In her essay in the May 2011 issue of Obstetrics and Gynecology Paola Gehrig discussed the 1889 theory of the great British physician Sir James Paget who proposed that certain cancers could shed cells and then those cells could travel to other organs and grow as metastasis and it became known as his “seed and soil” theory. Although it seems as obvious to us as how dandelions take over the lawn it wasn’t a well accepted theory in his day. Now we not only know the presence of circulating tumor cells can produce distant growth, but we now think that if we can detect these cells we can prevent the spread, and if in the midst of treatment we can use these cells to predict response to treatment.
Thus Dr. Gehrig said the “liquid biopsy” was born, essentially looking for those tumor cells in the blood stream. In 2017 Cleaveland Clinics Top Ten Medical Innovations for 2017 said that this liquid biopsy used to analyze genetics of tumors could be the easiest and most comprehensive way to approach cancer treatment in some tumors. Alternatives are to look for actual cirulating tumor cells (CTC) or parts of the tumor DNA that is free ctDNA. And the technique of finding cells in the blood stream with a specific draw can be so non-invasive the cancer physicians can use the test to see if the tumor changes genetically overtime.
We can use these liquid biopsies to predict responses to treatments. In breast cancer treatment, if you have less than 5 cells in a cc of blood you do much better with respect to treatment outcomes, colon cancer the cut off is 3 cells. But straight forward answers have not been the case in all tumors and the amount of circulating cells found in ovarian cancer has not predicted success of treatment. A new company is trying to use their techniques of finding cells, with their Magnetic Nest Cell Presentation Device that magnetically aligns cells so their CellTracks Analyzer can check them out. Researchers at Mass General are looking at this as a new way to treat cancer, and the media, like me, has pricked up their ears and are wondering if it could become that, to quote Dr. Gehrig again, golden challis of ovarian cancer: a screening test for the asymptomatic and low risk woman.
Currently using ultrasounds and CA125 tests, or ultrasounds and more expanded biomarker tests are both expensive and full of false results making them not yet useful in general populations. A summary of these kinds of tests can be found at Cancer blood tests: Lab tests used in cancer diagnosis – Mayo Clinic on line.
At Women’s Health Practice we suggest you come in to discuss what your personal risk profile is and what tests would be recommended for you to do, and which tests to avoid.