Masaru Oba
University of Tokyo
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Featured researches published by Masaru Oba.
Surgery | 2014
Ryuji Yoshioka; Kiyoshi Hasegawa; Yoshihiro Mise; Masaru Oba; Taku Aoki; Yoshihiro Sakamoto; Yasuhiko Sugawara; Eiji Sunami; Toshiaki Watanabe; Norihiro Kokudo
BACKGROUND It remains unclear whether primary colorectal cancer and synchronous liver metastases (SLMs) should be resected simultaneously or with a staged procedure. METHODS We reviewed the short-term outcomes of 127 patients who underwent simultaneous resection of primary colorectal cancer and SLM at our institution from January 1993 to December 2011. RESULTS The proportion of simultaneous resections was 84.7% (127 of 150 patients). There was no postoperative mortality, and the postoperative complication rate was 61.4%. Major complications occurred in 23 (18.2%) patients, and anastomotic failure occurred in 2 (1.6%). The 3-, 5-, and 10-year overall survival rates were 74%, 64%, and 52%, respectively. The median recurrence-free survival period was 7.0 months (95% confidence interval, 4.5-9.5 months) and the 5-year recurrence-free survival rate was 17%. CONCLUSION Simultaneous resection can be performed safely in patients with colorectal cancer and SLM.
PLOS ONE | 2016
Kiyoshi Hasegawa; Akio Saiura; Tadatoshi Takayama; Shinichi Miyagawa; Junji Yamamoto; Masayoshi Ijichi; Masanori Teruya; Fuyo Yoshimi; Seiji Kawasaki; Hiroto Koyama; Masaru Oba; Michiro Takahashi; Nobuyuki Mizunuma; Yutaka Matsuyama; Toshiaki Watanabe; Masatoshi Makuuchi; Norihiro Kokudo
Background The high recurrence rate after surgery for colorectal cancer liver metastasis (CLM) remains a crucial problem. The aim of this trial was to evaluate the efficacy of adjuvant therapy with uracil-tegafur and leucovorin (UFT/LV). Methods In the multicenter, open-label, phase III trial, patients undergoing curative resection of CLM were randomly assigned in a 1:1 ratio to either the UFT/LV group or surgery alone group. The UFT/LV group orally received 5 cycles of adjuvant UFT/LV (UFT 300mg/m2 and LV 75mg/day for 28 days followed by a 7-day rest per cycle). The primary endpoint was recurrence-free survival (RFS). Secondary endpoints included overall survival (OS). Results Between February 2004 and December 2010, 180 patients (90 in each group) were enrolled into the study. Of these, 3 patients (2 in the UFT/LV group and 1 in the surgery alone group) were excluded from the efficacy analysis. Median follow-up was 4.76 (range, 0.15–9.84) years. The RFS rate at 3 years was higher in the UFT/LV group (38.6%, n = 88) than in the surgery alone group (32.3%, n = 89). The median RFS in the UFT/LV and surgery alone groups were 1.45 years and 0.70 years, respectively. UFT/LV significantly prolonged the RFS compared with surgery alone with the hazard ratio of 0.56 (95% confidence interval, 0.38–0.83; P = 0.003). The hazard ratio for death of the UFT/LV group against the surgery alone group was not significant (0.80; 95% confidence interval, 0.48–1.35; P = 0.409). Conclusion Adjuvant therapy with UFT/LV effectively prolongs RFS after hepatic resection for CLM and can be recommended as an alternative choice. Trial Registration UMIN Clinical Trials Registry C000000013
Scandinavian Journal of Gastroenterology | 2014
Yoshikuni Kawaguchi; Kiyoshi Hasegawa; Akio Saiura; Rihito Nagata; Michiro Takahashi; Masaru Oba; Junichi Kaneko; Taku Aoki; Yoshihiro Sakamoto; Yasuhiko Sugawara; Masatoshi Makuuchi; Norihiro Kokudo
Abstract Objective. As a minimally invasive modality, radiofrequency ablation (RFA) has been increasingly applied not only for the treatment of hepatocellular carcinoma, but also for that of colorectal liver metastasis (CLM). However, RFA for CLM has been shown to be associated with a high local recurrence rate, and no optimal treatment for RFA failure has been established yet. The aim of this study was to evaluate the feasibility and outcome of surgical resection for local recurrence after RFA. Material and methods. A retrospective study of 17 patients, who underwent surgery for local recurrence after RFA for resectable CLM, was carried out. The surgical procedures involved in the actual surgery were compared with those envisioned for the primary resection if RFA had not been selected. Results. Surgical resection for RFA recurrence was more invasive than the envisioned surgical procedure in 10 cases (58%). In addition, the proportions of cases that required technically demanding procedures among the patients receiving surgery for RFA recurrence were higher than those in envisioned operations; major hepatectomy, eight cases [47%] versus two cases [12%] (p < 0.0205); excision and/or reconstruction of the major hepatic veins, three cases [18%] versus zero case [0%] (p = 0.035); excision of diaphragm: three cases [18%] versus zero case [0%] (p = 0.035). The 1-, 3- and 5-year overall survival rates were 92%, 45% and 45%, respectively. Conclusions. Surgical resection for RFA recurrence for CLM required more invasive and technically demanding procedures. Thus, RFA for CLM should be limited to unresectable cases, and patients with resectable CLM should be thoroughly advised not to undergo RFA, but rather surgical resection.
Annals of Surgical Oncology | 2014
Masaru Oba; Kiyoshi Hasegawa; Yutaka Matsuyama; Junichi Shindoh; Yoshihiro Mise; Taku Aoki; Yoshihiro Sakamoto; Yasuhiko Sugawara; Masatoshi Makuuchi; Norihiro Kokudo
Surgery | 2016
Masaru Oba; Kiyoshi Hasegawa; Junichi Shindoh; Suguru Yamashita; Yoshihiro Sakamoto; Masatoshi Makuuchi; Norihiro Kokudo
American Journal of Surgery | 2015
Michiro Takahashi; Kiyoshi Hasegawa; Masaru Oba; Taku Aoki; Yoshihiro Sakamoto; Yasuhiko Sugawara; Norihiro Kokudo
Journal of Gastrointestinal Surgery | 2015
Yujiro Nishioka; Junichi Shindoh; Ryuji Yoshioka; Wataru Gonoi; Hiroyuki Abe; Naoki Okura; Shuntaro Yoshida; Masaru Oba; Masaji Hashimoto; Goro Watanabe; Kiyoshi Hasegawa; Norihiro Kokudo
Drug discoveries and therapeutics | 2014
Akio Saiura; Junji Yamamoto; Kiyoshi Hasegawa; Masaru Oba; Tadatoshi Takayama; Shinichi Miyagawa; Masayoshi Ijichi; Masanori Teruya; Fuyo Yoshimi; Seiji Kawasaki; Hiroto Koyama; Masatoshi Makuuchi; Norihiro Kokudo
Breast Cancer | 2011
Nahomi Tokudome; Yoshinori Ito; Shunji Takahashi; Kokoro Kobayashi; Shinichiro Taira; Chizuko Tsutsumi; Masafumi Oto; Masaru Oba; Kenichi Inoue; Akiko Kuwayama; Kyoko Masumura; Yoshie Nakayama; Chie Watanabe; Kiyohiko Hatake
Molecular and Clinical Oncology | 2015
Hiroki Osumi; Eiji Shinozaki; Masahiko Osako; Yoshimasa Kawazoe; Masaru Oba; Takaharu Misaka; Takashi Goto; Hitomi Kamo; Mitsukuni Suenaga; Yosuke Kumekawa; Mariko Ogura; Masato Ozaka; Satoshi Matsusaka; Keisho Chin; Kiyohiko Hatake; Nobuyuki Mizunuma