Purpose: Breast-conserving surgery (BCS) followed by radiotherapy (RT) with or without endocrine therapy (ET) is a standard treatment option for ductal carcinoma in situ (DCIS). We sought to investigate national patterns in the use of adjuvant therapy after BCS for hormone receptor (HR)-positive DCIS over time.
Patients and methods: Using data from the National Cancer Data Base, we identified patients diagnosed with DCIS and treated with BCS between 2004 and 2013. Multivariable logistic regression was used to estimate the odds of adjuvant therapy use controlling for clinicopathologic demographic and facility-level characteristics.
Results: We identified 66,079 patients who underwent BCS for DCIS. Overall, 21% received no adjuvant treatment, 71% received RT, 48% received ET, and 38% received the combination therapy. In adjusted analyses among the patients with HR-positive DCIS (n = 50,147), the administration of RT decreased (odds ratio [OR] 0.86, 95% CI 0.77-0.97), while the use of ET increased (OR 1.5, 95% CI 1.4-1.6) in 2013 compared to 2004. Young patients, elderly patients, positive margin status, and Medicare insurance were associated with lower use of both RT and ET. We observed both clinicopathologic and geographic variation in the use of adjuvant therapies. In the lowest risk subgroup, the use of RT decreased from 57% in 2004 to 48% in 2013 (OR 0.64, 95% CI 0.45-0.89).
Conclusion: Our study suggests a shift in patterns of care for DCIS that is impacted by both clinicopathologic and demographic factors, with the use of RT decreasing and the use of ET increasing in HR-positive DCIS patients. Current trials are designed to address the possible over-treatment of low-risk DCIS.
Keywords: Adjuvant therapy; Ductal carcinoma in situ (DCIS); Endocrine therapy; Radiotherapy.