Cellular barcoding has been used to tag, track and pinpoint cells responsible for the spread of breast cancer from the main tumor into the blood and other organs, and also revealed how chemotherapy temporarily shrinks the number of harmful cells, rather than eliminating them, explaining how the cancer could eventually relapse.

Pinpointing the 'seeders' of disease

Most deaths from breast cancer are caused by the metastasis, or spread, of cancerous cells from the main tumor site into other organs. 

Breast cancers consist of thousands of different cell variants with diverse characteristics that may or may not play a role in the metastasis of the cancer. This makes effective treatment a challenge because it is difficult to know which cells are responsible for driving the spread of cancer.

The ability to pinpoint the 'clones' - subpopulations of cells arising from an original patient tumor - responsible for the spread of cancer was crucial for improving treatments because only a select few clones were actually responsible for the metastasis. They were also able to see what was happening to the clones after the chemotherapy agent Cisplatin was introduced. They learned that the treatment was able to shrink tumors and the size of individual clones, it did not kill them off completely. All the clones, including the nasty seeders, eventually grew again, accounting for cancer relapse.