Core-needle biopsy of breast cancer is associated with a higher rate of distant metastases 5 to 15 years after diagnosis than FNA biopsy.

Background: The literature offers discordant results regarding whether diagnostic biopsy is associated with the dissemination of cancer cells, resulting in local and/or distant metastasis. The long-term outcomes of patients with breast cancer were compared between those who were diagnosed using either fine-needle aspiration biopsy (FNAB) or core-needle biopsy (CNB) during 2 decades: the 1970s and 1990s.

Methods: In the 1970s, the only diagnostic needle biopsy method used for breast cancer in Sweden was FNAB.