EndoNET Study

ABOUT ENDONET

EndoNET is a research study for post-menopausal women with oestrogen receptor positive (ER+) breast cancer who require surgery. 

Breast cancer that is oestrogen receptor positive (ER+) uses the female hormone oestrogen to grow and survive. Endocrine therapy with an aromatase inhibitor (AI) stops the body making oestrogen. This starves tumours of this hormone.

Endocrine therapy is an extremely successful treatment, especially for strongly ER+ breast cancer. 

Treatment for ER+ breast cancer includes both endocrine therapy and surgery. Some women may also need radiotherapy. Some women may be given endocrine therapy before surgery to reduce the size of the cancer. This treatment is recognised in health care guidelines both nationally and internationally. 

This research aims to understand if this treatment option leads to a smaller operation and better recovery. This will help us to see if this will benefit more women in the future.

You can find out more by watching this video:

WHO CAN TAKE PART?

• Women who have strongly ER+ breast cancer and need both endocrine therapy and surgery.
• Women who have been through the menopause.
• Women who have highly hormone-sensitive breast cancer which is expected to respond to endocrine therapy.

TRIAL DETAILS

Women who agree to take part will sign a consent form. They will then be asked to complete some initial questionnaires about their health and wellbeing.

The study compares two treatment pathways recommended in national guidelines for use in the NHS:

Women will be allocated to one of the groups through a process called randomisation. Neither they nor their doctor can choose which treatment group they are allocated to. We are only offering this study to women that the clinical team believe would do equally well in either of the treatment groups. The process of randomisation helps to ensure there is a fair comparison between the two groups.

Everyone in the study starts endocrine therapy immediately. The endocrine therapy is the same in both groups, but the timing of the surgery differs.

TREATMENT GROUP 1

Women in Treatment Group 1 start endocrine therapy on study entry and will have their surgery within 4 weeks of joining the study (sometimes within 8 weeks).

Women will be followed up by the research team:

• With follow up phone calls at 6 weeks, 5 months, 7 months, 12 months and 15 months after joining the study
• Women will complete questionnaires electronically over 15 months.

Women will continue their endocrine therapy after surgery for 5-10 years as per standard of care.

TREATMENT GROUP 2

Women start endocrine therapy on study entry, and continue this treatment to shrink the tumour, with their surgery after 6 months of joining the study.

They will continue your endocrine therapy after surgery for 5-10 years as per standard of care.

Women with breast cancer told us that it’s important that the tumour is closely monitored. This means they will come to the hospital three times before their surgery to see their research team:

1. After 2-4 weeks of starting endocrine therapy, we will do a scan and take a tissue sample.
2. After 3 months of starting endocrine therapy, we will do a scan to check the tumour is responding and see how they are doing.
3. After 5 months of starting endocrine therapy, we will do a final scan to check the tumour is responding and see how they are doing.

These visits will:

✅         Ensure they are getting on well with the endocrine therapy.

✅         Check that the cancer is responding to the treatment.

✅         Reassure them that they are being monitored closely by your team.

✅         Ensure they can talk to the surgeon about their care.

If they are not coping well with their endocrine therapy, they can try another type of medication. Their medical team will always be able to schedule their surgery early if medically required.

IMPORTANT INFORMATION FOR BOTH GROUPS

We would expect women to:

✅         Attend all appointments.

✅         Take the endocrine therapy as prescribed. 

✅         Complete the questionnaires that are sent.

✅         Discuss and plan with their surgical team the timing of their surgery.

Women will be in the study for 15 months. Other treatments such as radiotherapy and chemotherapy will be given to them as required by their clinical team.

FURTHER INFORMATION FOR PATIENTS 

If you would like to find out more information about EndoNET, please read our Information Sheet. There is also a Frequently Asked Questions (FAQ) section on this website. 

We are incredibly grateful to the Independent Cancer Patients’ Voice (ICPV) for their input and support to ensure this study is safe and relevant for women.

TRIAL SCHEMA FOR PROSPECTIVE HOSPITALS

PROSPECTIVE HOSPITALS

If you are a UK hospital who would be interested in joining more than 30 hospitals taking part in EndoNET, please contact: endonet@nds.ox.ac.uk to find out more information and request a feasibility form. We are part of the NIHR Associate PI scheme and are on the NIHR Portfolio.

FURTHER INFORMATION FOR RESEARCHERS

EndoNET is funded by the National Institute for Health Research HTA Programme. 

Visit us on the Association for Breast Surgery website.