Cyclooxygenase-2 expression correlates with diminished survival in invasive breast cancer treated with mastectomy and radiotherapy

PURPOSE: To evaluate the relationship between cyclooxygenase-2 (COX-2) expression and pathologic features and outcome in invasive breast cancer. METHODS AND MATERIALS: Formalin-fixed, paraffin-embedded tumor specimens from 23 women with invasive breast cancer were stained for COX-2 expression. All women underwent mastectomy and locoregional radiotherapy. The distribution (percentage of positive staining cells) and intensity of COX-2 expression within the tumor cells were compared with clinical factors, including stage, grade, lymph node involvement, and outcome. RESULTS: For invasive breast cancer, the distribution and intensity of COX-2 tumor expression correlated significantly with diminished overall survival. The 5-year overall survival rate was 100% for patients with <75% of breast cancer cells expressing COX-2 compared with 49% for patients with > or =75% (p = 0.044). The 5-year overall survival rate was 100% for patients with COX-2 intensity <80 compared with 60% for patients with COX-2 intensity > or =80 (p = 0.018). The percentage and intensity of COX-2 expression also correlated significantly with disease-free survival. The percentage of cells expressing COX-2 was significantly greater in women <40 years old than in women > or =40 years old (81% vs. 59%, respectively, p = 0.04). CONCLUSION: Both the distribution and the intensity of COX-2 expression correlated significantly with disease-free and overall survival in patients with invasive breast cancer. Younger patients with invasive breast cancer may have a greater percentage of COX-2 expression in their tumors.