The impact of isolated tumor cells on loco-regional recurrence in breast cancer patients treated with breast-conserving treatment or mastectomy without post-mastectomy radiation therapy.

To compare the outcome of patients with invasive breast cancer, who had isolated tumor cells (ITC) in sentinel lymph nodes, pN0(i+), to patients with histologically negative nodes, pN0. We retrospectively studied 1,273 patients diagnosed with T1-T3 breast cancer from 1999 to 2009. Patients were divided into 2 populations: 807 patients treated with breast-conserving surgery (BCS) and radiotherapy (RT), 85(10.5 %) with pN0(i+) and 722(89.5 %) with pN0. And the other population had 466 patients treated with mastectomy without post-mastectomy radiation therapy (PMRT), 80(17.2 %) with pN0(i+),and 386(82.8 %)with pN0. All patients underwent sentinel node biopsy, and the presence of ITC was determined. Patients with axillary dissection only or neoadjuvant chemotherapy were excluded. Among the 1,273 patients studied; 87.3 % received adjuvant systemic therapy. Kaplan-Meier, Cox regression, and log-rank statistical tests were used. Median patient age was 55.7 years. Median follow-up was 69.5 months. The 5- and 10-year cumulative incidence of Loco-regional recurrence (LRR) for patients treated with BCS and RT was 1.6 and 3.5 % for 85 pN0(i+) patients, and 2.4 and 5 % for 722 pN0 patients, respectively. For patients treated with mastectomy without PMRT, 5- and 10-year LRR rates were 2.8 and 2.8 % for 80 pN0(i+) patients, and 1.8 and 3 % for 386 pN0 patients, respectively. There were no statistically significant differences in LRR (p = 0.9), distant recurrence (p = 0.3) ,and overall survival (p = 0.5) among all groups. On multivariate analysis, ITC were not associated with increased risk of LRR, distant recurrence and overall survival. Grade (p = 0.003) and systemic therapy (p = 0.02) were statistically significantly associated with risk of LRR. Sentinel node ITC have no significant impact on LRR, distant recurrence and overall survival in breast cancer patients. Additional treatments such as axillary dissection, chemotherapy, or regional radiation should not be given solely based on the presence of sentinel node ITC.