Japanese Journal of Clinical Oncology 30:463-00 (2000)
© 2000 Foundation for Promotion of Cancer Research
Letters to the Editor |
The Management of Patients with Gastric Cancer: Can West Meet East?
To the Editor:
Recent reviews of gastric cancer still point out the great disparity between the stage specific survival of patients with gastric cancer in Japan compared with that observed in the West (1). Whereas in Japan early gastric cancer is common and considered a curable disease, in the West the diagnosis of early gastric cancer is a rarity. The disease is still considered by patients and clinicians alike to have a poor prognosis. It is against this background that I became the eighth British surgeon to visit the Gastric Surgery Division of the National Cancer Center Hospital in Tokyo as a visiting fellow of the Foundation for Promotion of Cancer Research, in order to observe the differences in practice in Japan. There have been many proposals put forward by Western surgeons to explain the differences in survival of patients with gastric cancer in Japan. These have been summarized as due to different diseases, different staging systems and different treatments.
There is little evidence that what was proposed initially, that the tumours in Japan were less aggressive than those in Western patients, is true. Studies comparing genetic markers between comparable lesions in Japanese and Western patients have shown no convincing genetic difference. It is apparent, however, that in the West there has recently been a great increase in the number of cases of adenocarcinoma of the cardia and lower oesophagus rising in incidence in Europe and the USA at an alarming rate (2). It is surprising that this particular pattern has not been seen in Japan (3).
The staging systems of gastric cancer have always been different between Japan and the West, but some effort has been made to align the two in the recent revisions and with the publication of the Japanese classification in English (4). The differences stem from the belief in the West that the topographical node staging is too labour intensive and of no apparent benefit to the patient. The advantage of the Japanese classification is that it allows the topographical site of lymph nodes to be taken into account and is therefore an aid to the extent of surgical resection. The new TNM staging system relies on the identification of 15 individual lymph nodes, which are analysed by the pathologist, with the number of nodes with metastatic deposits defining the stage (5). This system when analysed using Japanese data gives a fairly accurate prediction for prognosis, but it relies on the dissection of at least 15 nodes. It is possible, therefore, that a large number of patients in Western series may be unclassifiable since the majority will not have undergone the necessary extent of dissection and analysis of lymph nodes. In most Western practices, it is left to the pathologists to dissect and subsequently analyse and stage a specimen and the new TNM system does provide a way of reducing the variability of pathological examination. This is in contrast to the system common in Japan where accurate dissection of the specimen is carried out by a member of the surgical team. This allows a higher lymph node yield and greater accuracy as a result of (i) a better knowledge of the predominant anatomical location of lymph nodes, (ii) more experience and dedication to the task of lymph node retrieval and (iii) immediate post-operative processing of the fresh specimens when the differences in the consistency between lymph and adipose tissue is most obvious. Despite this, it is a relatively new concept for British surgeons and I at first found the technique difficult. It has become established in Japanese surgical training and residents with practice become very adept. It is very difficult to persuade pathologists in the West of the necessity for analysing the lymph node stations separately and therefore if this is to be in common use in the West then surgeons will need to become familiar with this technique. Much has been reported about the stage migration effect, proposed as some explanation of the different stage stratified survival in Japan compared with the West. This results from the greater extent of lymph node dissection and pathological analysis in the Japanese patients which results in the assignation of a patient to a more advanced stage. This certainly is a phenomenon and perhaps explains why patients with reported stage I disease in one study from the USA had a 5-year survival of only 50% (6), some of these patients probably having undetected nodal disease. The effect of stage migration in effect is failure of the system in the West to stage patients correctly whereas the discipline established in Japan of radical node dissection and pathological analysis results in superior data and more realistic staging for each individual patient.
Apart from the differences above, the major impact to explain the differences in Japanese and Western outcomes for gastric cancer results from the management in terms of diagnosis, pre-operative staging and treatment. It is to this that centres such as the National Cancer Center Hospital in Tokyo, which represents the very best in oncological practice across the board, attract so many overseas visitors. One of the most informative parts of my stay at the National Cancer Center was the pre-operative conference which was attended by staff members in radiology, endoscopy and surgery. One of the greatest differences is the ability to stage a patient accurately from the endoscopic investigation alone. This has the great advantage of allowing the planning of the most effective treatment, based on the likelihood of the presence of lymph node metastases. Using techniques of indigocarmine spray and differing volumes of air insufflation, with experience it has been shown to be possible to determine accurately the size of the tumour and surface characteristics and estimate the depth of tumour invasion. It can then be decided whether the patient is suitable for local endoscopic mucosal resection or gastrectomy with lymph node dissection. In the West the pre-operative staging has not reached this level of accuracy and the emphasis has been on the identification of those patients deemed not suitable for surgical resection with locally advanced or metastatic disease. With a high mortality and morbidity reported following gastric surgery in patients who are elderly with significant medical problems, unnecessary laparotomy is to be avoided. There has therefore been developed in most Western practices rigorous pre-operative work-up for the patients including staging laparoscopy, with newer techniques of laparoscopic ultrasound, endoscopic ultrasound, spiral CT and MRI being increasingly available. Routine surgery may also require the availability of either ITU or HDU bed before extensive surgery is undertaken.
The differences in the radicality of surgery between Japanese surgeons and those in the West has been the subject of multiple trials (7,8). In general, Japanese surgeons believe that lymph nodes are the governors of metastatic disease and that for surgical curative resection, radical gastrectomy with prophylactic regional lymph node dissection is necessary. In the West, however, the traditional view has been that lymph nodes are merely the indicators of metastatic disease and that their involvement signifies widespread systemic disease and poor prognosis. The results of the two randomized trials were disappointing in terms of the high mortality and morbidity associated with the more radical resection and the lack of any detected difference in the 5-year survival. Despite this, however, there is still great debate and what these trials have shown are the difficulties in both the instruction of the methodology of the technique and the design of trials. There are specialist centres in the West which have over a period of time produced survival results which almost match those attained in Japan. For those who have witnessed the Japanese surgeons performing a standard D2 or radical D3 resection, it seems unfeasible to be able merely to copy the technique after video instruction. This is the method used in one particular trial (8). As one of my predecessors effectively demonstrated on his return to the UK, there must be a learning curve of approximately 15–25 cases in order to produce a consistent high standard with low morbidity and mortality (9). It is particularly noteworthy that residents during their rotation performed approximately 20–30 procedures during their training assisted by an experienced staff surgeon. The high mortality and morbidity highlighted in the trials may be due to the relative lack of prior instruction and experience with both the technical aspects of the extent of surgery and the management of post-operative complications. I was impressed to witness by Japanese surgeons a uniform surgical technique with little variation and consistent results from all four staff surgeons and residents. This paid enormous attention to the precise anatomy and meticulous bloodless dissection in carefully defined planes. The variability of individual surgeons in the West has been previously described in relation to gastrectomy (10) and also in the contamination and non-compliance in relation to lymph node dissection (11). This strongly puts the case for the establishment of greater specialization with the treatment in the hands of suitably dedicated centres. With this, the results from centres in the West may in the future improve. Consideration also needs to be made towards the great increase in the proximal tumours located at the gastro-oesophageal junction, that have become so familiar in the West. For the moment there is still much we can gain from the last few decades of considerable Japanese experience.
I would like to thank the Foundation for Promotion of Cancer Research and the British Council for their generous support during my stay and also to the staff surgeons in the gastric surgery division for their patience in allowing me to study their practice and ask many questions.
Peter A. Davis
Department of Surgery, Imperial College School of Medicine, St. Mary’s Hospital, London, UK
REFERENCES
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8 Cuschieri A, Weeden S, Fielding J, Bancewicz J, Craven J, Joypaul V, et al. Patient survival after D1 and D2 resections for gastric cancer: long-term results of the MRC randomized surgical trial. Surgical Co-operative Group. Br J Cancer 1999;79:1522–30.[Web of Science][Medline]
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