Bilateral pneumonic lesions are usually not cancer. Lung cancer is more common unilaterally, and bilateral pneumonic lesions usually refer to infectious lesions in the lungs, i.e. pneumonia. Pneumonia refers to the infectious inflammation of alveoli, terminal bronchioles, and interstitium of lungs, which is mostly caused by bacteria, viruses, and atypical pathogens, etc. The main clinical manifestations are coughing, sputum, fever, etc., which can be treated with targeted antibiotics as well as other drugs. The typical imaging sign of lung cancer is “S-shaped reflection” (or “anti-S sign”), which usually does not indicate bilateral pneumonic lesions. If the examination suggests bilateral pneumonic lesions, one should go to the hospital in time, complete the relevant examinations to clarify the cause of the disease, and take symptomatic treatment under the guidance of the doctor.