CT scans can be helpful in diagnosing cancer, but a normal result does not completely rule out cancer. CT scan is a common medical imaging test in clinic, which is very helpful for clinical diagnosis of diseases. However, CT scanning has a limited role in diagnosing tumors, which can only be detected when the tumors are large, and may not be detected in the early stage of malignant tumors, therefore, this examination cannot completely exclude cancer. To rule out cancer requires systematic examinations, such as blood sampling for tumor markers, CT enhancement, magnetic resonance enhancement, endoscopy, tracheoscopy, colposcopy and other examinations. In addition, a puncture biopsy of the tissue at the lesion site can be done to make a clear diagnosis. We should usually develop good living habits, pay attention to regular medical checkups, early detection and early treatment of diseases to avoid delays.