Background: The existence of microscopic tumor implants in the rectal wall, distal to the inferior edge of macroscopic tumor in rectal cancer (RC) (either in continuity with, or discontinuously) is called distal intramural spread (DIS).
Patients and methods: Between March 2006 and June 2008, in the Instituto de Oncología Ángel H Roffo, Universidad de Buenos Aires, the frequency and distance of DIS was studied in 21 patients undergoing surgery for RC who received neoadjuvant therapy. The study was observational, descriptive, longitudinal and prospective.
Results: Median age was 64 years and 66.7% ofpatients were male. Stages pre-treatment were: I in 2 patients (9.5%), II in 9 (42.8%), III in 7 (28.6%), IV in 2 (14.3%), and x in 1 (4.8%). Twenty patients received neoadjuvant combined radiotherapy plus chemotherapy modality. One patient received only radiotherapy. Pathological stages were: 0 in 1 case (4.8%), I in 3 (14.3%), II in 6 (28.6%), III in 6 (28.6%), and IV in 2 (9.5%). Three patients (14.3%) hada complete pathological response. We found DIS in only one case (4.8%) at 9 mm of the macroscopic tumor edge.
Conclusions: According to our experience and as recorded in the literature, we conclude that the DIS in RC is a rare phenomenon. The minimum distal margin to preserve must be at least 10 mm in the formalin-fixed specimen.