From the Guidelines
The recurrence risk for stage I breast cancer is significantly reduced with endocrine therapy compared to no treatment, with a recommended treatment duration of up to 10 years for high-risk patients. Without endocrine therapy, the 10-year recurrence risk is approximately 15-20% 1. With endocrine therapy, this risk can be reduced to about 5-10% 1. For hormone receptor-positive stage I breast cancer, endocrine therapy is strongly recommended, with options including:
- Tamoxifen 20 mg daily for 5-10 years for premenopausal women
- Aromatase inhibitor (e.g., anastrozole 1 mg, letrozole 2.5 mg, or exemestane 25 mg) daily for 5-10 years for postmenopausal women 1 Key considerations for treatment duration include:
- Cancer stage and risk of late recurrence
- Tolerability and adverse effects of treatment
- Patient preferences and individualized treatment decisions 1 Regular follow-ups and adherence to the prescribed regimen are crucial for optimal outcomes, and clinical teams should mitigate symptoms of extended therapy and ensure access to therapy in women who pursue adjuvant endocrine treatment 1.
From the FDA Drug Label
Among women with ER positive or unknown breast cancer and positive nodes who received about 5 years of treatment, overall survival at 10 years was 61.4% for tamoxifen vs. 50.5% for control (logrank 2p < 0.00001). The recurrence-free rate at 10 years was 59.7% for tamoxifen vs. 44.5% for control (logrank 2p < 0. 00001). Among women with ER positive or unknown breast cancer and negative nodes who received about 5 years of treatment, overall survival at 10 years was 78.9% for tamoxifen vs. 73.3% for control (logrank 2p < 0.00001). The recurrence-free rate at 10 years was 79.2% for tamoxifen vs. 64.3% for control (logrank 2p < 0. 00001).
The recurrence risk of stage I breast cancer with endocrine (hormone) therapy is:
- 40.3% (100 - 59.7%) for women with ER positive or unknown breast cancer and positive nodes
- 20.8% (100 - 79.2%) for women with ER positive or unknown breast cancer and negative nodes
The recurrence risk of stage I breast cancer without endocrine (hormone) therapy is:
- 55.5% (100 - 44.5%) for women with ER positive or unknown breast cancer and positive nodes
- 35.7% (100 - 64.3%) for women with ER positive or unknown breast cancer and negative nodes 2
From the Research
Recurrence Risk of Stage I Breast Cancer
The recurrence risk of stage I breast cancer with and without endocrine (hormone) therapy is a complex topic. Several studies have investigated this issue, providing valuable insights into the factors that influence recurrence risk.
Factors Influencing Recurrence Risk
- The risk of recurrence is influenced by various factors, including clinical tumor features, individual biomarkers, and genomic risk 3.
- The use of adjuvant endocrine therapy and chemotherapy should be driven by a patient's risk for recurrence, preferences, and risk for side effects 3.
- Patients with high-risk tumors have a persistently elevated risk for recurrence despite current standards of care 3.
Endocrine Therapy and Recurrence Risk
- Adjuvant tamoxifen has proven particularly effective in preventing relapses in hormone-receptor-positive (HR+) disease 4.
- The risk of relapse is highest during the first 2-3 years after surgery, but a residual risk remains indefinitely for those women who do not experience disease relapse in these early years 4.
- Extended endocrine therapy, such as 10 years of tamoxifen or letrozole, has been shown to reduce the risk of recurrence in patients with HR+ early breast cancer 5, 4.
Recurrence Risk Without Endocrine Therapy
- Women age 70 or above with low-risk, hormone-positive breast cancer who are reluctant or unable to pursue adjuvant aromatase inhibition can safely pursue adjuvant radiation alone with limited differences in outcome and a modest increase in costs 6.
- The 10-year event-free survival (EFS) rates for women with stage I breast cancer are high, ranging from 94.8% to 96.3% for women under 50 and 94.8% to 95.6% for women over 50 7.