Distal resection margin in colorectal surgery <i>in vivo</i> and after formalin fixation

Introduction. Historically, the standard for distal margin in rectal cancer surgery has been the 5 cm «rule». Currently, there is a trend to reduction the distal surgical margin. However, intraoperative specimen measurements and histological examination data differ. The phenomenon of surgical shrinkage plays a significant role, especially in determining the distal resection margin, as intraoperative data may not coincide with measurement after fixation of the specimen. Possible differences may lead to doubts about the oncological adequacy of the performed resection boundaries.Aim. To examine the shrinkage effect of distal resection margin in colorectal cancer after organ formalin fixation.Materials and methods. The prospective analysis included data of 20 patients with histologically confirmed rectal cancer and sigmoid cancer (adenocarcinoma G1–3) for whom surgical treatment is recommended. The distance between the lower edge of tumor to the distal resection margin was measured after resection (in vivo) and after 5–12 minutes after the last measurement. Then the determination of this distance was made after formalin fixation (in vitro).Results. The analysis revealed that the average shrinkage of the distal resection margin from in vivo to ex vivo was 30.5 mm (25,5 %) (p = 0.0001). The average shrinkage between in vivo and in vitro bowel samples was 51.0 mm.Conclusions. Measurement of the distal resection margin under different conditions influences the estimation of the oncological clearence in interpreting the results of pathological report and determining the results of treatment.