Evaluation of risk stratification using gene expression assays in patients with breast cancer receiving neoadjuvant...

To evaluate the association of various gene expression assays with pathologic complete response (pCR) in the setting of neoadjuvant chemotherapy among patients with breast cancer METHODS: The National Cancer Database (NCDB) was queried for women diagnosed between 2010 and 2017 with stage I-III breast cancer who underwent neoadjuvant chemotherapy and either 21-gene recurrence score (RS) or 70-gene signature (GS). Logistic multivariable analysis (MVA) was performed to identify variables associated with pCR.

A total of 3009 patients met our inclusion criteria. The median follow up was 48.0 months (interquartile range 32.2-66.7 months). On logistic MVA for all patients, those with a high risk from GS (adjusted odds ratio [aOR] 3.23, 95% confidence interval [CI] 1.49-8.13, p = 0.006) or with RS ≥ 31 (aOR 1.99, 95% CI 1.41-2.82, p < 0.001) were more likely to have pCR. When compared to RS ≥ 31, a high risk from GS was not associated with pCR (aOR 1.01, 95% CI 0.75-1.37, p = 0.94). However, among those with favorable hormone receptor status, similar findings were noted, except that those with a high risk group from GS were less likely to have pCR compared to those with RS ≥ 31 (aOR 0.65, 95% CI 0.43-0.96, p = 0.03). When analyses were repeated using a high risk group from RS defined as RS ≥ 26 among those with favorable hormone receptor status, RS ≥ 26 was not associated with pCR when compared to the high risk from GS (aOR 0.74, 0.50-1.07, p = 0.12).

To our knowledge, this is the largest study using a nationwide oncology database suggesting that high recurrence risk groups in both assays were associated with pCR. Among those with favorable hormone receptor status, RS ≥ 31 may be a more selective prognostic marker for pCR.