Purpose: Expression of the antiapoptotic and antiproliferative protein Bcl-2 has been repeatedly shown to be associated with better clinical outcome in breast cancer. We recently showed a novel regulatory (-938C>A) single-nucleotide polymorphism (SNP) in the inhibitory P2 BCL2 gene promoter generating significantly different BCL2 promoter activities.
Experimental design: Paraffin-embedded neoplastic and nonneoplastic tissues from 274 patients (161 still alive after a follow-up period of at least 80 months) with primary unilateral invasive breast carcinoma were investigated. Bcl-2 expression of tumor cells was shown by immunohistochemistry; nonneoplastic tissues were used for genotyping. Both the Bcl-2 expression and the (-938C>A) genotypes were correlated with the patients' survival.
Results: Kaplan-Meier curves revealed a significant association of the AA genotype with increased survival (P = 0.030) in lymph node-negative breast cancer patients, whereas no genotype effect could be observed in lymph node-positive cases. Ten-year survival rates were 88.6% for the AA genotype, 78.4% for the AC genotype, and 65.8% for the CC genotype. Multivariable Cox regression identified the BCL2 (-938CC) genotype as an independent prognostic factor for cancer-related death in lymph node-negative breast carcinoma patients (hazard ratio, 3.59; P = 0.032). Immunohistochemical Bcl-2 expression was significantly associated with the clinical outcome of lymph node-positive but not of lymph node-negative breast cancer patients. In lymph node-negative cases, the (-938C>A) SNP was both significantly related with the immunohistochemically determined level of Bcl-2 expression (P = 0.044) and the survival of patients with Bcl-2-expressing carcinomas (P = 0.006).
Conclusions: These results suggest the (-938C>A) polymorphism as a survival prognosticator as well as indicator of a high-risk group within patients with lymph node-negative breast cancer.