Local tumour cell seeding by fine-needle aspiration biopsy. A semiquantitative study.

We have performed fine-needle biopsies from solid or ascites-growing mouse tumours. The biopsies were taken via striated muscle or the peritoneal cavity of healthy mice syngeneic with the tumours and the tumour-bearing animals. The incidence of tumour takes in these new mice were compared with the intramuscular or intraperitoneal transplantability of the tumours. In order to estimate more accurately the number of seeded cells, we also performed aspiration biopsy through the leg muscles of healthy animals into ascites-growing tumours labelled with 125IUDR. The resulting radioactivity in the leg muscle was compared with the radioactivity of the ascites tumour cells. The studies indicate that one may seed 10(3)-10(4) cells, and sometimes more, into the needle track with fine-needle aspiration biopsy from extremely cellular and dedifferentiated tumors.