From practical point of view, in order to achieve a significant improvement of curability of patients with gastric cancer, it seems far more urgent to search for some useful measures to prevent recurrence than to concentrate on improvement of the detection rate of the early stage of gastric cancer, because at present the majority of patients who come to operation cannot be cured because of unavailability of suitable measures to inhibit postoperative recurrence of the disease.
In viewing of the reasons why X-ray irradiation or anticancer chemotherapy has failed in radical eradiation of a small population of cancer cells not cleared by operation, it seems reasonale to consider that the effective and curative measures for patients with gastric cancer should have, at least, the following 3 characteristics.
1) It should exhibit an inhibitory effect upon tumor growth.
2) Its anti-cancer effect should not be of temporal nature, but it should be maintained for a fairly long time after its application is discontinued.
3) It should be almost non-toxic for host to make its safe and repeated application possible. The clinical results due to application of HUD to human cases immediately after operation will be presented here to show its usefulness as one of the promissing measures to prevent postoperative recurrence of gastric cancer.

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