Virchows Archiv

, Volume 451, Issue 4, pp 757–762

TNM staging of midgut and hindgut (neuro) endocrine tumors: a consensus proposal including a grading system

Authors

    • Department of PathologyUniversity of Parma
    • Dipartimento di Patologia e Medicina di Laboratorio, Sezione di Anatomia PatologicaUniversità di Parma
  • G. Klöppel
    • Department of PathologyUniversity of Kiel
  • A. Couvelard
    • Department of PathologyHôpital Beaujon
  • P. Komminoth
    • Department of PathologyStadspital Triemli
  • M. Körner
    • Department of PathologyUniversity of Bern
  • J. M. Lopes
    • Department of PathologyPorto Medical School & IPATIMUP, University of Porto
  • A.-M. McNicol
    • Department of PathologyGlasgow Royal Infirmary
  • O. Nilsson
    • Department of PathologyGothenborg University
  • A. Perren
    • Department of PathologyKlinikum rechts der Isar
  • A. Scarpa
    • Department of PathologyUniversity of Verona
  • J.-Y. Scoazec
    • Department of PathologyUniversity of Lyon
  • B. Wiedenmann
    • Department of Internal MedicineCampus Virchow Klinikum
Open AccessOriginal Article

DOI: 10.1007/s00428-007-0452-1

Cite this article as:
Rindi, G., Klöppel, G., Couvelard, A. et al. Virchows Arch (2007) 451: 757. doi:10.1007/s00428-007-0452-1

Abstract

Criteria for the staging and grading of neuroendocrine tumors (NETs) of midgut and hindgut origin were established at the second Consensus Conference in Frascati (Rome) organized by the European Neuroendocrine Tumor Society (ENETS). The proposed tumor–node–metastasis (TNM) classifications are based on the recently published ENETS Guidelines for the Diagnosis and Treatment of gastroenteropancreatic NETs and follow our previous proposal for foregut tumors. The new TNM classifications for NETs of the ileum, appendix, colon, and rectum, and the grading system were designed, discussed, and consensually approved by all conference participants. These proposals need to be validated and are meant to help clinicians in the stratification, treatment and follow-up of patients.

Keywords

Neuroendocrine tumorsIleumAppendixColonRectumStagingTNMGradingMitotic indexKi-67 index

List of the participants (front authors excluded) in the “Consensus Conference on the ENETS Guidelines for the Diagnosis and Treatment of Neuroendocrine Gastrointestinal Tumors, Part 2: Midgut and Hindgut Tumors” held in Frascati (Rome, Italy), November 1–4, 2006.

Håkan Ahlman, Institute for Surgical Sciences, Dept. of Surgery, Sahlgrenska sjukhuset, S-41345 Gothenborg (Sweden); Rudolf Arnold, Wittelsbacherstr. 6, 80469 Münich (Germany); Christoph Auernhammer, Medizinische Klinik II, Grosshadern Klinikum der Ludwig-Maximilians-Universität München, Marchioninistr. 15, 81377 Münich (Germany); Martyn Caplin, Royal Free Hospital London, Centre for Gastroenterology, London NW3 2QG (UK); Emanuel Christ, Endokrinologie für Erwachsene, Inselspital, Freiburgstrasse, CH-3010 Bern (Switzerland); Wouter de Herder, Department of Internal Medicine, Section of Endocrinology, Erasmus MC, Dr. Molewaterplein 40, 3015 GD Rotterdam (The Netherlands); Gianfranco Delle Fave, Ospedale S. Andrea, Via di Grottarossa 1035, 00189 Rome (Italy); Barbro Eriksson, Medical Department, Endocrine Unit, University Hospital, S-75185 Uppsala (Sweden); Massimo Falconi, University of Verona, Medicine and Surgery, General Surgery Section, MED/18 - General Surgery, Via dell´Artigliere 8, 37129 Verona, (Italy); Diego Ferone, Departments of Internal Medicine and Endocrinological and Metabolic Sciences, University of Genoa, 16132 Genoa (Italy); Peter Goretzki, Städtisches Klinikum Neuss, Lukas-Krhs., Chirurgische Klinik I, Preussenstr. 84, 41456 Neuss (Germany); David Gross, Dep. of Endocrinology & Metabolism, Hadassah University Hospital, 91120 Jerusalem (Israel); Rudolf Hyrdel, University Hospital Martin, II. Internal med. dept., Kollarova 2 (street), SVK 036 59, Martin, (Slovakia); Robert Jensen, National Institutes of Health, Cell Biology Section, Building 10, Room 9C-193, Bethesda, MD, (USA); Gregory Kaltsas, G. Genimatas Hospital, Mesogion Ave., 10443 Athens (Greece); Fahrettin Keles̥timur, Erciyes University Medical School, Department of Endocrinology and Metabolism, 38039 Kayseri (Turkey); Reza Kianmanesh, UFR Bichat-Beaujon-Louis Mourier, Service de Chirurgie Digestive, Hôpital Louis Mourier, 178 Rue des Renouillers, 92700 Colombes (France); Wolfram Knapp MHH, Klinik für Nuklearmedizin, Carl-Neuberg-Str. 1, 30625 Hannover, (Germany); Ulrich-Peter Knigge, Dept. of Surgery, C 2122, Rigshospitalet Blegdamsuej, DK-2100 Copenhagen (Denmark); Beata Kos-Kudta, Slaska Akademia Medyczna, Klinika Endokrynologii, ul. 3 Maja 13/15, 41-800 Zabrze (Poland); Eric Krenning, Erasmus MC, Dr Molewaterplein 40, 3015G, Rotterdam (The Netherlands); Matthew Kulke, Dana-Farber Cancer Institute, 44 Binney Street, Dana 1220, Boston, MA 02115 (USA); Larry Kvols, H. Lee Moffitt Cancer Center/University of South Florida, Magnolia Drive 12902, Tampa, FL, 33612 (USA); Dik J. Kwekkeboom, Department of Nuclear Medicine, Erasmus University Medical Center, Dr. Molewaterplein 40, 3015 GD Rotterdam (The Netherlands); Riccardo Manfrodi, Istituto di Radiologia, Policlinico GB Rossi, Piazzale LA Scuro, 37134 Verona (Italy); Bruno Niederle, Universität Wien, Abt. Chirurgie, Allgemeines Krankenhaus Wien, Währinger Gürtel 18–20, Ebene 3L, A-1090 Vienna (Austria); George Nikou, 68, Plataion St, 15235 Vrilissia, Athens (Greece); Ola Nilsson, Dept. of Pathology, Sahlgrenska sjukhuset, S-41345 Gothenborg (Sweden); Kjell Öberg, Dept. of Internal Medicine, Endocrine Unit, University Hospital, S-75185 Uppsala (Sweden); Juan O’Connor, Instituto Alexander Fleming, Crámer 1180, C1426ANZ, Buenos Aires (Argentina); Dermot O’Toole, Service de Gastroentérologie, Centre Hospitalier Universitaire d'Angers, 49000 Angers (France); Ulrich-Frank Pape, Charité Universitäts Medizin, Department of Internal Medicine, Division of Hepatology and Gastroenterology, Campus Virchow Klinikum, Augustenburger Platz 1, 13353 Berlin, (Germany); Marianne Pavel, Medizinische Klinik I, Universitätsklinikum Erlangen, Krankenhausstr. 12, 91054 Erlangen (Germany); Ursula Plöckinger, Charité Universitäts Medizin, Campus Virchow-Klinikum, Department of Hepatology and Gastroenterology, Augustenburger Platz 1, 13353 Berlin (Germany); John Ramage, Dept of Gastroenterology, North Hamsphire Hospital, Aldermaston Rd, Basingstoke, RG249NA, Hampshire (UK); Jens Ricke, Otto-von-Guericke-Universität Magdeburg, Klinik für Radiologie und Nuklearmedizin, Leipziger Str. 44, 29120 Magdeburg, (Germany); Philippe Ruszniewski, Service de Gastroentérologie, Hôpital Beaujon, 100, avenue de Général Leclerc, 92118 Clichy (France); Ramon Salazar, Institut Català d´Oncologia, Av. Gran Via s/n, 08907 Barcelona (Spain); Maria Isabel Sevilla Garcia, Hospital Virgen de la Victoria, C/Colonia Santa Ines s/n, 29010 Malaga (Spain); Thomas Steinmüller, Vivantes Humboldt-Klinikum, Chirurgische Klinik, Am Nordgraben 2, 13509 Berlin, (Germany); Anders Sundin, Uppsala University Hospital, Department of Radiology, SE 751–85, Uppsala (Sweden); Babs Taal, Netherlands Cancer Centre, Plesmanlaan 121, 1066 (CX) Amsterdam (The Netherlands); Marie-Pierre Vullierme, Service de Radiologie, Hôpital Beaujon, 100, avenue de Général Leclerc, 92118 Clichy (France); Stefan Wildi, University Hospital of Zürich, Dept. of Visceral and Transplantation Surgery, CH-8091 Zürich (Switzerland); James C. Yao, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030 (USA).

Background

Based on recognized differences in morphology, function and clinical behavior [1, 2, 21, 30], the current WHO classification provides a prognosis-oriented definition of gastroenteropancreatic neuroendocrine tumors (GEP-NETs) [3, 5, 8, 12, 13, 34].

All GEP-NETs probably have a malignant potential, but their biological behavior differs from tumor type to tumor type [9, 10, 1417, 22, 25, 26, 36]. Given their rarity [10, 1417], correct diagnosis and appropriate treatment are often difficult in nonexpert settings and even for appendiceal “carcinoids,” probably the best known GEP-NETs with the most benign behavior [31]. Recent data on ileal, appendiceal, and rectal carcinoids, also indicated several variables influencing survival and prognosis [6, 15, 29, 35].

Guidelines for the management of patients with GEP-NETs were developed by the recently established European Neuroendocrine Tumor Society (ENETS) [23, 37]. In two separate meetings a consensus was sought on these guidelines. The papers deriving from the first conference dedicated to foregut tumors, including a detailed tumor–node–metastasis (TNM)/staging and grading proposals, have been published meanwhile [4, 27]. The “Consensus Conference on the ENETS Guidelines for the Diagnosis and Treatment of Neuroendocrine Gastrointestinal Tumors, Part 2: Midgut and Hindgut Tumors” was held in Frascati (Rome, Italy) from November 1 to 4, 2006. In this paper, we present the TNM staging and grading proposals for pure NETs of the lower jejunum/ileum, appendix, and colon/rectum.

Materials and methods

Fifty-seven experts in the field of GEP-NETs from 18 different countries attended the consensus conference. The attendees represented all medical branches involved in managing patients with GEP-NETs. They formed four working groups according to their specific clinical expertise: (1) pathology and genetics (11 participants, all listed as coauthors), (2) surgery (8 participants), (3) imaging and radiology (7 participants), (4) medicine and clinical pathology (31 participants, including the coauthor B.W.). Most of the participants also attended the first consensus conference held in Frascati in November 2005.

The conference was divided sequentially into five sessions devoted to specific topics on an anatomical basis (ileal well-differentiated NETs; appendiceal well differentiated NETs; colorectal well differentiated NETs; NETs metastatic to the liver; poorly differentiated neuroendocrine carcinomas of midgut and hindgut origin).

A working booklet with the ENETS guidelines text [23] and specific queries had been prepared in advance by the organizing committee. The work was organized as previously detailed [4, 27]. This procedure was followed for all five sessions. The TNM staging proposal was prepared by the pathology and genetics working group and amended and approved by the plenary session of the consensus conference. The grading system was mainly discussed and defined by the pathology and genetics working group.

Results and discussion

The consensus guidelines have been reported elsewhere. The TNM staging proposal for NETs of midgut and hindgut origin together with a grading system is intended to reflect, like its forerunner for the NETs of the stomach, duodenum and pancreas [27], the prognostic assessment by the pathologist. The intestinal NETs were separated into lower jejunum/ileum, appendix, and colon/rectum, but were not distinguished according to specific functional activity, main tumor cell type, or genetic background.

TNM staging proposal

The currently published TNM format was adopted as working template (see Tables 1, 2, 3, 4, 5, and 6) [32].
Table 1

Proposal for a TNM classification for endocrine tumors of lower jejunum and ileum

 

TNM

T-primary tumor

 TX

Primary tumor cannot be assessed

 T0

No evidence of primary tumor

 T1

Tumor invades mucosa or submucosa and size ≤1 cm

 T2

Tumor invades muscularis propria or size >1 cm

 T3

Tumor invades subserosa

 T4

Tumor invades peritoneum/other organs

For any T add (m) for multiple tumors

 N regional lymph nodes

  NX

Regional lymph nodes cannot be assessed

  N0

No regional lymph node metastasis

  N1

Regional lymph node metastasis

  M

Distant metastasis

  MX

Distant metastasis cannot be assessed

  M0

No distant metastases

  M1a

Distant metastasis

aM1 specific sites defined according to Sobin LH, Wittekind C [32].

Table 2

Disease staging for endocrine tumors of lower jejunum and ileum

Stage

 

 

 

Disease stages

T-primary tumor

N-regional nodes

M-distant metastasis

Stage I

T1

N0

M0

Stage IIA

T2

N0

M0

Stage IIB

T3

N0

M0

Stage IIIA

T4

N0

M0

Stage IIIB

Any T

N1

M0

Stage IV

Any T

Any N

M1

Table 3

Proposal for a TNM classification for endocrine tumors of the appendix

TNM

T-primary tumor

 TX

Primary tumor cannot be assessed

 T0

No evidence of primary tumor

 T1

Tumor ≤1 cm invading submucosa and muscularis propria

 T2

Tumor ≤2 cm invading submucosa, muscularis propria and/or minimally (up to 3 mm) invading subserosa/mesoappendix

 T3

Tumor >2 cm and/or extensive (more than 3 mm) invasion of subserosa/mesoappendix

 T4

Tumor invades peritoneum/other organs

N-regional lymph nodes

 NX

Regional lymph nodes cannot be assessed

 N0

No regional lymph node metastasis

 N1

Regional lymph node metastasis

M-distant metastasis

 MX

Distant metastasis cannot be assessed

 M0

No distant metastases

 M1a

Distant metastasis

aM1 specific sites defined according to Sobin LH and Wittekind Ch [32].

Table 4

Disease staging for endocrine tumors of the appendix

Stage

 

 

 

Disease stages

T-primary tumor

N-regional nodes

M-distant metastasis

Stage I

T1

N0

M0

Stage IIA

T2

N0

M0

Stage IIB

T3

N0

M0

Stage IIIA

T4

N0

M0

Stage IIIB

Any T

N1

M0

Stage IV

Any T

Any N

M1

Table 5

Proposal for a TNM classification for endocrine tumors of colon and rectum

 

TNM

T-primary tumor

 TX

Primary tumor cannot be assessed

 T0

No evidence of primary tumor

 T1

Tumor invades mucosa or submucosa

 

T1a size <1 cm

 

T1b size 1–2 cm

 T2

Tumor invades muscularis propria or size >2 cm

 T3

Tumor invades subserosa/pericolic/perirectal fat

 T4

Tumor directly invades other organs/structures and/or perforates visceral peritoneum

For any T add (m) for multiple tumors

N-regional lymph nodes

 NX

Regional lymph node status cannot be assessed

 N0

No regional lymph node metastasis

 N1

Regional lymph node metastasis

M-distant metastases (subspecification as in small bowel)

 MX

Distant metastasis cannot be assessed

 M0

No distant metastases

 M1a

Distant metastasis

aM1 specific sites defined according to Sobin LH and Wittekind Ch [32].

Table 6

Disease staging for endocrine tumors of colon and rectum

Stage

 

 

 

Disease stages

T-primary tumor

N-regional nodes

M-distant metastasis

Stage IA

T1a

N0

M0

Stage IB

T1b

N0

M0

Stage IIA

T2

N0

M0

Stage IIB

T3

N0

M0

Stage IIIA

T4

N0

M0

Stage IIIB

Any T

N1

M0

Stage IV

Any T

Any N

M1

Tumor

There is no proposed definition for in situ endocrine tumor of the jejunum, ileum, appendix, colon and rectum, because no specific precursor lesion has been described in the literature so far. For the lower jejunum and ileum, the size limits indicated for T1 and T2 are those defined for tumors of “benign behavior” and “uncertain behavior,” respectively, according to the WHO site-specific clinicopathological correlations [5, 8, 34]. For the appendix and colon and rectum tumors, lower size limits were defined for T1 and T2 based on current data [6, 15, 29]. For colon and rectum tumors, T1 was divided into T1A and T1B based on current information on the biology of tumors below 1 cm in size and between 1 and 2 cm [6].

Deeply invasive and large tumors are included in the T3 and T4 categories, taking into account site-specific features. For any T definition, the maximum tumor size should be reported and, in the case of multiple lesions, the largest one. The use of T3 category subdivision (pT3a, b, c, and d) according to distance below or higher than 5 mm from muscularis propria as proposed for the adenocarcinoma [33], could be of value. Its application could be implemented once data on endocrine carcinomas will be generated.

Lymph nodes

N1 indicates the presence of any single or multiple metastases in the regional lymph node group, according to TNM rules. A minimum of 12 nodes should be identified in a surgical specimen, assessed and, when possible, named according to their location in relation to tumor. Although regional lymph node metastases are a negative prognostic factor in GEP-NETs [11], the significance of the number of metastatic nodes is not yet known. Therefore, similar to the previous foregut TNM proposal, the N1 status in stage IIIB in Tables 1, 2, 3, 4, 5, and 6 has to be specified with regard to the number of lymph nodes involved to allow validation.

Distant metastasis

M1 indicates the presence of any single or multiple metastases at any distant anatomical site (including nonregional nodes). As extrahepatic bone metastases are a negative prognostic factor [7, 21], it is recommended to specify the anatomical site of the metastasis according to the TNM classification rules (PUL, pulmonary; HEP, hepatic; OSS, osseous; etc.) [32].

Staging

Stage I encompasses the T1 NETs with limited growth. Stage II identifies tumors that are larger in size or more invasive, either T2 or T3, although always in the absence of metastasis. At stage III, the increased malignancy refers either to invasion into surrounding structures (Stage IIIA) or to the presence of regional node metastases (Stage IIIB). Stage IV always implies the presence of distant metastases.

Grading proposal

Grading

Studies on well-differentiated NETs of midgut and hindgut origin have shown the usefulness of a grading system (see Table 7) [6, 35, 36]. Well-differentiated endocrine tumors with proliferative activity greater than 2%, but below that usually found in poorly differentiated endocrine carcinomas, may have a prognosis intermediate between the “2% NETs” and poorly differentiated carcinomas [1820, 23, 24]. We decided to follow the same grading system proposal as that devised for foregut tumors, with the aim of distinguishing G2 from G1 and G3 GEP-NETs. The three tumor categories are defined as follows: G1, <2 mitoses per 2 mm2 (10 high-power fields, HPF, 40× magnification) and/or Ki-67 index ≤2%; G2, 2–20 mitoses per 2 mm2 and/or Ki-67 index between 3% (intended as >2%) and 20%; G3 with 21 or more mitoses per 2 mm2 and Ki-67 index >20%.
Table 7

Grading proposal for (neuro)endocrine tumors of ileum, appendix, colon and rectum

Grade

Mitotic count (10HPF)*

Ki-67 index (%)**

G1

<2

≤2

G2

2–20

3–20

G3

>20

>20

* 10 HPF (High Power Field)=2 mm2, at least 40 fields (at 40× magnification) evaluated in areas of highest mitotic density; ** MIB1 antibody; % of 2000 tumor cells in areas of highest nuclear labeling.

The G1 and G2 well-differentiated NETs usually display diffuse and intense expression of the two general immunohistochemical neuroendocrine markers, chromogranin A and synaptophysin [28]. Punctate necrosis is per se indicative of a more aggressive tumor and points to a G2 or G3 status, which is then determined by the mitotic count and the proliferation fraction. G3 indicates a poorly differentiated neuroendocrine carcinoma with high mitotic counts/Ki-67 index, fields of necrosis, significantly reduced chromogranin A expression and intense staining for synaptophysin, meeting the current WHO histological criteria [5, 8, 34].

Mitotic count and Ki-67 index

As for the foregut proposal, mitoses should be counted on hematoxylin and eosin stained slides in at least 40 HPF when possible. The mitoses should be assessed in areas where they are most frequent after a general slide survey. For Ki-67 assessment, the MIB1 antibody is recommended at the conditions that have been established at the laboratory in question. The Ki-67 index should be assessed in 2,000 tumor cells in areas where the highest nuclear labeling is observed (often but not exclusively at the tumor periphery).

Concluding remarks

The TNM staging system proposed here for midgut and hindgut NETs closely follows its forerunner for foregut tumors [27]. It has the same basis, i.e., the current WHO classifications of GEP-NETs, and results from a consensus conference held by specialists and practicing physicians involved in the management of patients with GEP-NETs. The grading system described here is substantially identical to that proposed for foregut NETs and again attempts to close the gap between the advances of the most recent WHO classifications and the need for a better prognostic assessment of NETs. These proposals, as well as those already published, await confirmation by clinicopathologic work.

Acknowledgements

Source of support: grants from MIUR (COFIN 2005) and the University of Parma to GR. The Consensus Conference Part 2 in Frascati was supported by a generous grant to ENETS from Novartis Oncology.

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© Springer-Verlag 2007