Exact Sciences' (EXAS 0.96%) phase 3 trial for its colon cancer detection test passed, but the stock dropped 20%. What gives? In this video, David Williamson goes into the details of Exact Sciences' DNA-based test. The overall effectiveness of the Cologuard test was 92%. However, the detection rate was 42%, less than colonoscopy, and the 87% overall accuracy rate leads to a higher false positive rate than most doctors would like to see. Is Exact Sciences doomed? Not really -- it has $100 million in the bank. It may be a takeover target, and David sees Intuitive Surgical (ISRG -0.19%) as a possible buyer.