Preservation of the pectoralis major fascia has no impact on the long-term oncologic outcomes of breast cancer patients treated with conservative mastectomy and immediate breast reconstruction: a propensity score matching analysis

The oncologic safety of preserving the pectoralis major fascia (PMF) in patients with breast cancer remains controversial. In this study, we aimed to determine the impact of preserving the PMF on long-term oncologic outcomes in patients with breast cancer treated with immediate implant-based breast reconstruction (IBBR) following conservative mastectomy.We selected women with early-stage breast cancer who underwent conservative mastectomy and submuscular IBBR in our center during 2014-2019. The propensity score matching method was used to create well-balanced fascia-preserved and fascia-removed groups. Locoregional recurrence-free survival (LRFS), disease-free survival (DFS), distant metastasis-free survival (DMFS), and overall survival (OS) rates were calculated using the Kaplan-Meier method and compared using log-rank tests between the fascia-preserved and fascia-removed groups.After matching, there were 219 patients in each group. The mean follow-up time was 64.8 ± 18.1 months for the fascia-preserved group and 64.9 ± 18.4 months for the fascia-removed group. There were no significant differences between the groups in terms of LRFS (91.3% vs. 93.8%; p = 0.818), DMFS (94.0% vs. 92.3%; p = 0.056), DFS (89.9% vs. 88.4%; p = 0.261), and OS (95.8% vs. 95.4%; p = 0.783) rates. In the fascia-preserved group, 61.5% of the locoregional recurrence events occurred within 2 years after surgery.Preservation of the PMF did not significantly impact the long-term oncologic outcomes in patients with breast cancer who underwent conservative mastectomy and IBBR. The PMF might be safely preserved in patients without suspicious tumor invasion into this fascia.