Endocrine Therapy Without Radiotherapy for Breast Cancer

Not currently recruiting at 12 trial locations

Age: 18+

Sex: Female

Trial Phase: Academic

Sponsor: University of Michigan Rogel Cancer Center

Must be taking: Endocrine therapy

Disqualifiers: Metastatic disease, Bilateral breast cancer, others

Stay on Your Current Meds You can continue your current medications while participating

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Approved in 6 Jurisdictions This treatment is already approved in other countries

Compensation: Varies

Number of Visits: Unknown

Duration: Duration not specified

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial explores the safety of skipping radiation therapy for certain postmenopausal women with early-stage breast cancer who receive endocrine therapy (also known as hormone therapy) instead. The focus is on women with hormone receptor-positive and Her2-negative tumors, which typically indicate a lower risk of cancer recurrence. Participants should have undergone breast-conserving surgery and be prepared to start or continue endocrine therapy for at least five years. The trial targets women who have completed surgery for Stage 1 breast cancer and have specific tumor characteristics, such as a low Oncotype-DX RS score, indicating a lower risk of recurrence. As an unphased trial, it offers participants the chance to contribute to research that may redefine post-surgery treatment options for women with similar cancer profiles.

Will I have to stop taking my current medications?

The trial protocol does not specify whether you need to stop taking your current medications. However, you must be willing to take endocrine therapy for at least 5 years, which may affect your current medication plan.

Is there any evidence suggesting that endocrine therapy alone is likely to be safe for this patient population?

Research has shown that endocrine therapy, a common treatment for some breast cancers, is usually well-tolerated but can have side effects. Most women undergoing this therapy experience side effects, with hot flashes and joint pain being the most common. Despite these side effects, endocrine therapy effectively improves survival rates for patients with hormone receptor-positive breast cancer. While these side effects can be bothersome, they are usually not severe enough to stop treatment. Prospective participants in a clinical trial for endocrine therapy should discuss possible side effects with their doctor to determine if this treatment is suitable. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about using endocrine therapy alone for breast cancer because it could potentially eliminate the need for radiotherapy. Typically, breast cancer treatment includes a combination of endocrine therapy and radiotherapy, which can have challenging side effects. This approach focuses solely on endocrine therapy, which involves hormone-blocking medications that prevent cancer cells from growing. By skipping radiotherapy, patients may experience fewer side effects and still achieve effective results, making the treatment process potentially simpler and more comfortable.

What evidence suggests that endocrine therapy alone might be an effective treatment for breast cancer?

Research shows that hormone therapy effectively treats certain types of breast cancer. Studies have found that taking tamoxifen for five years can lower the chance of cancer returning by 40% and reduce the risk of death by 30%. Extending hormone therapy to seven or ten years can lead to even better results. This treatment significantly improves survival rates in patients with hormone receptor-positive, HER2-negative breast cancer. In this trial, participants will receive endocrine therapy alone, without radiotherapy, to evaluate if hormone therapy alone might suffice to reduce the risk of cancer recurrence. ^{2 3 5 6 7}

Who Is on the Research Team?

Reshma Jagsi, M.D., Ph.D.

Principal Investigator

University of Michigan

Are You a Good Fit for This Trial?

Postmenopausal women with hormone receptor-positive, Her2-negative stage 1 breast cancer who've had a lumpectomy can join this study. They must have an Oncotype-DX score ≤18 and agree to take endocrine therapy for at least 5 years. Women with prior breast cancer, known genetic predispositions like BRCA mutations, or evidence of more widespread disease are excluded.

Inclusion Criteria

My breast cancer is at an early stage and was confirmed after a surgery to remove it.

My underarm lymph node examination was done using one of the approved methods.

I can take care of myself and am up and about more than 50% of my waking hours.

Exclusion Criteria

I have had radiation therapy to my breast before.

I have had breast cancer or DCIS before.

I have cancer in both of my breasts.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants receive endocrine therapy alone without radiotherapy

Duration not specified

Follow-up

Participants are monitored for safety and effectiveness after treatment

5 years

What Are the Treatments Tested in This Trial?

Interventions

• Endocrine Therapy

Trial Overview The IDEA Study is exploring if certain low-risk postmenopausal women with early-stage breast cancer can skip radiotherapy after surgery and only receive endocrine therapy. It aims to understand the recurrence rates without radiation in patients meeting specific criteria.

How Is the Trial Designed?

Group I: Endocrine therapy alone Experimental Treatment 1 Intervention

Patients receive endocrine therapy alone without radiotherapy

Endocrine Therapy is already approved in European Union, United States, Canada, Japan, China, Switzerland for the following indications:

Approved in European Union as Hormone Therapy for:

• Breast cancer
• Prostate cancer
• Endometrial cancer
• Ovarian cancer

Approved in United States as Hormone Therapy for:

• Breast cancer
• Prostate cancer
• Endometrial cancer
• Ovarian cancer

Approved in Canada as Hormone Therapy for:

• Breast cancer
• Prostate cancer
• Endometrial cancer
• Ovarian cancer

Approved in Japan as Hormone Therapy for:

• Breast cancer
• Prostate cancer
• Endometrial cancer
• Ovarian cancer

Approved in China as Hormone Therapy for:

• Breast cancer
• Prostate cancer
• Endometrial cancer
• Ovarian cancer

Approved in Switzerland as Hormone Therapy for:

• Breast cancer
• Prostate cancer
• Endometrial cancer
• Ovarian cancer

Who Is Running the Clinical Trial?

University of Michigan Rogel Cancer Center

Lead Sponsor

Trials

303

Recruited

20,700+

Harvard University

Collaborator

Trials

237

Recruited

588,000+

Yale University

Collaborator

Trials

1,963

Recruited

3,046,000+

Rutgers Cancer Institute of New Jersey

Collaborator

Trials

72

Recruited

22,200+

East Carolina University

Collaborator

Trials

111

Recruited

42,400+

Johns Hopkins University

Collaborator

Trials

2,366

Recruited

15,160,000+

Medical College of Wisconsin

Collaborator

Trials

645

Recruited

1,180,000+

Stanford University

Collaborator

Trials

2,527

Recruited

17,430,000+

University of Texas Southwestern Medical Center

Collaborator

Trials

1,102

Recruited

1,077,000+

Loyola University

Collaborator

Trials

161

Recruited

31,400+

Published Research Related to This Trial

Endocrine therapy for breast cancer has evolved significantly, with a wide range of medical treatments now available that can effectively prolong survival in advanced stages, while being curative in early disease.

Recent advancements include new antiestrogens, aromatase inhibitors, and targeted therapies that utilize biological factors to personalize treatment, allowing for better selection of patients and treatment strategies.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Novel endocrine therapies in breast cancer. Klijn, JG., Setyono-Han, B., Bontenbal, M., et al.[2019]

Endocrine therapy is a highly effective and well-tolerated treatment for hormone receptor positive metastatic breast cancer, showing survival rates comparable to chemotherapy, making it the preferred initial treatment except in cases of rapid disease progression.

There are multiple options for endocrine therapy available for both premenopausal and postmenopausal women, and ongoing research is needed to optimize its use before considering chemotherapy.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Endocrine therapy in metastatic breast cancer: a closer look at the current clinical practice. Ebrahim, H.[2016]

Adjuvant endocrine treatment is crucial for postmenopausal women with hormone receptor-positive breast cancer, with options including tamoxifen and aromatase inhibitors, each having unique side effects.

For premenopausal women, tamoxifen is the standard treatment, and ongoing research is exploring the potential benefits of adding ovarian suppression to enhance treatment effectiveness.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Adjuvant hormonal therapy for early-stage breast cancer. Burstein, HJ., Griggs, JJ.[2010]

Tamoxifen, while a long-standing treatment for early breast cancer, only prevents about half of relapses and can lead to serious side effects like endometrial hyperplasia and venous thromboembolism due to its estrogenic activity.

Aromatase inhibitors are emerging as a more effective alternative, showing benefits in various treatment settings, including extending therapy after tamoxifen and providing upfront adjuvant therapy, potentially improving patient outcomes.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

[Adjuvant endocrine therapy in breast cancer. Management of early-risk relapse]. Chahine, G., Howayek, M., Atallah, D.[2013]

A longitudinal study from 2001 to 2012 across nine developed countries showed a significant shift in breast cancer treatment from tamoxifen to aromatase inhibitors, with aromatase inhibitors making up over half of total endocrine therapy use by 2012.

The study found that while tamoxifen use stabilized or slightly increased, the overall trend towards aromatase inhibitors aligns with clinical guidelines recommending their use for post-menopausal women, indicating a change in treatment practices based on evolving evidence.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Longitudinal trends in utilization of endocrine therapies for breast cancer: an international comparison. Kelly, E., Lu, CY., Albertini, S., et al.[2022]

Endocrine therapy is the first-line treatment for women with hormone receptor-positive metastatic breast cancer due to its effectiveness and lower toxicity compared to chemotherapy, aiming to maintain quality of life and prolong survival.

Various classes of endocrine therapies, including aromatase inhibitors and selective estrogen modulators, are available, but resistance to these treatments eventually develops, highlighting the need for optimal timing and sequencing of therapies.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Extending the clinical benefit of endocrine therapy for women with hormone receptor-positive metastatic breast cancer: differentiating mechanisms of action. Glück, S.[2014]

Endocrine therapy is a key treatment for metastatic breast cancer, offering effective and minimally toxic options, with tamoxifen being the preferred first-line therapy for both premenopausal and postmenopausal women.

Research is ongoing to develop new 'pure' antiestrogens and to combine endocrine therapy with biologic agents, which may enhance treatment effectiveness in both early and advanced stages of breast cancer.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Endocrine therapy in metastatic breast cancer. Kimmick, GG., Muss, HB.[2019]

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC10453164/

Extended Adjuvant Endocrine Therapy in Early Breast ... Taking tamoxifen for 5 years has been shown to reduce the risk of breast cancer recurrence by 40% and mortality by 30% compared to patients ...

2. esmoopen.com esmoopen.com/article/S2059-7029(25)00926-3/fulltext

Extended adjuvant endocrine therapy in early breast cancer 10 years of adjuvant ET is superior to 5 years in reducing recurrences. Seven to eight years of ET improves outcomes compared with 5 years.

3. ascopubs.org ascopubs.org/doi/10.1200/JCO.2025.43.16_suppl.e12516

The impact of adjuvant endocrine therapy on outcomes in ... This study demonstrates that endocrine therapy significantly improves survival outcomes in patients with ER-low positive, HER2-negative breast cancer.

4. nature.com nature.com/articles/s41523-025-00746-7

Impact of endocrine therapy regimens for early-stage ER+ ... Endocrine therapy for breast cancer may reduce the risk of contralateral breast cancer (CBC). However, there are no published estimates ...

5. nejm.org nejm.org/doi/full/10.1056/NEJMoa2212856

Interrupting Endocrine Therapy to Attempt Pregnancy after ... These results suggest that although endocrine therapy for a period of 5 to 10 years substantially improves disease outcomes in patients with ...

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC11880597/

Side-effects in women treated with adjuvant endocrine ... Almost all current endocrine therapy users experienced side-effects (92.7 %), most frequent were vasomotor- and musculoskeletal symptoms.

7. sciencedirect.com sciencedirect.com/science/article/pii/S0960977625005387

The effects of adjuvant endocrine therapy on long-term ... No significant association between ET and breast cancer specific survival was observed in either trials or cohort studies. Subgroup analyses within the cohort ...