A randomized trial of long term adjuvant tamoxifen plus postoperative radiation therapy versus radiation therapy alone for patients with early stage breast carcinoma treated with breast-conserving surgery. Stockholm Breast Cancer Study Group.

BACKGROUND

The use of adjuvant tamoxifen to treat postmenopausal breast carcinoma patients as an adjunct to primary surgery is well established. The current study reports the long term results for a low risk stratum in a randomized trial of adjuvant tamoxifen. The main focus of this analysis was to determine whether tamoxifen would result in a reduced local failure rate for lymph node negative, postmenopausal patients treated with breast-conserving surgery and postoperative radiotherapy.

METHODS

The study population included 432 lymph node negative, postmenopausal patients with invasive breast carcinoma (classified as T1-T2) who underwent breast-conserving surgery followed by radiotherapy in Stockholm during the period 1976-1990. The patients constituted a separate stratum of the Stockholm Adjuvant Tamoxifen Trial, which included a total of 2729 patients. Of 432 patients, 213 received 40 mg of tamoxifen daily for either 2 or 5 years. The median follow-up time was 8 years (range, 5-19 years).

RESULTS

At 10 years, the overall survival was 90% for the tamoxifen group and 88% for the control group. The event free survival at 10 years was 80% for the tamoxifen group and 70% for the control group (P=0.03). Tamoxifen reduced the overall rate of ipsilateral (hazard ratio=0.4, 95% confidence interval [CI]=0.2-0.9, P=0.02) and contralateral breast tumor recurrences (hazard ratio=0.4, 95% CI=0.1-1.1, P=0.06). Trends toward a reduced number of distant metastases (hazard ratio=0.6, 95% CI=0.3-1.2, P=0.1) and deaths due to breast carcinoma (hazard ratio=0.5, 95% CI=0.2-1.2, P=0.1) also were observed. CONCLUSIONS. The addition of tamoxifen to radiotherapy for postmenopausal, lymph node negative breast carcinoma patients treated with breast-conserving surgery resulted in a reduced rate of ipsilateral and contralateral breast tumor recurrences. The avoidance of salvage mastectomies, reexcisions, and new contralateral malignancies justifies the use of tamoxifen even in the treatment of patients with a 10-year survival rate of 90%.