Long-term outcome of breast cancer patients with pathologic N3a lymph node stage.

Purpose: To evaluate factors influencing the long-term outcome of patients presenting with 10 or more metastatic axillary lymph nodes (pN3a) after surgery for primary breast cancer.

Method: Between January 1990 and December 2015, a total of 130 patients with pN3a breast cancer at surgery were identified in our Institutions and included in the study. Twenty-nine of them (22.3%) received neoadjuvant chemotherapy. The Multivariate Cox proportional hazards model was used to determine independent prognostic factors associated with DFS and OS.

Results: After a median follow-up of 6.4 years (range 0.87-25 years), 2 patients had a local relapse, 59 distant metastases (1 with local relapse) and 52 patients died. The 5-year DFS and OS rates were 61.8% and 71.5%, respectively. At multivariate analysis, pN3a stage after neoadjuvant chemotherapy (ypN3a) was significantly associated with increased risk of recurrence (HR 1.92, p = 0.02) and death (HR 2.05, p = 0.029). Absence of progesterone receptor (PR) expression was the most important tumor characteristic associated with poor prognosis, both in terms of recurrence (HR 2.55, p < 0.001) and death (HR 2.23, p = 0.019). High levels of Ki-67 index (≥20%) were significantly associated with a shorter OS (HR 2.03, p = 0.027), but not with DFS.

Conclusions: The results of this study indicate that ypN3a stage, lack of expression of PR, and Ki-67 ≥ 20% negatively affect long-term outcome of patients with pN3a breast cancer.