Accurate Staging, Selective Preoperative Therapy and Optimal Surgery Can Deliver a Good Oncological and Functional Outcome in Low Rectal Cancer

Abstract

[3, 4] . Subsequent work has shown that in appropriately selected cases a distal margin of 10 mm does not increase the local recurrence rate or compromise survival [5] . The lower rectal and anorectal anatomy provides a challenge both from a staging and therapeutic standpoint in rectal cancer. In low rectal cancer (defined as the area below the insertion of the levator muscle), the mesorectal volume is reduced, and in anorectal tumors there is no mesorectal plane, as the rectal tube lies against the pelvic floor before passing through the external anal sphincter. The mesorectal fascia tapers as it fuses with the endopelvic fascia overlying the levator muscles, which in turn fuses with the muscles of the external anal sphincter. The intimate relationship between the mesorectum, levator muscle and external anal sphincter renders it essential to rule out tumor impingement of the sphincter complex, especially if an intersphincteric dissection is being contemplated. Indeed these lowest tumors are at the highest inherent risk of circumferential margin involvement regardless of stage by virtue of these anatomic relations. The first step in the management of a patient with low rectal cancer is to assess the tumor in terms of its stage and its relationship to the anal sphincter complex. Both EUS and MRI are employed to determine the size of the tumor (T stage) and lymph node status (N stage) as well as the preoperative stage of the tumor. In low rectal cancer close to the sphincter complex, additional information is required to assess the possibility of performing The primary surgical objective in a patient with rectal cancer is to perform a mesorectal excision achieving macroscopically clear proximal, distal and radial (circumferential or CRM) margins while restoring intestinal continuity wherever feasible. In this month’s journal, Pricolo et al. [1] report their experience of the impact of the length of the distal resection margin on outcome in rectal cancer. Fifty-three patients with advanced rectal cancer (T3/4 N0/N1) on endoscopic ultrasound (EUS) or MRI underwent neoadjuvant chemoradiation (5-fluorouracil and 50.4 Gy). Thirty-three patients (62%) underwent low anterior resection with a distal margin ranging from 1 to 74 mm (mean 18 mm) excluding the anastomotic rings. At a mean follow-up of 49 months, there was no evidence of locoregional recurrence [1] . This paper illustrates several important points: the evolution in the understanding of the biology of distal tumor spread in rectal cancer, the importance of accurate tumor staging, the value of meticulous surgical technique and the deployment of neoadjuvant therapy in appropriately selected patients to optimize outcome. Histopathological studies have demonstrated that intramural submucosal spread, present in 40% of patients, extends more than 10 mm in only 4–6% of patients with rectal cancer [2] . Such reports led to the revision of the traditional 5-cm distal resection margin rule and to the recommendation of a 2-cm distal margin where feasible Published online: June 22, 2010