Clinicians have traditionally used clinicopathological (CP) factors to determine locoregional recurrence (LR) risk of breast cancer and have generated the IBTR! nomogram to predict the risk of ipsilateral breast tumor recurrence (IBTR). The 21-gene recurrence score (RS) assay was recently correlated with LR in retrospective studies. The objective of this study was to examine the relationship between the RS and IBTR!. CP characteristics of 308 consecutive patients who underwent RS testing at our institution were examined. IBTR! was used to estimate the risk of 10-year IBTR. Descriptive statistics were used to compare the RS with the estimated IBTR!. Given a low event rate in this cohort, actual IBTR rates were not reported. Most patients had stage I/II (98%) and grade I/II (77%) disease. Median age was 54 years (range, 30-78). Median IBTR! without radiation therapy was 10% (mean, 12% [range, 4-43%]). RS was low (<18), intermediate (18-30), and high (>30) in 52% (n = 160), 40% (n = 123), and 8% (n = 25) patients. Overall, IBTR! did not correlate with RS (P = .77). We saw no correlation between RS and IBTR! in patients with less than (P = .32) or greater than (P = .48) a 10% risk of IBTR. Interestingly, Ki-67 expression correlated with both IBTR! (P = .019) and the RS (P = .002). Further study is warranted to determine if the RS can provide complementary biological information to CP factors in estimating the risk of LR. Prospective studies evaluating this association may potentially allow for individualized treatment decisions.
Keywords: 21-gene recurrence score; IBTR!; Ipsilateral breast tumor recurrence; Local recurrence; Molecular profiling; Oncotype Dx.