The paradoxical effect of oral prednisone in granulomatous lobular mastitis: An observational cohort study

Abstract

Background Despite being a cornerstone therapy for granulomatous lobular mastitis (GLM), the use of oral prednisone lacks a standardized protocol due to undefined optimal parameters and insufficient large-scale evidence regarding its impact on disease recurrence. Objectives The retrospective cohort study comprehensively assessed the efficacy of oral prednisone for GLM by utilizing a large-scale cohort. It aimed to identify the optimal therapeutic protocol, with the ultimate aim of establishing a robust evidence base to inform standardized clinical guidelines. Methods A cohort of 614 patients diagnosed with GLM was included in this study from January 2017 to December 2024. A three-dimensional evaluation of treatment timing (symptom-to-treatment interval), duration, and initial dosage (both absolute and weight-adjusted) was performed to identify prognostic factors and optimal cutoffs. Results Oral prednisone was identified as an independent risk factor for recurrence (HR = 2.534, 95% CI: 1.615–3.975, P < 0.001). Survival curve analysis revealed that the 1-year recurrence rate was significantly higher in the oral prednisone group than in the non-prednisone group (29.4% vs. 14.6%, P = 0.001). Subgroup analysis showed that the long-interval, low-dose group (symptom-to-treatment interval > 6 weeks, dosage ≤ 0.4 mg/kg/day) yielded the most favorable results. The one-year recurrence rate of this group (6.2%) was significantly lower than other groups (all P < 0.05) and comparable to the non-prednisone group (14.6%, P = 0.233). Conversely, the short-interval group (symptom-to-treatment interval: 0–6 weeks) demonstrated the highest one-year relapse rate (33.5%), significantly exceeding that of the non-prednisone group (P < 0.001). Conclusions While oral prednisone therapy may be associated with an increased relapse risk in GLM, an optimized protocol—initiating treatment after a 6-week symptom interval at a dose of ≤ 0.4 mg/kg/day—was identified to mitigate this risk. These findings highlight the paramount importance of treatment timing and dosage, offering a data-driven strategy to refine current therapeutic practices. Prospective studies are warranted to validate this proposed regimen.