Adjuvant Exemestane Equals Tamoxifen–Exemestane DFS At 10 Years

Disease-free survival at 10 years is the same for women with postmenopausal early-stage breast cancer who received a 5-year course of exemestane or sequential tamoxifen and exemestane

medwireNews: TEAM findings at 10 years show comparable survival outcomes for postmenopausal early-stage, hormone receptor-positive breast cancer patients after a 5-year course of the aromatase inhibitor (AIexemestane alone or a sequential regimen of tamoxifen and exemestane. 

“This finding allows the possibility for shared decision making between the clinician and patient, balancing individual patient characteristics and preferences, side-effect profiles, and tolerability”, say Cornelis van de Velde, from Leiden University Medical Center in the Netherlands, and co-investigators. 

“Future studies will hopefully show which subgroup, if any, benefits more from a particular strategy, and whether extension of any of these treatments beyond 5 years is worthwhile.” 

At a median of 9.8 years, 30% of the 3075 women randomly assigned to receive extended adjuvant therapy with exemestane 25 mg/day had died or developed disease recurrence, as had 31% of the 3045 patients who were treated with tamoxifen 20 mg/day for up to 3 years followed by exemestane 25 mg/day for a total of 5 years. 

Disease-free survival (DFS) at 10 years was 67% in both treatment groups and showed a consistent treatment effect across patient subgroups and clinicopathological characteristics, the team reports in The Lancet Oncology. 

Overall survival was also comparable at 10 years, at 74% with AI monotherapy and 73% with sequential tamoxifen–exemestane. 

And although the cumulative incidence of breast cancer recurrence was significantly lower with exemestane alone than sequential therapy (20 vs 22%, hazard ratio=0.88), the incidence of distant recurrence did not significantly differ, at 16% and 18%, respectively. 

Nor did breast cancer-specific mortality differ significantly between the exemestane monotherapy and sequential tamoxifen–exemestane treatment groups, at 13.5% versus 15.4%. 

“With no evident improvement in disease-related outcomes and overall survival, nor a clear superiority of either aromatase inhibitor monotherapy or sequential therapy in a specific subgroup, the choice of therapy might depend on safety and tolerability, not only during, but also after completion of treatment”, Cornelis van de Velde et al comment. 

They note that the 5-year TEAM analysis had suggested a higher rate of thromboembolic and gynaecological adverse events with tamoxifen use, and possible evidence of poorer cognitive function from sub-studies of TEAM, whereas exemestane therapy was associated with musculoskeletal disorders including osteoporosis and related fracture. 

However, noting that long-term adverse event outcomes were not collected for the TEAM study, the authors suggest: “It would be worthwhile to develop a cardiovascular risk profile, and potentially other risk profiles, enabling selection of the appropriate therapy regimen for a particular patient.” 

References 

Derks MGM, Blok EJ, Seynaeve C, et al. Adjuvant tamoxifen and exemestane in women with postmenopausal early breast cancer (TEAM): 10-year follow-up of a multicentre, open-label, randomised, phase 3 trial. Lancet Oncol; Advance online publication 18 July 2017. DOI: http://dx.doi.org/10.1016/S1470-2045(17)30419-9