Radiotherapy, chemotherapy, and tamoxifen as adjuncts to surgery in early breast cancer: a summary of three randomized trials

Abstract

The paper summarizes up-dated results of three randomized adjuvant trials from the Stockholm Breast Cancer Group. The objective of all studies included an evaluation of the role of megavoltage radiation in the primary management of patients with early breast cancer. The first trial was started in 1971 and included 960 pre- and postmenopausal patients with operable disease. The study compared adjuvant radiotherapy with surgery alone. All patients were treated with a modified radical mastectomy. There was a sustained improvement of the recurrence-free survival with radiotherapy (p less than 0.001). Among node positive cases radiation reduced the frequency of both loco-regional recurrence (p less than 0.001) and distant metastasis (p less than 0.01). This observation indicates that distant dissemination in subgroups of patients can originate from uncontrolled local deposits of tumor cells, for instance in the regional lymph nodes. No adverse effect from radiation on long-term survival was observed. The second study was started in 1976 and compared postmastectomy radiation with adjuvant chemotherapy in pre- and postmenopausal high-risk patients. At a mean follow-up of 6 1/2 years there was no significant difference in recurrence-free survival between the two treatments. However, postmenopausal patients fared better with radiotherapy (p less than 0.01). In this subgroup, radiation was more effective than adjuvant chemotherapy in reducing both distant metastases (p less than 0.01) and loco-regional recurrences (p less than 0.001). In the third trial--which only included postmenopausal patients--2 years of adjuvant tamoxifen was compared with no adjuvant endocrine treatment. The number of treatment failures was significantly reduced with tamoxifen (p less than 0.01) but there was no significant overall survival benefit. Subset analysis indicated that tamoxifen improved the recurrence-free survival among patients treated with adjuvant chemotherapy (p less than 0.01) but only to a level close to that achieved with radiotherapy alone. Addition of tamoxifen to radiotherapy failed to further increase the recurrence-free survival.