Heat shock protein hsp70 in patients with axillary lymph node-negative breast cancer: prognostic implications.
BACKGROUND
Cell synthesis of heat shock (stress-response) proteins is increased by a variety of environmental and pathophysiological stressful conditions. The 70-kd heat shock protein (hsp70) is thought to be involved in protein-protein interactions including those of the protein products of the human c-myc oncogene and the p53 (also known as TP53) tumor suppressor gene.


OBJECTIVE
The purpose of this study was to investigate whether elevated hsp70 expression may be an indicator of biological stress experienced by a breast cancer and may, therefore, predict disease outcome.


METHODS
Levels of hsp70 were determined by Western blot analysis in primary breast tumors from patients with negative axillary lymph nodes. We performed exploratory data analyses on a set of 162 primary breast cancers and constructed prognostic indexes of hsp70 expression levels. The optimal cutpoint for hsp70 expression was considered to be the value yielding the greatest separation for disease-free survival for the resulting two groups of patients. That cutpoint was then validated in a set of 345 tumors by univariate and multivariate analyses. Data were analyzed for overall survival, disease-free survival, tumor size, and patient age, as well as estrogen receptor and progesterone receptor status, ploidy (DNA content), and percentage of cells in S phase as determined by flow cytometry.


RESULTS
Expression of hsp70 emerged as a useful prognostic factor, both in univariate and in multivariate analyses. Patients whose tumors had high expression of hsp70 had significantly shorter disease-free survival (P = .006). The other statistically significant factors were S-phase fraction (P = .008) and tumor size (P = .01). For patients who received adjuvant therapy, hsp70 was the only independent predictor of disease recurrence (P = .05). For those with tumors 1-3 cm in diameter, hsp70 (P = .008) and S-phase fraction (P = .02) were statistically significant predictors of recurrence.


CONCLUSIONS
Measurement of hsp70 expression in primary tumors from patients with node-negative breast cancer may be useful in identifying patients at high risk for disease recurrence and thus may affect decisions regarding treatment after surgery.


CONCLUSIONS
Future studies should be performed to determine if detection of hsp70 by immunohistochemistry can be used to predict clinical outcome and to better understand the relationships between hsp70 and the effects of various treatment modalities.
Ciocca
D R
DR
Department of Medicine, University of Texas Health Science Center, San Antonio 78284-7884.
Clark
G M
GM
Tandon
A K
AK
Fuqua
S A
SA
Welch
W J
WJ
McGuire
W L
WL
D000704:Analysis of Variance; D001365:Axilla; D001943:Breast Neoplasms / Q000737:chemistry* / Q000473:pathology; D005260:Female; D006360:Heat-Shock Proteins / Q000032:analysis*; D006801:Humans; D008207:Lymphatic Metastasis; D011379:Prognosis; D012008:Recurrence; D016019:Survival Analysis
D006360:Heat-Shock Proteins