Life After Breast Cancer: Why Treatment Decisions Are Becoming More Personal
For many breast cancer survivors, treatment does not end after surgery, chemotherapy or radiation. Follow-up care may continue for years as oncology teams work to reduce the risk of recurrence.
For patients with hormone receptor-positive (HR+) breast cancer — the most common subtype — ongoing therapy often includes medications designed to block the production of hormones that can fuel cancer growth.1 These types of drugs can come with significant side effects.
Because this often represents the longest phase of treatment, patients and their physicians face an important and difficult question: how long should therapy continue?
Advances in genomic testing are helping answer that question with greater precision.
What is endocrine therapy?
For HR+ breast cancers, which grow in response to estrogen and/or progesterone, doctors often prescribe medications known as endocrine therapy. These treatments work by lowering hormone levels in the body or blocking hormones from reaching cancer cells, helping prevent remaining cancer cells from growing or spreading.
“Patients have surgery and maybe chemotherapy and radiation therapy, but then after that we really need to go after those tiny seeds that could be hiding somewhere else in the body,” said Dr. Sami Diab, Associate Medical Director, Oncology at Hologic.* “Endocrine therapy is one of the strategies for estrogen receptor-positive breast cancer to stop those seeds before they metastasize or grow.”
Five years or ten?
Endocrine therapy helps lower the risk of recurrence, but it can also cause long-term side effects, such as hot flashes, mood swings, sexual dysfunction, joint pain, lymphedema and changes to bone health.2
“It’s not unusual to have a patient after one or two years of taking the hormonal therapy say, ‘My quality of life is horrible,’” said Dr. Diab. “You really need to then stop and say, are we actually keeping the cancer at bay with these medications?”
These decisions can be especially challenging with HR+ breast cancers because they carry a persistent risk of recurrence. Studies show that over half of recurrences in HR+ breast cancer occur after the five-year mark.3
For some patients, the recommended minimum five years of endocrine therapy may be enough.4 Others may benefit from extended endocrine therapy that lasts a full 10 years to help reduce recurrence risk.5-10
To estimate risk, clinicians have traditionally relied on clinical features such as tumor size, grade, stage and lymph node involvement. But these features don’t always capture the full biological behavior of a tumor.
“Tumors that look exactly the same on the outside — the same size, grade and with the same lymph node status — can have very different biology,” said Dr. Diab. “Understanding the biology of the tumor is very important.”
Looking beyond traditional risk factors
One tool used to support this decision is the Breast Cancer Index® (BCI™) Test, a genomic test that analyzes gene expression within the tumor to help physicians better understand how an individual patient’s cancer behaves.
The test helps estimate the risk of breast cancer recurrence years after treatment and predicts whether a patient is likely to benefit from extended endocrine therapy.
Studies have shown that access to this type of information can significantly influence treatment planning. In one analysis, physicians changed their extended endocrine therapy recommendations for roughly 40% of patients after receiving BCI Test results.11
This test, said Dr. Diab, is “helping healthcare providers move beyond a one-size-fits-all approach to breast cancer survivorship.”
“Individualization of therapy is very important in breast cancer care,” he said. “We don’t want to overtreat our patients, and we don’t want to undertreat them.”
Over the past decade, the BCI Test has become widely used to help guide decisions about extended endocrine therapy. It has also received exclusive guideline recognition from the National Comprehensive Cancer Network (NCCN Guidelines®) and the ASCO® Clinical Practice Guideline. 4,12 The BCI Test is the only genomic assay recognized by both national guidelines to predict who is likely to benefit from extended endocrine therapy beyond five years.4,12
Using data to support tailored treatment decisions
At Duke Women’s Cancer Center in Raleigh, North Carolina, nurse practitioner Kassiane Saieed† works closely with patients on their survivorship care plan.
“We use the Breast Cancer Index Test almost every day because of how we can rely on it to help tailor someone’s endocrine therapy,” said Saieed.
Historically, the BCI Test has been used around the five-year mark to help inform decisions about whether endocrine therapy should continue beyond five years.
“When you bring up the thought of going five more years, it opens up a whole new conversation about tolerability,” she said. “These are not easy medications. They’re life altering in so many ways.”
“If there are patients who aren’t benefiting from more medicine, why would we keep them on it? We are trained to use the minimal effective dose,” said Saieed. “But there are women who tolerate these drugs beautifully; and if they can get a huge benefit by extending, then they should have that information and opportunity to decide.”
An estimated 30–50% of patients discontinue endocrine therapy early, often due to its adverse effects and before reaching this critical decision point.13-16 Emerging research suggests insights from the BCI Test may soon help providers address this challenge.‡
New published data show that the BCI Test can assess a patient’s risk of recurrence over ten years, providing additional insight and clearer expectations from the start of endocrine therapy planning.17-19‡
“When we can unlock genomic insights about a patient’s tumor sooner, it allows us to have more meaningful conversations and establish an agreed-upon treatment plan upfront,” said Dr. Diab. “This is key to helping patients stay committed to the treatment plan that makes the most sense for them personally.”
A more collaborative approach to breast cancer care
Advances in testing are helping clinicians and patients take a more personalized approach to breast cancer survivorship.
“We really need to empower our patients by providing them with the information they need to make decisions about risk and benefit from endocrine therapy,” said Dr. Diab.
For Saieed, those conversations are a core part of her practice.
“Women want to be involved in their care,” she said. “It’s not just a ‘here’s your pill, do this.’ Patients want to know why, how long and what [endocrine therapy] is going to do. We should be equipped to give them that information.”
As genomic testing and personalized treatment strategies continue to evolve, decisions about long-term breast cancer therapy are becoming more individualized, helping ensure patients receive treatment that fits both their risk and lifestyle.
1. National Cancer Institute. Breast cancer subtypes. SEER Cancer Stat Facts. Accessed 2026. https://seer.cancer.gov/statfacts/html/breast-subtypes.html 2. Jennifer Carr. Side Effects of Hormonal Therapy for Breast Cancer. BreastCancer.org. Updated May 4, 2026. Accessed June 1, 2026. https://www.breastcancer.org/treatment/hormonal-therapy/side-effects 3. Pan H, et al. N Engl J Med. 2017;377:1836-1846. 4. Referenced with permission from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Breast Cancer V.3.2026. © National Comprehensive Cancer Network, Inc. 2026. All rights reserved. Accessed June 1, 2026. To view the most recent and complete version of the guideline, go online to NCCN.org. NCCN makes no warranties of any kind whatsoever regarding their content, use or application and disclaims any responsibility for their application or use in any way. 5. Goss PE, et al. J Natl Cancer Inst. 2005;97:1262-1271. 6. Jakesz R, et al. J Natl Cancer Inst. 2007;99:1845-1853. 7. Gray R, et al. J Clin Oncol. 2013;31:(suppl;abstr 5). 8. Davies C, et al. Lancet. 2013;381:805-816. 9. Goss PE, et al. N Engl J Med. 2016;375:209-219. 10. Mamounas EP, et al. GS4-01; SABCS December 2019. 11. Sanft TB, et al. J Natl Compr Canc Netw. 2024; 22(2):99-107. 12. Andre F, et al. J Clin Oncol. 2022;40(16):1816-1837. Referenced with permission from the American Society of Clinical Oncology (ASCO® Clinical Practice Guideline) Clinical Practice Guideline Biomarkers for Adjuvant Endocrine and Chemotherapy in Early-Stage Breast Cancer. © American Society of Clinical Oncology. 2026. All rights reserved. To view the most recent and complete version of the guideline, go online to https://ascopubs.org/jco/special/guidelines. ASCO makes no warranties of any kind whatsoever regarding their content, use of application and disclaims any responsibility for their application or use in any way. 13. Hershman DL, et al. J Clin Oncol. 2010;20;28(27):4120-4128. 14. Friese CR, et al. Breast Can Res Treat. 2013;138(3):931-39. 15. Saha P, et al. J Clin Oncol. 2017;(35):3113-3122. 16. Wei J, et al. Breast Cancer Res Treat. 2025;214(2):239-246. 17. Jilderda MF, et al. Clin Cancer Res. 2025;3;31(11):2222-2229. 18. Jilderda MF, et al. npj Breast Cancer. 2026;12;21. 19. O'Regan RM, et al. Breast. 2026;86:104714.
*Sami Diab, MD is the Associate Medical Director of Biotheranostics, Inc., A Hologic Company. Statements reflect his own personal view and interpretations.
†Kassianne Saieed, NP is a consultant of Biotheranostics, Inc., A Hologic Company. Statements reflect her own personal views and interpretations.
‡Not currently available to order
The features and results of the Breast Cancer Index Test, to the extent they differ from the information found on the BreastCancerIndex.com website, including, but not limited to, the features concerning adjuvant endocrine therapy and ovarian function suppression: (i) are not currently available for clinical use; (ii) will be made available only after all required internal validations and regulatory requirements have been met; and (iii) is being provided herein for informational purposes only, and shall not be deemed to be an offer of availability.
For the Breast Cancer Index Test Intended Use and Limitations, visit BreastCancerIndex.com
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