Individualizing Extended Adjuvant Therapy in HR+ Breast Cancer.

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Date: June 2021
From: Oncology(Vol. 35, Issue 6)
Publisher: Intellisphere, LLC
Document Type: Article
Length: 1,899 words
Lexile Measure: 1630L

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In the setting of hormone receptor--positive (HR+), HER2-negative, lymph node-negative (pN0) breast cancer, postsurgical antiestrogen therapy (ie, adjuvant endocrine therapy) with tamoxifen or an aromatase inhibitor is recommended for at least 5 years to reduce the risk of recurrence and extend the disease-free survival (DFS) interval. (1) However, some patients benefit from extending adjuvant endocrine therapy beyond 5 years. (1) Identifying which patients are most likely to benefit from extended therapy while sparing others from prolonged drug exposure may become easier with a new recommendation from the National Comprehensive Cancer Network (NCCN). This was the topic of discussion in a recent OncView (TM), which featured insights and perspectives from Vijayakrishna (V. K.) Gadi, MD, PhD, professor and director of medical oncology, Department of Medicine, associate director, translational oncology, University of Illinois, Chicago; and Reshma L. Mahtani, DO, associate professor of clinical medicine, Division of Hematology/Oncology; coleader of the Breast Cancer Program; director of community outreach, Sylvester Comprehensive Cancer Center, University of Miami Health System, Deerield Beach, Florida.

NCCN-Recommended Assays

In the April 2021 version of its breast cancer guidelines, the NCCN endorsed the Breast Cancer Index (BCI) assay as one that can be treatment predictive in the HR+ setting. (1) Individualized precision medicine continues to gain traction in breast cancer because of several commercially available bioassays, including the 21-gene (Oncotype Dx), 70-gene (MammaPrint), 50-gene (Prosigna), 12-gene (EndoPredict), and BCI gene expression assays. (1) Although all these assays are recommended in NCCN guidelines as prognostic indicators to complement the TNM (tumor, node, metastasis) staging system and biomarker information, not all are predictive of treatment benefit associated with the pursuit of a particular therapeutic course. (1)

"Genomic assays really aim to give us a more in-depth understanding of the biology of the individual's tumor by looking at various levels of gene expression," explained Mahtani. "The information can aid in further prognostication beyond clin[ical]-path[ological] factors alone, and most importantly, [it] can help us predict the benefit, or sometimes the lack of benefit, of our treatments such as chemotherapy and endocrine therapy."

In the realm of bioassays, Gadi explained that, if a test is prognostic, it provides information about "the chance the cancer could come back," but if it is predictive, it provides "the chance that an intervention... works versus doesn't work." Tests with predictive ability refer to whether adjuvant chemotherapy should be recommended after surgery, but in the case of the BCI assay, its predictive ability references whether adjuvant endocrine therapy should be extended beyond 5 years. This makes the BCI unique among currently recommended bioassays used for those with HR+ breast cancer.

"Many of us forget that not too long ago, we were giving chemotherapy to the majority of women with localized breast cancer regardless of lymph node status, menopausal status, or [hormone] receptor status," said Mahtani. "[However], the availability of genomic assays... has really allowed...

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Gale Document Number: GALE|A677572507