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Dive into the research topics where Yoshinobu Komai is active.

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Featured researches published by Yoshinobu Komai.


European Radiology | 2011

Diagnostic performance of diffusion-weighted magnetic resonance imaging in bladder cancer: potential utility of apparent diffusion coefficient values as a biomarker to predict clinical aggressiveness

Shuichiro Kobayashi; Fumitaka Koga; Soichiro Yoshida; Hitoshi Masuda; Chikako Ishii; Hiroshi Tanaka; Yoshinobu Komai; Minato Yokoyama; Kazutaka Saito; Yasuhisa Fujii; Satoru Kawakami; Kazunori Kihara

ObjectivesThe diagnostic performance of diffusion-weighted magnetic resonance imaging (DW-MRI) in bladder cancer and the potential role of apparent diffusion coefficient (ADC) values in predicting pathological bladder cancer phenotypes associated with clinical aggressiveness were investigated.MethodsOne hundred and four bladder cancer patients underwent DW-MRI and T2-weighted magnetic resonance imaging (T2W-MRI) before transurethral resection. The image sets were reviewed by two independent radiologists. ADC values were measured in 121 eligible tumours.ResultsIn detecting patients with bladder cancer, DW-MRI exhibited high sensitivity equivalent to that of T2W-MRI (>90%). Interobserver agreement was excellent for DW-MRI (κ score, 0.88) though moderate for T2W-MRI (0.67). ADC values were significantly lower in high-grade (vs. low-grade, Pu2009<u20090.0001) and high-stage (T2 vs. T1 vs. Ta, Pu2009<u20090.0001) tumours. At a cut-off ADC value determined by partition analysis, clinically aggressive phenotypes including muscle-invasive bladder cancer (MIBC) and high-grade T1 disease were differentiated from less aggressive phenotypes with a sensitivity of 88%, a specificity of 85% and an accuracy of 87%.ConclusionDW-MRI exhibits high diagnostic performance in bladder cancer with excellent objectivity. The ADC value could potentially serve as a biomarker to predict clinical aggressiveness in bladder cancer.


Urology | 2008

Incidence of Benign Pathologic Lesions at Partial Nephrectomy for Presumed RCC Renal Masses: Japanese Dual-Center Experience with 176 Consecutive Patients

Yasuhisa Fujii; Yoshinobu Komai; Kazutaka Saito; Yasumasa Iimura; Junji Yonese; Satoru Kawakami; Yuichi Ishikawa; Jiro Kumagai; Kazunori Kihara; Iwao Fukui

OBJECTIVESnTo determine the incidence of benign pathologic findings at elective partial nephrectomy for renal masses thought to be renal cell carcinoma (RCC) on preoperative imaging in Japanese patients.nnnMETHODSnFrom 1993 to 2007, 176 patients (46 women and 130 men) underwent elective partial nephrectomy for presumed RCC masses in 2 Japanese centers. The mean size of the resected lesions was 2.3 cm (range 0.3-5.8). Overall, 97 and 79 patients had a renal mass of < or = 2 cm and > 2 cm, respectively. Of the 176 patients, 100%, 89%, and 32% had preoperatively undergone computed tomography, ultrasonography, and magnetic resonance imaging, respectively.nnnRESULTSnOf the 176 masses resected, the pathologic examination revealed benign findings in 19 (11%), angiomyolipoma in 10 (5.7%), oncocytoma in 5 (2.8%), complicated cysts in 2 (1.1%), and a solitary fibrous tumor and scar of the kidney 1 each (0.6%). Of the 46 women, 12 (26.1%) had benign lesions compared with 7 of the 130 men (5.3%; P = .0003). Of the 10 angiomyolipomas diagnosed, 8 were diagnosed in women (P = .0004). Tumor size was not associated with benign histologic findings. The incidence of benign lesions was equivalent (10% and 12%) between the 2 centers.nnnCONCLUSIONSnThe present incidence (11%) of benign lesions in presumed RCC masses at surgery in Japanese patients was lower than the incidence of 20%-30% previously reported from Western countries, probably because of the low incidence of oncocytomas in Japanese patients. Women had almost 5 times the likelihood of having a benign lesion compared with men, because of the high incidence of angiomyolipomas in women.


The Journal of Urology | 2013

High Diagnostic Ability of Multiparametric Magnetic Resonance Imaging to Detect Anterior Prostate Cancer Missed by Transrectal 12-Core Biopsy

Yoshinobu Komai; Noboru Numao; Soichiro Yoshida; Yoh Matsuoka; Yasukazu Nakanishi; C. Ishii; Fumitaka Koga; Kazutaka Saito; Hitoshi Masuda; Yasuhisa Fujii; Satoru Kawakami; Kazunori Kihara

PURPOSEnWe clarified the diagnostic ability of multiparametric magnetic resonance imaging to reveal anterior cancer missed by transrectal 12-core prostate biopsy based on the results of 3-dimensional 26-core prostate biopsy, which is a combination of transrectal 12-core and transperineal 14-core biopsies.nnnMATERIALS AND METHODSnThe study population consisted of 324 patients who prospectively underwent prebiopsy multiparametric magnetic resonance imaging and then 3-dimensional 26-core prostate biopsy at a single institution. We defined transrectal 12-core negative cancer as cancer detected by transperineal 14-core but not transrectal 12-core prostate biopsy. We focused on cancer in the anterior region. Any findings suspicious for malignancy in the region anterior to the urethra on multiparametric magnetic resonance imaging were defined as an anterior lesion on imaging. Significant cancer was defined as a biopsy Gleason score of 4 + 3 or greater, a greater than 20% positive core and/or a maximum cancer length of 5 mm or greater. Associations between an anterior lesion on imaging and transrectal 12-core negative cancer were investigated.nnnRESULTSnThe overall cancer detection rate on 3-dimensional 26-core prostate biopsy was 39% (128 of 324 cases), of which 28% (36 of 128) were transrectal 12-core negative cancers. An anterior lesion on prebiopsy multiparametric magnetic resonance imaging was identified in 20% of men overall (65 of 324). Of men with and without an anterior lesion on imaging 40% (26 of 65) and 3.8% (10 of 259), respectively, had transrectal 12-core negative cancer. Significant transrectal 12-core negative cancer was observed in 0.4% (1 of 259 men) without an anterior lesion on imaging. Prebiopsy multiparametric magnetic resonance imaging revealed an anterior lesion in 92% of cases (11 of 12) of significant transrectal 12-core negative cancer.nnnCONCLUSIONSnPrebiopsy multiparametric magnetic resonance imaging has the potential to efficiently select men who could advantageously undergo anterior samplings, in addition to transrectal 12-core prostate biopsy.


International Journal of Radiation Oncology Biology Physics | 2012

Role of diffusion-weighted magnetic resonance imaging in predicting sensitivity to chemoradiotherapy in muscle-invasive bladder cancer.

Soichiro Yoshida; Fumitaka Koga; Shuichiro Kobayashi; Chikako Ishii; Hiroshi Tanaka; Hajime Tanaka; Yoshinobu Komai; Kazutaka Saito; Hitoshi Masuda; Yasuhisa Fujii; Satoru Kawakami; Kazunori Kihara

PURPOSEnIn chemoradiation (CRT)-based bladder-sparing approaches for muscle invasive bladder cancer (MIBC), patients who respond favorably to induction CRT enjoy the benefits of bladder preservation, whereas nonresponders do not. Thus, accurate prediction of CRT sensitivity would optimize patient selection for bladder-sparing protocols. Diffusion-weighted MRI (DW-MRI) is a functional imaging technique that quantifies the diffusion of water molecules in a noninvasive manner. We investigated whether DW-MRI predicts CRT sensitivity of MIBC.nnnMETHODS AND MATERIALSnThe study cohort consisted of 23 MIBC patients (cT2/T3xa0= 7/16) who underwent induction CRT consisting of radiotherapy to the small pelvis (40 Gy) with two cycles of cisplatin (20 mg/day for 5 days), followed by partial or radical cystectomy. All patients underwent DW-MRI before the initiation of treatment. Associations of apparent diffusion coefficient (ADC) values with CRT sensitivity were analyzed. The proliferative potential of MIBC was also assessed by analyzing the Ki-67 labeling index (LI) in pretherapeutic biopsy specimens.nnnRESULTSnThirteen patients (57%) achieved pathologic complete response (pCR) to CRT. These CRT-sensitive MIBCs showed significantly lower ADC values (median, 0.63 × 10(-3) mm(2)/s; range, 0.43-0.77) than CRT-resistant (no pCR) MIBCs (median, 0.84 × 10(-3) mm(2)/s; range, 0.69-1.09; pxa0= 0.0003). Multivariate analysis identified ADC value as the only significant and independent predictor of CRT sensitivity (p < 0.0001; odds ratio per 0.001 ×10(-3) mm(2)/s increase, 1.03; 95% confidence interval, 1.01-1.08). With a cutoff ADC value at 0.74 × 10(-3) mm(2)/s, sensitivity/specificity/accuracy in predicting CRT sensitivity was 92/90/91%. Ki-67 LI was significantly higher in CRT-sensitive MIBCs (pxa0= 0.0005) and significantly and inversely correlated with ADC values (ρxa0= -0.67, pxa0= 0.0007).nnnCONCLUSIONSnDW-MRI is a potential biomarker for predicting CRT sensitivity in MIBC. DW-MRI may be useful to optimize patient selection for CRT-based bladder-sparing approaches.


The Journal of Urology | 2013

Usefulness of Pre-biopsy Multiparametric Magnetic Resonance Imaging and Clinical Variables to Reduce Initial Prostate Biopsy in Men with Suspected Clinically Localized Prostate Cancer

Noboru Numao; Soichiro Yoshida; Yoshinobu Komai; C. Ishii; Makoto Kagawa; Toshiki Kijima; Minato Yokoyama; Junichiro Ishioka; Yoh Matsuoka; Fumitaka Koga; Kazutaka Saito; Hitoshi Masuda; Yasuhisa Fujii; Satoru Kawakami; Kazunori Kihara

PURPOSEnWe evaluated the usefulness of pre-biopsy multiparametric magnetic resonance imaging and clinical variables to decrease initial prostate biopsies.nnnMATERIALS AND METHODSnWe prospectively evaluated 351 consecutive men with prostate specific antigen between 2.5 and 20 ng/ml, and/or digital rectal examination suspicious for clinically localized disease. All men underwent pre-biopsy multiparametric magnetic resonance imaging and initial 14 to 29-core biopsy, including anterior sampling. Three definitions of significant cancer were defined based on Gleason score and cancer volume (percent positive core and/or maximum cancer length). The overall cohort was divided into men at low risk-prostate specific antigen less than 10 ng/ml and normal digital rectal examination, and high risk-prostate specific antigen 10 ng/ml or greater and/or abnormal digital rectal examination. We evaluated the frequency of significant cancer according to magnetic resonance imaging and risk categories. Clinical variables as significant cancer predictors were analyzed using logistic regression. The sensitivity, specificity, and positive and negative predictive values of magnetic resonance imaging were calculated with or without clinical variables for significant cancer.nnnRESULTSnThe frequency of significant cancer in men with negative vs positive magnetic resonance imaging was 9% to 13% vs 43% to 50% in the low risk group and 47% to 51% vs 68% to 71% in the high risk group. In men at low risk with negative magnetic resonance imaging prostate volume was the only significant predictor of significant cancer. In the low risk group the negative predictive value for significant cancer of a combination of positive magnetic resonance imaging and lower prostate volume (less than 33 ml) was 93.7% to 97.5%.nnnCONCLUSIONSnPre-biopsy multiparametric magnetic resonance imaging along with prostate volume decreases the number of initial prostate biopsies by discriminating between significant cancer and other cancer in men with prostate specific antigen less than 10 ng/ml and normal digital rectal examination.


Urology | 2011

Young Age as Favorable Prognostic Factor for Cancer-specific Survival in Localized Renal Cell Carcinoma

Yoshinobu Komai; Yasuhisa Fujii; Yasumasa Iimura; Manabu Tatokoro; Kazutaka Saito; Yukihiro Otsuka; Fumitaka Koga; Chizuru Arisawa; Satoru Kawakami; Tetsuo Okuno; Toshihiko Tsujii; Yukio Kageyama; Shinji Morimoto; Tsuguhiro Toma; Yotsuo Higashi; Iwao Fukui; Kazunori Kihara

OBJECTIVESnTo evaluate the prognostic effect of age in patients with localized renal cell carcinoma (RCC) and investigate the incidence of Xp11 translocation RCC in young patients who developed recurrence.nnnMETHODSnFrom 1990 to 2007, 2403 Japanese patients underwent nephrectomy for presumed RCC at 9 institutions. Of those, 1143 patients had localized RCC (Stage pT1-2N0M0). Their clinical data were retrospectively reviewed. In the present study, 131 patients (11%) were considered young (≤45 years at diagnosis). In the young patients with recurrence, the nephrectomy specimens were immunostained with TFE3 to determine the incidence of Xp11 translocation RCC.nnnRESULTSnDuring the median follow-up of 47 months, 3 cancer deaths (2.2%) occurred among young patients and 51 (5.0%) among older patients. The 5-year cancer-specific survival (CSS) rate was significantly better for the younger patients than for the older patients (P = .049). Multivariate analysis showed that age was significantly associated with CSS, as were the pathologic T stage, tumor grade, and symptoms at diagnosis. The hazard ratio of young age was 0.31 (95% confidence interval 0.077-0.87). The recurrence-free survival curves revealed no difference between these 2 groups. Of the 74 patients with recurrence, the CSS after recurrence was significantly better in the younger patients than in the older patients (P = .0010). Of the 8 young patients with recurrence, 4 had Xp11 translocation RCC, and 3 survived for >5 years after recurrence.nnnCONCLUSIONSnCompared with the older patients, the young patients with RCC had similar recurrence-free survival rates but better CSS rates. This might have been because significant numbers of the young patients had Xp11 translocation RCC.


International Journal of Urology | 2008

Favorable response to combination treatment of cimetidine, cyclooxygenase-2 inhibitor and renin-angiotensin system inhibitor in metastatic renal cell carcinoma: Report of three cases

Manabu Tatokoro; Yasuhisa Fujii; Satoru Kawakami; Naotaka Fukui; Yoshinobu Komai; Kazutaka Saito; Fumitaka Koga; Shinji Morimoto; Iwao Fukui; Kazunori Kihara

Abstract:u2003 We report three cases of metastatic renal cell carcinoma (RCC) in which combination treatment of cimetidine, cyclooxygenase‐2 inhibitor and renin‐angiotensin system inhibitor (angiotensin converting enzyme inhibitor or angiotensin II type 1 receptor antagonist) (CCA therapy) was effective. Case 1: A 47‐year‐old man who had a 12‐cm right renal tumor with multiple pulmonary and hepatic metastases refused cytokine therapy for economic reasons and received CCA therapy. All of the metastases showed partial remission, which continued for 12 months. Case 2: A 62‐year‐old man with multiple pulmonary and mediastinal lymph node metastases from clear cell RCC refractory to interferon‐α and interleukin‐2 started CCA therapy. Partial remission has been maintained for 16 months. Case 3: A 64‐year‐old man with pulmonary metastases from clear cell RCC discontinued interferon‐α treatment due to its side effects after six months and received CCA therapy. Pulmonary metastases showed partial remission for 31 months. The CCA therapy could be an alternative treatment for metastatic RCC patients unfit for cytokine therapy.


Japanese Journal of Clinical Oncology | 2012

Pathological Complete Response and Two-year Disease-free Survival in a Primary Gastric Choriocarcinoma Patient with Advanced Liver Metastases Treated with Germ Cell Tumor-based Chemotherapy: A Case Report

Yuma Waseda; Yoshinobu Komai; Akihiro Yano; Yasuhisa Fujii; Norio Noguchi; Kazunori Kihara

Choriocarcinoma is an early metastasizing and highly invasive tumor and characterized as a high-level human chorionic gonadotropin-secreting tumor. It normally arises in the gestational trophoblast, gonads and much less frequently in the stomach. Primary gastric choriocarcinoma appears to have a poor prognosis; especially with liver metastasis, the survival period is expected to be <1 month. This unfavorable clinical outcome is partly due to the lack of defined chemotherapy against primary gastric choriocarcinoma. We herein report a case of a 68-year-old male primary gastric choriocarcinoma patient with advanced liver metastases in which germ cell tumor-based chemotherapy achieved a pathological complete response and 2-year disease-free survival.


BJUI | 2015

Diagnostic performance and safety of a three-dimensional 14-core systematic biopsy method.

Hideki Takeshita; Satoru Kawakami; Noboru Numao; Mizuaki Sakura; Manabu Tatokoro; Shinya Yamamoto; Toshiki Kijima; Yoshinobu Komai; Kazutaka Saito; Fumitaka Koga; Yasuhisa Fujii; Iwao Fukui; Kazunori Kihara

To investigate the diagnostic performance and safety of a three‐dimensional 14‐core biopsy (3D14PBx) method, which is a combination of the transrectal six‐core and transperineal eight‐core biopsy methods.


Urology | 2007

POS-03.109: Simple and easy technique to prevent post-radical retropubic ptostatectomy inguinal hernia

Yasuhisa Fujii; Shinya Yamamoto; Jyunji Yonese; Satoru Kawakami; Yuhei Okubo; D. Suyama; Yoshinobu Komai; Toshiki Kijima; Iwao Fukui

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Yasuhisa Fujii

Tokyo Medical and Dental University

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Satoru Kawakami

Japanese Foundation for Cancer Research

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Kazunori Kihara

Tokyo Medical and Dental University

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Kazutaka Saito

Tokyo Medical and Dental University

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Fumitaka Koga

Tokyo Medical and Dental University

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Iwao Fukui

Tokyo Medical and Dental University

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Hitoshi Masuda

Tokyo Medical and Dental University

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Soichiro Yoshida

Tokyo Medical and Dental University

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Toshiki Kijima

Tokyo Medical and Dental University

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Manabu Tatokoro

Tokyo Medical and Dental University

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