search, and further cell culture experiments, identified HYLS1 as a gene possessing the ability to regulate ciliogenesis in PC-positive lung carcinomas. In conclusion, our findings indicate that PC are frequently present in SCLCs but not in non-SCLCs (ACs and SCCs) or lung carcinoids, and their PC exhibit various specific pathobiological characteristics. This suggests an important link between lung carcinogenesis and PC.

Lipid biomarkers that reflect postoperative recurrence risk in lung cancer patients who smoke: a case-control study.

BACKGROUND: The risk of postoperative recurrence is higher in lung cancer patients who smoke than non-smokers. However, objective evaluation of the postoperative recurrence risk is difficult using conventional pathological prognostic factors because of their lack of reproducibility. Consequently, novel objective biomarkers that reflect postoperative risk in lung cancer patients who smoke must be identified. Because cigarette smoking and oncogenesis alter lipid metabolism in lung tissue, we hypothesized that the lipid profiles in lung cancer tissues are influenced by cigarette smoking and can reflect the postoperative recurrence risk in smoking lung cancer patients. This study aimed to identify lipid biomarkers that reflect the smoking status and the postoperative recurrence risk. METHODS: Primary tumor tissues of lung adenocarcinoma (ADC) (n = 26) and squamous cell carcinoma (SQCC) (n = 18) obtained from surgery were assigned to subgroups according to the patient's smoking status. The ADC cohort was divided into never smoker and smoker groups, while the SQCC cohort was divided into moderate smoker and heavy smoker groups. Extracted lipids from the tumor tissues were subjected to liquid chromatography-tandem mass spectrometry analysis. Lipids that were influenced by smoking status and reflected postoperative recurrence and pathological prognostic factors were screened. RESULTS: Two and 12 lipid peaks in the ADC and SQCC cohorts showed a significant positive correlation with the Brinkman index, respectively. Among them, in the ADC cohort, a higher lipid level consisted of three phosphatidylcholine (PC) isomers, PC (14:0_18:2), PC (16:1_16:1), and PC (16:0_16:2), was associated with a shorter recurrence free period (RFP) and a greater likelihoods of progressed T-factor (≥ pT2) and pleural invasion. In the SQCC cohort, a lower m/z 736.5276 level was associated with shorter RFP and greater likelihood of recurrence. CONCLUSIONS: From our data, we propose three PC isomers, PC (14:0_18:2), PC (16:1_16:1), and PC (16:0_16:2), and a lipid peak of m/z 736.5276 as novel candidate biomarkers for postoperative recurrence risk in lung ADC and SQCC patients who are smokers.

Thyroid transcription factor-1 expression in rectal adenocarcinoma metastatic to the lung.

Distinguishing metastatic lung tumors from primary lung cancer is essential for planning the appropriate treatment strategy. Thyroid transcription factor-1 (TTF-1) is a reliable immunohistochemistry (IHC) marker for differentiating between primary lung adenocarcinomas and metastatic lung tumors originating from colorectal adenocarcinomas. Herein, we report a rare case of TTF-1 expression in both the metastatic lung tumor and primary rectal adenocarcinoma. Aside from the similar histological characteristics of both tumors when stained with hematoxylin-eosin, the IHC patterns, including negative results for alveolar epithelium markers (napsin A and CK7) and positive results for intestinal markers (CK20, CDX2, SATB2, and ß-catenin), of the lung tumor and the primary rectal adenocarcinoma strongly supported the final diagnosis. Considering the non-negligible frequency of TTF-1 positivity in colorectal adenocarcinomas, applying the IHC panel including multiple markers for alveolar epithelium and intestinal differentiation, would be helpful to support the diagnosis of metastatic lung tumor from a rectal adenocarcinoma.

Association between EGFR gene mutant protein expression and T790M mutation after first-generation EGFR-TKI treatment resistance: a retrospective, single-arm clinical study.

Background: Epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) is an important treatment for lung adenocarcinoma patients with EGFR gene mutations. The purpose of this study was to review the efficacy of first-generation EGFR-TKIs and the incidence of T790M after first-generation TKI resistance in stage IV lung adenocarcinoma patients with positive EGFR gene mutation expression associated with EGFR mutant protein. Methods: Tumor tissues were collected from stage IV lung adenocarcinoma patients with EGFR gene mutation who received first-generation EGFR-TKI targeted therapy. Patients were followed up through outpatient and inpatient systems. Immunohistochemistry was used to detect the expression of corresponding EGFR mutant protein in tumor tissues. The incidence of T790M mutation after first-generation TKI resistance and the correlation between the mutant protein and progression-free survival (PFS) after first-generation TKI treatment were investigated. Results: T790M mutation rates were 37.93% (11/29) and 42.50% (17/40) in the EGFR mutation groups, respectively, after first-generation TKI treatment for drug resistance. In patients with exon 19 deletion, T790M mutations were found in 63.64% (7/11) of patients with positive protein expression and 22.22% (4/18) of patients with negative protein expression (P=0.026; χ2=4.974). The mutation rate of T790M after drug resistance in patients with L858R mutation was 53.57% (15/28) and 16.67% (2/12) in the protein expression-positive and negative groups, respectively (χ2=4.682, P=0.030). The variations were statistically significant. Conclusions: After resistance to the first-generation EGFR-TKI treatment, the occurrence of T790M mutation may be related to the expression of EGFR mutant protein in patients with EGFR gene mutation.

Left upper lobectomy with combined distal aortic arch and left subclavian artery resection after neoadjuvant chemoradiotherapy for locally advanced lung squamous cell carcinoma.

T4 locally advanced non-small cell lung cancer (NSCLC) is a heterogeneous group with a great variety of involved organs and is associated with a poor prognosis. However, appropriately selected patients benefit from surgical resection. The surgical indication must be carefully considered based on the risk-benefit between high surgical stress and expected prognosis, particularly in cases with probable aortic involvement. Here, we report a long-term survival case of left upper lobe squamous cell carcinoma, in which lobectomy and combined distal aortic arch and left subclavian artery resection achieved a complete resection after induction chemoradiotherapy (CRT). Appropriate patient selection considering expected prognosis, induction CRT and complete resection under well-planned cardiopulmonary bypass are essential to achieve a long-term survival on T4 NSCLC with a probable aortic involvement.

Placement of KANI® plate inside the chest wall for rib fixation: Prevention for organ injuries caused by crossed rib edges and plate claws.

The claw-type titanium plate has been successfully applied to manage a flail chest. However, rare and life-threatening organ injury occurs due to an insufficient claw bend. We report an ingenuity of surgical fixation using KANI® plates (USCI Japan, Tokyo, Japan) in a flail chest. A 60-year-old man with a severe flail chest underwent a surgical rib fixation. He had multiple rib fractures accompanied by dislocation and protruding crossed rib edges; we assumed a possibility of lung injury during a standard procedure in which the KANI® plates would be placed from outside the chest wall. Therefore, we placed KANI® plates inside the chest wall to ensure sufficient claw bend and to cover crossed rib edges to prevent organ injuries. We propose that our new ingenuity provides a safe and tight rib fixation in rib fractures with protruding crossed rib edges which the standard method cannot flatten.

m6A demethylase ALKBH5 promotes tumor cell proliferation by destabilizing IGF2BPs target genes and worsens the prognosis of patients with non-small-cell lung cancer.

The modification of N6-methyladenosine (m6A) in RNA and its eraser ALKBH5, an m6A demethylase, play an important role across various steps of human carcinogenesis. However, the involvement of ALKBH5 in non-small-cell lung cancer (NSCLC) development remains to be completely elucidated. The current study revealed that the expression of ALKBH5 was increased in NSCLC and increased expression of ALKBH5 worsened the prognosis of patients with NSCLC. In vitro study revealed that ALKBH5 knockdown suppressed cell proliferation ability of PC9 and A549 cells and promoted G1 arrest and increased the number of apoptotic cells. Furthermore, ALKBH5 overexpression increased the cell proliferation ability of the immortalized cell lines. Microarray analysis and western blotting revealed that the expression of CDKN1A (p21) or TIMP3 was increased by ALKBH5 knockdown. These alterations were offset by a double knockdown of both ALKBH5 and one of the IGF2BPs. The decline of mRNAs was, at least partly, owing to the destabilization of these mRNAs by one of the IGF2BPs. In conclusions, the ALKBH5-IGF2BPs axis promotes cell proliferation and tumorigenicity, which in turn causes the unfavorable prognosis of NSCLC.

Usefulness of a temporary shunt by cannulation during superior vena cava combined resection.

Superior vena cava invasive thoracic malignancy requires combined resection of the superior vena cava to achieve en bloc resection of the involved structures with negative margins. The superior vena cava combined resection requires the creation of collateral circulation from the head to the heart before performing the combined resection. Even for a short time, total superior vena cava clamping without a procedure is unsafe and should be avoided. We will present a surgical resection with superior vena cava reconstruction, involving a temporary extrathoracic shunt from the left brachiocephalic vein to the right auricle using a venous return cannula. This is an optional technique for convenient and safe superior vena cava combined resection. It provides an excellent intrathoracic surgical view by venous return via the unilateral brachiocephalic vein, with the advantages of being a simple procedure requiring short surgical time.

Ubiquitin-like 3 as a new protein-sorting factor for small extracellular vesicles.

Ubiquitin-like 3 (UBL3) is a well-conserved ubiquitin-like protein (UBL) in eukaryotes and regulates the ubiquitin cascade, but the significant roles of UBL3 in cellular processes remained unknown. Recently, UBL3 was elucidated to be a post-translational modification factor that promotes protein sorting to small extracellular vesicles (sEVs). Proteins sorted into sEVs have been studied as etiologies of sEV-related diseases. Also, there have been attempts to construct drug delivery systems (DDSs) by loading proteins into sEVs. In this review, we introduce the new concept that UBL3 has a critical role in the protein-sorting system and compare structure conservation between UBL3 and other UBLs from an evolutionary perspective. We conclude with future perspectives for the utility of UBL3 in sEV-related diseases and DDS.Key words: UBL3, small extracellular vesicles, protein sorting, ubiquitin-like protein, post-translational modification.

Decreased sphingomyelin (t34:1) is a candidate predictor for lung squamous cell carcinoma recurrence after radical surgery: a case-control study.

BACKGROUND: To reduce disease recurrence after radical surgery for lung squamous cell carcinomas (SQCCs), accurate prediction of recurrent high-risk patients is required for efficient patient selection for adjuvant chemotherapy. Because treatment modalities for recurrent lung SQCCs are scarce compared to lung adenocarcinomas (ADCs), accurately selecting lung SQCC patients for adjuvant chemotherapy after radical surgery is highly important. Predicting lung cancer recurrence with high objectivity is difficult with conventional histopathological prognostic factors; therefore, identification of a novel predictor is expected to be highly beneficial. Lipid metabolism alterations in cancers are known to contribute to cancer progression. Previously, we found that increased sphingomyelin (SM)(d35:1) in lung ADCs is a candidate for an objective recurrence predictor. However, no lipid predictors for lung SQCC recurrence have been identified to date. This study aims to identify candidate lipid predictors for lung SQCC recurrence after radical surgery. METHODS: Recurrent (n = 5) and non-recurrent (n = 6) cases of lung SQCC patients who underwent radical surgery were assigned to recurrent and non-recurrent groups, respectively. Extracted lipids from frozen tissue samples of primary lung SQCC were analyzed by liquid chromatography-tandem mass spectrometry. Candidate lipid predictors were screened by comparing the relative expression levels between the recurrent and non-recurrent groups. To compare lipidomic characteristics associated with recurrent SQCCs and ADCs, a meta-analysis combining SQCC (n = 11) and ADC (n = 20) cohorts was conducted. RESULTS: Among 1745 screened lipid species, five species were decreased (≤ 0.5 fold change; P < 0.05) and one was increased (≥ 2 fold change; P < 0.05) in the recurrent group. Among the six candidates, the top three final candidates (selected by AUC assessment) were all decreased SM(t34:1) species, showing strong performance in recurrence prediction that is equivalent to that of histopathological prognostic factors. Meta-analysis indicated that decreases in a limited number of SM species were observed in the SQCC cohort as a lipidomic characteristic associated with recurrence, in contrast, significant increases in a broad range of lipids (including SM species) were observed in the ADC cohort. CONCLUSION: We identified decreased SM(t34:1) as a novel candidate predictor for lung SQCC recurrence. Lung SQCCs and ADCs have opposite lipidomic characteristics concerning for recurrence risk. TRIAL REGISTRATION: This retrospective study was registered at the UMIN Clinical Trial Registry ( UMIN000039202 ) on January 21, 2020.