Did you know our blood is a big-time gossip? A little bit of it can reveal so much about you. For instance, it can tell us your gender, if you are overweight, and your age (Curran et al., 2017). For a mother, blood can also divulge information about her children because their genomic material still lingers on in her long after birth (It also can be used to identify the children’s father!) (Boddy, Fortunato, Wilson Sayres, & Aktipis, 2015; Stevens, 2016).
In addition to sharing information that is perfect fodder for reality shows and soap operas, blood also chatters away about our health. Compared to other medical testing that require biopsies, it is pretty easy to listen to the chatter. Docs already keenly listen and subject patients to many blood tests to get the inside scoop. The best part of using blood to glean medical insights is that it is minimally invasive!
Lately, news organizations have begun churning out many stories about liquid biopsies (looking at biomarkers in blood to gauge a health status) that captivate the public’s attention. The allure is understandable: A simple minimally invasive test that can give the needed insights into a person’s risk of potentially terminal diseases, such as cancer, that can be cured if caught early.
One such experimental test that had people wondering when it will make it to market came out of a recent collaboration (see comments section of Mone, 2018). This test was developed to monitor circulating tumor DNA (ctDNA) and protein biomarkers for about eight cancers of the ovaries, liver, stomach, pancreas, esophagus, colon, lung, or breast (Cohen et al., 2018). The authors reported that their test had good statistics for sensitivity (finding cancer) and specificity (only 1% false positives). What is remarkable is that the test could even pinpoint the location of the cancer, thanks to information from the protein biomarkers. Even though the test sounds like it is ready for primetime, the authors emphasized that there are still shortcomings to be solved and validation work to be done.
This caveat about cancer screening using ctDNAs is shared by other groups too. Recently, the American Society of Clinical Oncology and College of American Pathologists penned a review about assays using ctDNA (Merker et al., 2018). In the review, the reviewers noted the potential of using ctDNAs, but clinical validity and utility still need to be decided. [What is needed is a testbed, which involves looking at the practicality of the tests in a clinical setting!] The reviewers go on to mention that ctDNA tests have inherent problems, such as patients having different levels of ctDNA, tests might not be interchangeable (different protocols yield different results), and more.
As more news agencies publish about the latest means of listening to our blood’s juicy gossip, we must be careful to not get caught up in the hype. Yes, liquid biopsies show great promise, but a lot more work remains to make sure the messages being communicated are being interpreted correctly. Focusing on the wrong “words” could lead to a miscommunication or misinterpretation of what our blood is trying to tell us. This could result in missed diagnoses or people undergoing unnecessary and invasive procedures/treatments.
Boddy, A. M., Fortunato, A., Wilson Sayres, M., & Aktipis, A. (2015). Fetal microchimerism and maternal health: a review and evolutionary analysis of cooperation and conflict beyond the womb. Bioessays, 37(10), 1106-1118. doi:10.1002/bies.201500059
Cohen, J. D., Li, L., Wang, Y., Thoburn, C., Afsari, B., Danilova, L., . . . Papadopoulos, N. (2018). Detection and localization of surgically resectable cancers with a multi-analyte blood test. Science, 359(6378), 926-930. doi:10.1126/science.aar3247
Curran, A. M., Fogarty Draper, C., Scott-Boyer, M. P., Valsesia, A., Roche, H. M., Ryan, M. F., . . . Kaput, J. (2017). Sexual Dimorphism, Age, and Fat Mass Are Key Phenotypic Drivers of Proteomic Signatures. J Proteome Res, 16(11), 4122-4133. doi:10.1021/acs.jproteome.7b00501
Merker, J. D., Oxnard, G. R., Compton, C., Diehn, M., Hurley, P., Lazar, A. J., . . . Turner, N. C. (2018). Circulating Tumor DNA Analysis in Patients With Cancer: American Society of Clinical Oncology and College of American Pathologists Joint Review. J Clin Oncol, JCO2017768671. doi:10.1200/JCO.2017.76.8671
Mone, A. (2018, January 19) Johns Hopkins researchers develop single blood test that screens for eight common cancers. Hub. (Retrieved on March 21, 2018 from https://hub.jhu.edu/2018/01/19/cancer-blood-test-johns-hopkins/).
Stevens, A. M. (2016). Maternal microchimerism in health and disease. Best Pract Res Clin Obstet Gynaecol, 31, 121-130. doi:10.1016/j.bpobgyn.2015.08.005