Aust. N.Z. J. Surg. 1990, 60, 261-265
26 I
CURRENT PERSPECTIVES IN STAGING LARGE BOWEL CANCER P. H. CHAPUS,*R. C. NEWLAND,?0. F. DENT,!: E. L. BOKEY*AND J. M. HINDER" Colorectal Cancer Project, The University of Sydney, Departments of *Colati and Rectal Surgery and fAnatomical Pathology, Concord Hospital, Concord, New South Wales, and $The National Cerzire for Epidemiology and Population Health, Australian National University, Canberra, Australian Capital Territory Today. a standardized method of staging that is internationally accepted is urgently needed for the nianagement of patients with colorectal cancer. The use of a uniform, sensitive staging system would greatly improve case selection and avoid unnecessary bias when entering patients into adjuvant therapy trials. This would allow a more accurate evaluation of new treatment protocols and assist in the development of more effective followup programmes Key words: colorectal cancer, staging system.
Introduction Over the past 60 years, there have been numerous approaches to the staging of large bowel cancer. The aims of this paper are to detail the reasons for staging, to appraise critically the progress which has been made and to offer suggestions regarding the future evolution of staging.
Purpose of staging Anderson has defined stage classification as a 'short description of a carcinoma at a point in its natural history, relevant to the treatment of the patient, to prognosis and to comparison of end results'. The committee on clinical stage classification and applied statistics of the International Union Against Cancer cites five objectives of staging: (i) to aid the clinician in the planning of treatment; (ii) to give some indication of prognosis; (iii) to assist in the evaluation of results of treatment; (iv) to facilitate the exchange of information between treatment centres; and (v) to assist in the continuing investigation of human cancer.'
'
Historical background In 1926, J . P. Lockhart-Mummery developed a simple, clinical ABC staging system based on operative findings, to describe the prognosis of his Correspondence: Dr P. H . Chapuis, University of Sydney, Departincnt of Colon and Rectal Surgery, Clinical Sciences Building. Repatriation General Hospital, Concord, NSW 2139, Australia. Accepted for publication 22 November 1989.
patients with rectal cancer treated by perineal excision.3 Dukes subsequently refined this approach by giving histological definitions to each stage.4.' In 1939, Simpson and Mayo extended this classification to colon cancer' and, although it is widely used in this form, the numerous shbsequent modifications have resulted in confusion.'-" Regrettably, to date there is no universal agreement on staging colorectal cancer (CRC). Most schemes now in use are modifications of the Dukes method which is based exclusively on the extent of tumour spread observed by the pathologist in the resected specimen. A review of the recent literature indicates dissatisfaction with purely pathological staging and a trend towards the inclusion of clinical information, so-called clinicopathological (CP) staging. 14-21 Several groups are now engaged in developing better definitions and using more effective methods of data analysis for determining prognosis and end results. 22-24
Dukes staging system Most cancers of the large bowel are slowly growing tumours which spread in a stepwise fashion through successive layers of the bowel wall. For practical purposes, once the submucosa is invaded, pathways exist for metastatic spread along both venous and lymphatic channels. An additional pathway for spread is created when the mesothelial (peritoneal) surface of the bowel wall is invaded by tumour. This orderly spread was elegantly demonstrated by Dukes by careful dissection of operative specimens and forms the basis of his staging ~ y s t e m Dukes .~ supported his classification by a comprehensive statistical analysis of survival based on 2447 surgical
CHAPUIS ET AL.
262
stage is determined by the clinician, in those operations for rectal cancer performed at St Mark’s patients where, in their judgement, there is tumour Ho~pital.’~ remaining after operation. In this way, patients who Although the Dukes system has provided valuable information on the outcome for patients after are clinically considered or histologically are shown to be incurable are identified and classified resection, it does not recognize those in whom the tumour has been transected or in whom there are separately as a stage D. The concept of C P staging was first introduced known distant metastases at the time of operation. Dukes appreciated this problem and encouraged by Rupert Turnbull at the Cleveland Clinic to describe his results of ‘no-touch’ colectomy for surgeons at St Mark’s Hospital to distinguish becolon cancer.3’ The Turnbull CP stage D referred to tween curative (radical) and palliative operations, patients who were considered either clinically, or at although no attempt was made to place incurable cases into a separate stage. This has always created the time of operation, to have either metastases beyond the field of surgery or advanced local difficulties when evaluating results published from this institution, where the data reported invariably tumour. Thus, stage D tumours in Turnbull’s clashave included those patients considered by the sursification did not necessarily depend on histological geon to have had a radical resection. In effect, confirmation of incurability . therefore, the cases reported strictly reflect a form C P staging at Concord Hospital commenced in of modified Dukes staging. 1971 following a visit to Sydney by Turnbull and In the Dukes system, no specific reference is made data have been collected prospectively since that to either mucosal cancer or cancer in which there is time.32 The system of stages and substages develspread into the submucosa but not beyond. Subseoped at Concord is summarized in Table 1. Stage D quent modifications of Dukes classification have in this system requires either histological demonfurther confused the definition of ‘A’ t u m o u r ~ . ~ ~ .stration ~~ of transection of tumour (substage D,) or Gabriel ef al. divided stage C tumours into two the presence of metastases (demonstrated clinically subcategories according to the level of nodal inor histologically) beyond the limits of surgical revolvement in the main lymphovascular pedicle of Table 1. Concord Hospital CP staging system the resected specimen.2x Modifications by others have redefined stage C according to the depth of Stage Substage Spread penetration of the tumour through the bowel When fundamental differences such as these exist Not beyond mucosa Into subrnucosa hut not beyond between modifications and the original definition Into muscularis propria hut not by Dukes, confusion and difficulties of interpretabeyond tion are inevitable, especially when authors apply a Beyond muscularis propria; free different meaning to the same alphabetical symbols mesothelial surface not invaded; used by Dukes. Statements occurring in the literano lymph node metastases; no ture such as the ‘Gunderson-Sosin variant of the tumour in lines of resection; no Astler Coller modification of the Dukes staging distant metastases method’ illustrate the terminological tangle which As for substage B , hut with free B,S has developed.29 mesothelial surface invasion Metastatic spread to local lymph Despite these problems, the attraction of the C Cl nodes irrespective of depth of Dukes classification is its simplicity and objectivdirect spread of tumour; no ity. Nevertheless, there is a growing awareness that tumour in lines of resection; no any staging method requires continuous review .30 distant metastases There is now a need to develop a system of clasMetastatic spread to an apical sification which incorporates additional critical lymph node, irrespective of information on the extent of both the local and disdepth of direct spread of tumour; tant spread of tumour. However, it must be stressed no tumour in lines of resection; that alternative classifications should not be introno distant metastases Tumour involving a line of duced or accepted simply at the whim of a patholoresection (histological) gist or surgeon. Rather, they must be based on Distant metastases, that is, variables which have proven independent prognosmetastases not removed in tic value and which can be shown in prospective continuity with the bowel studies to have predictive power which is signifiresection specimen (clinical or cantly better than any existing system. histological)
CP staging and the Concord system CP staging of CRC is an improved method of staging. It differs from pathological Staging in that
* Incurablc. Substage A , as defined in this Tdblc is classified as stagc 0 using thc ACPS system.
26 I
CURRENT PERSPECTIVES IN STAGING LARGE BOWEL CANCER P. H. CHAPUS,*R. C. NEWLAND,?0. F. DENT,!: E. L. BOKEY*AND J. M. HINDER" Colorectal Cancer Project, The University of Sydney, Departments of *Colati and Rectal Surgery and fAnatomical Pathology, Concord Hospital, Concord, New South Wales, and $The National Cerzire for Epidemiology and Population Health, Australian National University, Canberra, Australian Capital Territory Today. a standardized method of staging that is internationally accepted is urgently needed for the nianagement of patients with colorectal cancer. The use of a uniform, sensitive staging system would greatly improve case selection and avoid unnecessary bias when entering patients into adjuvant therapy trials. This would allow a more accurate evaluation of new treatment protocols and assist in the development of more effective followup programmes Key words: colorectal cancer, staging system.
Introduction Over the past 60 years, there have been numerous approaches to the staging of large bowel cancer. The aims of this paper are to detail the reasons for staging, to appraise critically the progress which has been made and to offer suggestions regarding the future evolution of staging.
Purpose of staging Anderson has defined stage classification as a 'short description of a carcinoma at a point in its natural history, relevant to the treatment of the patient, to prognosis and to comparison of end results'. The committee on clinical stage classification and applied statistics of the International Union Against Cancer cites five objectives of staging: (i) to aid the clinician in the planning of treatment; (ii) to give some indication of prognosis; (iii) to assist in the evaluation of results of treatment; (iv) to facilitate the exchange of information between treatment centres; and (v) to assist in the continuing investigation of human cancer.'
'
Historical background In 1926, J . P. Lockhart-Mummery developed a simple, clinical ABC staging system based on operative findings, to describe the prognosis of his Correspondence: Dr P. H . Chapuis, University of Sydney, Departincnt of Colon and Rectal Surgery, Clinical Sciences Building. Repatriation General Hospital, Concord, NSW 2139, Australia. Accepted for publication 22 November 1989.
patients with rectal cancer treated by perineal excision.3 Dukes subsequently refined this approach by giving histological definitions to each stage.4.' In 1939, Simpson and Mayo extended this classification to colon cancer' and, although it is widely used in this form, the numerous shbsequent modifications have resulted in confusion.'-" Regrettably, to date there is no universal agreement on staging colorectal cancer (CRC). Most schemes now in use are modifications of the Dukes method which is based exclusively on the extent of tumour spread observed by the pathologist in the resected specimen. A review of the recent literature indicates dissatisfaction with purely pathological staging and a trend towards the inclusion of clinical information, so-called clinicopathological (CP) staging. 14-21 Several groups are now engaged in developing better definitions and using more effective methods of data analysis for determining prognosis and end results. 22-24
Dukes staging system Most cancers of the large bowel are slowly growing tumours which spread in a stepwise fashion through successive layers of the bowel wall. For practical purposes, once the submucosa is invaded, pathways exist for metastatic spread along both venous and lymphatic channels. An additional pathway for spread is created when the mesothelial (peritoneal) surface of the bowel wall is invaded by tumour. This orderly spread was elegantly demonstrated by Dukes by careful dissection of operative specimens and forms the basis of his staging ~ y s t e m Dukes .~ supported his classification by a comprehensive statistical analysis of survival based on 2447 surgical
CHAPUIS ET AL.
262
stage is determined by the clinician, in those operations for rectal cancer performed at St Mark’s patients where, in their judgement, there is tumour Ho~pital.’~ remaining after operation. In this way, patients who Although the Dukes system has provided valuable information on the outcome for patients after are clinically considered or histologically are shown to be incurable are identified and classified resection, it does not recognize those in whom the tumour has been transected or in whom there are separately as a stage D. The concept of C P staging was first introduced known distant metastases at the time of operation. Dukes appreciated this problem and encouraged by Rupert Turnbull at the Cleveland Clinic to describe his results of ‘no-touch’ colectomy for surgeons at St Mark’s Hospital to distinguish becolon cancer.3’ The Turnbull CP stage D referred to tween curative (radical) and palliative operations, patients who were considered either clinically, or at although no attempt was made to place incurable cases into a separate stage. This has always created the time of operation, to have either metastases beyond the field of surgery or advanced local difficulties when evaluating results published from this institution, where the data reported invariably tumour. Thus, stage D tumours in Turnbull’s clashave included those patients considered by the sursification did not necessarily depend on histological geon to have had a radical resection. In effect, confirmation of incurability . therefore, the cases reported strictly reflect a form C P staging at Concord Hospital commenced in of modified Dukes staging. 1971 following a visit to Sydney by Turnbull and In the Dukes system, no specific reference is made data have been collected prospectively since that to either mucosal cancer or cancer in which there is time.32 The system of stages and substages develspread into the submucosa but not beyond. Subseoped at Concord is summarized in Table 1. Stage D quent modifications of Dukes classification have in this system requires either histological demonfurther confused the definition of ‘A’ t u m o u r ~ . ~ ~ .stration ~~ of transection of tumour (substage D,) or Gabriel ef al. divided stage C tumours into two the presence of metastases (demonstrated clinically subcategories according to the level of nodal inor histologically) beyond the limits of surgical revolvement in the main lymphovascular pedicle of Table 1. Concord Hospital CP staging system the resected specimen.2x Modifications by others have redefined stage C according to the depth of Stage Substage Spread penetration of the tumour through the bowel When fundamental differences such as these exist Not beyond mucosa Into subrnucosa hut not beyond between modifications and the original definition Into muscularis propria hut not by Dukes, confusion and difficulties of interpretabeyond tion are inevitable, especially when authors apply a Beyond muscularis propria; free different meaning to the same alphabetical symbols mesothelial surface not invaded; used by Dukes. Statements occurring in the literano lymph node metastases; no ture such as the ‘Gunderson-Sosin variant of the tumour in lines of resection; no Astler Coller modification of the Dukes staging distant metastases method’ illustrate the terminological tangle which As for substage B , hut with free B,S has developed.29 mesothelial surface invasion Metastatic spread to local lymph Despite these problems, the attraction of the C Cl nodes irrespective of depth of Dukes classification is its simplicity and objectivdirect spread of tumour; no ity. Nevertheless, there is a growing awareness that tumour in lines of resection; no any staging method requires continuous review .30 distant metastases There is now a need to develop a system of clasMetastatic spread to an apical sification which incorporates additional critical lymph node, irrespective of information on the extent of both the local and disdepth of direct spread of tumour; tant spread of tumour. However, it must be stressed no tumour in lines of resection; that alternative classifications should not be introno distant metastases Tumour involving a line of duced or accepted simply at the whim of a patholoresection (histological) gist or surgeon. Rather, they must be based on Distant metastases, that is, variables which have proven independent prognosmetastases not removed in tic value and which can be shown in prospective continuity with the bowel studies to have predictive power which is signifiresection specimen (clinical or cantly better than any existing system. histological)
CP staging and the Concord system CP staging of CRC is an improved method of staging. It differs from pathological Staging in that
* Incurablc. Substage A , as defined in this Tdblc is classified as stagc 0 using thc ACPS system.
