Local recurrence rates are low in high-risk neoadjuvant breast cancer in the I-SPY 1 Trial (CALGB 150007/150012; ACRIN 6657).

Background: Increasingly, women with stage 2 and 3 breast cancers receive neoadjuvant therapy, after which many are eligible for breast-conserving surgery (BCS). The question often arises as to whether BCS, if achievable, provides adequate local control. We report the results of local recurrence (LR) from the I-SPY 1 Trial in the setting of maximal multidisciplinary treatment where approximately 50 % of patients were treated with BCS.

Methods: We analyzed data from the I-SPY 1 Trial. Women with tumors ≥3 cm from nine clinical breast centers received neoadjuvant doxorubicin, cyclophosphamide and paclitaxel followed by definitive surgical therapy, and radiation at physician discretion. LR following mastectomy and BCS were analyzed in relation to clinical characteristics and response to therapy as measured by residual cancer burden.

Results: Of the 237 patients enrolled in the I-SPY 1 Trial, 206 were available for analysis. Median tumor size was 6.0 cm, and median follow-up was 3.9 years. Fourteen patients (7 %) had LR and 45 (22 %) had distant recurrence (DR). Of the 14 patients with LR, nine had synchronous DR; one had DR > 2 years later. Only four (2 % of evaluable patients) had LR alone. The rate of LR was low after mastectomy and after BCS, even in the setting of significant residual disease.

Conclusions: Overall, these patients at high risk for early recurrence, treated with maximal multidisciplinary treatment, had low LR. Recurrence was associated with aggressive biological features such as more advanced stage at presentation, where LR occurs most frequently in the setting of DR.