Validation of the new AJCC TNM staging system for gastric cancer in a large cohort of patients (n = 2,155): Focus on the T category

https://doi.org/10.1016/j.ejso.2011.06.001Get rights and content

Abstract

Background

The prognostic value of T subclassification in patients with gastric carcinoma has been just implemented in the new AJCC TNM staging system, which has reclassified T2a and T2b into T2 and T3 tumors, respectively. The aim of the present study was to validate the prognostic significance of the new T categorization within the frame of the latest TNM staging system.

Methods

We retrospectively reviewed the records of 686 T2/T3 patients among 2155 subjects who underwent radical resection for gastric carcinoma at six Italian centers from 1988 through 2006.

Results

Upon multivariate analysis, the new T categories, extent of lymph node dissection (D) and patient’s age were retained by the survival model as independent prognostic factors. In particular, the death risk for patients with T3 tumors was higher than that of patients with T2 tumors (HR: 1.42, P = 0.005).

Among the 686 patients previously classified as having T2 tumors, patients with T2 and T3 disease were 270 (39.4%) and 416 (60.6%), respectively. After a median follow-up of 55 months, the 5-year overall survival rates were 67.3% and 52.3% for patients with T2 and T3 tumors, respectively (P < 0.001). The survival advantage for the T2 as compared to T3 category was maintained even when N0 and N+ patients were separately considered (P = 0.0154 and P < 0.001, respectively).

Conclusions

Our data confirm the prognostic difference between the newly proposed T2 and T3 categories, which should be implemented in the routine clinical practice to improve risk stratification of patients with gastric cancer.

Introduction

The prognosis of resectable gastric cancer is mainly related to the depth of invasion (T category) and lymph node involvement (N category).1, 2, 3, 4 Following the International Union Against Cancer–American Joint Committee on Cancer (UICC-AJCC) TNM classification released in 2002,5 the T2 category – which is defined as a tumor involving the muscularis propria or subserosa5, 6 – is considered advanced disease but represents a stage with an intermediate prognosis between early gastric cancer (EGC, T1) and serosal involvement gastric carcinoma (T3). Whereas the survival rates of EGC are high (independently of the lymph node status)7, 8, 9 and those of T3 are low,1, 2, 10 the survival rate of T2 gastric cancer varies significantly in relation to other prognostic parameters (i.e. nodal metastasis).11, 12, 13, 14, 15, 16 Since 1998, the College of American Pathologists suggested that a subclassification of T2 into T2a (tumor with invasion of muscolaris propria) and T2b (tumor with invasion of subserosa) should be recommended because “postsurgical survival after resection for cure is significantly different for patients with T2a and T2b lesions”.17

The prognostic role of T2 subclassification is supported by several lines of evidence. In particular, this T category has been associated with variable nodal involvement rates, N-ratio values as well recurrence and mortality rates. It is unclear whether these findings depend upon the extent of lymphadenectomy.11, 12, 18, 19 In a recently published study performed on 189 patients curatively resected with extended lymphadenectomy, we confirmed that patients with T2a tumors have a significantly better 5-year overall survival as compared to those with T2b neoplasms, with T2 subcategorization being an independent prognostic value at multivariate analysis.20

Although the 2002 UICC-AJCC classification split the T2 category into T2a and T2b, these subcategories were not maintained in the TNM stage grouping.5 In the light of the above mentioned evidence regarding the prognostic value of T2 subcategorization, this gap of the 2002 TNM version will be filled by the 2010 TNM release. In particular, the new version redefines the T category as follows: T1a = mucosa, T1b = submucosa, T2 = muscolaris propria, T3 = subserosa (formerly known as T2b), T4a = perforates the serosa (formerly known as T3), T4b = infiltration of adjacent structures (formerly known as T4).21

In the present multicentric study we confirm that the subdivision of the T2 category (T2 and T3 in the new TNM classification) has a significant prognostic value independently of lymph node status in patients with gastric cancer.

Section snippets

Patients selection and data collection

In this retrospective multicentric study, data were collected from the medical records of 2155 patients who underwent radical resection (R0) for histologically confirmed T1-T4a gastric carcinoma from January 1988 through December 2006. Patients were operated at six Italian centers experienced in gastric cancer treatment: Clinica Chirurgica Generale 2, University of Padova (n = 352); First Division of General Surgery, University of Verona (n = 387), Institute of Surgical Sciences, University of

Patients and tumor characteristics

Clinical and pathological data of 686 patients classified T2/T3 are shown in Table 1.

The male-to-female ratio was approximately 3:2, with a median (range) age of 69 (27–94) years. In 39% of patients the tumor was limited to the muscolaris propria (T2), while in the remaining 61% of cases the tumor involved the subserosa (T3). A D2 or more extended lymphadenectomy was performed in 86% of patients, while a D1 lymphadenectomy was performed in 14% of patients.

The distribution of T2 and T3 was

Discussion

In this retrospective study, which involved six Italian centers experienced in gastric cancer surgery, we investigated the prognostic impact of the new T categories recently implemented in the latest version of the AJCC TNM classification,21 with special attention to the T2 and T3 (formerly T2a and T2b) subcategories, in patients who underwent radical resection for gastric carcinoma. Univariate analysis demonstrated that the 5-years OS rate of patients with T2 tumors was significantly higher

Acknowledgments

This study was supported by the Italian Veneto Region Associazione Italiana Ricerca sul Cancro (AIRC) grant 2009.

All Authors had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

References (25)

  • P. Hohenberger et al.

    Gastric cancer

    Lancet

    (2003)
  • K. Soga et al.

    Prognostic impact of the width of subserosal invasion in gastric cancer invading the subserosal layer

    Surgery

    (2010)
  • G. Fotia et al.

    Factors influencing outcome in gastric cancer involving muscolaris and subserosal layer

    Eur J Surg Oncol

    (2004)
  • B.J. Dicken et al.

    Gastric adenocarcinoma: review and considerations for future directions

    Ann Surg

    (2005)
  • M.W. Kattan et al.

    Postoperative nomogram for disease-specific survival after an R0 resection for gastric carcinoma

    J Clin Oncol

    (2003)
  • F.L. Greene et al.

    AJCC cancer staging manual

    (2002)
  • Japanese classification of gastric carcinoma. 2nd English ed

    Gastric Cancer

    (1998)
  • S. Nomura et al.

    Surgical treatment of early gastric cancer

    Dig Surg

    (2007)
  • F. Roviello et al.

    Number of lymph node metastases and its prognostic significance in early gastric cancer: a multicenter Italian study

    J Surg Oncol

    (2006)
  • T. Gotoda et al.

    Incidence of lymph node metastasis from early gastric cancer: estimation with a large number of cases at two larger centers

    Gastric Cancer.

    (2000)
  • H. Baba et al.

    Width of serosal invasion and prognosis in advanced human gastric cancer with special reference to the mode of tumor invasion

    Cancer

    (1989)
  • A.I. Sarela et al.

    Accurate lymph node staging is of greater prognostic importance than subclassification of the T2 category for gastric adenocarcinoma

    Ann Surg Oncol

    (2003)
  • Cited by (0)

    h

    On behalf of the Italian Research Group for Gastric Cancer (G.I.R.C.G.).

    View full text