The PROOFS registry collects real-world data on the long-term follow-up of premenopausal or perimenopausal (the year after the last menstrual period) patients with early-stage luminal breast cancer who have an intermediate to high clinical risk of recurrence and a low genomic recurrence risk, as determined by MammaPrint® (a genomic test that creates an individual tumor profile and thus provides information about the metastatic risk of breast cancer), and who are being treated or are planned to be treated with standard endocrine therapy plus ovarian function suppression (OFS) or with standard chemotherapy followed by endocrine therapy.

What is this study investigating?

For pre- and perimenopausal patients in general, there is limited data regarding optimal treatment. Currently, patients are treated with various therapies: chemotherapy + endocrine therapy (ET), ET + ovarian function suppression in premenopause, or ET with or without OFS in perimenopausal women, each based on the recommendation of the treating physician and for a duration of endocrine treatment of 5-10 years. Therefore, this registry collects current treatment data for this patient group to enable future statements about the treatment success of current standard therapies.

What is the aim of the study?

The primary objective of this study is to determine the frequency of the 5-year distant recurrence-free interval in all patients treated with (intensified) endocrine therapy alone (and with ovarian suppression in cases with increased clinical risk according to current AGO recommendations). Insights are to be gained regarding treatment with chemotherapy followed by endocrine therapy versus endocrine treatment alone. The results also aim to inform changes in the duration of endocrine treatment (especially up to 10 years for high-risk patients), as well as the introduction of intensified endocrine therapy in combination with OFS.

How is the study conducted?

In this registry study, only routine clinical data is collected – participation in the study has no influence on the patients’ treatment. Treatment is carried out independently of study participation, according to medical practice and applicable guidelines. Additional visits to the clinic/practice are not required. Data documentation begins after written consent to participate in the registry.

Initially, for example, demographic data of the patients and the status of the cancer (e.g., tumor status at initial diagnosis, genomic risk by MammaPrint®, planned/ongoing cancer treatment, quality of life) are documented. This is followed by the follow-up phase, during which the current status regarding any local recurrences or distant metastases, further cancer treatments, and patient adherence to therapy is documented at least once a year during routine follow-up visits. The follow-up phase within this registry is planned for up to 10 years after initial diagnosis (at least annual examinations in years 0-5, followed by year 7 and 10 or at the time of tumor recurrence).

Are there any risks?

You will be informed about potential risks associated with participation during an informational discussion. Since this registry is purely a documentation of clinical routine without planned additional treatment, there is no additional health risk associated with participation.

Eligibility Criteria

Women can participate in this study if they have:

• early-stage primary breast cancer (without evidence of metastases)
• intermediate to high clinical risk and low genomic risk of recurrence (determined by MammaPrint®)
• pre- or perimenopausal
• Estrogen and/or progesterone hormone receptor positive
• HER2 receptor negative

In addition, there are further criteria that must be met for participation in the study. Interested patients should speak with the study physicians at a participating center, who can check if this study is suitable for them.