Abstract P4-09-16: WAVE3 Over-Expression Is Associated with Adverse Tumor Characteristics and Mortality in Breast Cancer

Background: WAVE3 regulates actin polymerization and subsequent cell migration leading to enhanced metastatic potential. Based on pilot data that suggested WAVE3 expression was associated with high histologic grade and absence of estrogen receptor (ER) expression we hypothesized that WAVE3 expression would correlate with ER status and tumor grade in a matched group of breast cancer (BC) patients. WAVE3 expression was alsoanalyzed in relation to adverse tumor characteristics, distant recurrence (DR) and BC specific mortality. Methods: Our institutional BC database was reviewed for patients who presented with, invasive BC from 1999-2009. Matching by stage and treatment was achieved for 61 patients with Scarff-Bloom-Richardson (SBR) grade 1 and ER+ tumors (SBR1/ER+) to 61 patients with SBR grade 3 and ER-tumors (SBR3/ER-). Cytosolic WAVE3 tumor expression was determined by immunohistochemistry. The product of stain intensity (0-3) and percentage of cells staining (0-100) was used to derive a WAVE3 score (0-300). The log rank test was utilized to compare BC specific mortality or distant recurrence free survival at various WAVE3 scores. A score of ≥212 was found to have the strongest association with poor outcome. The association between WAVE3 score and clinicopatholigic features, DR and BC specific mortality was assessed. Results: Increased frequency of Her2-neu (+) status, DR and BC specific mortality was noted in the SBR3/ER-group but WAVE3 score was no different between the two groups(Table1). In all 122 patients median WAVE3 score increased with tumor size (0.234, p=0.009), (+) lymph node status 200 vs. (-), 145, p =0.03, and stage (I, 160 vs. II,180 vs III, 240, p=0.012). There was no association between WAVE3 score and Her2-neu status(+200 vs. -180, p=0.51). In the SBR1/ER+ group only (+) lymph node status remained associated with WAVE3 score(+) 200 vs. (-) 130 (p=0.02). In the SBR3/ER-group only lymph node status lost association with WAVE3 score (+)180 vs.(-)170, (p=0.50). DR and BC specific survival could only be assessed in the SBR3/ER-group. Median WAVE3 score was elevated with DR (240 vs. none, 160, p=0.03) and BC specific mortality (270 vs. none 170, p=0.004). A WAVE3 score ≥212 was associated with distant recurrence and BC specific mortality on Kaplan Meier analysis (p=0.01) and P<0.001). On multivariate analysis a WAVE3 score ≥212 was associated with an increased risk for BC specific mortality (p=0.009). The association of DR and WAVE3 score ≥212 approached significance (p=0.068).

Table 1

Conclusion: WAVE3 expression is not associated with tumor grade, and ER or Her2 neu status. WAVE3 is associated with tumor size, stage, DR and BC specific mortality in the high risk SBR3/ER-group. A WAVE3 score of ≥212 is associated with distant recurrence and breast cancer specific mortality on univariate analysis and BC specific mortality on uni-and multivariate analysis. WAVE3 expression may contribute to adverse outcome in high risk breast cancer patients.

Genetic Susceptibility as a Possible Risk Factor for Breast Cancer

Background: Established risk factors for breast cancer (BC) only explain 25% to 47% of BC incidence. The Gail model is commonly used to assess BC risk and determine eligibility for prevention trials. Unfortunately, it has a discriminatory accuracy of 58% at the individual level. A greater understanding of BC risk factors is needed to offer improved risk stratification and prevention. It is plausible that BC risk may be related to deficiencies or abnormalities in DNA repair and cell cycle checkpoints because of their importance in maintaining genomic integrity. Recent epidemiologic studies support this hypothesis. In this pilot project, the bleomycin mutagen sensitivity assay (MSS), a measure of genetic susceptibility was performed on women of low, intermediate, and high risk based on commonly used risk models to determine if there was any correlation between MSS and established BC risk factors.Methods: Women in the Prevention Clinic at RPCI consented to donate blood for this study as part of the Data Bank and BioRepository (DBBR). Gail and Claus Models were calculated using CancerGene. Women were stratified into three groups low (<20%), intermediate (20%-35%), and high (> 35%) lifetime BC risk. For logistic regression analysis, women were grouped into low risk (<20%) and high risk (≥20%). MSS in blood lymphocytes were performed at LCCC using fresh blood samples. The mean values of MSS were compared between low, intermediate, and high risk groups using Wilcoxon-Mann-Whitney tests. Multivariate logistic regression was used to analyze the relationship between BC risk groups and MSS.Results: A total of 78 women were enrolled in the study. MSS were performed on 70 blood samples and 67 had evaluable slides. There were 30, 26 and 11 women in the low, intermediate, and high risk groups respectively. The mean age was 49.1 years. There was no statistical difference between the three groups with respect to age, race, menopausal status, proportion of patients with a family history of BC or another cancer, and smoking status (never, former, or current). The mean MSS score was not significantly different among the three risk groups: mean ±SD = 0.86±0.37, 0.84±0.37 (p=0.565), and 0.76+0.44 (0.361) for low, intermediate and high risk groups respectively. Spearman correlation revealed that MSS score did not correlate with Gail lifetime BC risk score (r=-0.054, p=0.668) or Claus model-10 year risk score (r=-0.057, p=0.722). Using the median in low risk women as a cut point, when women who had higher MSS score were compared with women had lower MSS score, the adjusted OR was 1.16 (95% CI, 0.29 to 4.57), adjusted for age, race, smoking status, BMI and menopausal status. When the MSS score were categorized into quartiles, no significant dose-response relationship was observed.Conclusions: In this pilot study, there was no correlation between commonly used breast cancer risk assessment models based on hormonal, family and biopsy history and the MSS in our study population. Previous case-control studies have consistently shown that MSS is significantly associated with BC risk. The lack of correlation between mutagen sensitivity and Gail or Claus risk score suggests that mutagen sensitivity may measure the host susceptibility factors that are not considered by Gail or Claus risk models.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6067.