Materials/Methods: The study population included a total of 5758 patients enrolled in the NSABP B-15, B16, B-18, B-22 and B-25 trials. From the B-18 study, only patients (pts) who had positive lymph nodes (LNϩ) and received postoperative adjuvant chemotherapy were included. Median follow-up without recurrence was 9.5 years (range: 0.04-15.8 years). The distribution of pathologic tumor size was as follows: Ͻϭ 2cm, 2.1-5cm and Ͼ 5cm in 30%, 52% and 11%, respectively (7% had unknown tumor size). The median number of LN removed was 16. Distribution of number of LNϩ was 1-3, 4-9 and 10ϩ in 51%, 32, and 16%, respectively. The distribution of the number of LN dissected was 1-5 (108 pts), 6-9 (579 pts), Ͼ10 (4849 pts) in 1.9%, 10.1%, and 84.2%, respectively (3.8% had unknown). Patients were treated either by doxorubicin-based chemotherapy (B-15, B-16, B-18, B-22 and B-25: 5199 patients), or CMF (B-15: 559 patients).
Results:The 10-year overall crude rate of locoregional failure as first event was 14.3% (821/5758). The majority of recurrences occurred on the chest wall / mastectomy scar (56.7%). Axillary and supraclavicular recurrences represented 11.8% and 22.4% of all loco-regional recurrences, respectively. In the group of patients who had only 1-5 LN dissected, the 10-year cumulative incidence of axillary recurrence was 9.3% compared to 2.2% and 1.5% for the group of patients who had 6-9 and Ͼ10 LN removed, respectively (pϽ0.0001). However, the supraclavicular recurrence rate remained similar for the three groups (0.9%, 2.6% and 3.4%, respectively, pϭ0.25). In patients who had 1-3 LNϩ, the rate of axillary recurrence was 8.9%, 1.1% and 0.5% in patients with 1-5, 6 -9 and Ͼ10 LN dissected, respectively. In patients with 4-9 LNϩ, the corresponding risk of axillary recurrence was 11.8%, 3.9% and 2.1%, respectively. Furthermore, in the group of patients who had Ͼ 10 positive LN, or Ͼ50% of the removed LN found to be positive, the rate of axillary lymph node recurrence remained relatively low (2.6%) as far as the number of LN dissected was 10 or more. The statistical analysis showed that the risk of axillary failure increased significantly with the number of positive lymph nodes (pϽ0.0001), smaller number of LN dissected (pϽ0.0001) or increase proportion of LNϩ (pϽ0.0001). However, regarding the rate of supraclavicular recurrence, only the number of LNϩ and the proportion of LNϩ were found to be significantly predictive for recurrence.
