Proliferative activity of early gastric cancer measured by in vitro and in vivo bromodeoxyuridine labeling

Forty seven patients with early gastric cancer received a 30-minute intravenous injection of bromodeoxyuridine (BrdU), 1000 mg each 1 hour before laparotomy, to label tumor cells in the S phase. In 13 of 47 patients, specimens obtained by endoscopic biopsy were cultured in vitro at 37 degrees C for 1 hour under three times the atmospheric pressure in a vial with 400 microM BrdU. Labeled cells were detected in the resected specimen and the cultured specimen by immunohistochemical staining procedure. The BrdU labeling index (LI, defined as the percentage of labeled cells in relation to the 1000 tumor cells) was calculated for each specimen. All patients without lymph node metastasis had an in vivo BrdU LI of less than 12%. In contrast, 31% of patients with early gastric cancer with an in vivo BrdU LI greater than 12% had lymph node metastasis. There was a correlation between the in vivo and the in vitro LI. Therefore, the in vitro BrdU LI of specimens obtained by endoscopic biopsy may be a useful indicator of lymph node status in patients with individual early gastric cancers before operations. If the in vitro BrdU LI is less than 12% lymph node dissection may not be necessary.