Answer 3: I would take the usual precautions of checking with the laboratory that there may not have been contamination with malignant cells from another patient during automatic processing and having the histology reviewed. (I assume this has been done already.)
Thirty years ago I was privileged to spend 6 months working in the gastroenterology unit in the Aichi Cancer Centre in Nagoya, Japan. Apart from seeing more early gastric cancer there than I have in the next 30 years in Sydney, I learned that in the situation being considered here the problem is much more likely to be a subtle mucosal or submucosal cancer rather than linitis plastica.
An early repeat endoscopy by an endoscopist with experience in diagnosing early gastric cancer would be optimal initial management. This is easier in Japan than in the West. It is a matter of experience, frequency of the lesion in a particular community and taking adequate time. Before doing the repeat endoscopy, the Western endoscopist should revise the Japanese classification of early gastric cancer and study a slide atlas of the various types of early gastric cancer. At the endoscopy, a lot of time should be devoted to looking for subtle abnormalities and taking multiple photographs and targeted biopsies in separately labeled containers. What had been written off at the first endoscopy as a "thickened fold" could be a Type 1 or Type 11a lesion; a slightly different colored patch of mucosa could be a 11b lesion or an insignificant depression a 11c. The signet cells are more likely to be found with Type 11c or Type 111 early cancer. A small lesion would be less likely to have lymph node metastases.
Dye scattering is worth considering in the very few units that do it routinely. Perhaps the patient should be referred to such a unit where they have a special interest and experience. As a one off procedure it usually doesn't help and the time spent is better devoted to detailed looking. It would be a shame to do an antrectomy if the early cancer is not in the antrum. Is it certain that the positive biopsies came from the antrum? Were the cells in the mucosa, submucosa or on the surface? Were the biopsies taken from mucosa that was clearly antral on histology? Was gastritis or metaplasia present?
One other thing I learned in Japan was that early cancers could take a long time to progress. In the patient we are considering, a follow-up gastroscopy now is recommended. Then, when additional information is available, the patient needs to be involved in further decision making but a third endoscopy in three months would be not unreasonable if doubt remains after the early second endoscopy.
The aim is to localize the lesion. Local operative resection of a documented early cancer is a possible option.
In some centers where ultrasound shows the lesion has not spread beyond the muscularis mucosae, endoscopic resection of this intestinal type adenocarcinoma might be considered and this would now be commonly done in Japan. However the cancer would need to be clearly identified at endoscopy before either of these two options would be possible.
I would be unhappy with a blind antrectomy as initial management but it might be justified in 3 months as outlined above if it were still not possible to identify the tumor.