Neoadjuvant Endocrine Therapy ‘Worthwhile Option’ For ER-Positive Local Breast Cancer

Neoadjuvant endocrine therapy for oestrogen receptor expressing local breast cancer equals neoadjuvant chemotherapy efficacy with reduced toxicity

medwireNews: Neoadjuvant endocrine therapy (NET) is a "reasonable treatment option" for patients with localised oestrogen receptor (ER)-positive breast cancer, conclude the authors of a meta-analysis of 20 clinical trials. Aditya Bardia, from Massachusetts General Hospital Cancer Center in Boston, USA, and team pooled information from 3490 participants of studies including at least one NET regimen, the majority of which recruited women with postmenopausal breast cancer. Compared with neoadjuvant chemotherapy, NET consisting of aromatase inhibitor (AI) monotherapy achieved similar rates of clinical response (odds ratio [OR]=1.08), radiological response (OR=1.38) and breast conserving surgery (BCS; OR=0.65).

There was also evidence of lower toxicity, for example, a significantly reduced risk of grade 3–4 adverse events reported in one study (OR=0.11). Other studies cited lower rates of adverse events such as nausea, neutropenia and anaemia.

The researchers also compared neoadjuvant regimens of tamoxifen and AIs, finding that AI NET offered a significantly better clinical response rate (OR=1.69), radiological response rate (OR=1.49) and BCS rate (OR=1.62), with low toxicity for both options.

Finally, dual combination therapy including growth factor pathway inhibitors significantly improved the patient radiological response rate compared with endocrine monotherapy (OR=1.59) although there was no significant impact on the clinical response rate.

"Given the low toxicity associated with NET, reconsideration of NET as a worthwhile treatment option in the neoadjuvant setting is reasonable, particularly as combination therapy, similar to [neoadjuvant chemotherapy] in combination, for the correct patient population", the authors conclude in JAMA Oncology. But they emphasize: "Determining the correct patient population for NET remains an unanswered question, and will be best addressed by additional studies incorporating NET with strong biomarker–driven hypotheses.

“Neoadjuvant endocrine therapy also provides the opportunity to examine mechanisms of endocrine resistance, to optimize and compare endocrine therapies, and to investigate combination approaches with novel targeted therapies that may delay or prevent endocrine resistance.”


Spring LM, Gupta A, Reynolds KL, et al. Neoadjuvant endocrine therapy for estrogen receptor-positive breast cancer. A systematic review and meta-analysis. JAMA Oncol 2016; Advance online publication 30 June. doi:10.1001/jamaoncol.2016.1897

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