Open Access Open Badges Study protocol

Methylene blue-assisted technique for harvesting lymph nodes after radical surgery for gastric cancer: a prospective randomized phase III study

Toru Aoyama13, Takaki Yoshikawa13*, Satoshi Morita2, Junya Shirai13, Hirohito Fujikawa13, Kenichi Iwasaki1, Tsutomu Hayashi13, Takashi Ogata1, Haruhiko Cho1, Norio Yukawa3, Takashi Oshima3, Yasushi Rino3, Munetaka Masuda3 and Akira Tsuburaya1

Author Affiliations

1 Department of Gastrointestinal Surgery, Kanagawa Cancer Center, 1-1-2 Nakao, Asahi-ku, Yokohama 241-0815, Japan

2 Department of Biostatistics and Epidemiology, Yokohama City University Medical Center, Yokohama, Japan

3 Department of Surgery, Yokohama City University, Yokohama, Japan

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BMC Cancer 2014, 14:155  doi:10.1186/1471-2407-14-155

Published: 5 March 2014



This randomized Phase III trial will evaluate whether the methylene blue-assisted technique is efficient for harvesting lymph nodes after radical surgery for gastric cancer.


Patients that undergo distal or total gastrectomy with radical nodal dissection will be randomly assigned to Group A: the standard group, the lymph nodes (LNs) will be harvested from the fresh specimen immediately after surgery, or Group B: the methylene blue-assisted group, where the LNs will be harvested from specimens fixed with 10% buffered formalin with methylene blue for 48 hours after surgery. The primary endpoint is the ratio of the number of the harvested LNs per time (minute). The secondary endpoint is the number of harvested LNs. A 25% reduction in the ratio of harvested lymph-node/time (minute) was determined to be necessary for this test treatment, considering the balance between the cost and benefit. Retrospective data was used to estimate the ratio of the number of the harvested LNs per time (minute) to be 40/30 minutes in Group A. A 25% risk reduction and a rate of 40/22.5 minutes is expected in Group B. Therefore, the sample size required ensuring a two-sided alpha error of 5% and statistical power of 80% is 52 patients, with 26 patients per arm. The number of patients to be accrued was set at 60 in total, due to the likelihood of enrolling ineligible patients.

Trial registration


Clinical trial design; Gastrointestinal surgery; Pathology