Genomic prediction of locoregional recurrence after mastectomy in breast cancer.
OBJECTIVE
This study aims to explore gene expression profiles that are associated with locoregional (LR) recurrence in breast cancer after mastectomy.


METHODS
A total of 94 breast cancer patients who underwent mastectomy between 1990 and 2001 and had DNA microarray study on the primary tumor tissues were chosen for this study. Eligible patient should have no evidence of LR recurrence without postmastectomy radiotherapy (PMRT) after a minimum of 3-year follow-up (n = 67) and any LR recurrence (n = 27). They were randomly split into training and validation sets. Statistical classification tree analysis and proportional hazards models were developed to identify and validate gene expression profiles that relate to LR recurrence.


RESULTS
Our study demonstrates two sets of gene expression profiles (one with 258 genes and the other 34 genes) to be of predictive value with respect to LR recurrence. The overall accuracy of the prediction tree model in validation sets is estimated 75% to 78%. Of patients in validation data set, the 3-year LR control rate with predictive index more than 0.8 derived from 34-gene prediction models is 91%, and predictive index 0.8 or less is 40% (P = .008). Multivariate analysis of all patients reveals that estrogen receptor and genomic predictive index are independent prognostic factors that affect LR control.


CONCLUSIONS
Using gene expression profiles to develop prediction tree models effectively identifies breast cancer patients who are at higher risk for LR recurrence. This gene expression-based predictive index can be used to select patients for PMRT.
Cheng
Skye H
SH
Department of Radiation Oncology, Koo Foundation Sun Yat-Sen Cancer Center, Pei-Tou District, Taipei, Taiwan. skye@mail.kfcc.org.tw
Horng
Cheng-Fang
CF
West
Mike
M
Huang
Erich
E
Pittman
Jennifer
J
Tsou
Mei-Hua
MH
Dressman
Holly
H
Chen
Chii-Ming
CM
Tsai
Stella Y
SY
Jian
James J
JJ
Liu
Mei-Chin
MC
Nevins
Joseph R
JR
Huang
Andrew T
AT
D000328:Adult; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000235:genetics* / Q000473:pathology / Q000601:surgery*; D005260:Female; D016678:Genome; D006801:Humans; D008207:Lymphatic Metastasis; D008408:Mastectomy; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D016016:Proportional Hazards Models; D011859:Radiography; D011878:Radiotherapy; D016896:Treatment Outcome