Background: Expression of sialyl Tn antigen (STN) or serum STN levels were reported to be the independent prognostic factors of colon and ovarian cancers, respectively. The clinical significance of serum STN was evaluated as a tumor marker in gastric cancer.
Methods: Preoperative STN levels were examined in 350 patients with gastric cancer, surgically treated in the Department of Surgery II, Kyushu University Hospital, and in the National Kyushu Cancer Center, between April, 1981 and April, 1986. The patients were divided into two groups: a high STN group (n = 304), with over 45 U/ml of STN, and a low STN group (n = 46), with less than or equal to 45 U/ml.
Results: In the high STN group, the patients were older and the tumors were larger, compared to the low STN group. Histologically, tumors in the high STN group were deeply penetrating and the rates of lymphatic involvement, vascular involvement, and lymph node and hepatic metastases were higher. Infiltrative growth patterns dominated. Thus, the tumors were in an advanced stage. The 5-year survival rate for patients in the high STN group was significantly less than that of patients in the low STN group (44.8% +/- 7.9% versus 75.1% +/- 2.6%, P < 0.05).
Conclusions: Because a high STN level correlates with an advanced tumor stage and a poorer prognosis, close follow-up and aggressive therapy are recommended.