Dec 26, 2025 By Kristin Emery 4 min read

Radiation has been a staple of breast cancer treatment for decades, but a new study is casting doubt on whether it is necessary or beneficial for some patients.

The study published recently in the New England Journal of Medicine found that radiation of the chest wall led to no difference in survival rates among patients with early-stage breast cancer who had undergone lymph node surgery and mastectomy and taken anti-cancer drugs.

The study had a very long follow-up period and looked at patients at intermediate risk (Stage II cancer) with affected lymph nodes or aggressive tumors with no affected lymph nodes. Out of the 1,600 women studied, only 29 had recurrent cancer in the chest area within 10 years even without undergoing radiation.

“This is an important trial in the management of breast cancer patients,” says Dr. Chirag Shah, Department Chair of Radiation Oncology at the Allegheny Health Network Cancer Institute. “This will help define the standard of care for appropriately selected patients.”

He pointed out one major limitation of the study. “The majority of patients in the trial had axillary lymph node dissections, which may reduce the benefit of radiation and may not be applicable to modern care patterns,” he said. “Based on other trials (AMAROS trial), we will often forgo an axillary dissection in lieu of radiation therapy.”

In this study, half the patients were assigned radiation after surgery while the other half were not. After 10 years, both groups showed a nearly identical survival rate of 81%. While the results show survival rates, they did not show whether radiation treatment or lack of it prevented recurrence of the cancer or spread to other parts of patients’ bodies.

Radiation therapy treats cancerous tumors by directing high-energy beams or particles to damage the DNA of cancer cells. This causes them to stop growing and die. The drawback is that the radiation can also affect healthy, non-cancerous cells, but they can often recover from the treatment. Doctors have traditionally used chemotherapy and radiation to treat cancer based on studies that have shown their benefits.

“For example, with regards to radiation following mastectomy, previous randomized trials showed not only a reduction in recurrence but improvement in survival,” explains Shah. “Radiation therapy for breast cancer is localized to the breast/chest wall and/or lymph nodes based on the clinical scenario where in contrast chemotherapy tends to be considered systemic therapy, where treatment is given through an IV or orally and goes throughout the body.” Radiation treatment can come with short-term and long-term side effects and risks.

“Short-term side effects can include fatigue, redness/peeling of the skin most commonly,” says Shah. “Long-term side effects can include skin changes, arm swelling (lymphedema), heart/lung side effects, and in very rare cases a second cancer. Modern techniques have reduced the risk of side effects.” It can also make breast reconstruction more difficult.

According to the American Cancer Society, breast cancer is the most common cancer in women in the United States behind skin cancer. Nearly 1 in every 8 women in the United States (or around 13%) will be diagnosed with invasive breast cancer in their lifetime. Advances in radiation treatment and more targeted therapy have shortened the duration of treatment in recent years, and doctors have begun reducing radiation treatment for women at low risk of recurrence or spread.

While this study shows that some women at intermediate risk can likely skip radiation, doctors say it is still vital for higher risk patients and Shah still urges caution.

“My takeaway is that for patients matching the trial eligibility criteria of the trial, that patients should be informed that radiation therapy has been shown in this study to not improve survival, though there may be an increase in chest wall recurrences,” says Shah. “Additionally, with many women not having lymph node dissection, those women would still be recommended for radiation therapy based on other clinical trials. The most important thing is shared decision making with the patient and their oncologist.”