Survival and prognostic factors for breast cancer patients with regional oligo-recurrence

Purpose: This study aimed to evaluate survival outcomes and identify prognostic factors for regional oligo-recurrence in breast cancer patients who received salvage local treatment. Methods: In the breast cancer registry of our institution, 18,790 patients received curative surgery for stage I–III breast cancer between January 1995 and June 2016. Of those patients, only 87 (0.5%)underwent salvage local treatment for isolated nodal recurrence on the axillary lymph nodes (ALNs) (n = 58), supraclavicular lymph nodes (SCNs) (n = 17), or internal mammary lymph nodes (IMNs) (n = 12). Results: The median follow-up duration after regional oligo-recurrence was 49 months (range: 6–194 months). For patients with recurrence of ALN, SCN, or IMN, the 5-year progression-free survival (PFS) and overall survival (OS) rates were 40.0%, 32.1%, and 25.0%, respectively (p = 0.3) and 62.7%, 70.0%, and 58.3%, respectively(p = 0.97). In the multivariable analysis for PFS, age at recurrence ≥ 65 years, disease-free interval < 24 months, non-luminal A subtype, and in-field failure (marginally significant) were found to be risk factors (RFs). However, the location of the tumor was not a significant factor for PFS (p = 0.71). When we stratified patients by the number of RFs, the 5-year PFS rates were 67.5% for patients with ≤ 1 RF and 7.3% for those with > 1 RF (p < 0.01). For patients with ≤ 1 RF, the 5-year PFS rates were 73.5% in the ALN group and 51.1% in the SCN/IMN group (p = 0.09). For patients with > 1 RF, the 5-year PFS rates were 7.3% in the ALN group and 7.1% in the SCN/IMN group (p = 1.00). Conclusion: In breast cancer patients with regional oligo-recurrence, clinical outcomes after salvage treatment were favorable in patients with ≤ 1 RF, while patients with > 1 RF had poor prognoses irrespective of the location of recurrence.