Temporal trends in active surveillance and treatment strategies for low-risk, hormone receptor-positive ductal carcinoma in situ in the US.

181 Background: Active surveillance (AS) has emerged as a de-escalation strategy for low-risk ductal carcinoma in situ (DCIS), seeking to reduce overtreatment while maintaining favorable outcomes. Clinical trials (e.g., COMET) have highlighted growing interest in AS for carefully selected patients. However, real-world adoption and national trends in managing low-risk, hormone receptor-positive (HR+) DCIS have not been comprehensively evaluated in the US in recent years. Methods: Using the National Cancer Database, we analyzed treatment patterns for grade 1-2, HR+ DCIS between 2004 and 2022. Five local treatment strategies—AS, lumpectomy only, lumpectomy plus adjuvant radiotherapy (Lum+RT), unilateral mastectomy (UM), and bilateral mastectomy (BM)—and endocrine therapy (ET) were tracked. Results: Among 316,590 eligible patients (mean age 60.8 years), the racial/ethnic distribution was 73.3% White, 13.9% Black, 6.1% Hispanic, 5.8% Asian or Pacific Islander, and 0.9% Other. Initial management consisted of AS in 2.6%, lumpectomy only in 24.2%, Lum+RT in 46.0%, UM in 18.6%, and BM in 8.6%. From 2004 to 2022, the proportion of patients undergoing AS increased from 2.1% to 3.5%, lumpectomy only from 22.0% to 25.1%, and BM from 4.1% to 8.7% (peaking at 10.9% in 2013), while Lum+RT declined from 50.9% to 45.6% and UM from 20.9% to 17.1%. AS was more common in Black than White patients (3.6% vs 2.2%) and in uninsured patients (4.4%) or Medicare beneficiaries (3.1%) than those privately insured (1.9%) (all p < .001). BM was undertaken in 8.9% of White and 6.0% of Black patients. ET uptake was highest after Lum+RT (69.6%), followed by lumpectomy only (43.9%), UM (35.3%), and AS (29.2%). Younger women were generally less likely to initiate ET, except in the Lum+RT group, where uptake was slightly higher in older women. ET use across treatment groups increased from 2004 to 2020 but declined thereafter. Conclusions: Although the number of patients diagnosed with low-risk, HR+ DCIS has increased, treatment selection has become more heterogeneous across age groups, sociodemographic backgrounds, and pandemic-related shifts in clinical practice. This highlights the need for more precise, preference-aligned care. Moving forward, precision prevention—anchored in improved risk stratification and individualized intervention—may enhance the identification of patients who would benefit most from preventive surgery, prolonged endocrine therapy, or active surveillance, paving the way for more tailored strategies for managing patients with DCIS.