Background: We aimed to determine the prognostic impact of time between primary breast cancer and diagnosis of distant metastasis (metastatic-free interval, MFI) on the survival of metastatic breast cancer patients.
Methods: Consecutive patients diagnosed with metastatic breast cancer in 2007-2009 in eight hospitals in the Southeast of the Netherlands were included and categorised based on MFI. Survival curves were estimated using the Kaplan-Meier method. Cox proportional hazards model was used to determine the prognostic impact of de novo metastatic breast cancer vs recurrent metastatic breast cancer (MFI 24 months), adjusted for age, hormone receptor and HER2 status, initial site of metastasis and use of prior (neo) adjuvant systemic therapy.
Results: Eight hundred and fifteen patients were included and divided in three subgroups based on MFI; 154 patients with de novo metastatic breast cancer, 176 patients with MFI 24 months. Patients with de novo metastatic breast cancer had a prolonged survival compared with patients with recurrent metastatic breast cancer with MFI 24 months (median, 29.4 vs 27.9 months, P = 0.73). Adjusting for other prognostic factors, patients with MFI 24 months with de novo metastatic breast cancer no significant difference in mortality risk was found. The association between MFI and survival was seen irrespective of use of (neo) adjuvant systemic therapy.
Conclusion: Patients with de novo metastatic breast cancer had a significantly better outcome when compared with patients with MFI 24 months, patients with de novo metastatic breast cancer had similar outcome.
- metastatic breast cancer
- metastatic-free interval
- STAGE IV
- SYNCHRONOUS METASTASES
- PRIMARY TUMOR