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The Pelican Centre Foundation, North Hampshire Hospital, The Ark, Aldermaston Road, Basingstoke, Hampshire RG24 9NA, UK
Total mesorectal excision (TME) is now widely accepted as the gold standard operation for rectal cancer surgery and its implementation is stimulating the development of an exciting new chapter in surgical education [1–4]. It is also key to the important rise of MRI as an imaging modality in pelvic tumour management.
TME is a system of rectal cancer management that defines the block of tissue to be excised and describes the surgical detail of how this is to be achieved [5, 6]. It is now more readily comprehended by non-surgeons because of the development by specialist MRI radiologists of images that are far superior to anything previously achievable [7]. The fine slice high resolution methods are demonstrably superior to any X-ray based modality, which inevitably suffers limitations in differentiating tumour tissue from muscle wall. MRI demonstrates, for the first time, the contours of the mesorectum and the distribution of the cancer within it. Such imaging will in the future provide a rational basis for selecting those cases for radiotherapy or chemotherapy where the mesorectal margin is in danger of being breached during surgery. It can also provide a "workshop guide" for the detailed surgery, whether this be performed laparoscopically or open. This may become a crucial "route map" as laparoscopic surgeons increasingly extend their dissection into the challenging depths of the true pelvis where the inability to feel the cancer can be a serious disadvantage.
The value of a "concept operation" like TME depends ultimately on how effectively it can be taught. The principal practical weapon in teaching the actual surgery has become the video camera and the measurement of progress is the meta-analysis of results from whole populations. Many years ago the distinguished American Professor Bill Silen made the following prescient observation in the Lancet [8]:
"The likelihood that a proper prospective randomized controlled trial (PRCT) will ever be carried out to see whether TME provides an advantage over conventional surgery for rectal cancer is essentially nil. Possibly meta-analysis will help...In my view it is unconscionable to dismiss comparisons with retrospective controls when the procedure is SO superior in terms of both Local Recurrence and Survival."
The impossibility of applying prospective randomized trial techniques to the detail of technical surgery has been a major impediment to its establishment as the new gold standard. No PRCT has ever been successfully mounted to underpin a complex advance in surgical technique. Furthermore, significant confusion stems from the development of alternative basic technologies such as laparoscopic surgery. These are to some extent amenable to PRCT methods, and trials are continuing, but it is likely that the inherent difficulties of applying PRCT methods to surgical techniques will make every trial suspect in one way or another. It is impossible to compare optimal open with optimal laparoscopic cancer surgery because so few surgeons are optimal at both, whilst different surgeons on the two sides of a trial invalidate that trial completely. It is important to understand that TME is an oncological principle that is theoretically achievable by either open or laparoscopic methods; these trials will add nothing to the most crucial surgical controversy – the detail of the excision of the tumour. As with so many cancers the greatest current challenge lies with imaging technology and its application in the planning of treatment.
Conceptually TME has a basis in scientific thought, which is attractive to all members of the multidisciplinary team with background training in basic science. The theory behind it is that cancer spread will tend, initially at least, to remain within the embryological hindgut "envelope". The gut, after all, spent its early fetal existence actually outside the abdomen. When secondly it became "plastered" back onto the retroperitoneal structures and into the developing pelvis it retained its midline lymphovascular integrity and remained separate from the surrounding paired organs and parietes. Its adherence to them is by a collagenous cobweb of areolar tissue which is recognizable by the surgeon as a "surgical plane" and is almost entirely avascular. In a number of publications, the author has drawn attention to this "holy plane of rectal surgery" and attempted to point out the value of painstakingly following this particular perimesorectal avascular plane around the midline hindgut into the depth of the pelvis as a practical surgical policy which could be shown to improve local recurrence rates [1–4, 9]. Straying into the field of cancer spread within was, and still is in conventional practice, an extremely common cause of involved surgical margins and residual pelvic disease: straying out can damage the autonomic nerve layers and is a common cause of impotence. Some workers in the past postulated a physical barrier to the spread of cancer at this interface: it seems intrinsically more probable, in the light of Judah Folkman's work, that tumour angiogenesis is impeded by the avascular interface [10]. The great step forward of the new millennium is the establishment by Brown [7] that specialized fine slice high resolution MRI can also visualize this holy plane and thus predict the detail of the oncological specimen that the surgeon endeavours to remove and its probable contours around the tentacles of tumour.
The TME concept can now be extended to embrace a multi disciplinary six stage process:
TME for the surgeon comprises six basic principles:
Total mesorectal excision and precise perimesorectal plane dissection are being introduced in all the major countries of Europe. Increasingly the specimen is being audited by the detailed histopathology of Quirke and Dixon [12]. The most significant new evidence regarding results and the effects of treatment comes from a joint publication from the Stockholm Colorectal Cancer Group and the Pelican group in Basingstoke. In The Lancet in July 2000 [4] the first published report appeared, showing a major impact of a teaching programme on cancer outcomes in a whole population. This project was supported throughout by Tyco Healthcare. Both the permanent colostomy rate and the local recurrence rate have been more than halved for the entire population of Stockholm County [4]. The 5 year follow up on the series will be published shortly and analysis will be presented. The most assiduous attendees at the 11 Stockholm workshops are now performing half of all the rectal cancer surgery in Stockholm – all with local recurrence rates below 5% in "curative" cases. A major publication has also been presented from Norway [13] where a somewhat similar teaching programme was introduced, and a Danish study is also completed. Individual surgeon's series such as those already published in the USA by Enker [14] and in New Zealand by Hill [15] show strikingly similar results to those in Basingstoke. Hill called what is essentially an identical technique "extra fascial excision" and he also published similar results on all outcome parameters. Certainly the initial widespread dismissal of the early Basingstoke results with single figure local recurrence rates as "inconceivable" are now set aside by others who are achieving exactly the same results. In all the individual surgeon series from established specialists there is a significant improvement on the multi-surgeon series, as would be anticipated for a technique that remains technically demanding and challenging, whether performed through an abdominal incision or by laparoscopic techniques.
At the beginning of 2005 there is only a modest number of surgeons in the world who will attempt the TME operation laparoscopically – especially on patients with cancer below around 6 cm from the anal verge. In Germany for example, where a great deal of laparoscopic bowel surgery is regularly undertaken, the true rectum below 12 cm from the anal verge is regarded as a "no go" area by most surgeons.
With a combination of this unique series of TME workshops and training and a steady trend towards specialization what was once the most common mode of death from rectal cancer – locally recurrent malignancy – has become a relative rarity in the best centres. The further contribution of radiotherapy (RT), which does reduce local recurrence to near zero, has to be balanced against undoubted impairment of bowel function when it is combined with low and ultra low anastomosis. In this regard the absence of any demonstrable benefit of RT in survival terms in the Dutch Trial must be borne in mind. There is a real possibility that patients with cancers around 4–5 cm will soon be faced with a need to choose, on the basis of MRI staging and the advice of their doctors, between retaining their anal sphincter function and the marginal benefits of radiation in their particular case.
It is now generally accepted in Europe and in many parts of the world that more precise surgery directed toward total mesorectal excision is the principal determinant of outcome and the principal hope for improvement. The author has undertaken over 350 television workshop demonstration operations in more than 25 countries. TME has become the national standard in Norway, Sweden, Denmark and the Netherlands. In the larger countries – Germany, France and the UK – official guidelines support the TME concept. In Germany major studies are ongoing to introduce it and even embrace the specialization and audit routines necessary to eliminate the surgeon variability that Hermanek et al [16] so ably demonstrated.
Another key step is audit, which equates with gold standard histopathology. Championed by Quirke [12], the importance of CMI in the management of rectal cancer is that it provides a key quality check for the technique of the surgery. It is axiomatic that the margins of any surgical cancer specimen must be clear of cancer: low CMI rates reflect "better" surgery and are an end in themselves: if TME surgeons deliver lower CMI rates then this is a self evident benefit. Modern MRI provides the basis for a whole new discipline in prediction of the relationship of the outer tentacles of cancer to the mesorectal fascia and thus to the risk of an involved margin. Furthermore those where the mesorectal fascia appears "threatened" may prove to be those that require long course pre-operative chemotherapy and radiotherapy. This certainly provides a rational basis for selection of those patients most likely to benefit from therapy which is certainly not without side effects.
A further "first" in the TME story has been the backing by the National Cancer Director of a series of TME workshops for all specialist colorectal surgeons in England. The workshops are modelled on those undertaken by the Pelican team in Sweden and Norway. Professor Michael Richards' plan was to repeat this Nordic crusade back home in England and to combine it with the development of multidisciplinary team working – a major philosophical change in all cancer care policy for the new millennium. The government has thus engaged the Pelican centre in Basingstoke to convene monthly seminars for cancer teams from all over England. On the one hand the TME surgical concept is shared via live video links with the visiting surgeons: on the other hand the teams are drawn together by the interlinking impact of MRI staging and selection for chemotherapy and radiotherapy when combined with optimal surgical technique. All of these are being re-appraised in the light of histopathological audit, which completes the coherent "team" concept. Throughout these the 3 year British programme encompasses 190 English MDTs, of which the initial workshops have already been completed for 75 and a further 65 have registered voluntarily for future months in 2005–2006. This probably represents the first attempt to introduce a new standard surgical technique across the whole country with the support of all the professional groups involved in cancer care. Specialization in deep pelvic surgery and the recognition that two consultants operating together is sometimes a good investment of specialist time are key steps forward. Selection of the low or ultralow anterior cancer in a technically difficult male patient for referral to such a team is a further logical step.
In this most challenging malignancy selective use of neo adjuvant treatments based on MRI, combined with improvements in surgery, mean that complete elimination of local residual or recurrent disease is now a real possibility. This promises a substantial knock on survival advantage and a real reduction in human suffering. Furthermore advanced video and imaging technology have been factors, and the Basingstoke unit has received unstinting support over the years from Sony Broadcast. Sony is now on the verge of introducing high definition television and thus further enhancing the dissemination of surgical skills. These were once a matter of one to one apprenticeship but are now increasingly a technology dependant discipline with enormous potential for benefit to patients in the future. MRI selection will be crucial in making costly adjuvant therapies affordable for healthcare providers in an increasingly expensive future.
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