S Maetani

Kyoto University, Kioto, Kyōto, Japan

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Publications (73)157.08 Total impact

  • Tenri Medical Bulletin. 01/2013; 16(2):70-78.
  • Shunzo Maetani, John W Gamel
    Journal of Biometrics & Biostatistics. 01/2012; 03(03).
  • Shunzo Maetani, John W Gamel
    Surgical Oncology 04/2010; 19(2):49-51; discussion 61. · 2.37 Impact Factor
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    ABSTRACT: Although the outcome of surgery for locally advanced pancreatic cancer remains poor, it is improving, with 5-year survival up to about 10% in Japan. The preliminary results of our multi-institutional randomized controlled trial revealed better survival after surgery than after radiochemotherapy. We report the final results of this study after 5 years of follow-up. Patients with preoperative findings of pancreatic cancer invading the pancreatic capsule without involvement of the superior mesenteric or common hepatic arteries, or distant metastasis, were included in this randomized controlled trial, with their consent. If the laparotomy findings were consistent with these criteria, the patient was randomized to a surgery group or a radiochemotherapy group (5-fluorouracil 200 mg/m2/day and 5040 Gy radiotherapy). We compared the mean survival time, 3-and 5-year survival rates, and hazard ratio. The surgery and radiochemotherapy groups comprised 20 and 22 patients, respectively. Patients were followed up for 5 years or longer, or until an event occurred to preclude this. The surgery group had significantly better survival than the radiochemotherapy group (P<0.03). Surgery increased the survival time and 3-year survival rate by an average of 11.8 months and 20%, respectively, and it halved the instantaneous mortality (hazard) rate. Locally invasive pancreatic cancer without distant metastases or major arterial invasion is treated most effectively by surgical resection.
    Surgery Today 11/2008; 38(11):1021-8. · 1.21 Impact Factor
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    ABSTRACT: Survival benefit of radical surgery for locally recurrent rectal cancer depends on whether disease is cured rather than whether death is delayed. Cured patients gain decades of life and are spared from sufferings with recurrence. Unfortunately, the majority of patients undergoing surgery, particularly those with extrarectal pelvic recurrence, have poor outcomes with occult disseminated disease. This study was designed to identify which of these patients are curable. Of 61 patients with pelvic recurrence treated by radical reexcision more than nine years before, 36 patients whose initial surgery was abdominoperineal resection were examined retrospectively. We used the logistic regression and Gamel-Boag regression models to estimate curability and identify predictors of cure. Ten patients survived five years and seven survived ten years. The cumulative disease-specific mortality curve leveled off 6.5 years after reexcision and remained at 74 percent (95 percent confidence interval, 60-89), indicating that the remaining 26 percent are curable. This value is comparable with the 23 percent curability estimated by the Gamel-Boag model, which also found that the disease-free interval from the initial surgery to the first recurrence is the best predictor of cure (P = 0.005). Of 11 patients with disease-free interval three years or more, 6 survived ten years, whereas 8 of 9 patients with disease-free interval less than one year died of second recurrence within three years of reexcision. Even patients with extrarectal pelvic recurrence may have isolated disease that is amenable to complete eradication. As a biologic marker, the disease-free interval serves to predict curability and may distinguish isolated disease from occult disseminated disease.
    Diseases of the Colon & Rectum 11/2007; 50(10):1558-65; discussion 1565-7. · 3.20 Impact Factor
  • Toshikuni Nishikawa, Shunzo Maetani
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    ABSTRACT: The goal of radical cancer surgery with or without adjuvant therapy is to cure disease rather than to delay death. There is concern that the survival benefit of curative treatment may not be properly appreciated by the log-rank test (LRT), which is more sensitive to treatment that delays death than to treatment that achieves cure. To confirm this concern and to evaluate the survival benefit of adjuvant chemotherapy, the data from a previous randomized controlled trial are analyzed using both traditional and new methods. In this trial, 1410 gastric cancer patients with serosal or subserosal invasion had been classified by nodal and serosal status into four strata and randomized to receive high-dose or low-dose adjuvant regimens (mitomycin and tegafur-uracil) after gastrectomy. The two treatment groups were compared using the LRT as well as the life expectancy (LE) derived from the Boag model and the competing risk model. The LRT showed no significant difference between the two groups, whereas the LE increased significantly with high-dose chemotherapy (1.4-year gain; 95% CI = 0.1-2.8). A greater gain of 4.4 years occurred exclusively in the serosa-negative node-positive stratum, associated with a 21% increase in cure rate. The gain in LE was particularly greater in younger patients. Parametric LE analysis offers more relevant information about curative treatment than LRT. It suggests that high-dose chemotherapy may achieve cure in a subset of patients, eradicating residual malignancies left behind after gastrectomy and providing greater survival benefit than expected from LRT.
    Annals of Surgical Oncology 03/2007; 14(2):348-54. · 3.94 Impact Factor
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    ABSTRACT: Though the outcome of resection for locally invasive pancreatic cancer is still poor, it has gradually improved in Japan, and the 5-year survival is now about 10%. However, the advantage of resection over radiochemotherapy has not yet been confirmed by a randomized trial. We conducted this study to compare surgical resection alone versus radiochemotherapy without resection for locally invasive pancreatic cancer using a multicenter randomized design. Patients with pancreatic cancer who met our preoperative criteria for inclusion (pancreatic cancer invading the pancreatic capsule without involvement of the superior mesenteric artery or the common hepatic artery, or without distant metastasis) underwent laparotomy. Patients with operative findings consistent with our criteria were randomized into a radical resection group and a radiochemotherapy group (200 mg/m(2)/day of intravenous 5-fluorouracil and 5040 cGy of radiotherapy) without resection. The 2 groups were compared for mean survival, hazard ratio, 1-year survival, quality of life scores, and hematologic and blood chemical data. Twenty patients were assigned to the resection group and 22 to the radiochemotherapy group. There was 1 operative death. The surgical resection group had better results than the radiochemotherapy group as measured by 1-year survival (62% vs 32 %, P=.05), mean survival time (>17 vs 11 months, P < .03), and hazard ratio (0.46, P=.04). There were no differences in the quality of life score or laboratory data apart from increased diarrhea after surgical resection. Locally invasive pancreatic cancer without distant metastases and major arterial invasion appears to be best treated by surgical resection.
    Surgery 11/2004; 136(5):1003-11. · 3.11 Impact Factor
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    ABSTRACT: The mean survival time (MS) has acquired increasing importance as an outcome indicator for patient care and technology assessment. The authors use lifelong follow-up data from gastric cancer patients to study whether the MS is predictable from 5-year follow-up information based on 2 parametric models. The authors used 3597 gastric cancer patients operated on between 1950 and 1969 to create 50 groups. For each group, the disease-related survival curve (DRSC) was estimated from the 5-year follow-up data using the Boag model. The MS for the group was then estimated by combining the DRSC with the survival curve for the age and sex-matched contemporaries (control group) based on the competing risk model. Alternatively, it was estimated by using the DRSC and the MS for the control group (the survival limit model). These predicted MS values were compared with the full follow-up observations. Although individual prediction errors varied depending on the group size (63 to 3597 patients) and the length of MS (0.3 to 20.2 years), the mean prediction errors were reasonably small; the survival limit model overestimated MS by 4.7% (95% confidence interval [CI], 1.6 to 7.8) and the competing risk model by 3.2% (95% CI, 0.1 to 6.5). MS for gastric cancer patients is parametrically predictable from 5-year follow-up data. This analysis should be applicable to other diseases showing log-normal failure time distributions.
    Medical Decision Making 04/2004; 24(2):131-41. · 2.27 Impact Factor
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    ABSTRACT: We created a novel surgical repair for intractable rectovaginal fistula and treated four patients who had previously undergone unsuccessful surgery. An X-shaped skin incision was made on the perineum, and then the rectum was carefully divided from the vagina. Defects of both the rectum and the vagina were closed with vertical mattress sutures. The external sphincter muscle also was approximated. The gluteus muscle was identified through another skin incision to the buttock, and cut at the attachment to the femur. Bilateral gluteus muscles were approximated at the midline of the perineum so that the vagina was sufficiently separated from the rectum. Established anorectal angle was 92.5 degrees (SD=6.4 degrees ). Mean resting pressure was 101.3 cm H2O (SD=13.1). All patients retained complete anal function without soiling. The unusual problem of erosion of the posterior vaginal wall with fistulation in a sexually active woman justifies greater efforts, and this surgical technique offers good prospects in this small group of patients.
    Techniques in Coloproctology 11/2003; 7(3):198-202. · 1.34 Impact Factor
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    ABSTRACT: Although TI-201 SPECT has been used to evaluate the malignant grade of cerebral gliomas, the gold standard continues to be histopathologic examination. The authors assessed and compared the prognostic abilities of the two studies using survival analysis. Twenty-nine patients underwent 34 sessions of TI-201 SPECT plus surgery for primary or recurrent cerebral gliomas 12 to 78 months before this analysis. Using conventional survival analyses, such as the log-rank test, Cox regression, and the Akaike cross-tab method, the authors evaluated the prognostic significance of 10 variables: histopathologic grade, TI-201 SPECT, Tc-99m HMPAO SPECT, tumor cell viability, radionecrosis, neurologic defects, clinical improvement, surgery, chemotherapy, and external beam radiotherapy. TI-201 SPECT was most strongly related to prognosis, followed by histopathologic grade. The other variables had little prognostic value. The Cox stepwise selection procedure indicated that TI-201 SPECT was the only independent predictor of outcome, whereas histopathologic analysis was eliminated from the prognostic model. However, the Kaplan-Meier survival curve and the Akaike method indicated that histopathologically low-grade tumors were more closely associated with longer-term survival than were TI-201 low uptake tumors. TI-201 SPECT is not only closely correlated with the histopathologic grade of tumor but is a significantly better predictor of outcome than histopathologic grade. However, histopathologic examination may provide additional information on longer-term survival. TI-201 SPECT is a valuable procedure, especially in patients in whom a histologic diagnosis of possible glioma cannot be made.
    Clinical Nuclear Medicine 03/2001; 26(2):119-24. · 2.86 Impact Factor
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    ABSTRACT: It has recently been demonstrated that the tumor growth rate is a stronger determinant of survival than the extent of the growth in local recurrence of rectal cancer. We studied which factors controlled the tumor growth rate using modern immunohistochemical methods. In 51 patients who underwent extended resection for this condition, paraffin-embedded specimens were examined for 1) tumor angiogenesis by CD31 staining and microvessel counting, 2) apoptosis by terminal deoxynucleotide transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling staining, and 3) cellular proliferative activity using anti-proliferative cell nuclear antigen antibody. The results were compared with carcinoembryonic antigen doubling time and survival. The five-year survival rate was 20 percent. The postoperative carcinoembryonic antigen doubling time, which was the strongest predictor of survival, correlated highly with proliferative cell nuclear antigen labeling index, but did not correlate with the apoptotic index or microvessel counts. Our study shows that cancer cell proliferation rather than apoptosis or angiogenesis is a major determinant of tumor growth rate and survival in patients with locally recurrent rectal cancer.
    Diseases of the Colon & Rectum 07/2000; 43(6):775-81. · 3.20 Impact Factor
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    ABSTRACT: We developed a novel blood glucose control system, using a model predictive method, to achieve optimal control of the blood glucose level in severely diabetic or pancreatectomized patients. This system is designed to predict glucose level changes in advance, considering delayed response time and the administered doses of insulin. This method is also designed to calculate the most appropriate insulin infusion rate by considering differences in individual response to insulin. In this study, we compared our system with a conventional proportional and differential controller (PD controller) to determine whether the new system could regulate the glucose level efficiently in pancreatectomized dogs. The model predictive control method resulted in a significant reduction of mean insulin infusion rate compared with the conventional PD controller (0.71 mU/kg per min vs. 1.81 mU/kg per min, p = 0.0005), when the glucose level in both methods reached the planned target level (100 mg/dl). The new system also tended to have a reduced mean glucose infusion rate for compensating for overshooting of the glucose level compared with the PD controller (0.7 mg/kg per min vs. 1.1 mg/kg per min, p = 0.16). These results indicate that the new system should be a useful tool for regulating the glucose level in severely diabetic patients.
    ASAIO Journal 01/2000; 46(6):657-62. · 1.39 Impact Factor
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    ABSTRACT: A blood pressure autoregulation system based on the state-predictive control method was developed to minimize intraoperative blood loss and hence avoid blood transfusion. In this report, the system is further improved by incorporating fuzzy logic with a fail-safe function and an individual parameter-identifying function. The safety and stability of this system had been confirmed by preclinical experiments with dogs. Thereafter clinical application with 17 patients was conducted to maintain their mean arterial pressure at around 60 mmHg during major surgery. The use of this system resulted in decreased blood loss and more speedy and accurate surgery due to a clearer surgical field. Unwanted effects of hypotension were not observed clinically or in laboratory tests. This system is therefore safe, stable, and effective in reducing the blood loss during major surgery that otherwise might cause substantial blood loss.
    World Journal of Surgery 01/2000; 23(12):1258-63. · 2.35 Impact Factor
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    ABSTRACT: Although bursting pressure and tensile strength have long been measured to evaluate anastomotic techniques, it has yet to be clarified whether or not they are correlated, what implications they have, and which should be used as a gold standard. Using an experimental model to estimate pressure and tension in the same colonic anastomosis, the following variables were measured in 48 rats between days 0 and 14: bursting pressure (BP); minimal tensile strength (MITS) necessary to break a part of the anastomosis, and maximal tensile strength (MATS) needed to disrupt the whole anastomosis. Also, circulatory wall tension (CWT) was derived from BP and the anastomotic circumference (AC), and longitudinal wall tension (LWT) from MITS and AC. These variables were compared using correlation and regression analysis. During the lag phase (days < or = 4) there was poor correlation between pressure-related and tension-related variables whereas highly significant correlations were noted in the subsequent fibroplastic phase (day > or = 5). It was shown by regression lines that positive MITS and MATS were expected when BP was zero. Contrary to the previous assumption, no correlation was found between BP and tensile strength in the critical postoperative period. Based on our present and previous studies, measurement of MITS is recommended to evaluate the healing of colonic anastomosis.
    Digestive Surgery 01/1999; 16(6):478-85. · 1.74 Impact Factor
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    ABSTRACT: A highly sensitive system was previously developed by us to detect the presence of colorectal carcinoma cells in blood in the form of cytokeratin 20 (CK20) mRNA. In the present study, we used an improved version of this system to analyse the peripheral blood of 28 patients with colorectal carcinoma, five patients with non-cancerous intestinal diseases and six normal controls for the presence or absence of CK20 mRNA and to investigate the relationship between the mRNA results and prognosis. All eight patients with recurrence were positive for CK20 mRNA, as were four patients in the Dukes' C stage with either distant metastasis or dissemination. Five of the nine patients in the Dukes' C stage with neither distant metastasis nor dissemination were positive, and three of these developed recurrence within 11 months after the analysis. Only one of the seven patients in the Dukes' A or B stage was positive, and none showed recurrence during the 1-19 months of observation. None of the five patients without carcinomas or of the six normal controls was positive. Although the follow-up period is limited and the recurrences were all local at present, these results suggest that the presence of CK20 mRNA in circulation may be a useful indicator for the screening of advanced colorectal carcinoma patients with a high risk of recurrence.
    British Journal of Cancer 05/1998; 77(8):1327-32. · 4.82 Impact Factor
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    ABSTRACT: The nature of 'local recurrence' of rectal cancer remains unclear. Fifty-nine patients with locally recurrent rectal cancer who underwent extended repeat resections including total pelvic exenteration (39) and sacrectomy (43) were reviewed. Twelve patients had distant metastases before or at the time of repeat resection. The 5-year survival rate was 25 per cent. A second recurrence occurred in 45 patients including five of the eight 5-year survivors. Thirty-six of these recurrences had locoregional manifestations and 29 had distant metastases. Of 18 prognostic factors examined, the most significant determinant was the postoperative carcinoembryonic antigen doubling time (CEADT), followed by the preoperative CEADT, carcinoembryonic antigen (CEA) level and occurrence of distant metastases, in decreasing order. Late onset of first recurrence was also a favourable indicator. Thus, the growth rate of the tumour had a more profound impact on survival than the current extent of tumour progression. After operation the CEADT was reduced in patients with second recurrence (P = 0.05). Locally recurrent rectal cancer is a manifestation of disseminated disease spreading locoregionally and often to distant organs with a low probability of long-term cure. However, survival varies widely depending on the tumour growth rate, which is biologically predetermined and is also influenced by surgery.
    British Journal of Surgery 05/1998; 85(4):521-5. · 5.21 Impact Factor
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    ABSTRACT: Expression of insulin-like growth factor-2 (IGF-2) has been reported in tissue specimens and cell lines of human colorectal cancers. However, the effects of IGF-2 in colorectal cancer patients are not well known. In this study, IGF-2 staining was performed on tissue samples from 92 patients with colorectal cancer, and the relationship of IGF-2 staining to clinicopathological variables, proliferating cell nuclear antigen (PCNA) staining and patient survival was analyzed. IGF-2 staining was correlated with tumor progression, PCNA staining and patient survival. Our results suggest that IGF-2 plays an important role in tumor progression and that IGF-2 staining is useful as a prognostic factor in colorectal cancer patients.
    Oncology 01/1998; 55(3):242-8. · 2.61 Impact Factor
  • S Maetani, H Onodera, M Imamura
    Rinsho byori. The Japanese journal of clinical pathology 05/1997; 45(4):347-9.
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    ABSTRACT: A case of poorly differentiated adenocarcinoma of the small bowel with extensive lymph node metastases is herein presented, which responded to methotrexate/5-fluorouracil (MTX/5-FU) sequential therapy. The lymph node metastases disappeared completely after 10 months of treatment. After recurrence, combination therapy with radiation, hyperthermia, and cisplatinum were also effective in reducing the degree of nodal swelling while still allowing the patient to maintain her accustomed lifestyle for a prolonged period of time. Further multi-institutional studies are still needed, however, to fully assess this new therapeutic regimen for small bowel cancers.
    Surgery Today 02/1997; 27(1):60-3. · 1.21 Impact Factor
  • Transplantation Proceedings 05/1996; 28(2):1094-6. · 0.95 Impact Factor

Publication Stats

986 Citations
157.08 Total Impact Points

Institutions

  • 1981–2004
    • Kyoto University
      • • Graduate School of Medicine / Faculty of Medicine
      • • Department of Electrical Engineering
      Kioto, Kyōto, Japan
  • 1993
    • Kyoto Prefectural University of Medicine
      Kioto, Kyōto, Japan