Masanori Naito
Kitasato University
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Featured researches published by Masanori Naito.
Surgery Today | 2009
Takatoshi Nakamura; Wataru Onozato; Hiroyuki Mitomi; Masanori Naito; Takeo Sato; Heita Ozawa; Kazuhiko Hatate; Atsushi Ihara; Masahiko Watanabe
PurposeThe short- and long-term outcomes of laparoscopic surgery for right-sided colon cancer remain largely uninvestigated. This study was undertaken to compare the morbidity and mortality after either a laparoscopic right hemicolectomy (LRHC) or an open right hemicolectomy (ORHC) for this type of tumor.MethodsThe study group included 100 patients who underwent an LRHC and 100 patients who underwent an ORHC for right-sided colon cancer from 1990 through 2004. The two groups were retrospectively well matched with respect to sex, age (±5 years), and pathological tumor-node-metastasis (TNM) stage.ResultsThe median follow-up period was 83 months in the LRHC group and 105 months in the ORHC group. The LRHC group had a lower volume of intraoperative bleeding (P < 0.001), a lower rate of wound infection (P = 0.019) or postoperative intestinal obstruction (P = 0.013), and a shorter hospital stay (P < 0.001) than the ORHC group. The rate of recurrence did not differ significantly between the LRHC group (19%) and the ORHC group (22%). In patients with TNM stage I or II, the disease-free survival (DFS) rate (94.9% vs 95.1%) and overall survival (OS) rate (95.8% vs 95.0%) did not differ significantly between the two groups. A similar tendency was observed in patients with stage III with the rates for DFS (71.3% vs 60.4%) and OS (73.6% vs 64.1%), respectively.ConclusionsAn LRHC for right-sided colon cancer has the advantage over an ORHC of better short-term outcomes, and both groups have similar long-term oncologic outcomes. An LRHC is thus an acceptable alternative to an ORHC for the treatment of this type cancer.
International Journal of Radiation Oncology Biology Physics | 2011
Takeo Sato; Heita Ozawa; Kazuhiko Hatate; Wataru Onosato; Masanori Naito; Takatoshi Nakamura; Atsushi Ihara; Wasaburo Koizumi; Kazushige Hayakawa; Isao Okayasu; Keishi Yamashita; Masahiko Watanabe
PURPOSE We aimed to validate our hypothesis that a preoperative chemoradiotherapy regimen with S-1 plus irinotecan is feasible, safe, and active for the management of locally advanced rectal cancer in a single-arm Phase II setting. METHODS AND MATERIALS Eligible patients had previously untreated, locally advanced rectal adenocarcinoma. Radiotherapy was administered in fractions of 1.8 Gy/d for 25 days. S-1 was administered orally in a fixed daily dose of 80 mg/m2 on Days 1 to 5, 8 to 12, 22 to 26, and 29 to 33. Irinotecan (80 mg/m2) was infused on Days 1, 8, 22, and 29. Four or more weeks after the completion of the treatment, total mesorectal excision with lateral lymph node dissection was performed. The primary endpoint was the rate of completing treatment in terms of feasibility. The secondary endpoints were the response rate and safety. RESULTS We enrolled 43 men and 24 women in the study. The number of patients who completed treatment was 58 (86.6%). Overall, 46 patients (68.7%) responded to treatment and 24 (34.7%) had a complete histopathologic response. Three patients had Grade 3 leukopenia, and another three patients had Grade 3 neutropenia. Diarrhea was the most common type of nonhematologic toxicity: 3 patients had Grade 3 diarrhea. CONCLUSIONS A preoperative regimen of S-1, irinotecan, and radiotherapy to the rectum was feasible, and it appeared safe and effective in this nonrandomized Phase II setting. It exhibited a low incidence of adverse events, a high rate of completion of treatment, and an extremely high rate of pathologic complete response.
International Journal of Radiation Oncology Biology Physics | 2014
Takatoshi Nakamura; Keishi Yamashita; Takeo Sato; Akira Ema; Masanori Naito; Masahiko Watanabe
PURPOSE To assess the long-term outcomes of patients with rectal cancer who received neoadjuvant chemoradiation therapy (NCRT) with concurrent S-1 and irinotecan (S-1/irinotecan) therapy. METHODS AND MATERIALS The study group consisted of 115 patients with clinical stage T3 or T4 rectal cancer. Patients received pelvic radiation therapy (45 Gy) plus concurrent oral S-1/irinotecan. The median follow-up was 60 months. RESULTS Grade 3 adverse effects occurred in 7 patients (6%), and the completion rate of NCRT was 87%. All 115 patients (100%) were able to undergo R0 surgical resection. Twenty-eight patients (24%) had a pathological complete response (ypCR). At 60 months, the local recurrence-free survival was 93%, disease-free survival (DFS) was 79%, and overall survival (OS) was 80%. On multivariate analysis with a proportional hazards model, ypN2 was the only independent prognostic factor for DFS (P=.0019) and OS (P=.0064) in the study group as a whole. Multivariate analysis was additionally performed for the subgroup of 106 patients with ypN0/1 disease, who had a DFS rate of 85.3%. Both ypT (P=.0065) and tumor location (P=.003) were independent predictors of DFS. A combination of these factors was very strongly related to high risk of recurrence (P<.0001), which occurred most commonly in the lung. CONCLUSIONS NCRT with concurrent S-1/irinotecan produced high response rates and excellent long-term survival, with acceptable adverse effects in patients with rectal cancer. ypN2 is a strong predictor of dismal outcomes, and a combination of ypT and tumor location can identify high-risk patients among those with ypN0/1 disease.
Surgery Today | 2011
Atsuko Tsutsui; Takatoshi Nakamura; Hiroyuki Mitomi; Wataru Onozato; Takeo Sato; Heita Ozawa; Masanori Naito; Atsushi Ikeda; Atsushi Ihara; Masahiko Watanabe
Sacrococcygeal teratoma is a relatively rare congenital retroperitoneal tumor in adults. The standard treatment is a complete tumor resection. This report describes the successful laparoscopic resection of a sacrococcygeal teratoma. The patient was a 27-year-old woman with a well-demarcated cystic mass, 6 cm in diameter, in the retroperitoneum overlying the anterior surface of the sacrum. The mass was resected laparoscopically. A histopathological examination showed a mature teratoma. The magnifying function of the laparoscope allowed an en bloc resection in the narrow pelvic cavity, without damaging the tumor. The aesthetic outcome was excellent. The patient remains relapse-free at 1 year 6 months after surgery.
Hepato-gastroenterology | 2011
Takatoshi Nakamura; Hiroyuki Mitomi; Wataru Onozato; Takeo Sato; Atsushi Ikeda; Masanori Naito; Naoto Ogura; Hiroki Kamata; Akira Ooki; Masahiko Watanabe
BACKGROUND/AIMS We compared the results of laparoscopic resection of colon cancer between patients 75 years or older and those 64 years or younger, to confirm whether this procedure is warranted in elderly patients. METHODOLOGY The study group was comprised of patients with stage I to III colon cancer treated by laparoscopic surgery from 1995 through 2006. Oncologic outcomes were compared between 74 patients 75 years or older (elderly group) and 74 patients 64 years or younger (younger group) who were matched for gender, tumor location and pathological tumor-node-metastasis (TNM) stage. RESULTS In patients with stage I or II disease, the disease-free survival rate and overall survival rate were similar in the elderly group (100% and 100%, respectively) and the younger group (95.6% and 95.8%, respectively). In patients with stage III disease, the disease-free survival rate and overall survival rate were also similar in the elderly group (76.7% and 88.5%, respectively) and the younger group (88.5% and 88.5%, respectively). CONCLUSIONS Postoperative complications and long-term oncologic outcomes were similar in elderly patients and younger patients with colon cancer who underwent laparoscopic colectomy in our hospital. These results demonstrate that laparoscopic resection of colon cancer is warranted in patients 75 years or older.
Hepato-gastroenterology | 2011
Takatoshi Nakamura; Hiroyuki Mitomi; Wataru Onozato; Takeo Sato; Atsushi Ikeda; Masanori Naito; Naoto Ogura; Hiroki Kamata; Akira Ooki; Masahiko Watanabe
BACKGROUND/AIMS In Japan, the safety and long-term outcomes of laparoscopic surgery for advanced colorectal cancer remains a matter of debate. We studied the safety and outcomes of laparoscopic surgery in patients with pathological stage II and III colon cancer. METHODOLOGY The study group comprised 253 patients with colon cancer who underwent laparoscopic surgery from January 1998 through December 2006. We studied surgical outcomes, invasiveness, safety, recurrence rates, recurrence patterns, and long-term outcomes. RESULTS Median follow-up was 67 months (range, 7-149). Laparoscopic surgery was converted to open surgery in 5 patients (2%). Postoperative complications occurred in 23 patients (9%); wound infections were most common (11 patients, 4.3%), followed by ileus (5 patients, 1.9%). Recurrence developed in 66 patients (26%). Liver and lung metastases were the most common types of recurrence; there was no port-site recurrence. The 10-year recurrence-free survival rate and the overall survival rate were respectively 92.9% and 93.3% in stage II disease, 82.7% and 82.9% in stage IIIA and IIIB disease, and 70.3% and 68.6% in stage IIIC disease. CONCLUSIONS In patients with pathological stage II and III colon cancer, laparoscopic surgery is safe, minimally invasive, and has good surgical outcomes, overall survival rates and recurrence-free survival rates. Our results suggest that laparoscopic surgery is a viable treatment option for pathological stage II and III colon cancer.
Asian Journal of Endoscopic Surgery | 2017
Masanori Naito; Takahiro Yamanashi; Takatoshi Nakamura; Hirohisa Miura; Atsuko Tsutsui; Takeo Sato; Masahiko Watanabe
Laparoscopic surgery is widely used for the treatment of colorectal cancer, but it is often associated with postoperative anastomotic complications. Generally, gastrointestinal anastomosis for colorectal surgery is performed using mechanical anastomosis with a double stapling technique. Using the automatic suture device with bioabsorbable polyglycolic acid (PGA) felt is expected to adequately reinforce staple lines on fragile tissue, helping to prevent anastomotic complications, including leakage.
Asian Journal of Endoscopic Surgery | 2017
Masanori Naito; Takeo Sato; Takatoshi Nakamura; Takahiro Yamanashi; Hirohisa Miura; Atsuko Tsutsui; Masahiko Watanabe
Despite the availability of various anastomosis techniques, postoperative anastomotic complications such as anastomosis failure and bleeding develop in some patients. Automatic suturing devices have been widely used for gastrointestinal anastomosis. However, overly thick or thin tissue, displacement of tissue, and the creation of a staple‐on‐staple site may lead to incomplete staple formation. These factors are considered to be related to postoperative complications such as anastomosis failure.
Asian Journal of Endoscopic Surgery | 2017
Masanori Naito; Naoto Ogura; Takahiro Yamanashi; Takeo Sato; Takatoshi Nakamura; Hirohisa Miura; Atsuko Tsutsui; Yasutoshi Sakamoto; Rieko Tanaka; Yuji Kumagai; Masahiko Watanabe
Clinical use of an adhesion barrier made of oxidized, regenerated cellulose, Interceed®, has been reported in the field of obstetrics and gynecology to help prevent adhesions between the peritoneum and the bowel in various types of operations. In gastrointestinal surgery, sodium hyaluronate/carboxymethylcellulose has been reported as an absorbable membrane to reduce postoperative adhesions. The present study was a prospective randomized controlled study to investigate the safety and usefulness of Interceed in laparoscopic colorectal surgery.
Annals of medicine and surgery | 2017
Masanori Naito; Hirohisa Miura; Takatoshi Nakamura; Takeo Sato; Takahiro Yamanashi; Atsuko Tsutsui; Masahiko Watanabe
Background Gastrointestinal anastomosis remains associated with a considerable burden of morbidity and, in some cases, mortality. Functional end-to-end anastomosis, whilst extremely efficient, is vulnerable to increased intestinal pressure in the immediate postoperative period, which may predispose to development of anastomotic leakage or bleeding. Therefore, there is a requirement for new techniques that facilitate safe and efficacious anastomotic procedures. Materials and methods This study examined the clinical application of functional end-to-end anastomosis with a stapler that automatically applies a bioabsorbable polyglycolic acid sheet (Endo GIA™ Reinforced Reload with Tri-Staple™ Technology). A porcine model was used to examine functional end-to-end anastomosis with and without application of a bioabsorbable polyglycolic acid sheet. As the crotch of the anastomosis is considered the weakest point, a probe was used to test the integrity of these anastomoses. Furthermore, we performed functional end-to-end anastomosis using the Endo GIA™ Reinforced stapler in a clinical series of 20 patients undergoing gastrointestinal tract resection. In all cases, functional end-to-end anastomosis was performed without suture reinforcement. Results Small intestine anastomoses in the animal study exhibited no weakness at the crotch of the anastomosis, as tested with a probe, suggesting an increased resiliency to conventional complications of functional end-to-end anastomosis. In the clinical population, no postoperative complications were noted. No adhesive intestinal obstruction was noted. Conclusion Sutureless functional end-to-end anastomosis using the Endo GIA™ Reinforced appears to be safe, efficacious, and straightforward. Reinforcement of the crotch site with a bioabsorbable polyglycolic acid sheet appears to mitigate conventional problems with crotch-site vulnerability.