Multicenter validation of a gene expression-based prognostic signature in lymph node-negative primary breast cancer.
OBJECTIVE
We previously identified in a single-center study a 76-gene prognostic signature for lymph node-negative (LNN) breast cancer patients. The aim of this study was to validate this gene signature in an independent more diverse population of LNN patients from multiple institutions.


METHODS
Using custom-designed DNA chips we analyzed the expression of the 76 genes in RNA of frozen tumor samples from 180 LNN patients who did not receive adjuvant systemic treatment.


RESULTS
In this independent validation, the 76-gene signature was highly informative in identifying patients with distant metastasis within 5 years (hazard ratio, [HR], 7.41; 95% CI, 2.63 to 20.9), even when corrected for traditional prognostic factors in multivariate analysis (HR, 11.36; 95% CI, 2.67 to 48.4). The actuarial 5- and 10-year distant metastasis-free survival were 96% (95% CI, 89% to 99%) and 94% (95% CI, 83% to 98%), respectively, for the good profile group and 74% (95% CI, 64% to 81%) and 65% (53% to 74%), respectively for the poor profile group. The sensitivity for 5-yr distant metastasis-free survival was 90%, and the specificity was 50%. The positive and negative predictive values were 38% (95% CI, 29% to 47%) and 94% (95% CI, 86% to 97%), respectively. The 76-gene signature was confirmed as a strong prognostic factor in subgroups of estrogen receptor-positive patients, pre- and postmenopausal patients, and patients with tumor sizes 20 mm or smaller. The subgroup of patients with estrogen receptor-negative tumors was considered too small to perform a separate analysis.


CONCLUSIONS
Our data provide a strong methodologic and clinical multicenter validation of the predefined prognostic 76-gene signature in LNN breast cancer patients.
Foekens
John A
JA
Department of Medical Oncology, Erasmus Medical Center, Daniel den Hoed Cancer Center, Rotterdam, The Netherlands. j.foekens@erasmusmc.nl
Atkins
David
D
Zhang
Yi
Y
Sweep
Fred C G J
FC
Harbeck
Nadia
N
Paradiso
Angelo
A
Cufer
Tanja
T
Sieuwerts
Anieta M
AM
Talantov
Dmitri
D
Span
Paul N
PN
Tjan-Heijnen
Vivianne C G
VC
Zito
Alfredo F
AF
Specht
Katja
K
Hoefler
Heinz
H
Golouh
Rastko
R
Schittulli
Francesco
F
Schmitt
Manfred
M
Beex
Louk V A M
LV
Klijn
Jan G M
JG
Wang
Yixin
Y
D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D018572:Disease-Free Survival; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology; D008875:Middle Aged; D016019:Survival Analysis