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NCT Number: NCT06223698

Optimizing Extended Adjuvant Endocrine Therapy in Patients With Breast Cancer

Based on the risk of late recurrence in breast cancer patients with luminal disease with high-risk for recurrence, extended adjuvant endocrine therapy beyond 5 years is recommended as a valid treatment option. In premenopausal women at diagnosis converted to postmenopausal after the first five years of tamoxifen, two treatment strategies for extended adjuvant endocrine therapy are available, namely continuing with tamoxifen or switching to aromatase inhibitors (AI). No randomized evidence does exist and both treatment strategies are used in clinical practice. In postmenopausal women with higher recurrence risk initially treated with AI for five years, extended adjuvant therapy with additional two years of AI has shown to be as effective as additional five years of AI. However, no randomized evidence on whether a switching strategy of five-year extended tamoxifen is better compared to two-year extended AI is available. Both treatment strategies are used in clinical practice.

The primary objective of this register-based randomized trial is to investigate the overall survival between patients treated with switching strategy for extended adjuvant endocrine therapy compared to continuing with the same treatment as the initial 5 years in two different clinical scenarios:

* In premenopausal women at diagnosis who converted to postmenopausal after 5 years of tamoxifen. * In postmenopausal women at diagnosis.

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Key information

Conditions

Breast Cancer Breast Diseases Breast Neoplasms Neoplasms Neoplasms by Site Skin Diseases Skin and Connective Tissue Diseases

Age range

18 year–90 year

Sex eligibility

Female

Study type

Interventional

Phase

Phase 3

Primary location

Visby Hospital, Visby, Gotland County, Sweden

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Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Cohort 1 (premenopausal women at diagnosis converted to postmenopausal)

  • Women who were pre- or perimenopausal at diagnosis
  • Luminal breast cancer (defined as estrogen-receptor positive >/=10%, HER2-negative disease).
  • Treated with tamoxifen for at least 80% of a 5-year period (+/- 6 months from treatment completion).
  • No clinical signs of metastasis after 5 years tamoxifen treatment.
  • cN+ breast cancer at diagnosis indicating the need for extended adjuvant endocrine therapy.
  • Postmenopausal status at study entry defined according to the National Comprehensive Cancer Network Guidelines.

Cohort 2 (postmenopausal women at breast cancer diagnosis)

  • Women who were postmenopausal at diagnosis.
  • Luminal breast cancer (defined as estrogen-receptor positive >/=10%, HER2-negative disease).
  • Treated with AI for at least 80% of a 5-year period (+/- 6 months from treatment completion).
  • No clinical signs of metastasis after 5 years AI treatment.
  • cN+ breast cancer at diagnosis indicating the need for extended adjuvant endocrine therapy.

Exclusion criteria

Cohort 1

  • Prior invasive breast cancer diagnosis.
  • Other invasive malignancy within 5 years before or after breast cancer diagnosis
  • Non-luminal breast cancer (defined as estrogen-receptor < 10%).
  • Patients who were unable to complete at least 80% of 5-year initial treatment with tamoxifen.
  • Uncertain menopausal status (unable to evaluate menopausal status according to aforementioned definitions).
  • Recurrent or metastatic breast cancer within or after 5-year initial treatment with tamoxifen (DCIS-only is allowed at any time before or after breast cancer diagnosis).
  • Unable to give informed consent in Swedish. Cohort 2
  • Prior invasive breast cancer diagnosis.
  • Other invasive malignancy within 5 years before or after breast cancer diagnosis; non-Luminal breast cancer (defined as estrogen-receptor < 10%).
  • Patients who were unable to complete at least 80% of 5-year initial treatment with AI.
  • Recurrent or metastatic breast cancer within or after 5-year initial treatment with AI (DCIS-only is allowed at any time before or after breast cancer diagnosis).
  • No contraindication for tamoxifen therapy. 7) Unable to give informed consent in Swedish.

Treatment and study plan

letrozole

Drug

Letrozole 2.5 mg daily

Anastrozole

Drug

Anastrozole 1 mg daily

Exemestane

Drug

Exemestane 25 mg daily

Tamoxifen

Drug

Tamoxifen 20 mg daily

Primary outcomes

  1. Overall survival

    Time frame: 120 months

Secondary outcomes

  1. Invasive disease-free survival

    Time frame: 36 months; 60 months; 120 months

  2. Distant disease-free survival

    Time frame: 36 months; 60 months; 120 months

  3. Breast cancer-specific survival

    Time frame: 36 months; 60 months; 120 months

  4. Overall survival

    Time frame: 36 months; 60 months

  5. Frequency of selected grade 3/4 toxicities

    Time frame: 36 months; 60 months; 120 months

    Selected grade 3 or 4 toxicities that lead to hospitalization will be captured and analyzed for each study arm.

  6. Overall quality of life (EORTC QLQC30)

    Time frame: 24 months; 60 months

    Assessment of overall quality of life through global health status from EORTC QLQC30 (scale 0 to 100; higher score indicates better overall quality of life)

  7. Adherence to treatment strategies (medical possession ratio)

    Time frame: 36 months; 60 months; 120 months

    Adherence will be calculated by using medication possession ratio (MPR; the sum of the days' supply for all fills of a given drug in a particular time period, divided by the number of days in the time period). A MPR of >/= 80% is defined as good adherence

  8. Duration of sick leave

    Time frame: 36 months; 60 months; 120 months

Study contacts

Contact information is provided by the study sponsor or research team.

Antonis Valachis, MD, PhD

CONTACT

[email protected]

0046 196021000

Sponsors and collaborators

Lead sponsor

Region Örebro County

Other

Collaborators

  • Mid-Sweden Regional Cancer Centre
  • Uppsala University Hospital

Registry information

Official study title

Optimizing Extended Adjuvant Endocrine Therapy in Patients With Breast Cancer: a Registry-based Randomized Clinical Trial - SWE-Switch Breast Cancer Trial

Acronym: SWE-Switch

Important dates

Study start
2025
Primary completion
2032
Study completion
2035
First posted
Jan 25, 2024
Registry last updated
Apr 20, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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