Skipping surgical axillary staging does not compromise survival in breast cancer

In patients with clinically node-negative, T1 or T2 invasive breast cancer, omission of axillary staging does not appear to have a negative impact on disease–free survival, according to the results of the INSEMA trial.

INSEMA included 5,502 patients with clinically node-negative invasive breast cancer staged as T1 or T2 (tumour size, ≤5 cm) who were scheduled to undergo breast-conserving surgery. Of these, 90 percent had clinical T1 disease and 79 percent had pathological T1 disease. The patients were randomly assigned to undergo treatment without axillary surgery (surgery-omission group) or to undergo sentinel-lymph-node biopsy (surgery group).

The primary outcome was invasive disease–free survival in the per-protocol population. Noninferiority of the omission of axillary surgery was established if the 5-year invasive disease–free survival rate was at least 85 percent, and the upper limit of the confidence interval [CI] for the hazard ratio [HR] for invasive disease or death was below 1.271.

The per-protocol population comprised 4,858 patients, including 962 in the surgery-omission group and 3,896 in the surgery group. Over a median follow-up of 73.6 months, the estimated 5-year invasive disease–free survival rate was 91.9 percent (95 percent CI, 89.9–93.5) among patients in the surgery-omission group and 91.7 percent (95 percent CI, 90.8–92.6) among patients in the surgery group. The corresponding HR of 0.91 (95 percent CI, 0.73–1.14) met the prespecified noninferiority criteria.

When the first primary-outcome events were analysed individually, recurrence of invasive disease or death from any cause occurred in 525 patients (10.8 percent) overall. Axillary recurrence was reported in 1.0 percent of patients in the surgery-omission group vs 0.3 percent in the surgery group, while death was documented in 1.4 percent vs 2.4 percent of patients in the respective groups.

In terms of safety, the surgery-omission group had fewer lymphedema events, greater arm mobility, and less pain with movement of the arm or shoulder compared with the surgery group.