Radiation after breast cancer surgery did not impact distant recurrence or overall survival among older women, suggesting that certain patients may safely choose to forego the treatment, according to a new study published in the New England Journal of Medicine.

Study details and key findings

In a randomized clinical trial, researchers recruited 1,326 older female patients with hormone receptor-positive, node-negative, T1-2 primary breast tumors and who had surgery to remove their tumors. The median age of the participants was 70 years, and 1,263 were recruited from the United Kingdom.

Between 2003 and 2009, the patients underwent 1:1 randomization to either receive radiation or go without it post-surgery. In total, 658 patients received radiation, and 668 did not. All patients were also recommended to receive endocrine therapy for five years, and around 60% and 70% followed this guidance.

At the end of the 10-year follow-up period, the researchers found that while radiation reduced the risk of local cancer recurrence, it did not adversely impact either distant recurrence or overall survival rates.

Overall, 9.5% of patients in the no radiation group had their breast cancer recur locally within 10 years compared to 0.9% of those in the radiation group.

According to the researchers, the difference in local recurrence among the two groups was "modest," and the incidence rate among patients in the no radiation group "lies within range from the European Society of Mastology (EUSOMA) guidelines, which cited a maximum rate of locoregional recurrence of 10% at 10 years."

However, in a post-hoc subgroup analysis, cumulative recurrence was higher among women with estrogen receptor (ER)-low tumors at 19.1% vs. 8.6% for those with ER-high tumors. Patients in the no radiation group who discontinued the recommended five years of endocrine therapy also had a four-times greater risk of local recurrence than those who completed the therapy.

When it came to distant recurrence and overall survival at 10 years, patients in both groups saw similar rates. In total, 1.6% of the no radiation group had distant recurrence of their cancer compared to 3% of the radiation group. Overall survival rates were also roughly 80% for both groups.

Overall, the researchers said that the trial "provides robust evidence" that older women with ER-high breast cancer tumors can safely omit radiation "provided that they receive 5 years of adjuvant endocrine therapy."

Commentary

In an accompanying editorial, Alice Ho, from Duke University School of Medicine, and Jennifer Bellon, from Dana-Farber Cancer Institute, said the study's findings "offer a response to the long-standing problem of overtreatment in older women with low-risk breast cancer" and "put[s] to rest" any doubt about whether omitting radiation is possible for certain older women with breast cancer.

In particular, they said that the 10-year follow up is "extremely reassuring, given the long natural history of ER-positive breast cancer."

However, they noted that radiation may still be beneficial for certain patients, especially those who are concerned about local recurrence of the cancer.

"Even if radiation does not change survival for an older woman, many may say, 'If it cuts down my risk of local recurrence, and I can do it in five days without burdening my life, then very well,'" Ho said.

In general, patients should carefully consider whether receiving or skipping radiation is best for them and their health goals. According to Ho and Bellon, the study's findings can "help patients navigate these complex choices so that they can make well-informed and prudent decisions for the management of their breast cancer."

"It's about tailoring the treatment and customizing it to the patient’s disease and preferences," Ho said. "… How you make that decision has changed. There are nuances that we didn't ask, the patient didn’t ask, in the past like the degree of estrogen receptor positivity and what types of regimens your radiation oncologist offers. I think this trial will change much. It demonstrated details not available before." (Chen, STAT, 2/15; Bassett, MedPage Today, 2/15; Kunkler et al., New England Journal of Medicine, 2/16)