The Breast Cancer Index Impacts Physicians’ Decision to Extend Endocrine Therapy for HR+ Early-Stage Disease

Tara Sanft, MD

After incorporating the Breast Cancer Index (BCI) test assay into practice, many clinicians changed their recommendation regarding administration of extended endocrine therapy to patients with hormone receptor (HR)–positive, early-stage breast cancer, according to findings from a prospective BCI Registry study published in the Journal of the National Comprehensive Cancer Network (JNCCN).

“The BCI test can help take the guesswork out of extended endocrine therapy decision-making. BCI [testing] helps us understand a patient’s individual risk of late-distant recurrence and predicts the benefit of continuing endocrine therapy for an additional 5 years,” Tara Sanft, MD, the primary author of the study, wrote to OncLive®. “It is supported by comprehensive validation and is recognized by both ASCO and NCCN Guidelines as the only test to predict which patients are likely to benefit from extended endocrine therapy. This translates to more informed, confident decisions from both doctors and patients.”

In the study, questionnaires were completed by 843 clinicians and revealed that 56.8% (n = 479) recommended extended endocrine therapy prior to BCI testing, whereas 42.5% (n = 358) did not and0.7% (n = 6) did not answer. Following BCI testing, among the physicians who recommended extended endocrine therapy, many changed their minds; 54.1% still advised endocrine therapy, 44.7% did not, and 1.3% did not answer. Among those who originally did not advise extended endocrine therapy, 65.1% still did not recommend the therapy whereas 34.6% did and 0.3% did not answer. The findings highlighted that physicians changed their recommendations in 40.1% of patients (P < .0001).

Additionally, 45.1% of patients changed their preferences for receiving extended endocrine therapy (P < .0001), and 20.9% of patients were less concerned about the cost (P < .0001) of the therapy. Further, 25.4% and 29.3% were less concerned about drug safety (P = .0014) and the benefits of extended endocrine therapy(P = .0002), respectively.

Sanft, an associate professor of Medicine at Yale School of Medicine and chief patient experience officer at Smilow Cancer Hospital, in New Haven, detailed the findings of the study to OncLive, expanding on the importance of the assay.

OncLive: What was the rationale for conducting this research?

Sanft: [Although] extension of endocrine therapy beyond 5 years has been shown across multiple studies to help reduce the risk of late recurrence for some women, the absolute benefit is modest, and most do not benefit. The treatment is also accompanied by the potential for adverse effects [AEs] such as bone and cardiovascular toxicities, endometrial cancer, and other AEs that decrease quality of life.

The BCI test provides an individualized risk of late distant recurrence—5 to 10 years—and predicts whether a patient with HR-positive, early-stage breast cancer is likely to benefit from extended endocrine therapy. The test’s ability to predict extended endocrine therapy benefit has previously been validated in 5 studies and over 4500 patients, and over the past 3 years has been recognized by ASCO and NCCN Guidelines as the only test to predict extended endocrine therapy benefit. This research was conducted to assess the clinical impact of the test on decision-making related to extended endocrine therapy, as well as the impact on confidence and comfortability around those decisions for both doctors and patients.

What methods were used to conduct this research?

These are the first results to come out of the BCI Registry Study [which is] a large-scale, prospective, multicenter study that investigates the impact of BCI testing on treatment decisions in patients with early-stage HR-positive breast cancer. This study reports findings on the clinical decision-making experience [of] the first 1000 patients enrolled in the study.

Of the first 1000 patients enrolled, we had complete data on 823 patients. Both patients and their physicians took pre- and post-BCI test questionnaires. The physician questionnaire asked about initial physician treatment recommendations regarding extended endocrine therapy and physician confidence levels with this decision. The patient questionnaire looked at preferences for extended endocrine therapy, patient comfort levels regarding the treatment recommendation, and patient concerns about the cost, AEs, drug safety, and benefits of the therapy. We then compared the survey responses to assess the impact of testing on these factors.

What were the key findings from the study published in JNCCN?

We found that 40% of treatment recommendations related to extended endocrine therapy changed following the results of the BCI test. To us, this indicates that a significant proportion of patients with HR-positive, early-stage breast cancer may be either over- or under-treated without incorporation of BCI.

Of the physician treatment decisions that changed, 63% changed from a “yes” to a “no” recommendation for extended endocrine therapy, suggesting BCI may be a tool to help avoid over-treatment. On the other hand, the 37% of decisions that shifted from a “no” to “yes” underscore the importance of BCI to also help identify women who may clinically be thought of as “low risk” due to tumor size, age, etc., yet may benefit from longer treatment to help reduce their risk of a potentially life-threatening metastatic recurrence.

We also saw that 45% of patients changed their preferences for extended endocrine therapy after receiving BCI results, and 41% felt more comfortable with their treatment decisions. This increase in comfort is especially important because when patients know the treatment is helping them, there is a greater chance of adherence to the medication.

How has the BCI assay impacted your practice in particular?

As a clinician treating patients, it feels good to be able to recommend treatments with more confidence and precision. For patients who need to extend their endocrine therapy, the results of the BCI test can help them adhere to the treatment, knowing it is likely to help reduce the risk of recurrence.

In a previous study, we found that 82% of patients who were recommended extended endocrine therapy based on their BCI results reported they were more likely to stick with their treatment plan.

Patients whose BCI results indicate that they are not likely to benefit from extended endocrine therapy are often happy to discontinue the medication, particularly if they are experiencing AEs that impact their daily lives.

What do you want colleagues to take away from this research?

These results help reinforce what we already know—the traditional clinical and pathologic factors we have used for years to make treatment decisions are limited, and we now have predictive biomarkers like the BCI test to assess the biology of a patient’s tumor to help us make more personalized recommendations for our patients. This study truly highlights the clinical utility of using BCI to help avoid over- and undertreatment in our patients, and to ensure that we are making the most informed decisions possible as it relates to the use of extended endocrine therapy.

As part of the study, we also look forward to assessing how the test impacts patient adherence in the future, a major issue for patients on long-term endocrine therapy.

Reference

Sanft TB, Wong J, O'Neal B, et al. Impact of the breast cancer index for extended endocrine decision-making: first results of the prospective BCI registry study. J Natl Compr Canc Netw. 2024;22(2):99-107. doi:10.6004/jnccn.2023.7087