Researchers have surgically implanted small glass windows (similar to ship port holes) into the abdomen of living mice to watch cancer spread over the course of 14 days, as reported in Science Translational Medicine.

“Visualization of the formation of metastasis [spread of cancer cells] has been hampered by the lack of long-term imaging windows for metastasis-prone organs, such as the the spleen, kidney, small intestine, pancreas, and liver,” the researchers said.

They observed that single tumor cells in the liver proliferated in two stages:

• “Pre-micrometastases,” in which cells were active and motile (moving around a lot) within the confined region of the growing clone.
• Micrometastases, where cell migration was strongly diminished but proliferation continued.

“If we block the cells in the Pre-micrometastasis phase [with a drug], these cells cannot grow into a micrometastasis,” said researcher Jacco van Rheenen of Hubrecht Institute-Royal Netherlands Academy of Arts and Sciences — suggesting a new strategy for fighting cancer.