New DCIS Radiation Findings Presented at SABCS: What High-Risk Patients Should Know

At the San Antonio Breast Cancer Symposium (SABCS) in December, researchers presented updated results from a large international clinical trial examining radiation treatment after surgery for ductal carcinoma in situ (DCIS). The study offers important insights into how radiation can reduce the chance of DCIS returning in the same breast — particularly for people considered at higher risk of recurrence.

Background: Radiation After DCIS Surgery

After a lumpectomy for DCIS, many patients are offered whole breast radiation to lower the risk that DCIS will come back. One long-standing question has been whether adding an extra, targeted dose of radiation to the area where the DCIS was removed — called a tumor bed boost — provides additional benefit.

Tumor bed boosts are commonly used in invasive breast cancer, but until recently, there has been limited high-quality data specifically addressing their role in DCIS.

About the BIG 3-07 / TROG 07.01 Trial

This study (ClinicalTrials.gov ID NCT00470236) enrolled more than 1,600 women with DCIS who had undergone breast-conserving surgery and were considered to have non-low-risk DCIS (based on factors such as age, grade, size, or margins).

Participants were randomized to receive:

• Whole breast radiation alone, or
• Whole breast radiation plus a tumor bed boost

The trial also examined different radiation schedules, including hypofractionated radiation, which delivers treatment over fewer sessions.

How Long Were Patients Followed?

• The results presented at SABCS and reported publicly so far are based on a median follow-up of approximately 6.5–7 years.
• While the trial was designed to collect up to 10 years of follow-up, those longer-term results are not yet available.

In other words, these are intermediate long-term results, not final 10-year data.

Key Findings So Far

Despite not yet reaching the full 10-year follow-up, the findings are notable:

• Adding a tumor bed boost reduced the risk of DCIS or invasive cancer returning in the same breast.
• The benefit of the boost was seen across different radiation schedules.
• Shorter radiation schedules (hypofractionated radiation) appeared safe and effective, offering a more convenient option for many patients.

Overall, the study provides strong evidence that a tumor bed boost can further lower local recurrence risk in people with non-low-risk DCIS who choose lumpectomy and radiation.

What This Means for People Diagnosed With DCIS

These results do not mean that every person with DCIS needs a radiation boost. But they do suggest that:

• For patients with higher-risk features, a tumor bed boost may offer additional protection against recurrence.
• Patients should feel empowered to ask their radiation oncologist about:
  • Whether a boost is recommended in their case
  • Different radiation schedules and their trade-offs
• Treatment decisions should continue to be individualized, weighing recurrence risk, side effects, and personal values.

What Comes Next

Researchers will continue to follow participants to assess outcomes over a full 10-year period, including long-term recurrence rates and potential side effects. These future results will help further refine which patients benefit most from additional radiation.

Why This Matters

DCIS treatment decisions often occur in a space filled with uncertainty. Clinical trials like this one help move the field toward more precise, evidence-based, and personalized care — so patients can make informed choices rather than relying on one-size-fits-all recommendations.

At DCIS Understood, we will continue tracking these data and translating new research into clear, accessible information for patients and families.

Click here to read the study.