Effect of local therapy on locoregional recurrence in postmenopausal women with breast cancer in the Tamoxifen Exemestane Adjuvant Multinational (TEAM) trial

Background and purpose

The TEAM trial investigated the efficacy and safety of adjuvant endocrine therapy consisting of either exemestane or the sequence of tamoxifen followed by exemestane in postmenopausal hormone-sensitive breast cancer. The present analyses explored the association between locoregional therapy and recurrence (LRR) in this population.

Material and methods

Between 2001 and 2006, 9779 patients were randomized. Local treatment was breast conserving surgery plus radiotherapy (BCS + RT), mastectomy without radiotherapy (MST-only), or mastectomy plus radiotherapy (MST + RT). Patients with unknown data on surgery, radiotherapy, tumor or nodal stage (n = 199), and patients treated by lumpectomy without radiotherapy (n = 349) were excluded.

Results

After a median follow-up of 5.2 years, 270 LRRs occurred (2.9%) among 9231 patients. The 5-years actuarial incidence of LRR was 4.2% (95% CI 3.3–4.9%) for MST-only, 3.4% (95% CI 2.4–4.2%) for MST + RT and 1.9% (95% CI 1.5–2.3%) for BCS + RT. After adjustment for prognostic factors, the hazard ratio (HR, reference BCS + RT) for LRR remained significantly higher for MST-only (HR 1.53; 95% CI 1.10–2.11), not for MST + RT (HR 0.78; 95% CI 0.50–1.22).

Conclusion

This explorative analysis showed a higher LRR risk after MST-only than after BCS + RT, even after adjustment for prognostic factors. As this effect was not seen for MST + RT versus BCS + RT, it might be explained by the beneficial effects of radiation treatment.