Percutaneous microwave ablation combined with endocrine therapy versus standard therapy for elderly patients with HR-positive and HER2-negative invasive breast cancer: a propensity score-matched analysis of a multi-center, prospective cohort study

Background: There is a growing trend to apply minimally invasive local treatments for elderly patients with early-stage breast cancer. As a minimally invasive thermal therapy, microwave ablation (MWA) has been attempted to treat breast cancer of small lesions, but its long-term local efficacy on elderly patients has seldom been reported. In this study, we aimed to compare outcomes of MWA combined with endocrine therapy to standard surgery combined with adjuvant therapy in the treatment of hormone receptor (HR) -positive and human epidermal growth factor receptor 2 (HER2)-negative invasive breast cancer for elderly patients.Methods: This prospective multi-center cohort study enrolled patients over 70 years old diagnosed with HR-positive and HER2-negative early-stage invasive breast cancer between January 2016 and July 2021. Patients chose either non-randomized to undergo MWA combined with endocrine therapy (MWA group) or standard surgery combined with adjuvant therapy (surgery group). Endpoints for the comparisons were disease-free survival (DFS), overall survival (OS) and length of hospital stay (LOS) after adjusting for previously reported risk factors using propensity score matching (1:3).Results: Of the enrolled 132 patients, 33 were in the MWA group and 99 were in the surgery group. MWA was successfully performed in all cases, and technical effectiveness was achieved in all cases. With a median follow-up of 31 months, only one case had local recurrence 23 months after MWA. MWA combined with endocrine therapy and standard surgery combined adjuvant therapy for elderly patients with breast cancer achieved similar DFS (hazard ratio, 0.536; 95% CI, 0.128-2.249) and OS (hazard ratio, 0.537; 95% CI, 0.089-3.235). Besides, MWA had much shorter LOS than standard surgery (7.1 versus 13.0 days, P<0.001).Conclusions: MWA combined with endocrine therapy and standard surgery combined with adjuvant therapy for elderly breast cancer patients achieved similar outcomes. MWA combined with endocrine may be a feasible treatment strategy for elderly patients with HR-positive and HER2-negative invasive breast cancer.