Accelerated Partial Breast Irradiation (APBI) For Ductal Carcinoma In Situ

Area of Science:

• Oncology
• Radiation Oncology
• Surgical Oncology

Background:

• Partial breast irradiation (PBI) criteria for ductal carcinoma in situ (DCIS) are restrictive.
• Limited guidance exists for PBI application in DCIS compared to invasive breast cancer.

Purpose of the Study:

• To evaluate disease outcomes in a heterogeneous cohort of DCIS patients treated with PBI.
• To assess the efficacy of PBI in DCIS patients, including those not meeting standard suitability criteria.

Main Methods:

• A prospectively maintained database identified 176 DCIS patients treated with lumpectomy and PBI (2008-2022).
• Patients were categorized as suitable, cautionary, or unsuitable based on ASTRO criteria.
• Local recurrence (LR) was the primary endpoint, with a median follow-up of 24 months.

Main Results:

• The cohort had a median age of 60, with 20% multifocal disease and 91% negative margins.
• 67% were suitable, 32% cautionary, and 0.6% unsuitable for PBI by ASTRO criteria.
• A single local recurrence (0.6% at 2 years) was observed, occurring in a cautionary-classified patient (1.8% 2-year LR rate for this subset). No breast cancer mortality occurred.

Conclusions:

• Early results demonstrate excellent local control with PBI for DCIS patients, including those in the cautionary group.
• These findings suggest that PBI may be a viable option for a wider range of DCIS patients.
• Further investigation into expanding PBI application for DCIS is warranted.