Colonic surgery for cancer: a new paradigm

Over the last two decades or so, the world of coloproctology has had cause to celebrate significant advances in the treatment of rectal cancer including total mesorectal excision (TME), trans-anal endoscopic microsurgery, Submucosal resection, the reincarnation of Miles’ original approach for abdomino-perineal resection first described a century ago and adjuvant chemo-radiotherapy to name but a few examples. One of the most important, was TME popularized by Heald in the 1980s [1]. Heald emphasized several points the most important being the concept of dissection in the anatomical ⁄ surgical planes created during embryological development. This approach has been associated with low rates of local recurrence which is the end point for a loco-regional treatment such as surgery. TME is also relevant to the pathologist. Quirke in his classical study [2]) has shown that local recurrence is related to the state of the circumferential resection margin when examined in the resected specimen. Both surgical and histopatological approaches compliment each other since they are both reflections of the same pathological feature which is essentially the degree of surgical clearance. This is one of the triumphs of the multidisciplinary approach to a given scientific problem. While these advances were being made in rectal cancer,, surgery for colonic cancer has been left almost untouched. In this issue we publish the results of a large study by Hohenberger et al. from Erlangen, Germany, in which the same principle of TME in rectal cancer has been applied to the colon [3]. They call the technique complete mesocolic excision (CME). This important study has to be read in conjunction with two other papers to complete the triad of observation, application and verification. The first of these is from Bokey and colleagues of the Concord Hospital, Sydney, Australia [4] who were the first to publish data on the surgical planes and clinical outcome of surgery for colon cancer with a clear description of the embryology of the large intestine. The authors reported 867 patients with colonic cancer treated with curative intent with no neo-adjuvant chemotherapy followed for a median of 49 months. They divided the observation period into two time periods;1971–1979 in which general surgeons carried out surgery on colon cancer with no unified or standardized technique and 1980–1995 during which the surgical technique was standardized to respect the ‘embryological ⁄ surgical planes’. The embryological development of the colonic ‘fusion’ fascia easily recognized retroperitoneally was regarded as analogous to the fascia propria of the rectum. The principle of their surgical technique involved removal of the colonic tumour and its lymphovascular drainage with the layer of the fusion fascia intact. The technique was based on ‘precise dissection along anatomic planes facilitating an operation that will not compromise or breach the facial envelope of the colon and its mesentery’ These surgical ⁄ embryological planes varied slightly when doing a left or right hemicoloectomy or a sigmoid colectomy. The pathologist described the circumferential resection margins as either involved or not involved. They found that the outcome of colonic cancer surgery was directly related to the completeness of excision and the absence of peritoneal involvement They found that the overall 5 years survival rose by 15% from 48.1% in the first era to 63.7 after the introduction of the standardized technique. The second relevant and important recently published study is that by West et al. from Leeds, UK [5]. This was the first attempt to relate pathological features of mesocolic (MC) excision to outcome adopting the quality of colon surgery from the Medical Research Council Conventional Versus Laproscopic Assisted Surgery in patients with Colorectal Cancer (CLASICC) study [6] and the pathological grading from the CR07 trial [7]. It was a retrospective observational study of 399 cases of colonic cancer in which the photographs of anterior and posterior views of the specimen were analysed with special reference to grade of MC excision and the results were compared with outcome. The authors divided their cases into three groups or grades according to the surgical plane of dissection (MP, IMC and MC). The muscularis propria (MP) grade in which the surgical plane was regarded as poor and the specimen showed little amount of mesocolon with disruption extending down to the MP. The second grade was the intermesocolic (IMC) plane in which the surgical plane was regarded as moderate and the specimen showed moderate amount of mesocolon with some irregularity but without exposure of the MP. The third grade was the MC plane in which the plane of surgery was regarded as good and the mesocolon was smooth with intact peritoneum. One of the strong points of the study was the photographic documentation of the specimens, which