Culture and Expansion of Circulating Tumor Cells from Breast Malignant Effusions as Organoids.

Circulating tumor cells (CTCs) shed by solid tumors can travel to distant sites to initiate metastatic foci. These cells can be detected in the blood and bone marrow. In addition, CTCs can be found in fluids that accumulate in the pleural or peritoneal cavity, a complication of metastatic cancer called malignant effusion. Efforts to characterize CTCs in malignant effusions can face limitations because of the low proportion of CTCs relative to other cells (primarily immune cells) in these fluids. Therefore, expanding CTCs through in vitro culture could address this limitation and enable functional studies. Here, we describe a method for culturing breast cancer CTCs as organoids (clusters of tumor cells) amenable to downstream profiling and functional studies.