Three Weeks of Radiation After Mastectomy Works as Well as Five, 10-Year Data Show

For many women with high-risk breast cancer, radiation after mastectomy means five weeks of daily treatments. New 10-year results suggest three weeks can be just as effective.

The findings, from a phase 3 trial at the National Cancer Center in China, were presented at the American Society for Radiation Oncology (ASTRO) 2026 Annual Meeting in Boston.

What the Trial Compared

The trial enrolled 820 patients with high-risk breast cancer after mastectomy. Most (94%) had stage 3 disease, and all had received chemotherapy. Patients were randomly assigned to:

• Standard radiation: 25 treatments over five weeks, or
• Shorter (hypofractionated) radiation: 15 slightly larger treatments over three weeks.

Both groups received radiation to the chest wall and the lymph nodes above the collarbone.

What It Found After 10 Years

Researchers followed patients for a median of 11.5 years, one of the longest follow-ups of any trial testing shorter radiation after mastectomy. Of the 820 people enrolled, 810 were included in the final analysis: 401 in the three-week group and 409 in the five-week group.

The trial was designed to answer one main question: Is the shorter schedule no worse than the standard one at keeping cancer from coming back in the treated area? At 10 years, the answer held up.

• Cancer returning in the chest wall or nearby lymph nodes (locoregional recurrence): This was the trial's main measure. At 10 years, it happened in 12.0% of people in the three-week group and 10.3% in the five-week group. That 1.7-percentage-point gap was not statistically significant, meaning it could be due to chance. The 5-year results, which the trial was built around, were similarly close: 9.6% vs 8.6%.
• Disease-free survival: This measures how many people were alive with no sign of cancer anywhere in the body. At 10 years, it was 69.9% in the three-week group and 65.2% in the five-week group.
• Overall survival: At 10 years, 77.5% of people in the three-week group were alive, compared with 72.9% in the five-week group.

Survival was slightly higher with the shorter schedule, but that difference was not statistically significant either. The takeaway is not that three weeks works better, but that it works about as well. There was no sign that giving the treatment in fewer, slightly larger doses let more cancer come back over time.

That matters because some doctors have hesitated to use shorter schedules after mastectomy, especially when lymph nodes are treated, out of concern that problems might appear only years later. Ten-year data speak directly to that concern. Earlier results from this trial were published in The Lancet Oncology in 2019.

Long-term side effects were similar. Arm swelling (lymphedema) occurred at similar rates, and skin problems, shoulder problems, heart disease and rib fractures didn't differ. Mild, symptom-free lung scarring was more common with the shorter schedule (20% vs 12%).

The investigators concluded that the results further establish shorter radiation after mastectomy as a standard of care.

What It Means for You

Fewer treatments means fewer trips, less time off work and lower travel costs, which matters especially for people who live far from a radiation center. Shorter schedules are already widely used after lumpectomy; these results add long-term support for using them after mastectomy, too. Whether it's right for you depends on factors such as breast reconstruction plans and which areas need treatment.

Questions to Ask Your Radiation Oncologist

• Am I a candidate for a three-week schedule?
• Would a shorter schedule affect my breast reconstruction?
• What long-term side effects should I watch for?

References

1. American Society for Radiation Oncology. "Hypofractionated Versus Conventional Fractionated Postmastectomy Radiotherapy in High-Risk Breast Cancer: 10-Year Outcomes From a Phase 3 Randomized Trial." Sept. 28, 2026.
2. CancerNetwork. "Hypofractionated PMRT Shows Durable 10-Year Control in High-Risk Breast Cancer." September 2026.
3. Newswise. "Additional Research Highlights From the 2026 ASTRO Annual Meeting." Sept. 25, 2026.
4. Wang, Shu-Lian, et al. "Hypofractionated Versus Conventional Fractionated Postmastectomy Radiotherapy for Patients With High-Risk Breast Cancer: A Randomised, Non-Inferiority, Open-Label, Phase 3 Trial." The Lancet Oncology, 2019.

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