Neoadjuvant endocrine therapy (NET) may be associated with similar response rates as neoadjuvant combination chemotherapy, but with significantly lower toxicity, findings from a study published in JAMA Oncology show.
NET is already a staple of adjuvant treatment for patients with estrogen receptor-positive (ER+) breast cancer, but its role in the neoadjuvant setting is still unclear. Therefore, researchers led by Laura M Spring, MD, Massachusetts General Hospital (Boston, MA) conducted a study to evaluate the effect of NET on the response rate and rate of breast conservation surgery (BCS) for patients with ER+ breast cancer.
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For the study, researchers conducted a librarian-led search of PubMed and Ovid MEDLINE to identify prospective, randomized, neoadjuvant clinical trials that reported response rates with at least 1 arm incorporating NET. They estimated pooled odds ratios (ORs) for end points using fixed- and random-effects statistical models.
A total of 20 studies with 3490 unique patients were identified as eligible for inclusion in the analysis. Compared with combination chemotherapy, NET monotherapy with aromatase inhibitors produced a similar clinical response (OR, 1.08), radiological response rate (OR, 1.38), and BCS rate (OR, 0.65), but with lower toxicity. Use of aromatase inhibitors was associated with significantly higher clinical response rate (OR, 1.69), radiological response rate (OR, 1.49), and BCS rate (OR, 1.62) compared with tamoxifen.
Additionally, while dual combination therapy with growth factor pathway inhibitors had a higher radiological response rate (OR, 1.59), they were also associated with a lower clinical response rate (OR, 0.76) compared with endocrine therapy.
Thus, researchers concluded that response rates for endocrine therapy has a lower toxicity than neoadjuvant chemotherapy, but with a similar response rate, suggesting that it should be considered as a potential option for the appropriate patients with ER+ breast cancer. They added that more research will be needed to examine predictive biomarkers capable of personalizing NET plus targeted therapy combinations.
