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Dive into the research topics where Yasutaka Chiba is active.

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Featured researches published by Yasutaka Chiba.


Journal of Clinical Oncology | 2010

Phase III Study Comparing Second- and Third-Generation Regimens With Concurrent Thoracic Radiotherapy in Patients With Unresectable Stage III Non–Small-Cell Lung Cancer: West Japan Thoracic Oncology Group WJTOG0105

Nobuyuki Yamamoto; Kazuhiko Nakagawa; Yasumasa Nishimura; Kayoko Tsujino; Miyako Satouchi; Shinzoh Kudo; Toyoaki Hida; Masaaki Kawahara; Koji Takeda; Nobuyuki Katakami; Toshiyuki Sawa; Soichiro Yokota; Takashi Seto; Fumio Imamura; Hideo Saka; Yasuo Iwamoto; Hiroshi Semba; Yasutaka Chiba; Hisao Uejima; Masahiro Fukuoka

PURPOSE This phase III trial of concurrent thoracic radiotherapy (TRT) was conducted to compare third-generation chemotherapy with second-generation chemotherapy in patients with unresectable stage III non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS Eligible patients received the following treatments: A (control), four cycles of mitomycin (8 mg/m(2) on day 1)/vindesine (3 mg/m(2) on days 1, 8)/cisplatin (80 mg/m(2) on day 1) plus TRT 60 Gy (treatment break for 1 week); B, weekly irinotecan (20 mg/m(2))/carboplatin (area under the plasma concentration-time curve [AUC] 2) for 6 weeks plus TRT 60 Gy, followed by two courses of irinotecan (50 mg/m(2) on days 1, 8)/carboplatin (AUC 5 on day 1); C, weekly paclitaxel (40 mg/m(2))/carboplatin (AUC 2) for 6 weeks plus TRT 60 Gy, followed by two courses of paclitaxel (200 mg/m(2) on day 1)/carboplatin (AUC 5 on day 1). RESULTS The median survival time and 5-year survival rates were 20.5, 19.8, and 22.0 months and 17.5%, 17.8%, and 19.8% in arms A, B, and C, respectively. Although no significant differences in overall survival were apparent among the treatment arms, noninferiority of the experimental arms was not achieved. The incidences of grade 3 to 4 neutropenia, febrile neutropenia, and gastrointestinal disorder were significantly higher in arm A than in arm B or C (P < .001). Chemotherapy interruptions were more common in arm B than in arm A or C. CONCLUSION Arm C was equally efficacious and exhibited a more favorable toxicity profile among three arms. Arm C should be considered a standard regimen in the management of locally advanced unresectable NSCLC.


The American Journal of Gastroenterology | 2012

Characterization of Small Solid Tumors in the Pancreas: The Value of Contrast-Enhanced Harmonic Endoscopic Ultrasonography

Masayuki Kitano; Masatoshi Kudo; Kenji Yamao; Tadayuki Takagi; Hiroki Sakamoto; Takamitsu Komaki; Ken Kamata; Hajime Imai; Yasutaka Chiba; Masahiro Okada; Takamichi Murakami; Yoshifumi Takeyama

OBJECTIVES:Contrast-enhanced harmonic endoscopic ultrasonography (CH-EUS), a novel technology, visualizes parenchymal perfusion in the pancreas. This study prospectively evaluated how accurately CH-EUS characterizes pancreatic lesions and compared its diagnostic ability with that of contrast-enhanced multidetector-row computed tomography (MDCT) and endoscopic ultrasonography-guided fine needle aspiration (EUS-FNA).METHODS:A total of 277 consecutive patients with pancreatic solid lesions that were detected by conventional EUS underwent CH-EUS for evaluation of vascularity. After infusing an ultrasound contrast, CH-EUS was performed by using an echoendoscope and a specific mode for contrast harmonic imaging. On the basis of the intensity of enhancement, the lesions were categorized into four patterns: nonenhancement, hypoenhancement, isoenhancement, and hyperenhancement. For comparison, all patients underwent MDCT. The ability of CH-EUS to differentiate ductal carcinomas from the other solid tumors, particularly small lesions (≤2 cm in diameter) was assessed, and compared with the differentiating abilities of MDCT and EUS-FNA.RESULTS:In terms of reading the CH-EUS images, the κ-coefficient of the interobserver agreement test was 0.94 (P<0.001). CH-EUS-depicted hypoenhancement diagnosed ductal carcinomas with a sensitivity and specificity of 95.1% (95% confidence interval (CI) 92.7–96.7%) and 89.0% (95% CI 83.0–93.1%), respectively. For diagnosing small carcinomas by CH-EUS, the sensitivity and specificity were 91.2 % (95% CI 82.5–95.1%) and 94.4% (95% CI 86.2–98.1%), respectively. CH-EUS-depicted hypervascular enhancement diagnosed neuroendocrine tumors with a sensitivity and specificity of 78.9% (95% CI 61.4–89.7%) and 98.7% (95% CI 96.7–98.8%), respectively. Although CH-EUS and MDCT did not differ significantly in diagnostic ability with regard to all lesions, CH-EUS was superior to MDCT in diagnosing small (≤2 cm) carcinomas (P<0.05). In 12 neoplasms that MDCT failed to detect, 7 ductal carcinomas and 2 neuroendocrine tumors had hypoenhancement and hyperenhancement on CH-EUS, respectively. When CH-EUS was combined with EUS-FNA, the sensitivity of EUS-FNA increased from 92.2 to 100%.CONCLUSIONS:CH-EUS is useful for characterizing conventional EUS-detected solid pancreatic lesions. EUS equipped with contrast harmonic imaging may play an important role in the characterization of small tumors that other imaging methods fail to depict and may improve the diagnostic yield of EUS-FNA.


Endoscopy | 2013

Value of EUS in early detection of pancreatic ductal adenocarcinomas in patients with intraductal papillary mucinous neoplasms.

Ken Kamata; Masayuki Kitano; Masatoshi Kudo; Hiroki Sakamoto; Kumpei Kadosaka; Takeshi Miyata; Hajime Imai; Kiyoshi Maekawa; Takaaki Chikugo; Masashi Kumano; Tomoko Hyodo; Takamichi Murakami; Yasutaka Chiba; Yoshifumi Takeyama

BACKGROUND AND STUDY AIMS Pancreatic ductal adenocarcinomas (PDAC) sometimes arise in patients with intraductal papillary mucinous neoplasms (IPMNs). This study examined the incidence of PDACs concomitant to or derived from branch duct IPMNs. The usefulness of endoscopic ultrasonography (EUS) relative to other imaging methods for detecting these tumors was also assessed. PATIENTS AND METHODS This retrospective study used data from clinical records and imaging studies that were collected prospectively. During 2001-2009, 167 consecutive patients with IPMNs underwent EUS, ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI). The 102 patients whose branch duct IPMNs lacked mural nodules/symptoms and thus did not qualify for resection were followed up by semiannual EUS and annual ultrasonography, CT, and MRI. The sensitivity and specificity with which the four modalities detected IPMN-derived and -concomitant PDACs at the first examination and throughout the study period were evaluated. The rate of PDAC development during follow-up was analyzed by the Kaplan-Meier method. RESULTS A total of 17 IPMN-derived and 11 IPMN-concomitant PDACs were diagnosed at the first examination. Lesions that did not qualify for resection or chemotherapy were followed up for a median of 42 months. Seven IPMN-concomitant PDACs and no IPMN-derived PDACs were detected during follow-up. The 3- and 5-year rates of IPMN-concomitant PDAC development were 4.0% and 8.8%, respectively. At the first examination, EUS was superior to other imaging modalities in terms of IPMN-derived and -concomitant PDAC detection. Throughout the study period, including follow-up, EUS was significantly better at detecting IPMN-concomitant PDACs than the other modalities. CONCLUSIONS IPMN-concomitant PDACs are quite often found at diagnosis and during follow-up. EUS examination of the whole pancreas plays an important role in the management of IPMNs as it allows the early detection of these small invasive carcinomas.


PLOS ONE | 2014

Risk Factors for Cisplatin-Induced Nephrotoxicity and Potential of Magnesium Supplementation for Renal Protection

Yasuhiro Kidera; Hisato Kawakami; Tsutomu Sakiyama; Kunio Okamoto; Kaoru Tanaka; Masayuki Takeda; Hiroyasu Kaneda; Shinichi Nishina; Junji Tsurutani; Kimiko Fujiwara; Morihiro Nomura; Yuzuru Yamazoe; Yasutaka Chiba; Shozo Nishida; Takao Tamura; Kazuhiko Nakagawa

Background Nephrotoxicity remains a problem for patients who receive cisplatin chemotherapy. We retrospectively evaluated potential risk factors for cisplatin-induced nephrotoxicity as well as the potential impact of intravenous magnesium supplementation on such toxicity. Patients and Methods We reviewed clinical data for 401 patients who underwent chemotherapy including a high dose (≥60 mg/m2) of cisplatin in the first-line setting. Nephrotoxicity was defined as an increase in the serum creatinine concentration of at least grade 2 during the first course of cisplatin chemotherapy, as assessed on the basis of National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0. The severity of nephrotoxicity was evaluated on the basis of the mean change in the serum creatinine level. Magnesium was administered intravenously to 67 patients (17%). Results Cisplatin-induced nephrotoxicity was observed in 127 patients (32%). Multivariable analysis revealed that an Eastern Cooperative Oncology Group performance status of 2 (risk ratio, 1.876; P = 0.004) and the regular use of nonsteroidal anti-inflammatory drugs (NSAIDs) (risk ratio, 1.357; P = 0.047) were significantly associated with an increased risk for cisplatin nephrotoxicity, whereas intravenous magnesium supplementation was associated with a significantly reduced risk for such toxicity (risk ratio, 0.175; P = 0.0004). The development of hypomagnesemia during cisplatin treatment was significantly associated with a greater increase in serum creatinine level (P = 0.0025). Magnesium supplementation therapy was also associated with a significantly reduced severity of renal toxicity (P = 0.012). Conclusions A relatively poor performance status and the regular use of NSAIDs were significantly associated with cisplatin-induced nephrotoxicity, although the latter association was marginal. Our findings also suggest that the ability of magnesium supplementation to protect against the renal toxicity of cisplatin warrants further investigation in a prospective trial.


Annals of Oncology | 2017

Tumor immune microenvironment and nivolumab efficacy in EGFR mutation-positive non-small-cell lung cancer based on T790M status after disease progression during EGFR-TKI treatment

Koji Haratani; Hidetoshi Hayashi; Tomonori Tanaka; Hiroyasu Kaneda; Yosuke Togashi; Kazuko Sakai; Kentaro Hayashi; Shuta Tomida; Yasutaka Chiba; Kimio Yonesaka; Yoshikane Nonagase; Takayuki Takahama; Junko Tanizaki; Kaoru Tanaka; Takeshi Yoshida; K. Tanimura; Masayuki Takeda; Hiroshige Yoshioka; Teruyoshi Ishida; Tetsuya Mitsudomi; Kazuto Nishio; Kazuhiko Nakagawa

Background The efficacy of programmed death-1 blockade in epidermal growth factor receptor gene (EGFR) mutation-positive non-small-cell lung cancer (NSCLC) patients with different mechanisms of acquired resistance to EGFR tyrosine kinase inhibitors (TKIs) is unknown. We retrospectively evaluated nivolumab efficacy and immune-related factors in such patients according to their status for the T790M resistance mutation of EGFR. Patients and methods We identified 25 patients with EGFR mutation-positive NSCLC who were treated with nivolumab after disease progression during EGFR-TKI treatment (cohort A). Programmed death-ligand 1 (PD-L1) expression and tumor-infiltrating lymphocyte (TIL) density in tumor specimens obtained after acquisition of EGFR-TKI resistance were determined by immunohistochemistry. Whole-exome sequencing of tumor DNA was carried out to identify gene alterations. The relation of T790M status to PD-L1 expression or TIL density was also examined in an independent cohort of 60 patients (cohort B). Results In cohort A, median progression-free survival (PFS) was 2.1 and 1.3 months for T790M-negative and T790M-positive patients, respectively (P = 0.099; hazard ratio of 0.48 with a 95% confidence interval of 0.20-1.24). Median PFS was 2.1 and 1.3 months for patients with a PD-L1 expression level of ≥1% or <1%, respectively (P = 0.084; hazard ratio of 0.37, 95% confidence interval of 0.10-1.21). PFS tended to increase as the PD-L1 expression level increased with cutoff values of ≥10% and ≥50%. The proportion of tumors with a PD-L1 level of ≥10% or ≥50% was higher among T790M-negative patients than among T790M-positive patients of both cohorts A and B. Nivolumab responders had a significantly higher CD8+ TIL density and nonsynonymous mutation burden. Conclusion T790M-negative patients with EGFR mutation-positive NSCLC are more likely to benefit from nivolumab after EGFR-TKI treatment, possibly as a result of a higher PD-L1 expression level, than are T790M-positive patients.


Diabetes | 2015

Role of Plasminogen Activator Inhibitor-1 in Glucocorticoid-Induced Diabetes and Osteopenia in Mice

Yukinori Tamura; Naoyuki Kawao; Masato Yano; Kiyotaka Okada; Katsumi Okumoto; Yasutaka Chiba; Osamu Matsuo; Hiroshi Kaji

Long-term use of glucocorticoids (GCs) causes numerous adverse effects, including glucose/lipid abnormalities, osteoporosis, and muscle wasting. The pathogenic mechanism, however, is not completely understood. In this study, we used plasminogen activator inhibitor-1 (PAI-1)–deficient mice to explore the role of PAI-1 in GC-induced glucose/lipid abnormalities, osteoporosis, and muscle wasting. Corticosterone markedly increased the levels of circulating PAI-1 and the PAI-1 mRNA level in the white adipose tissue of wild-type mice. PAI-1 deficiency significantly reduced insulin resistance and glucose intolerance but not hyperlipidemia induced by GC. An in vitro experiment revealed that active PAI-1 treatment inhibits insulin-induced phosphorylation of Akt and glucose uptake in HepG2 hepatocytes. However, this was not observed in 3T3-L1 adipocytes and C2C12 myotubes, indicating that PAI-1 suppressed insulin signaling in hepatocytes. PAI-1 deficiency attenuated the GC-induced bone loss presumably via inhibition of apoptosis of osteoblasts. Moreover, the PAI-1 deficiency also protected from GC-induced muscle loss. In conclusion, the current study indicated that PAI-1 is involved in GC-induced glucose metabolism abnormality, osteopenia, and muscle wasting in mice. PAI-1 may be a novel therapeutic target to mitigate the adverse effects of GC.


JAMA Oncology | 2017

Association of Immune-Related Adverse Events With Nivolumab Efficacy in Non–Small-Cell Lung Cancer

Koji Haratani; Hidetoshi Hayashi; Yasutaka Chiba; Keita Kudo; Kimio Yonesaka; Ryoji Kato; Hiroyasu Kaneda; Yoshikazu Hasegawa; Kaoru Tanaka; Masayuki Takeda; Kazuhiko Nakagawa

Importance Immune-related adverse events (irAEs) have been associated with the efficacy of PD-1 (programmed cell death protein 1) inhibitors in patients with melanoma, but whether such an association exists for non–small-cell lung cancer (NSCLC) has remained unknown. Objective To evaluate the relation of irAEs to nivolumab efficacy in NSCLC. Design, Setting, and Participants In this study based on landmark and multivariable analyses, a total of 134 patients with advanced or recurrent NSCLC who were treated with nivolumab in the second-line setting or later between December 2015 and August 2016 were identified from a review of medical records from multiple institutions, including a university hospital and community hospitals. Data were updated as of December 31, 2016. Exposures The absence or presence of any irAE before the landmark date. Main Outcomes and Measures Kaplan-Meier curves of progression-free survival (PFS) according to the development of irAEs in 6-week landmark analysis were evaluated with the log-rank test as a preplanned primary objective. Overall survival (OS) was similarly evaluated. Multivariable analysis of both PFS and OS was performed with Cox proportional hazard regression models. Results In a cohort of 134 patients (median [range] age, 68 [33-85] years; 90 men [67%], 44 women [33%]), irAEs were observed in 69 of the 134 study patients (51%), including 12 patients (9%) with such events of grade 3 or 4, and 24 patients (18%) requiring systemic corticosteroid therapy. In 6-week landmark analysis, median PFS was 9.2 months (95% CI, 4.4 to not reached [NR]) and 4.8 months (95% CI, 3.0 to 7.5) (P = .04) whereas median OS was NR (95% CI, 12.3 to NR) and 11.1 months (95% CI, 9.6 to NR) (P = .01) for patients with or without irAEs, respectively. Multivariable analysis also revealed that irAEs were positively associated with survival outcome, with hazard ratios of 0.525 (95% CI, 0.287 to 0.937; P = .03) for PFS and 0.282 (95% CI, 0.101 to 0.667; P = .003) for OS. Conclusions and Relevance Development of irAEs was associated with survival outcome of nivolumab treatment in patients with advanced or recurrent NSCLC. Further studies are needed to confirm our findings.


Endoscopy | 2015

Contrast-enhanced harmonic endoscopic ultrasonography for differential diagnosis of pancreatic cysts

Ken Kamata; Masayuki Kitano; Shunsuke Omoto; Kumpei Kadosaka; Takeshi Miyata; Kentaro Yamao; Hajime Imai; Hiroki Sakamoto; Yogesh Harwani; Takaaki Chikugo; Yasutaka Chiba; Ippei Matsumoto; Yoshifumi Takeyama; Masatoshi Kudo

BACKGROUND AND STUDY AIM Comparison of fundamental B-mode endoscopic ultrasonography (FB-EUS) and contrast-enhanced harmonic endoscopic ultrasonography (CH-EUS) in the differential diagnosis of pancreatic cysts according to presence of mural nodules. PATIENTS AND METHODS Between April 2007 and April 2012, FB-EUS and CH-EUS data were prospectively collected from 581 consecutive patients with pancreatic cysts, and were retrospectively analyzed from 70 with subsequent cyst resection. Presence and height of mural nodules as detected on FB-EUS and CH-EUS were evaluated, and thence accuracies of both methods for diagnosing mucinous versus nonmucinous and malignant versus benign cysts. RESULTS On pathological examination 48 cysts were mucinous and 22 were nonmucinous; 30 cysts were malignant (high grade dysplasia or invasive carcinoma) and 40 were benign. If presence of a mural nodule was considered to indicate a mucinous cyst, FB-EUS and CH-EUS accuracies did not differ significantly (respectively: sensitivity 85 % vs. 79 %; specificity 46 % vs. 96 %; accuracy 73 % vs. 84 %, P = 0.057). If presence of mural nodule was considered to indicate malignancy, CH-EUS was significantly more accurate than FB-EUS (respectively: sensitivity 97 % vs. 97 %; specificity 75 % vs. 40 %; accuracy 84 % vs. 64 %, P = 0.0001). For diagnosing malignancy by evaluating mural nodule height, the area under the receiver operating characteristic (AUROC) was 0.84 and 0.93 for FB-EUS and CH-EUS, respectively (P = 0.028). Presence of a mural nodule of height ≥ 4 mm on CH-EUS was a sign of malignancy (false-positive fraction 0.2; true-positive fraction 0.93; odds ratio 56.0). CONCLUSIONS CH-EUS is more accurate than FB-EUS for diagnosing malignant pancreatic cysts.


Endoscopy | 2015

Comparison of the clinical impact of endoscopic ultrasound-guided choledochoduodenostomy and hepaticogastrostomy for bile duct obstruction with duodenal obstruction

Takeshi Ogura; Yasutaka Chiba; Daisuke Masuda; Masayuki Kitano; Tatsushi Sano; Onda Saori; Kazuhiro Yamamoto; Hiroshi Imaoka; Akira Imoto; Toshihisa Takeuchi; Shinya Fukunishi; Kazuhide Higuchi

BACKGROUND AND STUDY AIM To date, only a few reports with small numbers of patients have described double stenting (biliary and duodenal), in particular endoscopic ultrasound (EUS)-guided biliary drainage, for patients with obstructive jaundice. In addition, no reports have sought to determine which EUS-guided biliary drainage route has better outcomes. The aim of the current study was to investigate adverse events and stent patency in patients who underwent EUS-guided biliary drainage and duodenal stenting. PATIENTS AND METHODS Patients who were admitted to the Osaka Medical College with obstructive jaundice caused by lower biliary obstruction and duodenal obstruction due to malignant tumor between June 2012 and April 2014 were retrospectively enrolled in the study. RESULTS A total of 39 patients were enrolled in the study; 13 underwent EUS-guided choledochoduodenostomy (EUS-CDS), and 26 underwent EUS-guided hepaticogastrostomy (EUS-HGS). Adjusted analyses for covariates using propensity scores showed that the EUS-HGS group had significantly longer stent patency than the EUS-CDS group (duodenal stent patency: median 113 vs. 34 days; hazard ratio [HR] 0.415, 95 % confidence interval [CI] 0.175 - 0.984; P = 0.046; biliary stent patency: median 133 vs. 37 days; HR 0.391, 95 %CI 0.156 - 0.981; P = 0.045). On logistic regression analysis, only EUS-CDS was associated with adverse events, in particular reflux cholangitis (OR 10.285, 95 %CI 1.686 - 62.733; P = 0.012). CONCLUSION In cases of obstructive jaundice with duodenal obstruction, EUS-HGS may be better than EUS-CDS, with longer stent patency and fewer adverse events.


International Journal of Occupational and Environmental Health | 2009

Mesothelioma Risk and Environmental Exposure to Asbestos: Past and Future Trends in Japan

Kenichi Azuma; Iwao Uchiyama; Yasutaka Chiba; Jiro Okumura

Abstract Although asbestos has been widely distributed in the environment, health risks due to general environmental exposure to asbestos have not been estimated. Future mesothelioma risk from environmental exposure to asbestos in Japan was estimated by comparing historical exposure data and mortality attributed to environmental exposure. We developed an equation to estimate environmentally-attributable mesothelioma based on the US Environmental Protection Agencys model for occupational mesothelioma mortality. Based on our calculations, mesothelioma risks per year of exposure will reach peak levels in 2033 and range from 4.8 × 10−6 to 1.1 × 10−5. The number of deaths is estimated to range from 542–1276 in 2033. The cumulative number of deaths will reach around 17,000–37,000 in the years 1970–2070. Our estimation of risk approximately corresponded to observed risks. Past and predicted future disease suggest the need for social and medical support in these areas.

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Masayuki Kitano

Wakayama Medical University

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