Complete mesocolic excision.

The last 2 issues of Techniques in Coloproctology present 2 examples of the technique referred to as complete mesocolic excision (CME). Shin and colleagues report in the current issue on a series of 168 patients with stages II and III colon carcinoma treated with laparoscopic CME, who achieved a remarkable overall survival of 89.6 % after a median follow-up of almost 5 years [1]. In their recently published experience, Storli and colleagues compared the results of resection for stage I–II colon carcinoma in 1 community hospital in which CME was used with results obtained in 2 control hospitals using standard surgical technique [2]. After a median follow-up of 50.2 months, the use of CME was associated with significantly improved 3-year overall survival and disease-free survival, while the difference in cancer-specific survival was not statistically significant. Both series, in different ways, pose the question of whether the technique of colonic dissection should be revisited to incorporate the principles of CME. The technique has been popularized by Hohenberger and colleagues who described the removal of colon cancer with ligation of vascular pedicles at their origin and preservation of the mesocolic investment of the removed specimen to minimize tumor spread. The principles of CME are intended to replicate in colon carcinoma the principles of total mesorectal excision, which have been associated with significant improvement of oncologic outcomes in rectal cancer and have been replicated in several centers throughout the world. In this respect, it is important to point out that CME requires a substantial technical dexterity when compared with standard technique, especially when using a laparoscopic approach. For example, a right colectomy with CME requires mobilization of the duodenum with the head of the pancreas and the mesenteric root to allow full exposure of the superior mesenteric vessels [3]. Pathological studies on the specimens resulting from such procedures have indicated advantages in surrogate metrics of oncologic benefits, namely preservation of the mesocolic envelope, increased lymph node retrieval and increased size of the removed specimen. However, the extent of the actual oncologic advantages deriving from CME remains unclear. For example, a study specifically assessing the impact of pathology grading of colon cancer surgical resection failed to demonstrate improved overall survival associated with mesocolic plane surgery, except for the subset of patients with stage III disease and did not report on cancer-specific survival [4]. On the other hand, the series, which did report improved cancer-specific outcomes after the introduction of CME when compared with an earlier time period, might not have adequately considered the influence on cancer outcomes of improved pathology staging and unequal use of chemotherapy treatments over time [3]. Storli and colleagues also reported a statistically marginal improvement in cancer-specific survival associated with CME as opposed to other important oncologic end points such as disease-free and overall survival. While lack of statistical power in the assessment of an individual end point is possible, an alternative explanation could be a difference in the comorbidity rate in the two groups, disproportionally accounting for the increased mortality noted in the standard group, as could be suggested by the 8.6 % in—hospital mortality after standard colonic resections compared with 2.9 % in the CME group. In the absence of reported data on comorbidity, this can only remain a L. Stocchi (&) Desk A30, Department of Colorectal Surgery, Digestive Disease Institute, Cleveland Clinic, 9500 Euclid Ave, Cleveland, OH 44195, USA e-mail: stocchl@ccf.org