The development of noninvasive methods to detect and monitor tumors continues to be a major challenge in oncology.
For most tumors, a tissue biopsy is quite challenging because it is costly, painful, or potentially risky for the patient.

These are good reasons to learn about cancer through the blood, by carrying out liquid biopsies. Tumor-related circulating-free DNA, RNA, or proteins are released by tumor cells and circulate in the blood of cancer patients; assays using these molecules can be used for early tumor detection, monitoring, or detection of resistance mutations.

Liquid biopsies can provide a noninvasive, ongoing picture of a patient’s cancer, offering valuable insight into how best to fight it.
They offer clues about stage and spread, and can be used to monitor the effects of cancer treatment, give an early warning about possible recurrence, and offer clues to reasons for treatment resistance.

Adapted from Karachaliou N, Mayo-de-las-Casas V, Molina-Vila MA and Rosell. Real-time liquid biopsies become a reality in cancer treatment. Ann Transl Med. 2015 Mar; 3(3): 36. doi: 10.3978/j.issn.2305-5839.2015.01.16. Internet. Accessed on August 5, 2016. Available at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4356857/