Fig. 1

Labeling of the tumor visible margin with naked eyes. A Visible tumor margin was determined during operation and labeled with 5-0 sutures right after resection. The white arrow indicates the lateral resection margin, and the black arrow indicates the distal resection margin. B The red arrows marked with 5, 6, and 7 indicate the position labeled by sutures made at the tumor visible margins at 5, 6, and 7 o’clock. C The red squares marked with 5, 6, and 7 indicate the positions three tissues were retrieved from the specimen