Oncologists for years have been trying to develop more sensitive techniques for discovering when cancer is recurring, so that treatment can begin right away. Until now, for most cancers, that most sensitive technique was the CAT scan. However, by the time a CAT scan can detect recurrence there are hundreds of millions of cancer cells in the body. How can we do better? For the last ten years investigators have been trying to measure miniscule quantities of tumor-associated genetic material — DNA — circulating in the bloodstream that could form the basis of a cancer blood tests.
Now scientists from Denmark and Silicon Valley have developed a blood test for people with bladder cancer whose bladders have already been removed to see whether tiny remnants of cancer left behind could be growing back. Published in the Journal of Clinical Oncology, a top-rate cancer journal, in May, 2019 was an article measuring miniscule amounts of DNA, genetic material shed from tumor cells. All of us have free DNA, not present inside cells, floating in our circulation, but this DNA contained abnormal sequences of genetic material associated with have bladder cancer. Click on the link to view the abstract. Dr. Stark can send you the entire article.
What they found that if people with bladder cancer got chemo before their bladders were removed, the tumor DNA measured at the end of chemo should be zero. If not, these people would have a recurrence of their cancer and die They also found that a delayed appearance of tumor DNA after surgyer predicted accurately that the CAT scan would turn positive, but the blood test beat the CAT scan by almost 100 days.
Dr. Stark comments: we have been looking for a blood test to detect very early recurrenc of cancer. As therapy of recurrence improves, this technology becomes even more important in an effort to diagnose recurrence when something can still be done about it. This paper is a landmark in this endeavor.