1. ¹1st Division of General Surgery, University of Verona, Verona, Italy
2. ²Unit of Epidemiology and Medical Statistics, University of Verona, Verona, Italy
3. ³Division of Surgical Oncology, University of Siena, Siena, Italy
4. ⁴Division of Surgery, Forl ì Hospital, Forl ì, Italy
5. ⁵Division of Pathology, Forl ì Hospital, Forl ì, Italy
6. ⁶Division of Surgery, University of Milan, Milan, Italy
7. ⁷Chair of Medical Oncology, University of Verona, Verona, Italy for the Italian Research Group for Gastric Cancer (IRGGC)

Correspondence: G de Manzoni, 1st Department of General Surgery, Borgo Trento Hospital, 37126 Verona, Italy; E-mail: Nadaffona@interfree.it; or E-mail: chirurgia.urgenza@univr.it

Received 8 February 2002; Revised 29 April 2002; Accepted 8 May 2002.

Abstract

The present study aimed at investigating whether in gastric cancer patients stage migration occurs with extension of lymphadenectomy, when node metastases are staged according to the new pN classification (UICC 1997). The investigation involved 921 patients, who underwent R0 gastric resection for gastric cancer between 1988 and 1998 in three different Italian centres: Verona (n=236), Forlì (n=409), Siena (n=276). The relation among lymphadenectomy and pN category was assessed by Kendall's partial rank-order correlation coefficient, controlling for depth of tumour invasion. A direct evaluation of the Will Rogers phenomenon was accomplished in the Verona series, by comparing the number of positive nodes actually observed with the number of positive nodes which would have been retrieved by a less extended lymphadenectomy (D1). The number of positive nodes increased remarkably with the enlargement of lymphadenectomy, especially in pT2 patients (from 2.23.9 in D1 to 3.95.0 in D3) and in pT3/pT4 patients (from 5.15.9 in D1 to 11.312.6 in D3). Non-parametric statistics highlighted a weak (Kendall's partial T=0.128) but significant (P<0.001) correlation between pN category and extension of lymphadenectomy. In the direct analysis of the Verona series, 22 patients out of 230 (9.6%) migrated to a lower pN tier when ignoring positive nodes retrieved from the second and third level. This percentage increased to 39.1% (90 out of 230) when adopting the TNM 87 classification. In conclusion stage migration is of minor importance in gastric cancer patients, staged according to the new pN classification.