Clinicopathological features and sites of recurrence according to breast cancer subtype in the National Comprehensive Cancer Network (NCCN)

Abstract

543 Background: Gene expression profiling has defined multiple breast cancer subtypes which can approximated using standard immunohistochemical markers. Methods: We assessed clinicopathological features and sites of recurrence for patients (pts) presenting to NCCN sites with stage I-III breast cancer from Jan 2000 to Dec 2006 where estrogen receptor (ER), progesterone receptor (PR), and HER2 status were known. Tumors were grouped as luminal A (ER+ and/or PR+, and HER2-), HER2+ (any ER or PR, and HER2+), or triple-negative (ER-, PR-, and HER2-). Chi-square compared proportions across tumors; univariate logistic regression estimated risk of first site of recurrence. Results: 12,858 pts met inclusion criteria. Median follow-up from NCCN presentation was 3.2 years. Subtype distribution was: triple-negative (TN) 17%; HER2+ 18%; luminal A 66%. Compared to pts with luminal A and HER2+ tumors, TN were younger (p<0.0001), more likely African-American (p<0.0001) and overweight (p=0.0006). TN and HER2+ tumors were less often detected by screening mammography (TN, 28.9%; HER2+, 33.6%; luminal A, 48.4%) and less likely to present as T1 (TN, 46.5%; HER2+, 50.5%; luminal A, 67.0%) or diagnosed as stage I (TN, 32.6%; HER2+ 33.2%; luminal A, 49.4%) than luminal A (all p<0.0001). Rate of node positivity was lowest in TN (TN, 37.1%; HER2+, 44.9%; luminal A, 38.1%; p<0.0001). 83% of TN tumors were high grade; 93% were invasive ductal histology. Extensive intraductal component and lymphovascular invasion were more often associated with HER2+, compared to TN or luminal A (p<0.0001). Recurrences were recorded for 1,235 pts. Relative to luminal A, TN and HER2+ were more likely to experience lung (TN, odds ratio [OR] 2.27, 95% confidence interval [CI] 1.50, 3.43; p=0.0001; HER2+, OR 1.65, 95% CI 1.05, 2.60; p=0.03) and brain (TN, OR 5.32, 95% CI 2.85, 9.91; p<0.0001; HER2+, OR 5.53, 95% CI 2.93, 10.43; p<0.0001) as first site of recurrence; bone was less likely (TN, OR 0.23, 95% CI 0.16, 0.33; p<0.0001; HER2+, OR 0.38, 95% CI 0.28, 0.53; p<0.0001). Conclusions: Clinicopathological features and patterns of recurrence differed significantly by subtype and may inform the design of future clinical trials. No significant financial relationships to disclose.