Dr Diab on the Role of the BCI for Optimizing Endocrine Therapy Use in Breast Cancer

“We need to order the right tests for the right patients, otherwise we might be over-treating or under-treating our patients.”

Sami Diab, MD, medical director of the Center for Cancer and Blood Research at the Pagosa Springs Medical Center, discussed clinical insights regarding the nuanced application of genomic assays in determining the necessity of extended adjuvant therapy for patients with breast cancer.

Diab noted that he frequently asks for second opinions on complex treatment decisions, emphasizing the importance of adhering to evidence-based guidelines rather than extrapolating data from tests designed for other clinical questions. He explained that although 21-gene and 70-gene assays are highly validated tools for guiding initial decisions about chemotherapy, their utility does not extend to the decision-making process for extended adjuvant endocrine therapy.

Diab acknowledged that oncologists often recommend extended therapy based on results from these early-stage molecular tests, a practice he cautioned against because different clinical questions require distinct, specialized assays. He highlighted that clinical research has confirmed the unique role of the Breast Cancer Index (BCI) in this setting. According to Diab, the BCI can stratify patients in ways that other assays cannot. For instance, Diab said that a subset of patients identified as having low-risk disease per the 21-gene recurrence score may still derive benefit from extended adjuvant endocrine therapy, based on their BCI results.

Conversely, Diab added that patients categorized as having high-risk disease by the 21-gene assay can be further stratified by the BCI into a low-risk group that may not require or benefit from extended adjuvant endocrine therapy. He concluded by stressing that oncologists must prioritize ordering the right test for an individual patient at the correct time in their treatment journey. Failure to do so, he warned, increases the risk of either over-treating patients who will not benefit or under-treating those who require extended therapeutic intervention.