Evaluation of the malignant potential of the α-fetoprotein (AFP)-producing gastric cancer

　α-fetoprotein (AFP) gastric cancer is defined as a gastric cancer partially consisting of tumor cells producing AFP.
In the present study, we investigated the malignant potential of AFP producing gastric cancer (n=11) and AFP-non-producing gastric cancer (n=73).
The immunohistochemical expression of AFP was demonstrated in all specimens of AFP producing gastric cancer. However, it was not shown in all specimens of AFP non-producing gastric cancer. From the viewpoint of clinical pathology, the incidence of low-differentiated adenocarcinoma and liver metastasis　was higher in AFP producing gastric cancer. The argyrophilic nuclear organizer region (Ag-NOR) score and area of AFP producing gastric cancer were 3.28±1.19 and 4.68±1.57u㎡, respectively, signifi-cantly (P<0.05) higher than those of AFP non-producing gastric cancer. On the other hand, the incidence of the aneuploid pattern of AFP producing gastric cancer was 80.0%, significantly (P<0.05) higher than that of AFP non-producing gastric cancer.
Moreover, the 4c exceeding rate (4cER), which is defined as the percentage of cells with an aneuploid nuclear DNA content over the tetraploid (4c) of AFP producing gastric cancer was 23.07±7.97%, significantly (P<0.05) higher than that of AFP non-producing gastric cancer.
In conclusion, the poor prognosis of patients with AFP producing gastric cancer may be attributed to the extremely malignant potential of neoplastic cells.