Axillary dissection versus no axillary dissection in older T1N0 breast cancer patients: 15-year results of trial and out-trial patients.

BACKGROUND: Our randomized trial found no survival advantage for axillary dissection (AD) compared observation only (no AD) in older patients with early breast cancer and a clinically negative axilla, indicating that AD is unnecessary. We compared characteristics and outcomes in out-trial patients with those in trial patients to provide indications as to whether AD can be safely omitted outside the trial setting.

METHODS: The trial started in 1996, recruiting 238 patients age 65-80 years with cT1cN0 breast cancer, randomized to conservative surgery with or without AD. Over the recruitment period, 109 eligible patients who refused to participate in the trial, also received conservative breast surgery with or without AD depending on patient preference/surgeon opinion. Trial and out-trial patients received conventionally-fractioned whole breast radiation and tamoxifen for five years. Endpoints were breast cancer mortality, overall survival, and cumulative incidence of axillary disease in patients not receiving AD.

RESULTS: After 15 years of follow-up, breast cancer mortality and overall survival did not differ between the AD and no AD arms, in either the trial or out-trial cohorts. The 15-year cumulative incidence of axillary relapse was 6% in the no AD arm of the trial group, and zero in the no AD arm of the out-trial group.

CONCLUSIONS: Outside the trial setting, older patients with T1N0 breast cancer can be safely treated by conservative surgery, postoperative radiotherapy and tamoxifen for five years (if ER-positive). Axillary surgery is appropriate only for the small proportion of patients who develop overt axillary disease during follow-up.