Masayuki Kamata

Kochi Medical School, Kôti, Kōchi, Japan

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Publications (4)1.54 Total impact

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    ABSTRACT: We report 12 renal cell carcinomas in 6 patients with Von Hippel-Lindau (VHL) disease treated with radiofrequency ablation (RFA). The mean age of the patients was 46 (range 38-53) years (male : 4, female : 2). Computed tomography (CT)-guided transcutaneous RFA was performed under conscious sedation with local anesthetics. The mean size of the tumors was 2.4 (range 0.7-8.1) cm. Nine of the 12 tumors (75%) were locally well controlled. However, 3 tumors in 2 patients developed visceral metastases after RFA. While minimal flank pain, nausea, perinephritic hematoma and lumbago were observed, there was no major complication during or after the procedure. The therapy with CT-guided transcutaneous RFA is efficient and minimal invasive for renal cell carcinoma in patients with VHL, leading to preservation of renal function.
    No preview · Article · Sep 2014 · Hinyokika kiyo. Acta urologica Japonica
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    ABSTRACT: To evaluate pathological factors for prognosis, intravesical recurrence and distant metastasis of upper urinary tract cancer. This clinical study included 105 patients with renal pelvic and ureteral cancer who were treated at the Kochi Medical School Hospital between 1982 and 2008. Of these patients, 90 who underwent nephroureterectomy were analyzed for pathological risk factors using uni- and multivariate analysis. The mean follow-up period of the 105 patients was 53 months. The disease-specific survival rates were 70% and 62% at 3 and 5 years. Twenty-three patients (23%) developed intravesical recurrence, and the mean and median times to recurrence were 18.8 and 9.2 months, respectively. Seventeen patients (19%) had distant metastasis, and the mean and median times to distant metastasis were 25.2 and 25.3 months, respectively. Multivariate analysis identified the pathological grade as an independent risk factor for prognosis (P = 0.031), age (≥67 years) and tumor diameter (≥3 cm) as independent risk factors for intravesical recurrence (P = 0.007 and 0.003, respectively), and the pathological grade (G1,2 vs G3) and lymphatic invasion as independent risk factors for distant metastasis (P = 0.006 and 0.003, respectively). Patients with higher-grade upper urinary tract cancer show a poor prognosis, and often develop distant metastasis, suggesting the need for careful postoperative follow-up. Those with lymphatic invasion or tumors of 3 cm or more in diameter frequently develop intravesical recurrence and distant metastasis, respectively, indicating the need for strict follow-up.
    No preview · Article · Dec 2013 · Asia-Pacific Journal of Clinical Oncology
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    ABSTRACT: Diffusion-weighted imaging (DWI) is a magnetic resonance imaging (MRI) method and is considered potentially useful for detecting prostate cancer. We evaluated the clinical value of DWI with apparent diffusion coefficient (ADC) maps in addition to T2-weighted imaging (T2WI) using 3 tesla (3 T) MRI. Thirty-three patients with elevated prostate specific antigen were evaluated by MRI with T2WI and DWI prior to transperineal template-guided mapping biopsy. The MRI findings were compared with the pathology of biopsy specimens in six parts of prostate : both sides of outer peripheral zones, inner peripheral zones, and transition zones. The sensitivities, specificities and accuracies were 42.1, 84.4 and 76.3% in T2WI, 57.1, 84.7 and 80.8% in T2WI/DWI, and 87.5, 85.2 and 85.4% in DWI/ADC using 0.951×10 -3 mm2/s as cutoff ADC value. The hazard ratio of patients whose ADC values were under the cutoff was 25.86 by multivariate analysis. Mean ADC values were significantly different between cancer positive and negative cores (p<0.001). The ADC value showed a negative correlation with increasing tumor length (p=0.0047). Although further study with a large number of patients is necessary, DWI/ADC using 3 T MRI is a useful tool for detecting prostate cancer.
    No preview · Article · Mar 2012 · Hinyokika kiyo. Acta urologica Japonica
  • Taro Shuin · Masayuki Kamata · Shingo Ashida
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    ABSTRACT: Renal Cell Carcinoma (RCC) is classified into six cell pathological types by the Thoenes classification (5). Deletion of DNA (loss of heterozeigosity: LOH) is seen with a high frequency in human RCC of all 6 types at chromosome 3p 14-25. The presence of at least three tumor suppressor genes at this domain has been pointed out. The VHL gene, one of the tumor suppressor genes (TSG), was identified in 1993 at chromosome 3p25-26 as the gene responsible for VHL disease. As a consequence, it was demonstrated that inactivation of the von Hippel-Lindau (VHL) gene is responsible for sporadic clear cell RCC. Activating mutations of c-Met receptor type tyrosine kinase has been demonstrated in papillary renal cell carcinoma families. Possible involvement of the FHIT tumor suppressor gene, located at the fragile site (FRA3B) of chromosome 3p14, has been detected in sporadic RCC. Recently, methylation of RASSF1A at chromosome 3p21.3 was pointed out in sporadic RCC. Thus, it has become apparent that chromosome 3p14-25 3 has possible TSGs for RCC. Furthermore, it was pointed out in April that germline mutation of fumarate hydratase, a Krebs cycle enzyme (FH), is present in multiple cutaneous and uterine leiomyomatosis families that develop papillary RCC. The functional significance in these genes for the development of RCC is still not apparent, except for the VHL gene. Thus, there is still a long way to go before we find all responsible TSGs in all pathological subtypes in sporadic RCC.
    No preview · Article · Nov 2002 · Gan to kagaku ryoho. Cancer & chemotherapy