Defining the clinical benefits of adding a neurokinin-1 receptor antagonist to control chemotherapy-induced nausea and vomiting in moderately emetogenic chemotherapy: a systematic review and meta-analysis of the clinical practice guidelines for antiemesis 2023 from the Japan society of clinical oncology.

BACKGROUND: Chemotherapy-induced nausea and vomiting (CINV) commonly affects patient quality of life and the overall effectiveness of chemotherapy. This study aimed to evaluate whether adding neurokinin-1 receptor antagonists (NK1RAs) to 5-hydroxytryptamine-3 receptor antagonists (5-HT3RAs) and corticosteroids provides clinically meaningful benefits in preventing CINV in patients receiving moderately emetogenic chemotherapy (MEC). METHODS: We conducted a systematic review of PubMed, Cochrane Library, and Ichushi-Web to identify clinical studies evaluating NK1RAs combined with 5-HT3RAs and dexamethasone for managing CINV in MEC. The endpoints were complete response (CR), complete control (CC), total control (TC), adverse events, and costs. The data were analyzed using a random effects model. RESULTS: From 142 articles identified, 15 randomized controlled trials (RCTs), involving 4,405 patients, were included in the meta-analysis. Approximately 60% of the patients received carboplatin (CBDCA)-based chemotherapy. The meta-analysis showed that triplet antiemetic prophylaxis with NK1RA was significantly more effective for achieving CR than doublet prophylaxis in each phase. Regarding CC, the triplet antiemetic prophylaxis was significantly more effective than the doublet in the overall (risk difference [RD]: 0.11, 95% confidence interval [CI]: 0.06-0.17) and delayed (RD: 0.08, 95% CI: 0.02-0.13) phases. For TC, no significant differences were observed in any phase. Adding NK1RA did not cause adverse events. CONCLUSIONS: Adding NK1RA to CBDCA-based chemotherapy has shown clinical benefits. However, the clinical benefits of NK1RA-containing regimens for overall MEC have not yet been established and require RCTs that exclusively evaluate MEC regimens other than CBDCA-based chemotherapy.

Long-term Survival in Esophageal Cancer: Comparison of Minimally Invasive and Open Esophagectomy.

BACKGROUND: Thoracoscopic esophagectomy is a less invasive surgical procedure; however, evidence of its effect on long-term survival is limited. We evaluated long-term survival after the procedure in patients with esophageal carcinoma. METHODS: This retrospective multicenter study involved 1,559 consecutive patients with esophageal carcinoma who underwent thoracoscopic esophagectomy or open esophagectomy between 2012 and 2019 at two Japanese high-volume cancer centers. Propensity score matching analysis was performed to compare short- and long-term outcomes. Additionally, stage-specific survival rates were compared between the two groups. RESULTS: Three-hundred-and-thirteen patients were matched and analyzed. The 1-, 3-, and 5-year overall survival rates were 84.5%, 60.5%, and 52.1%, respectively, in the matched open esophagectomy group; and 87.2%, 68.6%, and 61.8%, respectively, in the matched thoracoscopic esophagectomy group. The weighted Cox regression model showed significantly better survival in the thoracoscopic esophagectomy group than in the open esophagectomy group (hazard ratio = 0.74, 95% confidence interval: 0.582-0.941). Deaths from other causes occurred more frequently in the open esophagectomy group than in the thoracoscopic esophagectomy group. Stratified analysis showed no significant survival differences between the cStage I or II and pStage 0 or I subgroups. However, the thoracoscopic esophagectomy groups with cStage III or IV and pStage II, III, or IV had significantly better overall survival. CONCLUSIONS: This study demonstrated the survival benefits of thoracoscopic esophagectomy particularly for highly advanced esophageal carcinoma.

Impact of taxanes after PD-1 blockade exposure in advanced esophageal squamous cell carcinoma.

BACKGROUND: Programmed cell death-1 (PD-1) blockade improves survival in patients with advanced esophageal squamous cell carcinoma (ESCC). However, the efficacy of taxanes after exposure to PD-1 blockade remains unclear in patients with advanced ESCC. METHODS: We retrospectively analyzed the clinical outcomes of advanced ESCC patients treated with taxanes (paclitaxel or docetaxel) with/without prior exposure to PD-1 blockade (Exposed /Naïve group) at National Cancer Center Hospital from June 2016 to December 2020. RESULTS: Ninety-nine patients (Exposed group, n = 32; Naïve group, n = 67) were included. The objective response rate (ORR) of the Exposed group was significantly higher than that of the Naïve group (37.5% vs. 13.4%, p = 0.009). The median progression-free survival was similar between the Exposed and Naïve groups (3.8 vs. 2.8 months, HR 1.12, 95% CI 0.65-1.86, p = 0.66). PD-1 blockade exposure independently predicated higher ORR to taxanes in multivariate analysis. Grade ≥ 3 adverse events were comparable between the Exposed and Naïve groups (45.8% vs. 40.3%, p = 0.64). CONCLUSIONS: Taxanes following PD-1 blockade in advanced ESCC showed a higher ORR but similar PFS compared to taxanes without prior PD-1 exposure.

Safety and Efficacy of Conversion Therapy After Systemic Chemotherapy in Advanced Esophageal Cancer with Distant Metastases: A Multicenter Retrospective Observational Study.

BACKGROUND: Patients with esophageal squamous cell carcinoma (ESCC) with distant metastasis were treated with systemic chemotherapy. Recent advances in multimodal treatments have made conversion therapy a viable option for patients with incurable ESCC. OBJECTIVE: We aimed to assess the safety and efficacy of conversion therapy for ESCC with distant metastases. METHODS: Conversion therapy was defined as surgery or chemoradiotherapy (CRT) used to cure tumors that were previously considered incurable because of distant metastasis. We conducted a retrospective review of patients who underwent ESCC conversion therapy and assessed the treatment outcomes, including adverse events and survival rates. RESULTS: A total of 147 patients from 22 institutions were included. Systemic chemotherapy was initially administered to all patients. The most common M1 factor was the para-aortic lymph node, accounting for 55% of cases. Following the initial treatment, 116 patients underwent surgery, with 31 receiving CRT as conversion therapy. Postoperative complications in surgery patients included pneumonia (16%), anastomotic leakage (7%), and recurrent laryngeal nerve palsy (6%). During CRT, 18% of patients developed grade 3 or higher non-hematological toxicities. The 5-year overall survival (OS) rate was 31.7%. Pathological responders had significantly longer OS than non-responders (hazard ratio 0.493, p = 0.012). The distribution of distant metastasis, regimen type, clinical response, and conversion therapy modality did not have a significant impact on OS. CONCLUSIONS: Conversion therapy can be safely performed for ESCC with distant metastasis and has a favorable prognosis.

An autopsy case of pulmonary tumor thrombotic microangiopathy that developed during chemotherapy for salivary duct carcinoma of the parotid gland.

Pulmonary tumor thrombotic microangiopathy (PTTM) is a rapidly progressive cancer-related disease with a dismal clinical course. The patient in this report was a 43-year-old man with metastatic salivary duct carcinoma arising from the parotid gland. Combined androgen blockade therapy was administered started as first-line treatment, but failed after 5 months, followed by docetaxel plus carboplatin therapy as second-line treatment, which failed after 3 months. Genomic profiling revealed a BRAF V600E mutation, and combined BRAF and MEK inhibitor therapy was started as third-line treatment. The cancer remained stable during the first 10 months of third-line treatment, but treatment was subsequently discontinued due to the onset of symptoms of fatigue, myalgia and arthritis. Twenty days after the onset of these symptoms and interruption of third-line treatment, the patient was urgently admitted to hospital with respiratory distress and severe thrombocytopenia. CT images at the time of admission led our radiologist to the possibility of PTTM, but the patient died the day after admission and autopsy findings indicated that PTTM was the cause of death. This report describes a very informative case of PTTM with sequential imaging and detailed autopsy findings were available and provides a literature review.

Efficacy and Safety of Salvage-line Nivolumab Monotherapy for Advanced Esophageal Squamous Cell Carcinoma: Comparison of 240 mg Versus 480 mg Doses.

BACKGROUND: Nivolumab monotherapy is the standard second-line treatment for advanced esophageal squamous cell carcinoma (ESCC) after failure of platinum-based chemotherapy without anti-PD-1 antibody. Fixed dosing with 240 mg every 2 weeks was approved initially, followed by fixed dosing with 480 mg every 4 weeks based on pharmacokinetics data. However, information on the comparative efficacy and safety of the two doses remains limited. METHODS: We compared progression-free survival (PFS), overall survival (OS), objective response rate (ORR), and the incidence of adverse events (AEs) between the two doses in 117 patients who received second-line (n = 85) or later-line (n = 32) nivolumab monotherapy at our institution between January 2016 and December 2021. RESULTS: In the second-line group, patient characteristics for the 240 mg and 480 mg groups were as follows (240 mg vs. 480 mg): performance status (PS) 0/1/2 was 34/61/5% vs. 54/42/4%, and prior fluoropyrimidine plus platinum therapy (FP) was 81.3% vs. 42.3%. In the later-line group, the characteristics were: PS 0/1/2 was 28/60/12% vs. 14/86/0%, and prior FP was 60.0% vs. 42.8%. ORR was 11.9 vs. 24.0% in the second-line group (p = 0.19) and 0 vs. 14.3% in the later-line group (p = 0.22). Median PFS was 1.7 vs. 4.1 months on second-line (hazard ratio [HR] 0.60, 95% confidence interval [CI] 0.35-1.01, p = 0.056) and 1.4 vs. 1.8 months on later-line (HR 0.58, 95% CI 0.23-1.46, p = 0.25); AEs of any grade were observed in 58.3 vs. 69.7%, respectively. CONCLUSIONS: The efficacy and safety of the two doses of nivolumab monotherapy were comparable in patients with advanced ESCC.

Progress in second-line antibody therapies for advanced esophageal squamous cell carcinoma.

INTRODUCTION: The prognosis of advanced esophageal squamous cell carcinoma (ESCC) is poor. Although cytotoxic drugs have been widely used in advanced ESCC, several antibody agents have recently been reported to be effective. AREAS COVERED: Nivolumab and pembrolizumab are anti-PD-1 antibodies that improve immunosuppression by binding to programmed death-1 (PD-1), leading to an antitumor effect. Randomized phase III trials have found these immune checkpoint inhibitors (ICIs) to be effective as second-line treatment. ATTRACTION-3, which compared nivolumab monotherapy with taxane monotherapy in patients with previously treated advanced ESCC, reported prolonged overall survival in the nivolumab group. KEYNOTE-181 found that overall survival was longer in patients with PD-L1-positive ESCC who received second-line treatment with pembrolizumab than in those who received chemotherapy. Sym004 and amivantamab are antibodies that target the epidermal growth factor receptor and have demonstrated efficacy in the treatment of other tumors in recent phase I studies. Furthermore, clinical trials on antibody-drug conjugates such as enfortumab vedotin and DS-7300 for solid tumors are currently ongoing. EXPERT OPINION: The standard first-line treatments for patients with advanced ESCC contain ICIs. Therefore, drugs with different mechanisms of action that can overcome resistance to ICIs are needed as second-line or later-line treatments to improve clinical outcomes in these patients.

Development of perioperative immune checkpoint inhibitor therapy for locally advanced esophageal squamous cell carcinoma.

The standard preoperative treatment for resectable locally advanced esophageal squamous cell carcinoma (ESCC) is chemoradiotherapy in western countries (based on the CROSS trial) and triplet chemotherapy in Japan (based on the JCOG1109 trial). Postoperative nivolumab has recently been shown to improve disease-free survival in resectable locally advanced esophageal cancer after preoperative chemoradiotherapy in patients who had residual pathological disease, based on the CheckMate 577 trial. Furthermore, preoperative immune checkpoint inhibitor-containing treatments have also been developed. The JCOG1804E trial is presently evaluating the safety and efficacy of preoperative nivolumab-containing chemotherapy for resectable locally advanced ESCC. This review discusses the treatment of resectable locally advanced ESCC and future perspectives on perioperative immune checkpoint inhibitor-containing treatments.

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Neoadjuvant Chemotherapy Improves Feasibility of Larynx Preservation and Prognosis in Resectable Locally Advanced Cervical Esophageal Cancer.

BACKGROUND: The optimal strategy for cervical advanced esophageal cancer remains controversial in terms of oncologic outcome as well as vocal and swallowing function. Recently, in East Asian countries, neoadjuvant chemotherapy (NAC) has been a standard strategy for advanced esophageal cancer. METHODS: This study included 37 patients who underwent NAC, and 33 patients who underwent definitive chemoradiation therapy (dCRT) as larynx-preserving treatment for locally advanced cervical esophageal cancer from 2016 to 2021. This study retrospectively investigated outcomes, with comparison between NAC and dCRT for locally advanced cervical esophageal cancer. RESULTS: Larynx preservation was successful for all the patients with NAC and dCRT. After NAC, the rate of complete or partial response was 78.4%, and 30 patients underwent larynx-preserving surgery. On the other hand, after dCRT, the complete response rate was 71.9%, and 4 patients underwent larynx-preserving salvage surgery. Overall survival (OS) and progression free survival were similar between the two groups. However, for the patients with resectable cervical esophageal cancer (cT1/2/3), the 2-year OS rate was significantly higher with NAC (79.9%) than with dCRT (56.8%) (P = 0.022), and the multivariate analyses identified only NAC and cN0, one of the two as a significantly independent factor associated with a better OS (NAC: P = 0.041; cN0, 1: P = 0.036). CONCLUSION: The study showed that NAC as larynx-preserving surgery for resectable cervical esophageal cancer preserved function and had a better prognosis than dCRT. The authors suggest that NAC may be standard strategy for larynx preservation in patients with resectable cervical esophageal cancer.

Pembrolizumab for recurrent locally advanced or metastatic squamous cell carcinoma of the esophagus: a drug safety evaluation.

INTRODUCTION: The prognosis of advanced esophageal squamous cell carcinoma (ESCC) remains poor and few effective drugs are available. Cisplatin plus 5-FU (CF) has been the standard first-line treatment for advanced ESCC. However, in the KEYNOTE-181 trial, the clinical outcomes were better in patients with programmed death ligand 1 (PD-L1)-positive advanced ESCC who received pembrolizumab, an immune checkpoint inhibitor (ICI), than in those who received cytotoxic agents as second-line treatment. Moreover, the KEYNOTE-590 trial demonstrated the superiority of pembrolizumab plus CF over CF alone in terms of overall survival. Based on the results of KEYNOTE-590, pembrolizumab plus CF has become one of the standard treatments for advanced ESCC. However, the safety profile of ICI-containing therapy is different from that of conventional cytotoxic agents. AREAS COVERED: Safety of pembrolizumab-containing therapies in patients with advanced ESCC. EXPERT OPINION: Pembrolizumab-containing therapies are tolerable as first- and second-line treatments in patients with advanced ESCC. Although infrequent, immune-related adverse events may occur in patients on pembrolizumab-containing therapies. These events are potentially fatal and require treatment with steroids or immunosuppressive drugs. Regular physical and laboratory examinations, including measurement of hormone levels, are needed during and after pembrolizumab-containing therapies in clinical practice.

Preoperative docetaxel, cisplatin, and 5-fluorouracil for resectable locally advanced esophageal and esophagogastric junctional adenocarcinoma.

BACKGROUND: Chemotherapy consisting of 5-fluorouracil, leucovorin, oxaliplatin, and docetaxel is the standard perioperative treatment for resectable esophageal adenocarcinoma and esophagogastric junctional adenocarcinoma (EGJ-AC) in Western countries. Meanwhile, preoperative chemotherapy consisting of docetaxel, cisplatin, and 5-fluorouracil (DCF) has been developed for esophageal squamous cell carcinoma in Japan. However, there are few reports on the safety and efficacy of preoperative DCF for resectable EGJ-AC in the Japanese population. METHODS: Patients with histologically confirmed resectable EGJ-AC who received preoperative DCF (docetaxel 70 mg/m2 and cisplatin 70 mg/m2 on day 1 and continuous infusion of 5-fluorouracil 750 mg/m2/day on days 1-5 every 3 weeks with a maximum of three cycles) between January 2015 and April 2020 were retrospectively evaluated. We assessed the rates of completion of ≥ 2 courses of DCF and R0 resection, histopathological response, progression-free survival (PFS), overall survival (OS), and adverse events. RESULTS: Thirty-two patients were included. Median follow-up was 28.7 (range, 5.2-70.8) months and median age was 63 (range, 42-80) years. Twenty-one patients (66%) had a performance status of 0. The proportions of clinical stage IIA/IIB/III/IVA/IVB disease were 3%/0%/44%/44%/9%, respectively. The treatment completion rate was 84%. A histopathological response of grade 1a/1b/2/3 was obtained in 58%/26%/13%/3% of cases. Median PFS was 40.7 months (95% confidence interval 11.8-NA). Median OS was not reached (80.8% at 3 years). Grade ≥ 3 adverse events were observed in 63% of cases (neutropenia, 44%; febrile neutropenia, 13%). No treatment-related deaths occurred. CONCLUSIONS: Preoperative DCF for resectable EGJ-AC was well tolerated and has promising efficacy.

Retrospective Analysis of Definitive Chemoradiotherapy With FOLFOX in Patients With Esophageal Cancer Intolerant to Cisplatin.

BACKGROUND/AIM: Definitive chemoradiotherapy with cisplatin (CDDP) plus 5-fluorouracil is the standard treatment for locally advanced esophageal squamous cell carcinoma (LA-ESCC); however, CDDP is unsuitable for patients with cardiac and/or renal dysfunction. Based on the results of the PRODIGE5/ACCORD17 trial, 5-fluorouracil and leucovorin with oxaliplatin plus radiotherapy (FOLFOX-RT) has been recognized as a treatment option. However, the efficacy and safety of FOLFOX-RT is still unclear in Japan. PATIENTS AND METHODS: Medical records were reviewed for patients with LA-ESCC who received FOLFOX-RT between April 2019 and July 2021 at our institution. We evaluated complete response rate, progression-free survival (PFS), overall survival (OS), and adverse events. RESULTS: Fifteen patients were analyzed and median age was 72.5 years (range=51-83 years). All patients completed three courses of FOLFOX and the planned radiotherapy. The complete response rate was 40.0%. With a median follow-up of 10.6 months, the 6-month PFS rate was 63.0% (95%CI=32.3-82.8%), and the 6-month OS rate was 85.7% (95%CI=53.9-96.2%). Common adverse events were esophagitis (80.0%), leukopenia (53.3%), fatigue (53.3%), and neutropenia (46.7%). Only one patient had grade 4 esophageal perforation. CONCLUSION: FOLFOX-RT for LA-ESCC was well tolerated and could be a treatment option for CDDP-intolerant patients.

Long-term outcomes after non-curative endoscopic resection for esophageal squamous cell carcinoma followed by additional chemoradiotherapy.

Endoscopic resection (ER) of esophageal squamous cell carcinoma (ESCC) is evaluated pathologically, and additional treatment is recommended for cases resulting in non-curative resection, defined as pMM with lymphovascular invasion (LVI), pSM, or positive vertical margin. This study aimed to assess long-term outcomes and risk factors for recurrence in patients with ESCC treated with non-curative ER followed by additional chemoradiotherapy (CRT). We retrospectively reviewed the clinical courses of patients who underwent non-curative ER followed by additional CRT for ESCCs between August 2007 and December 2017. Recurrence rates and risk factors for recurrence were analyzed. Among 97 patients with non-curative ER, 73 underwent additional CRT. With a median follow-up period of 71 months, recurrences were observed in 10 (14%) of 73 patients, with a median interval of 24.5 (1-59 months). The 3- and 5-year recurrence-free survival were 89 and 85%, respectively, and the 3- and 5-year overall survival rates were 96 and 91%, respectively. Multivariate analysis showed that lymphatic invasion was an independent risk factor for recurrence in patients with non-curative ESCC receiving additional CRT. Among the 10 patients with recurrence, 4, 3, 2, and 1 underwent surgery, chemotherapy, supportive care, and CRT, respectively. Notably, all four patients who underwent surgery survived, regardless of regional and/or distant lymph node metastasis. Lymphatic invasion is an independent risk factor for the recurrence of non-curative ESCCs. Careful follow-up is required for at least 5 years after ER with additional CRT.

Rare malignant neoplasm of the esophagus: current status and future perspectives.

Esophageal cancer is common worldwide, including in Japan, and its major histological subtype is squamous cell carcinoma. However, there are some rare esophageal cancers, including neuroendocrine neoplasm, gastrointestinal stromal tumor, carcinosarcoma and malignant melanoma. The biological and clinical features of these cancers differ from those of esophageal squamous cell carcinoma. Therefore, different treatment strategies are needed for these cancers but are based on limited evidence. Neuroendocrine neoplasm is mainly divided into neuroendocrine tumor and neuroendocrine carcinoma by differentiation and the Ki-67 proliferation index or mitotic index. Epidemiologically, the majority of esophageal neuroendocrine neoplasms are neuroendocrine carcinoma. The treatment of neuroendocrine carcinoma is similar to that of small cell lung cancer, which has similar morphological and biological features. Gastrointestinal stromal tumor is known to be associated with alterations in the c-KIT and platelet-derived growth factor receptor genes and, if resectable, is treated in accordance with the modified Fletcher classification. Carcinosarcoma is generally resistant to both chemotherapy and radiotherapy and requires multimodal treatments such as surgery plus chemotherapy to achieve cure. Primary malignant melanoma is resistant to cytotoxic chemotherapy, but immune checkpoint inhibitors have recently demonstrated efficacy for malignant melanoma of the esophagus. This review focuses on the current status and future perspectives for rare cancer of the esophagus.

Significance of Surgery for Resectable M1 Lymph Node Metastases Without Organ Metastasis in Esophageal Carcinoma in the Era of Neoadjuvant Treatment.

BACKGROUND: M1 esophageal carcinoma goes beyond localized disease and requires treatment with systemic therapy. M1 status is primarily divided into two categories: M1 lymph node metastasis and distant organ metastasis. Oligometastasis is defined as a state of limited metastatic disease, and surgery for oligometastasis of distant organs is reported to be beneficial in limited conditions. The aim of this study was to investigate resected cases of M1 lymph node metastases as the only metastatic site in stage IVB esophageal carcinoma. PATIENTS AND METHODS: This study was a single-center retrospective cohort study. Patients with esophageal carcinoma who underwent esophagectomy with curative intent between April 2017 and December 2021 were examined. Neoadjuvant chemotherapy was our standard therapy and administered in almost all cases. We hypothesized that four sites of metastatic M1LN (supraclavicular (no. 104), pretracheal (no. 106pre), posterior thoracic para-aortic (no. 112aoP), and abdominal para-aortic (no. 16a2lat) LNs) were potentially resectable M1LN (rM1LN) metastases with curative intent and compared the prognosis of patients with and without rM1LN metastasis. RESULTS: Six hundred eight-two patients were included in the study. Among these patients, 80 had rM1LN metastasis and received surgery for curative intent. Short-term safety outcomes were equivalent between patients with and without rM1LN metastases. After propensity score matching, there were no significant differences in overall survival between patients with and without rM1LN metastasis. Multivariate analyses revealed that the only independent prognostic factor was ypN status. CONCLUSION: The present study suggests the feasibility and favorable OS in the patients with resection of rM1LN metastasis.

Nivolumab in unresectable advanced, recurrent or metastatic esophageal squamous cell carcinoma.

Esophageal cancer (EC) is the eighth most common cancer worldwide. In view of biology and anatomical restrictions, multimodality treatment strategies have been developed for EC. However, the prognosis of patients with advanced EC remains especially poor. Immunotherapy, such as PD-1/PD-L1 and CTLA-4/B7 blockade, has emerged as a potent treatment for many types of cancer and has been approved in many countries. Based on the results of the ATTRACTION-3 trial, nivolumab, an anti-PD-1 monoclonal antibody, was approved by the US FDA for patients with platinum-resistant, unresectable, recurrent or metastatic esophageal squamous cell carcinoma. The CheckMate 648 trial demonstrated that the combination of nivolumab with platinum-based fluoropyrimidine chemotherapy and combination immunotherapy with nivolumab and ipilimumab, an anti-CTLA-4 monoclonal antibody, showed a survival benefit in patients with advanced esophageal squamous cell carcinoma compared with doublet chemotherapy. This review focuses on nivolumab-containing treatments for patients with advanced esophageal squamous cell carcinoma.

Detecting groundwater level changes related to the 2016 Kumamoto Earthquake.

This study presented the first attempt to detect precursory changes in groundwater level before the 2016 Kumamoto Earthquake. This detection was achieved by accurately determining the relationship between long-term groundwater level fluctuation and crustal deformation over 16 years through analysis of groundwater level time-series data acquired at 17 sites within the study area. Here, we show that the observed groundwater levels were lower than the modelled levels in aquifers composed of porous strata (Togawa lava and part of the pre-Aso volcanic rocks), and that there were larger differences until 2014, which diminished until the occurrence of the Kumamoto Earthquake. The initial reduction in the modelled groundwater level and the latter recovery were most likely caused by crustal strain relaxation associated with the large 2011 earthquake off the Pacific coast of Tohoku (Mw 9.0) and the strain accumulation prior to the 2016 Kumamoto Earthquake.