Radiotherapy Strategies for Stage II Breast Cancer With Lymphovascular Invasion After Mastectomy

Lymphovascular invasion (LVI) is a strong prognostic factor associated with poor survival outcomes in breast cancer. However, the clinical benefit of postmastectomy radiotherapy (PMRT) for early-stage disease remains uncertain. This study aimed to evaluate PMRT efficacy and related prognostic factors in real-world settings.

We retrospectively analyzed 322 postoperative breast cancer patients with pathologically confirmed LVI who received radiotherapy (RT) between October 2017 and July 2020. Patients were categorized into two groups: Group A (pT1-2N1M0, n=273), who underwent modified radical mastectomy (MRM) with or without adjuvant RT; and Group B [stage II, ypN0 after neoadjuvant chemotherapy (NAC) and surgery, with or without adjuvant RT, n=49]. Intergroup differences were assessed using the chi-squared test, and Kaplan-Meier analysis estimated local recurrence-free survival (LRFS), disease-free survival (DFS), overall survival (OS), and distant DFS (DDFS).

Group A: Patients who received adjuvant RT had significantly improved 5-year LRFS (94.4% vs. 85.5%, HR=0.359, 95% CI=0.147-0.879; p<0.05) and DFS (88.9% vs. 78.8%, HR=0.488, 95% CI=0.253-0.940; p<0.05) compared to those without RT. No significant difference was observed in 5-year OS or DDFS. Subgroup analysis indicated a higher recurrence risk among patients with two to three positive lymph nodes or triple-negative tumors. Group B: Among patients who achieved ypN0 status, adjuvant RT significantly improved 5-year DFS (95.8% vs. 76.0%), OS (100.0% vs. 84.0%), and DDFS (100.0% vs. 80.0%) (p<0.05), with no significant difference in LRFS.

In stage II LVI-positive breast cancer patients, adjuvant RT improves local control and leads to an increase in DFS but not OS. PMRT provides survival benefits for LVI-positive patients who achieve ypN0 status after NAC and is recommended. Larger studies are needed to validate these findings.