Updated NCCN Guidelines Strengthen Support for Breast Cancer Index® in Extended Endocrine Therapy Decision-Making

​​Key Clinical Takeaways: 

• The updated NCCN Breast Cancer Guidelines recognize Breast Cancer Index® (BCI) as the only genomic test that predicts benefit from extended endocrine therapy, supporting evidence-based decisions beyond 5 years of treatment.
• BCI is endorsed for prognostic assessment of late distant recurrence and predictive assessment of extended endocrine therapy benefit in both node-negative patients and those with 1 to 3 positive lymph nodes, including enhanced acknowledgment of its value in node-positive disease.
• By incorporating tumor biology alongside clinical features, BCI enables individualized therapy duration, identifying patients who are likely to benefit from extended therapy while sparing others unnecessary long-term toxicity.

Sami Diab, MD, Pagosa Springs Medical Center, Colorado, discusses recent updates to the National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines in Oncology for Breast Cancer, which reinforces the Breast Cancer Index® (BCI™) as the only genomic test predictive of benefit from extended endocrine therapy in patients with hormone receptor (HR)-positive, HER2-negative disease.

The updated guidance supports use of BCI for prognostic assessment of late distant recurrence and for predicting benefit from extended endocrine therapy in both node-negative patients and those with 1 to 3 positive lymph nodes. Enhanced recognition of BCI in node-positive disease highlights its role in integrating tumor biology with clinical factors to individualize treatment duration, helping clinicians avoid both overtreatment and undertreatment while minimizing unnecessary toxicity.

Transcript: 

My name is Sam Diab, I’m a board-certified medical oncologist, I’ve been in practice for approximately 28 years, and my specialty is breast cancer. I’m the medical director for the oncology program at Pagosa Medical Center and also the medical director for the Breast Cancer Index. 

A little bit of background, additional background, I practiced in an academic setting at the University of Texas, San Antonio, and the University of Colorado, and I also practiced in the community part of the US Oncology Network and was the associate director for the US Oncology Research Program. 

I would like to take this opportunity to talk about a lot of research that led to an important update in the NCCN guideline– that last update was published and finalized on January 16, 2026, so very recently. 

I think when we think about our patients in the clinic, individualization of therapy is really very important, that’s kind of the big thing that we want to give our patients advice on. We don’t want to overtreat them, we don’t want to undertreat them. Over the last 30 years, there’s been a lot of refinement in terms of our thinking and how we make decisions. One thing I want to talk about is the potential for undertreatment and also overtreatment for estrogen receptor-positive breast cancer patients. 

When we are trying to make decisions about adjuvant endocrine therapy, we’re faced with 1 major question, and that major question that we really ask early on is how long do we think we need to recommend adjuvant endocrine therapy—whether we’re talking about premenopausal or postmenopausal patients, whether we’re talking about node-negative or node-positive patients, and especially those with 1 to 3 positive lymph nodes. That’s where the guidelines kind of emphasize that individualization of therapy and using Breast Cancer Index (BCI) is very important not only for node-negative patients, but also for patients with node-positive disease with 1 to 3 positive lymph nodes.

In my practice, when I get second opinions, I’ve seen patients who are node-negative and are told, “your tumor size and grade don’t justify extended adjuvant therapy.” I think we are really missing an opportunity in these patients if we don’t do BCI, which is supported by NCCN guidelines as the only test that is able to predict the benefit of extended adjuvant therapy. There is no other molecular test available to help us with that decision about extended adjuvant therapy, we’re talking about therapy after 5 years, that’s what I mean by extended adjuvant therapy, so BCI is the only test. 

If you’re going to take patients that you think are lower risk, we really know from the biology of breast cancer that those patients still have a significantly increased risk of relapse at 20 years, referring to a paper published in 2017 in the New England Journal of Medicine, [and] that study showed that even low-grade (grade 1) node-negative patients have a significantly increased risk of relapse, up to 10%, sometimes up to 30%, depending on the clinical characteristics, there is really no group that you can identify as low risk of relapse at 20 years based on size or grade alone. BCI in this subset of patients really helps us determine who would benefit from extended adjuvant therapy. 

As you know, BCI has both prognostic and predictive components. The prognostic component for node-negative patients tells you what the risk of relapse is, and then the predictive part tells you, based on the biology, if they have a high BCI, those patients would benefit from extended adjuvant therapy. It’s really a fantastic test to give you information about recurrence [and] it’s a fantastic test to tell us the benefit of extended adjuvant therapy, because the last thing you want to do is use prognostic information alone and say, “everybody needs to go on extended adjuvant therapy,” when you realize that there are some patients who would not benefit from extended adjuvant therapy and you can avoid a lot of toxicity.

For node-negative patients, those are the patients that I sometimes see undertreated with adjuvant endocrine therapy. BCI can really identify the appropriate subset that needs extended adjuvant therapy based on prognostic and predictive information. 

Let me move on to the higher-risk patients, these are patients with node-positive disease with 1 to 3 positive lymph nodes. I’ve also seen in my practice that a lot of these patients are told “just because you’re node-positive, you have a high risk of relapse,” which is true, “and therefore you really need to proceed with extended adjuvant therapy.” That might not be the case– we might be overtreating patients if we take that approach. BCI in this subset, again, provides 2 sets of information, prognostic information, which is recognized by NCCN guidelines with new language allowing incorporation of clinical characteristics plus tumor biology based on BCI to derive prognostic information for the patient. 

When a patient asks the question, “I want to stop at 5 years, what’s my risk of relapse?” We always get asked that question, we can answer it accurately, not just based on size, not just based on grade or lymph nodes, but by incorporating the biology of the tumor with BCI to derive a more accurate prediction of relapse risk – that’s the first component. 

The second component is when the patient asks, “you’re telling me I have a 20% risk of relapse, what do I do about it?” We cannot have a uniform answer of, “you just need to stay on hormonal therapy,” because we know that BCI has predictive value for who would benefit and who would not benefit from extended adjuvant therapy. In that situation, BCI can tell us, based on your score, whether you are predicted to benefit from continued treatment and therefore should stay on therapy, or whether you would not benefit and instead should be monitored carefully so that recurrence can be detected early and intervention can occur early in the process. 

I really find BCI in my practice to be very helpful, whether we are talking about node-negative or node-positive patients.

Source: 

National Comprehensive Cancer Network. NCCN Guidelines. Accessed on January 23, 2026. https://www.nccn.org/guidelines/guidelines-detail