Masashi Oka

5.0k total citations · 2 hit papers
80 papers, 3.6k citations indexed

About

Masashi Oka is a scholar working on Surgery, Pulmonary and Respiratory Medicine and Gastroenterology. According to data from OpenAlex, Masashi Oka has authored 80 papers receiving a total of 3.6k indexed citations (citations by other indexed papers that have themselves been cited), including 52 papers in Surgery, 42 papers in Pulmonary and Respiratory Medicine and 18 papers in Gastroenterology. Recurrent topics in Masashi Oka's work include Gastric Cancer Management and Outcomes (28 papers), Helicobacter pylori-related gastroenterology studies (23 papers) and Metastasis and carcinoma case studies (12 papers). Masashi Oka is often cited by papers focused on Gastric Cancer Management and Outcomes (28 papers), Helicobacter pylori-related gastroenterology studies (23 papers) and Metastasis and carcinoma case studies (12 papers). Masashi Oka collaborates with scholars based in Japan, United States and Germany. Masashi Oka's co-authors include Masao Ichinose, Mitsuhiro Fujishiro, Naohisa Yahagi, Masao Omata, Naomi Kakushima, Nobutake Yamamichi, Mikitaka Iguchi, Shinya Kodashima, Satoshi Ono and Shotaro Enomoto and has published in prestigious journals such as Gastroenterology, PLoS ONE and Biochemical and Biophysical Research Communications.

In The Last Decade

Masashi Oka

78 papers receiving 3.6k citations

Hit Papers

align trajectories

What are hit papers?

Hit papers significantly outperform the citation benchmark for their cohort. A paper qualifies if it has ≥500 total citations, achieves ≥1.5× the top-1% citation threshold for papers in the same subfield and year (this is the minimum needed to enter the top 1%, not the average within it), or reaches the top citation threshold in at least one of its specific research topics.

Guidelines for endoscopic submucosal dissection and endoscopic mucosal resection for early gastric cancer

2015 389 citations Mitsuhiro Fujishiro, Naohisa Yahagi et al. Digestive Endoscopy profile →
Guidelines for endoscopic submucosal dissection and endoscopic mucosal resection for early gastric cancer (second edition)

2020 264 citations Mitsuhiro Fujishiro, Naohisa Yahagi et al. Digestive Endoscopy profile →

Peers — A (Enhanced Table)

Peers by citation overlap · career bar shows stage (early→late) cites · hero ref

Name	h						Papers	Cites
Masashi Oka Japan	28	2.7k	2.1k	1.2k	419	303	80	3.6k
Navtej Buttar United States	37	2.1k 0.8×	3.0k 1.5×	750 0.6×	411 1.0×	639 2.1×	169	4.2k
Hideyuki Tamai Japan	26	1.1k 0.4×	1.5k 0.7×	365 0.3×	326 0.8×	279 0.9×	92	2.3k
Kazutaka Obama Japan	30	1.7k 0.6×	1.4k 0.7×	838 0.7×	758 1.8×	386 1.3×	176	2.9k
J. R. Siewert Germany	31	1.8k 0.7×	2.1k 1.0×	601 0.5×	759 1.8×	319 1.1×	92	3.4k
Wan‐Sik Lee South Korea	28	908 0.3×	967 0.5×	447 0.4×	487 1.2×	451 1.5×	137	2.2k
Kun Yang China	30	1.7k 0.6×	1.2k 0.6×	615 0.5×	804 1.9×	506 1.7×	177	3.1k
Hyun Joo Jang South Korea	25	630 0.2×	847 0.4×	456 0.4×	385 0.9×	288 1.0×	120	1.8k
Norihito Wada Japan	25	1.5k 0.6×	1.6k 0.8×	508 0.4×	648 1.5×	261 0.9×	170	2.6k
Saburo Shikuwa Japan	24	1.5k 0.6×	1.2k 0.6×	830 0.7×	207 0.5×	169 0.6×	76	2.2k
Tsutomu Namikawa Japan	24	1.1k 0.4×	1.1k 0.5×	342 0.3×	743 1.8×	195 0.6×	235	2.3k

Countries citing papers authored by Masashi Oka

Since Specialization

Citations

This map shows the geographic impact of Masashi Oka's research. It shows the number of citations coming from papers published by authors working in each country. You can also color the map by specialization and compare the number of citations received by Masashi Oka with the expected number of citations based on a country's size and research output (numbers larger than one mean the country cites Masashi Oka more than expected).

Fields of papers citing papers by Masashi Oka

Since Specialization

Physical SciencesHealth SciencesLife SciencesSocial Sciences

This network shows the impact of papers produced by Masashi Oka. Nodes represent research fields, and links connect fields that are likely to share authors. Colored nodes show fields that tend to cite the papers produced by Masashi Oka. The network helps show where Masashi Oka may publish in the future.

Co-authorship network of co-authors of Masashi Oka

This figure shows the co-authorship network connecting the top 25 collaborators of Masashi Oka. A scholar is included among the top collaborators of Masashi Oka based on the total number of citations received by their joint publications. Widths of edges represent the number of papers authors have co-authored together. Node borders signify the number of papers an author published with Masashi Oka. Masashi Oka is excluded from the visualization to improve readability, since they are connected to all nodes in the network.

All Works

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20 of 20 papers shown

Matsubara, Saburo, et al.. (2023). A novel tapered plastic stent with an ultrafine delivery system for one-step endoscopic ultrasound-guided hepaticogastrostomy. Endoscopy. 55(S 01). E354–E355. 2 indexed citations

Yoshihara, Masaharu, Masanori Ito, Kazuhiko Inoue, et al.. (2016). Characteristics of gastric cancer in negative test of serum anti-Helicobacter pylori antibody and pepsinogen test: a multicenter study. Gastric Cancer. 20(5). 764–771. 25 indexed citations

Yokoyama, Yoko, Katsuyoshi Matsuoka, Taku Kobayashi, et al.. (2014). A large-scale, prospective, observational study of leukocytapheresis for ulcerative colitis: Treatment outcomes of 847 patients in clinical practice. Journal of Crohn s and Colitis. 8(9). 981–991. 37 indexed citations

Shimamoto, Takeshi, Nobutake Yamamichi, Shinya Kodashima, et al.. (2013). No Association of Coffee Consumption with Gastric Ulcer, Duodenal Ulcer, Reflux Esophagitis, and Non-Erosive Reflux Disease: A Cross-Sectional Study of 8,013 Healthy Subjects in Japan. PLoS ONE. 8(6). e65996–e65996. 45 indexed citations

Enomoto, Shotaro, Mika Watanabe, Takeichi Yoshida, et al.. (2012). Relationship between vomiting reflex during esophagogastroduodenoscopy and dyspepsia symptoms. Digestive Endoscopy. 24(5). 325–330. 6 indexed citations

Enomoto, Shotaro, Hideyuki Tamai, Naoki Shingaki, et al.. (2011). Assessment of hepatocellular carcinomas using conventional magnetic resonance imaging correlated with histological differentiation and a serum marker of poor prognosis. Hepatology International. 5(2). 730–737. 24 indexed citations

Ueda, Kazuki, Hideyuki Tamai, Hiroki Maeda, et al.. (2010). Diagnosis of pancreatic tuberculosis by combined, contrast-enhanced sonography and endoscopic ultrasound-guided fine-needle aspiration. Clinical Journal of Gastroenterology. 3(3). 159–164. 6 indexed citations

Mori, Yoshiyuki, Hideyuki Tamai, Naoki Shingaki, et al.. (2009). Diffuse intrahepatic recurrence after percutaneous radiofrequency ablation for solitary and small hepatocellular carcinoma. Hepatology International. 3(3). 509–515. 43 indexed citations

Yanaoka, Kimihiko, Masashi Oka, Noriko Yoshimura, et al.. (2009). Preventive effects of etodolac, a selective cyclooxygenase‐2 inhibitor, on cancer development in extensive metaplastic gastritis, a Helicobacter pylori ‐negative precancerous lesion. International Journal of Cancer. 126(6). 1467–1473. 35 indexed citations

10.

Yanaoka, Kimihiko, Masashi Oka, Hiroshi Ohata, et al.. (2009). Eradication of Helicobacter pylori prevents cancer development in subjects with mild gastric atrophy identified by serum pepsinogen levels. International Journal of Cancer. 125(11). 2697–2703. 121 indexed citations

11.

Yamamichi, Nobutake, Ken-ichi Inada, Kouhei Sakurai, et al.. (2009). Cdx2 and the Brm-type SWI/SNF complex cooperatively regulate villin expression in gastrointestinal cells. Experimental Cell Research. 315(10). 1779–1789. 33 indexed citations

12.

Ueda, Kazuki, Takashi Ueyama, Kenichi Yoshida, et al.. (2008). Adaptive HNE-Nrf2-HO-1 pathway against oxidative stress is associated with acute gastric mucosal lesions. American Journal of Physiology-Gastrointestinal and Liver Physiology. 295(3). G460–G469. 53 indexed citations

13.

Oka, Masashi, Izumi Inoue, Mikitaka Iguchi, et al.. (2007). PROSPECTIVE STUDY COMPARING TRANS-ORAL AND TRANS-NASAL UPPER GASTROINTESTINAL ENDOSCOPY ON THE CARDIORESPIRATORY PARAMETER AND TOLERABILITY. Acta gastro-enterologica belgica. 49(10). 2684–2689. 2 indexed citations

14.

Oka, Masashi, Yasuo Matsubara, Tohru Niwa, et al.. (2007). Developmentally regulated expression of matrix metalloproteinases during fetal rat colon morphogenesis. Development Growth & Differentiation. 50(1). 41–48. 4 indexed citations

15.

Fujishiro, Mitsuhiro, Naohisa Yahagi, Naomi Kakushima, et al.. (2006). Endoscopic Submucosal Dissection of Esophageal Squamous Cell Neoplasms. Clinical Gastroenterology and Hepatology. 4(6). 688–694. 289 indexed citations

16.

Fujishiro, Mitsuhiro, Naohisa Yahagi, Masanori Nakamura, et al.. (2006). Successful outcomes of a novel endoscopic treatment for GI tumors: endoscopic submucosal dissection with a mixture of high-molecular-weight hyaluronic acid, glycerin, and sugar. Gastrointestinal Endoscopy. 63(2). 243–249. 196 indexed citations

17.

Kakushima, Naomi, Naohisa Yahagi, Mitsuhiro Fujishiro, et al.. (2005). THE HEALING PROCESS OF GASTRIC ARTIFICIAL ULCERS AFTER ENDOSCOPIC SUBMUCOSAL DISSECTION. Acta gastro-enterologica belgica. 47(6). 1266–1271. 24 indexed citations

18.

Tamai, Hideyuki, Masashi Oka, Hiroki Maeda, et al.. (2005). Contrast Harmonic Sonographically Guided Radio Frequency Ablation for Spontaneous Ruptured Hepatocellular Carcinoma. Journal of Ultrasound in Medicine. 24(7). 1021–1026. 4 indexed citations

19.

Tamai, Hideyuki, Masashi Oka, Naoki Shingaki, et al.. (2005). Contrast-Enhanced Ultrasonography in the Diagnosis of Solid Renal Tumors. Journal of Ultrasound in Medicine. 24(12). 1635–1640. 117 indexed citations

20.

Matsubara, Yasuo, Masao Ichinose, Masae Tatematsu, et al.. (1996). Stage-Specific Elevated Expression of the Genes for Hepatocyte Growth Factor, Keratinocyte Growth Factor, and Their Receptors during the Morphogenesis and Differentiation of Rat Stomach Mucosa. Biochemical and Biophysical Research Communications. 222(3). 669–677. 19 indexed citations

Rankless uses publication and citation data sourced from OpenAlex, an open and comprehensive bibliographic database. While OpenAlex provides broad and valuable coverage of the global research landscape, it—like all bibliographic datasets—has inherent limitations. These include incomplete records, variations in author disambiguation, differences in journal indexing, and delays in data updates. As a result, some metrics and network relationships displayed in Rankless may not fully capture the entirety of a scholar's output or impact.

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