Ovarian Suppression in Adjuvant Endocrine Therapy for Premenopausal Breast Cancer

Breast Cancer Index in Premenopausal Women With Early-Stage Hormone Receptor-Positive Breast Cancer

Importance

Adjuvant ovarian function suppression (OFS) with oral endocrine therapy improves outcomes for premenopausal patients with hormone receptor-positive (HR+) breast cancer but adds adverse effects. A genomic biomarker for selecting patients most likely to benefit from OFS-based treatment is lacking.

Objective

To assess the predictive and prognostic performance of the Breast Cancer Index (BCI) for OFS benefit in premenopausal women with HR+ breast cancer.

Design, Setting, and Participants

This prospective-retrospective translational study used all available tumor tissue samples from female patients from the Suppression of Ovarian Function Trial (SOFT). These individuals were randomized to receive 5 years of adjuvant tamoxifen alone, tamoxifen plus OFS, or exemestane plus OFS. BCI testing was performed blinded to clinical data and outcome. The a priori hypothesis was that BCI HOXB13/IL17BR ratio (BCI[H/I])-high tumors would benefit more from OFS and high BCI portended poorer prognosis in this population. Settings spanned multiple centers internationally. Participants included premenopausal female patients with HR+ early breast cancer with specimens in the International Breast Cancer Study Group tumor repository available for RNA extraction. Data were collected from December 2003 to April 2021 and were analyzed from May 2022 to October 2022.

Main Outcomes and Measures

Primary end points were breast cancer-free interval (BCFI) for the predictive analysis and distant recurrence-free interval (DRFI) for the prognostic analyses.

Results

Tumor specimens were available for 1718 of the 3047 female patients in the SOFT intention-to-treat population. The 1687 patients (98.2%) who had specimens that yielded sufficient RNA for BCI testing represented the parent trial population. The median (IQR) follow-up time was 12 (10.5-13.4) years, and 512 patients (30.3%) were younger than 40 years. Tumors were BCI(H/I)-low for 972 patients (57.6%) and BCI(H/I)-high for 715 patients (42.4%). Patients with tumors classified as BCI(H/I)-low exhibited a 12-year absolute benefit in BCFI of 11.6% from exemestane plus OFS (hazard ratio [HR], 0.48 [95% CI, 0.33-0.71]) and an absolute benefit of 7.3% from tamoxifen plus OFS (HR, 0.69 [95% CI, 0.48-0.97]) relative to tamoxifen alone. In contrast, patients with BCI(H/I)-high tumors did not benefit from either exemestane plus OFS (absolute benefit, -0.4%; HR, 1.03 [95% CI, 0.70-1.53]; P for interaction = .006) or tamoxifen plus OFS (absolute benefit, -1.2%; HR, 1.05 [95% CI, 0.72-1.54]; P for interaction = .11) compared with tamoxifen alone. BCI continuous index was significantly prognostic in the N0 subgroup for DRFI (n = 1110; P = .004), with 12-year DRFI of 95.9%, 90.8%, and 86.3% in BCI low-risk, intermediate-risk, and high-risk N0 cancers, respectively.

Conclusions and Relevance

In this prospective-retrospective translational study of patients enrolled in SOFT, BCI was confirmed as prognostic in premenopausal women with HR+ breast cancer. The benefit from OFS-containing adjuvant endocrine therapy was greater for patients with BCI(H/I)-low tumors than BCI(H/I)-high tumors. BCI(H/I)-low status may identify premenopausal patients who are likely to benefit from this more intensive endocrine therapy.

Suboptimal use of ovarian function suppression in very young women with early breast cancer: a real-world data study

PURPOSE

The incidence of breast cancer in young women (BCYW) has increased in recent decades. Malignant disease in this subset is characterized by its aggressiveness and poor prognosis. Ovarian function suppression (OFS) in these patients improves survival especially in hormone receptor-positive (HR +) cases. The Regan Composite Risk (RCR) is a prognostic tool to identify high-risk HR + BC candidates for OFS. Our study sought to characterize a Chilean cohort of early HR + BCYW assessing the use of OFS and its related prognosis and the utility of RCR in our patients.

METHODS

This was a retrospective population cohort study that included ≤ 35-year-old early HR + /human epidermal growth factor receptor 2 -negative (HER2-) BC patients treated between 2001 and 2021. Analysis included clinical-pathological characteristics, treatment strategies, and survival. Also, we evaluated the association between RCR and survival.

RESULTS

A total of 143 patients were included into our study, representing 2.9% of all early BC cases in our registry. Median age was 31 years old (range: 19-35). Most patients (93%) received endocrine therapy (ET). Of these, 18% received OFS. No survival differences were observed among treatment strategies. Median RCR score for patients treated with CT plus ET was significantly higher vs. ET alone (2.95 vs. 1.91; p = 0.0001). Conversely, patients treated with tamoxifen alone had significantly lower RCR scores vs. OFS (2.72 vs. 3.14; p = 0.04). Higher RCR scores were associated with poorer overall survival.

CONCLUSION

Less than 20% of very young women with early HR + /HER2-BC in our cohort received OFS, in most cases, this involved surgical oophorectomy. RCR score was higher in patients that underwent CT and OFS and was associated with survival, regardless of treatment. We confirm the RCR score as a valuable prognostic tool to identify high-risk BC patients who could benefit from OFS.

Optimal Endocrine Therapy in Premenopausal Women: A Pragmatic Approach to Unanswered Questions

Recent epidemiologic data show an increasing incidence of breast cancer among premenopausal women in many higher-income countries. Among premenopausal women, those diagnosed under age 40 years experience inferior long-term outcomes, particularly in the setting of hormone receptor-positive, human epidermal growth factor receptor 2-negative disease. In addition to more advanced disease presentation and/or less favorable disease biology, suboptimal adjuvant endocrine therapy (ET) has emerged as an important driver of this age-related disparity. Historically, young women have been excluded from treatment with aromatase inhibitors (AIs), attained low rates of chemotherapy-related amenorrhea, and exhibited low adherence to ET. Recently, several studies have demonstrated treatment with ovarian function suppression (OFS) during the first 5 years postdiagnosis to be associated with improvements in breast cancer recurrence and mortality, with additional benefits achieved from pairing OFS with an AI. As the first 5 years of ET for premenopausal women has been transformed, extended ET, administered in years 5-10 postdiagnosis, has also become more common. However, the only studies of extending ET in premenopausal women have tested an additional 5 years of tamoxifen following an initial 5 years of tamoxifen and studies of AIs in the second 5 years have been limited to postmenopausal women. Herein, we review available data concerning potential benefits and risks to be considered when counseling premenopausal women on extended ET, including the continuation of OFS. We offer a pragmatic framework to support decision making given the current body of knowledge and call out the need for additional research into this issue.

Endocrine Therapy in Early Breast Cancer

Background

Endocrine therapy with a standard duration of 5 years is well known as an effective treatment for endocrine-sensitive breast cancer.

Summary

In the adjuvant setting this treatment reduces the 15-year mortality rates by about 30 and 40% with tamoxifen and aromatase inhibitor, respectively. The well-known long-term recurrence risk of luminal cancers led to multiple trials examining the benefit of extended endocrine treatment for up to 15 years. Additional benefit with extended therapy was seen for patients with high recurrence risk. Also, additional ovarian suppression for premenopausal women exhibited a significant benefit for patients at higher risk.

Key Messages

The data of the last years will be summarized and discussed, also considering the side effects of the different treatment options.

Role of Bone Targeting Agents in the Prevention of Bone Metastases from Breast Cancer

Breast cancer (BC) is the most common malignancy in women worldwide and leads, in more than 70% of patients with advanced disease, to skeleton colonization and formation of bone metastases (BM). This condition implies a severe disability and deterioration of the quality of life, with consequent additional social costs. In recent decades, several studies explored the role of agents acting within the bone microenvironment to counteract BM development, and several bone-targeting agents (BTAs) have been introduced in the clinical practice to manage bone lesions and reduce the risk of skeletal complications. However, long-term exposure to these agents is not free from potential toxicities and needs careful monitoring. In this context, the potential capability to prevent BM onset in selected BC patients, through the early administration of BTAs, has been explored by several researchers, with the belief that “prevention is better than cure” and that, ultimately, metastatic BC is an incurable condition. Here, we revised the mechanisms of BM development in BC as well as the strategies for selecting high-risk patients suitable for early BTA treatment.