What means "liquid biopsy" in cancer research?

Liquid biopsy is kind of novel test done on a sample of blood to look for cancer cells from a tumor that are circulating in the blood or for pieces of DNA from tumor cells that are in the blood. A liquid biopsy may be used to help find cancer at an early stage. It may also be used to help plan treatment or to find out how well treatment is working or if cancer has come back. Being able to take multiple samples of blood over time may also help doctors understand what kind of molecular changes are taking place in a tumor. The liquid biopsy is still in the reaseach but the current available results indicates its great potential for being used in the medical practice specially detecting new cancers at very early stage an enhance the probabilities of cure and to treat relapsed cancer patients before the disease is identified by the physician and increase the chances to cure or to prolong their survival.