Omission of postoperative radiotherapy considered in older patients with breast cancer

The omission of radiotherapy after breast-conserving surgery in older patients with a low risk of local recurrence could be safe. Evidence shows that without radiotherapy, the risk of local recurrence at 10 years is low according to the results of a study by the Swedish Breast Cancer Group.¹

A key finding of the study is the feasibility of identifying patients at low risk of local recurrence who would benefit from omitting radiotherapy after breast-conserving surgery based on clinicopathological characteristics without the need for additional data from gene expression analysis. Investigators found that a small tumor with luminal-like features and nonaggressive histological characteristics was predictive of a low risk of local recurrence.

Antonis Valachis, MD, an associate professor of oncology at Örebro University in Sweden and a study coauthor, says that the results add to the growing body of evidence supporting the safe de-escalation of radiotherapy after breast-conserving surgery in older patients with breast cancer who have the described clinicopathological characteristics.

“Safely omitting radiotherapy benefits patients by eliminating the need to travel to radiotherapy facilities and reducing the risk of adverse events,” he says. “It also benefits the health care system by conserving resources.”

The prospective, national, multicenter cohort study included women aged 65 years or older who had undergone breast-conserving surgery for newly diagnosed primary invasive breast cancer and were scheduled for 5 years of endocrine therapy. All patients had low-risk, estrogen receptor–positive, T1N0 disease. Patients were followed at least annually via mammography to assess local recurrence (the primary outcome) and contralateral breast cancer, recurrence-free survival, and overall survival (secondary outcomes). The final analysis consisted of 601 women with a median age of 71 years and a median tumor size of 11 mm.

Previously published results at 5 years showed a cumulative incidence of 1.2% for local recurrence.² In the current final analysis at a median follow-up of 119 months, the cumulative incidence of local recurrence was 1.5% and 5.5% at 5 and 10 years, respectively. The cumulative incidence of contralateral breast cancer was 1.7% and 4.5% at 5 and 10 years, respectively. At 10 years, the overall survival rate was 83.1%. In the full cohort, three patients died of breast cancer.

One caveat to the study is that all women in the study had to agree to undergo endocrine therapy. “In this study, all patients received endocrine therapy for 5 years; therefore, the omission of radiotherapy is supported only for women who are willing to undergo endocrine therapy,” says Dr Valachis. The study, therefore, is not able to answer an emerging question of whether it may be preferable to treat low-risk women with breast cancer exclusively with radiotherapy or exclusively with endocrine therapy to reduce the adverse effects of both.

Dr Valachis says that further evidence looking at patients’ quality of life in relation to radiotherapy and endocrine therapy will be forthcoming in ongoing randomized trials that address this issue.