Prognostic factors of conversion surgery for stage IV gastric cancer: A multi-institutional retrospective analysis.

Background: Conversion surgery (CS) is a highly anticipated strategy for stage IV advanced gastric cancer (AGC) with a good response to chemotherapy. However, prognostic factors limiting R0 resection remain unclear. In this multi-institutional study, we investigated the clinical outcomes of CS for stage IV AGC and the prognostic factors of CS-limiting R0 resection and analyzed them according to metastatic patterns. Methods: Clinical data on 210 patients who underwent CS for stage IV AGC at six institutions between 2007 and 2017 were retrospectively retrieved. The patient background, preoperative treatment, operative outcomes, and survival times were recorded. Prognostic factors for overall and recurrence-free survival were investigated using univariate and multivariate analyses for patients who underwent R0 resection. Results: R0 resection was achieved in 146 (70%) patients. The median survival time was 32 months, and the 3-year survival rate was 45%. Patients who achieved R0 resection had significantly longer survival than those with R1/2 resection (median survival time: 41.5 months vs. 20.7 months). Multivariate analysis identified pathological N positivity for overall and relapse-free survival and pathological T4 for relapse-free survival as significant independent poor prognostic factors of R0 resected patients. There was no significant difference in survival among the peritoneum, liver, and lymph node groups regarding the initial metastatic sites. Conclusions: CS with R0 resection for patients with stage IV AGC can lead to longer survival. Patients with pathological T4 and pathological N positivity were eligible for intensive adjuvant therapy after CS with R0 resection.

Efficacy and survival of nivolumab treatment for recurrent/unresectable esophageal squamous-cell carcinoma: real-world clinical data from a large multi-institutional cohort.

BACKGROUND: Real-world clinical outcomes of and prognostic factors for nivolumab treatment for esophageal squamous-cell carcinoma (ESCC) remain unclear. This study aimed to evaluate real-world outcomes of nivolumab monotherapy in association with relevant clinical parameters in recurrent/unresectable advanced ESCC patients. METHODS: This population-based multicenter cohort study included a total of 282 patients from 15 institutions with recurrent/unresectable advanced ESCC who received nivolumab as a second-line or later therapy between 2014 and 2022. Data, including the best overall response, progression-free survival (PFS), and overall survival (OS), were retrospectively collected from these patients. RESULTS: Objective response and disease control rates were 17.0% and 47.9%, respectively. The clinical response to nivolumab treatment significantly correlated with development of overall immune-related adverse events (P < .0001), including rash (P < .0001), hypothyroidism (P = .03), and interstitial pneumonia (P = .004). Organ-specific best response rates were 20.6% in lymph nodes, 17.4% in lungs, 15.4% in pleural dissemination, and 13.6% in primary lesions. In terms of patient survival, the median OS and PFS was 10.9 and 2.4 months, respectively. Univariate analysis of OS revealed that performance status (PS; P < .0001), number of metastatic organs (P = .019), C-reactive protein-to-albumin ratio (CAR; P < .0001), neutrophil-lymphocyte ratio (P = .001), and PMI (P = .024) were significant. Multivariate analysis further identified CAR [hazard ratio (HR) = 1.61, 95% confidence interval (CI) 1.15-2.25, P = .0053)] in addition to PS (HR = 1.65, 95% CI 1.23-2.22, P = .0008) as independent prognostic parameters. CONCLUSIONS: CAR and PS before nivolumab treatment are useful in predicting long-term survival in recurrent/unresectable advanced ESCC patients with second-line or later nivolumab treatment. TRIAL REGISTRATION: UMIN000040462.

Curative resection via right hemicolectomy and regional lymph node dissection for colonic adenomatous polyposis of unknown etiology with adenocarcinomas localized in the right side of the colon: a case report.

BACKGROUND: APC and MUTYH are both well-known colorectal polyposis causative genes. However, 30-50% of colorectal adenomatous polyposis cases are classified as colonic adenomatous polyposis of unknown etiology and lack identifiable pathogenic variants. Although guidelines recommend total proctocolectomy for colonic adenomatous polyposis of unknown etiology with over 100 adenomas, evidence is lacking. This study presents a unique case of localized colonic adenomatous polyposis of unknown etiology with multiple adenocarcinomas, treated with hemicolectomy and regional lymph node dissection. CASE PRESENTATION: The patient was a 72-year-old woman whose colonoscopy revealed numerous polyps and two adenocarcinomas localized in the right side of the colon, with no lesions in the left side. The patient had no family history of polyposis or colorectal cancer. No extracolonic lesions, enlarged lymph nodes, or distant metastases were found. Considering the patient's age and lesion localization, laparoscopic right hemicolectomy with regional lymph node dissection was performed. Histopathological diagnosis revealed three adenocarcinoma lesions with no lymph node metastasis. The most advanced pathological stage was T2N0M0 Stage I (UICC 8th edition). The patient was alive 5 years postoperatively, without recurrence of cancer or polyposis in the remaining colon and rectum. To diagnose hereditary colorectal cancer/polyposis, a germline multigene panel testing for APC, EPCAM, MBD4, MLH1, MLH3, MSH2, MSH3, MSH6, MUTYH, NTHL1, PMS2, POLD1, POLE, and TP53 was performed using DNA extracted from blood samples: however, no pathogenic variant was detected. Therefore, the patient was diagnosed with colonic adenomatous polyposis of unknown etiology. CONCLUSIONS: In this rare case, colonic adenomatous polyposis of unknown etiology, with numerous adenomatous polyps and multiple adenocarcinomas localized in the right side of the colon, was successfully treated with right hemicolectomy and regional lymph node dissection. Despite genetic analysis, no causative germline variants were identified. Segmental colectomy according to the distribution of polyps might be a curative approach.

Prognostic factors and significance of postoperative adjuvant chemotherapy in patients with advanced gastric cancer undergoing neoadjuvant chemotherapy followed by gastrectomy.

PURPOSE: In Japan, gastrectomy with D2 lymph node dissection and postoperative adjuvant chemotherapy are the standard treatments for locally advanced gastric cancer. Neoadjuvant chemotherapy (NAC) is not affected by postgastrectomy syndromes or postoperative complications. This multicenter retrospective study investigated the prognostic factors and significance of postoperative adjuvant chemotherapy in patients with advanced gastric cancer who underwent NAC followed by gastrectomy. METHODS: Consecutive patients (n = 221) with advanced gastric cancer who underwent NAC followed by curative surgery were enrolled in this study. Prognostic factors including postoperative adjuvant chemotherapy were investigated using univariate and multivariate analyses. RESULTS: A multivariate analysis revealed that pathological lymph node metastasis (ypN) status and postoperative adjuvant chemotherapy were independent prognostic factors for the overall and relapse-free survival. Forty-five patients (20.4%) did not receive postoperative adjuvant chemotherapy. There were no significant differences between patients with and without adjuvant chemotherapy for all factors, except age. The most common reason for not undergoing postoperative adjuvant chemotherapy was a poor condition (n = 23). CONCLUSIONS: ypN status and postoperative adjuvant chemotherapy were independent prognostic factors in gastric cancer patients who underwent NAC followed by curative gastrectomy. It is important to maintain the patient's condition during NAC and the perioperative period so that they can receive postoperative adjuvant chemotherapy.

Clinical Impact of Conversion Surgery After Induction Therapy for Esophageal Cancer with Synchronous Distant Metastasis: A Multi-institutional Retrospective Study.

BACKGROUND: The standard treatment for advanced esophageal cancer with synchronous distant metastasis is systemic chemotherapy or immunotherapy. Conversion surgery is not established for esophageal cancer with synchronous distant metastasis. This study aimed to investigate the clinical impact of conversion surgery for esophageal cancer with synchronous distant metastasis after induction therapy. METHODS: This multi-institutional retrospective study enrolled 66 patients with advanced esophageal cancer, including synchronous distant metastasis, who underwent induction chemotherapy or chemoradiotherapy followed by conversion surgery between 2005 and 2021. Short- and long-term outcomes were investigated. RESULTS: Distant lymph node (LN) metastasis occurred in 51 patients (77%). Distant organ metastasis occurred in 15 (23%) patients. There were 41 patients with metastatic para-aortic LNs, and 10 patients with other metastatic LNs. Organs with distant metastasis included the lung in seven patients, liver in seven patients, and liver and lung in one patient. For 61 patients (92%), R0 resection was achieved. The postoperative complication rate was 47%. The in-hospital mortality rate was 1%, and the 3- and 5-year overall survival (OS) rates for all the patients were 32.4% and 24.4%, respectively. The OS rates were similar between the patients with distant LN metastasis and the patients with distant organ metastasis (3-year OS: 34.9% vs. 26.7%; P = 0.435). Multivariate analysis showed that pathologic nodal status is independently associated with a poor prognosis (hazard ratio, 2.43; P = 0.005). CONCLUSIONS: Conversion surgery after chemotherapy or chemoradiotherapy for esophageal cancer with synchronous distant metastasis is feasible and promising. It might be effective for improving the long-term prognosis for patients with controlled nodal status.

Cardiac tamponade complicating esophagectomy and retrosternal gastric tube reconstitution in a patient with an abnormal ascending aorta position: a case report.

BACKGROUND: Cardiac tamponade is a rare postoperative complication of esophageal cancer surgery, which leads to rapid hemodynamic changes and can be fatal if not treated properly and promptly. Herein, we report a case of cardiac tamponade after thoracoscopic subtotal esophagectomy and retrosternal gastric tube reconstitution for esophageal cancer that was successfully treated with surgical drainage. CASE PRESENTATION: An 86-year-old man with lower thoracic esophageal cancer underwent thoracoscopic subtotal esophagectomy and retrosternal gastric tube reconstitution. No intra-operative complications were observed. On the first postoperative day, tachycardia and hypotension were observed, and pericardial effusion was identified on computed tomography images. The patient was diagnosed with obstructive shock secondary to cardiac tamponade. As percutaneous puncture drainage was not possible due to the presence of a retrosternal gastric tube, pericardiotomy with a small left anterior thoracotomy was performed, and a large amount of hematogenous fluid was drained, which instantly improved circulation. On the second postoperative day, the patient showed decreased pulse pressure, and computed tomography revealed a residual and enlarged hematoma around the right ventricle. The patient underwent surgical drainage and another pericardiotomy with a small right anterior thoracotomy was performed to drain the hematoma. At this time, multiple injuries to the fatty tissue, epicardium, and myocardium with active bleeding were observed on the anterior surface of the right ventricle near the root of the pulmonary artery. In this patient, the ascending aorta ran further to the right and dorsal sides than usual, causing the anterior wall of the right ventricle near the root of the pulmonary artery to be closer to the back of the sternum. This abnormality may have contributed to injury during the creation of the retrosternal pathway, leading to cardiac tamponade. CONCLUSIONS: Cardiac tamponade after esophagectomy can occur because of manipulation during creation of the retrosternal route, with an anomaly in the aortic position being present in this case. Gentle manipulation and selection of the reconstruction route according to the patient's condition are necessary in cases with such anatomical abnormalities.

Comparison of percutaneous ablation and hepatectomy for liver metastasis: A single center retrospective study.

AIM: To investigate the current treatment for liver metastasis and clarify the indications for percutaneous thermal ablation for liver metastasis. METHODS: Ninety-two patients were enrolled and retrospectively analyzed. The patients underwent hepatectomy and/or percutaneous thermal ablation for liver metastases between January 2012 and December 2018. Twenty-six patients who underwent ablation treatment and seven patients who underwent both ablation and hepatectomy were included in the ablation treatment group (group A). We compared these patients with 59 patients who underwent hepatectomy only (group H). Subgroup analyses were performed between ablation (group AC) for colorectal liver metastasis and hepatectomy (group HC) for colorectal liver metastasis in 17 and 53 patients, respectively. RESULTS: The percentage of liver metastases other than colorectal cancer in group A was higher than that in the group H. Maximum tumor size in group A was significantly smaller than that in group H. Similarly, the patients in group AC were significantly older and demonstrated higher total bilirubin, lower serum albumin, and lower platelet counts than those in group HC. Overall survival was poorer in the AC group than that in the HC group. However, no differences were observed at metastasis ≤2 cm in size. CONCLUSIONS: Percutaneous thermal ablation was performed for many cancer types than hepatectomy. It is performed in elderly patients. We suggested that ablation for colorectal liver metastasis sized ≤2 cm is a suitable indication.

Impact of the perioperative assessment of deglutition on postoperative respiratory complications in elderly patients undergoing gastrectomy for gastric cancer.

PURPOSE: To investigate the association between perioperative deglutition screening and postoperative respiratory complications (PRCs) in elderly patients undergoing gastrectomy for gastric cancer. METHODS: We analyzed data from 86 patients with gastric cancer (aged ≥ 70 years) who underwent gastrectomy between October, 2016 and November, 2018. Videofluoroscopic swallowing examinations (VFSEs) were performed before and after surgery. We examined the association of these results with postoperative respiratory complications, as well as the relationships between demographic, operative, and swallowing function assessment data. RESULTS: PRCs were identified in 16 patients. The results of pre- and postoperative VFSE showed abnormalities in 28 and 32 patients, respectively. Multivariate analysis revealed that abnormalities in the postoperative VFSEs were strongly associated with the development of PRCs (P = 0.002). The findings of this analysis suggests that ventilatory impairment, a Charlson comorbidity index score ≥ 3, and an open surgical approach are independent risk factors for PRCs. CONCLUSION: This is the first study to demonstrate the efficacy of perioperative assessment of swallowing function using VFSE for predicting PRCs in elderly patients undergoing gastrectomy for gastric cancer.

Long-Term Outcomes of Pylorus-Preserving Gastrectomy for Early Gastric Cancer.

BACKGROUND: In the short term, pylorus-preserving gastrectomy (PPG) has been reported to have advantages over distal gastrectomy (DG) with regard to postprandial symptoms and dumping syndrome. We aimed to evaluate the quality of life after PPG for early gastric cancer in the long term in comparison to that after DG. METHODS: Twenty-six patients who underwent gastrectomy (11 PPG, 15 DG) for early gastric cancer at Osaka University Hospital participated and were followed for more than 4 years. Body weight changes, nutritional status, dual-phase scintigraphy findings, endoscopic survey results, and questionnaire responses after gastrectomy were examined. RESULTS: There were significantly lower ratios of weight changes in PPG than in DG, 5 years after surgery. There were no differences in the clinicopathological characteristics, nutritional parameters, questionnaire responses, and endoscopic findings between the two groups. Based on gastric scintigraphy, although the gastric emptying of liquids showed similar curves in the two groups, gastric emptying of solids was significantly slower in the PPG group than in the DG group (P = .039). DISCUSSION: PPG had advantages with regard to long-term outcomes over DG in terms of weight maintenance and the prevention of rapid gastric emptying. PPG might be efficient in patients with early gastric cancer.

Three-Course Neoadjuvant Chemotherapy Associated with Unfavorable Survival of Non-responders to the First Two Courses for Locally Advanced Esophageal Cancer.

BACKGROUND: Three-course neoadjuvant chemotherapy (NAC) followed by surgery has become a standard of care for locally advanced esophageal cancer (EC). However, some patients occasionally experience a poor tumor response to the third course and have a poor clinical outcome. METHODS: An exploratory analysis of data from the authors' recent multicenter randomized phase 2 trial compared patients with locally advanced EC who received two courses (n = 78) and those who received three courses (n = 68) of NAC. The association between tumor response and clinico-pathologic factors, including survival, was evaluated to identify risk factors in the three-course group. RESULTS: Of 68 patients who received three courses of NAC, 28 (41.2%) had a tumor reduction rate lower than 10% during the third course. This rate was associated with unfavorable overall survival (OS) and progression-free survival (PFS) compared with a tumor reduction rate of 10% or higher (2-year OS rate: 63.5% vs. 89.3%, P = 0.007; 2-year PFS rate: 52.6% vs. 79.7%, P = 0.020). The independent prognostic factors for OS were tumor reduction rate lower than 10% during the third course (hazard ratio [HR], 2.735; 95% confidence interval [CI] 1.041-7.188; P = 0.041) and age of 65 years or older (HR, 9.557, 95% CI 1.240-73.63; P = 0.030). Receiver operating characteristic curve and multivariable logistic regression analyses identified a tumor reduction rate lower than 50% after the first two courses as an independent predictor of a tumor reduction rate lower than 10% during the third course of NAC (HR, 4.315; 95% CI 1.329-14.02; P = 0.015). CONCLUSION: Continuing NAC through a third course may worsen survival for patients who do not experience a response to the first two courses in locally advanced EC.

Long-term survival and prognostic factors associated with curative conversion surgery for ct4b esophageal squamous cell carcinoma: Analysis of 200 consecutive cases.

BACKGROUND: The optimal treatment strategy for cT4b esophageal cancer has not been established yet. Although curative surgery is sometimes performed after induction treatments, the prognostic factor of cT4b esophageal cancer cases who underwent R0 resection remains unknown. METHODS: A total of 200 patients with cT4b esophageal cancer who underwent R0 resection after induction treatments between 2001 and 2020 in our institute were included in the present study. The relationship between clinicopathological factors and patient survival is evaluated to identify useful prognostic factors. RESULTS: The median and 2-year overall survival were 40.1 months and 62.8%, respectively. Disease recurrence occurred in 98 (49%) patients after surgery. Compared to induction chemotherapy alone, chemoradiation-based induction treatments were associated with decreased locoregional recurrence (34.0% vs 60.8%, P = .0077) but increased pulmonary metastases (27.7% vs 9.8%, P = .0210) and dissemination (19.1% vs 3.9%, P = .0139) after surgery. Multivariate analysis of overall survival identified the preoperative C-reactive protein/albumin ratio (hazard ratio 1.7957, P = .0031), response to induction treatments (hazard ratio 2.9663, P = .0009), postoperative pneumonia (hazard ratio 2.3784, P = .0010), and pN (2-3) (hazard ratio 1.5693, P = .0355) as independent prognostic factors. Preoperative C-reactive protein/albumin ratio (hazard ratio 1.6760, P = .0068) and postoperative pneumonia (hazard ratio 1.8365, P = .0200) were also independent prognostic factors for recurrence-free survival. CONCLUSION: Curative surgery after induction therapy for cT4b esophageal cancer achieved favorable survival. Preoperative C-reactive protein/albumin ratio, postoperative pneumonia, response to induction treatments, and pN were useful prognostic factors.

Gut microbiota associated with the mitigation effect of synbiotics on adverse events of neoadjuvant chemotherapy in patients with esophageal cancer: A retrospective exploratory study.

Introduction. Our synbiotics (Lacticaseibacillus paracasei strain Shirota, Bifidobacterium breve strain Yakult, and galacto-oligosaccharides: LBG) helps mitigate serious adverse events such as febrile neutropenia (FN) and diarrhoea in oesophageal cancer patients receiving neoadjuvant chemotherapy (NAC). Unfortunately, LBG therapy does not benefit all patients.Hypothesis/Gap Statement. Identification of the gut microbiota species involved in adverse events during chemotherapy could help predict the onset of adverse events. Identification of the gut microbiota that influence the efficacy of LBG could also help establish a diagnostic method to identify patients who will respond to LBG before the initiation of therapy.Aim. To identify the gut microbiota involved in adverse events during NAC and that affect the efficacy of LBG therapy.Methodology. This study was ancillary to a parent randomized controlled trial in which 81 oesophageal cancer patients were recruited and administered either prophylactic antibiotics or LBG combined with enteral nutrition (LBG+EN). The study included 73 of 81 patients from whom faecal samples were collected both before and after NAC. The gut microbiota was analysed using 16S rRNA gene amplicon sequencing and compared based on the degree of NAC-associated adverse events. Furthermore, the association between the counts of identified bacteria and adverse events and the mitigation effect of LBG+EN was also analysed.Results. The abundance of Anaerostipes hadrus and Bifidobacterium pseudocatenulatum in patients with no FN or only mild diarrhoea was significantly higher (P<0.05) compared to those with FN or severe diarrhoea. Moreover, subgroup analyses of patients receiving LBG+EN showed that the faecal A. hadrus count before NAC was significantly associated with a risk of developing FN (OR, 0.11; 95 % CI, 0.01-0.60, P=0.019). The faecal A. hadrus count after NAC was positively correlated with intestinal concentrations of acetic acid (P=0.0007) and butyric acid (P=0.00005).Conclusion. Anaerostipes hadrus and B. pseudocatenulatum may be involved in the ameliorating adverse events and can thus be used to identify beforehand patients that would benefit from LBG+EN during NAC. These results also suggest that LBG+EN would be useful in the development of measures to prevent adverse events during NAC.

Chemoradiotherapy versus triplet chemotherapy as initial therapy for T4b esophageal cancer: survival results from a multicenter randomized Phase 2 trial.

BACKGROUND: We report the long-term results as primary endpoint in a multicentre randomized prospective Phase 2 trial which compared chemoradiotherapy (CRT) and triplet chemotherapy (CT) as the initial therapy for conversion surgery (CS) in T4b esophageal cancer (EC). METHODS: Patients with T4b EC were randomly assigned to the CRT group or CT group as initial treatment. CS was performed if resectable after initial or secondary treatment. The primary endpoint was 2-year overall survival, analysed by intention-to-treat. RESULTS: The median follow-up period was 43.8 months. The 2-year survival rate was higher in the CRT group (55.1%; 95% CI: 41.1-68.3%) compared to the CT group (34.7%; 95% CI: 22.8-48.9%), although the difference was not significant (P = 0.11). Local and regional lymph node recurrence in patients undergoing R0 resection was significantly higher in the CT group compared to the CRT group (local: 30% versus 8%, respectively, P = 0.03; regional: 37% versus 8%, respectively, P = 0.002). CONCLUSIONS: Upfront CT was not superior to upfront CRT as induction therapy for T4b EC in terms of 2-year survival and was significantly inferior to upfront CRT in terms of local and regional control. REGISTRATION: The Japan Registry of Clinical Trials (s051180164).

Clinical Impact of Metastatic Lymph Node Size on Therapeutic Effect and Prognosis in Patients with Esophageal Squamous Cell Carcinoma Who Underwent Preoperative Chemotherapy Followed by Esophagectomy.

BACKGROUND: Pretreatment metastatic lymph node (LN) size has been reported to be associated with prognosis in esophageal squamous cell carcinoma (ESCC). However, its relationship with response to preoperative chemotherapy or prognosis has not been clarified. We investigated the relationship between metastatic LN size and response to preoperative treatment, and prognosis in patients with metastatic esophageal cancer who underwent surgery. PATIENTS AND METHODS: A total of 212 clinically node-positive patients who underwent preoperative chemotherapy followed by esophagectomy for ESCC were enrolled. Patients were stratified into three groups on the basis of the length of the short axis of the largest LN in pretreatment computed tomography images: < 10 mm (group A), 10-19 mm (group B), and ≥ 20 mm (group C). RESULTS: Group A had 90 patients (42%), group B had 103 patients (49%), and group C had 19 patients (9%). Group C had significantly lower percent reduction in total metastatic LN size than groups A and B (22.5% versus 35.7%, P = 0.037). Group C had significantly more metastatic LNs based on histological examination than groups A and B (10.1 versus 2.4, P < 0.001). Group C patients whose LNs responded had significantly fewer metastatic LNs than nonresponders (5.1 versus 11.9, P = 0.042). Group C had significantly poorer overall survival than groups A and B (3-year survival, 25.4% versus 67.3%, P < 0.001). However, group C patients whose LNs responded had better survival than nonresponders (3-year survival, 57.1% versus 0%, P = 0.008). CONCLUSIONS: Patients with large metastatic LNs have poor response and poor prognosis. However, if a response is obtained, long-term survival can be expected.

Plasma trough concentration of imatinib and its effect on therapeutic efficacy and adverse events in Japanese patients with GIST.

BACKGROUND: Imatinib mesylate (IM) is the standard chemotherapy for patients with gastrointestinal stromal tumors (GISTs) and has a favorable safety profile. Pharmacokinetics (PK), such as plasma trough concentration (Cmin), varies among patients, requiring the need for therapeutic drug monitoring (TDM) during IM administration. Despite some reports from overseas, the relationship between Cmin, adverse events (AEs), and treatment efficacy in Japanese patients with GIST has still been lacking. This study aimed to investigate the relationship between IM plasma concentration and AEs in Japanese patients with GISTs. METHODS: This retrospective study analyzed the data of 83 patients who underwent IM treatment for GISTs at our institution between May 2002 and September 2021. RESULTS: The IM Cmin was associated with any grade of AEs (with AEs vs. without AEs = 1294 (260-4075) vs. 857 (163-1886) ng/mL, P < 0.001), edema (with edema vs. without edema = 1278 (634-4075) vs. 1036 (163-4069) ng/mL, P = 0.017), and fatigue (with fatigue vs. without fatigue = 1373 (634-4069) vs. 1046 (163-4075) ng/mL, P = 0.044). Moreover, a Cmin ≥ 1283 ng/mL was a risk factor for severe AEs. The median progression-free survival (PFS) was 3.04 years in the lowest Cmin tertile (T1, < 917 ng/mL) compared with 5.90 years for T2 and T3 (P = 0.010). CONCLUSION: Edema and fatigue are potentially associated with IM plasma trough concentrations of ≥ 1283 ng/mL in Japanese patients with GISTs. Further, maintaining an IM plasma trough concentration above 917 ng/mL may improve PFS.