Abstract:
Objective This study aimed to evaluate retrospectively the effects of extracapsular extension (ECE) on the benefits of post-mastectomy radiation therapy (PMRT) in patients with different axillary lymph-node positive levels (1-3, 4-9, and ≥10 positive axillary nodes).
Methods A total of 1220 axillary node-positive patients who had undergone mastectomy, received PMRT or not, and with (n = 66) or without (n = 24) ECE. The patients were divided into four groups based on the ECE status and treatment of PMRT, which were evaluated in terms of the LRR rate. The groups were "radio+ ECE+, " "radio-ECE+, " "radio + ECE-, " and "radio-ECE-." The 5- and 10-year Kaplan –Meier disease-free survival (DFS) and overall survival (OS) rates were analyzed.
Results Statistically significant differences were found in the effects of ECE on the 5- and 10-year loco-regional DFS (LRDFS) and OS rates between the ECE and non-ECE groups. The 5-year LRDFS was 82.69% vs. 91.83% (P < 0.001), the 10-year LRDFS was 75.39% vs. 90.02 % (P < 0.001), the 5-year OS was 52.12% vs. 74.46%(P < 0.001), and the 10-year OS was 35.17% vs. 67.63% (P < 0.001) for the ECE and non-ECE groups, respectively. For patients with 1-3 (P= 0.572 0) or ≥10 positive axillary nodes, no apparent effect of ECE was observed on the benefits of PMRT. However, for patients with 4-9 positive axillary nodes, ECE had significant effects on PMRT in terms of the 5- and 10-year LRDFS rates (P<0.05).
Conclusion Regardless of the ECE status, PMRT did not significantly improve the LRDFS rate of patients with 1-3 or ≥10 positive axillary nodes. However, for patients with 4-9 positive axillary nodes, ECE can be an important criterion for deciding whether a patient can benefit from PMRT.