Prognosis of locoregional recurrence after early breast cancer with immediate breast reconstruction.

e12595 Background: Several studies have shown no difference in the prognosis of breast cancer patients who underwent total mastectomy (MT) with or without immediate breast reconstruction (IBR), which is now a standard surgical technique in the treatment of breast cancer. While some studies have reported a poor prognosis for locoregional recurrence (LRR) following breast cancer surgery, the prognosis of LRR without simultaneous distant metastasis after IBR is not known. We conducted a multi-facility retrospective observational study to investigate the prognosis of breast cancer patients with LRR after IBR. Methods: Of the 4,726 primary breast cancer patients for whom IBR was performed at 12 Japanese medical facilities between January 1, 2008, and December 31, 2016, MT or skin-sparing mastectomy (SSM) was performed in 3,295 patients. LRR was observed in 87 of these patients, 17 of whom had distant metastasis (n=13) or metastasis to the supraclavicular or internal mammary lymph nodes (n=4) before LRR was excluded. The measured outcomes were IBR-LRR-related prognostic factors, five-year distant metastasis-free survival (DMFS), and five-year overall survival (OS). The statistical analyses employed Kaplan–Meier curves and a Cox proportional hazards model. Results: The median observation period was 39.3 months and the median age at which IBR was performed was 44 years. There were 61 cases (87.1%) of invasive cancer. Sixty-one cases (87.1%) were ER-positive, 54 (77.1%) were PR-positive, and 13 (19.7%) were HER2-positive. Fifteen cases (21.4%) had pathological lymph node metastasis (pN), 60 cases (85.7%) underwent implant reconstruction, 33 cases (47.1%) had a disease-free interval ≤ 36 months, 9 cases (12.9%) had regional lymph node recurrence (RR), and 65 cases (92.9%) underwent surgical resection to treat LRR. The five-year DMFS after LRR was 92.4%, and the five-year OS was 91.2%. The relationship between DMFS and clinical pathology factors was analyzed using a Cox proportional hazards model. Univariate analysis revealed significant differences for pN (HR 10.634, 95% CI 1.102–102.616, P=0.041) and RR (HR 9.960, 95% CI 1.400–70.862, P=0.022), and multivariate analysis indicated that RR was the only independent prognostic factor for DMFS (HR 7.834, 95% CI 1.085–56.587, P=0.041) (Table 1). Univariate analysis revealed significant differences for post-mastectomy radiation therapy (PMRT) (HR 130.676, 95% CI 1.552–412.278, P=0.023) and RR (HR 8.181, 95% CI 1.106–60.503, P=0.043), and multivariate analysis indicated that both PMRT (HR 61.281, 95% CI 2.540–1478.426, P=0.010) and RR (HR 15.687, 95% CI 1.354–181.772, P=0.028) were independent prognostic factors for OS. Conclusions: This is the first study to report the prognosis of breast cancer patients with LRR after IBR. Although these patients have a favorable prognosis overall, our results indicate that RR may be a significant factor for poor prognosis.