Cancer detection tests open a new era of developing cancer markers, allowing early detection and improving cancer treatments. Existing cancer detection technologies, for example, CA125, CA 19.9, CT, MRI, and others, are either not highly sensitive or specific enough for early detection. Recent technological development of “liquid biopsy” research led to more sensitive biomarkers. Newly developed multiple-cancer early-detection tests can screen up to multiple cancers in asymptomatic individuals with one blood draw. These tests, however, might pose significant challenges in our clinical practice. This paper highlights the issues we face and how to solve their problems.