A diagnosis of cancer is scary enough on its own. But cancer cells’ ability to hide out in the body after an initial round of treatment is especially insidious. And it isn’t possible yet to tell which patients still have any residual disease.
Even a few surviving cancer cells can multiply over time, moving out of the original site — the breast or colon, for example — to form a tumor in another part of the body. By the time that new tumor has grown large enough to show up on a CT scan, the cancer is likely incurable.
When cancer patients seek treatment, scars from initial therapies like radiation can make detecting new and old tumors difficult. And a traditional biopsy, a tissue sample a pathologist scrutinizes under a microscope for telltale signs of cancer, can be hard to obtain from an internal organ like the lung.
For all these reasons, doctors have high hopes for a technology still in its infancy called liquid biopsy, which looks for cancer in bodily fluids. It may identify cancer patients whose disease has persisted past the primary treatment, and help home in on effective therapies for them.
