Blood in sputum is not necessarily lung cancer. Blood in sputum may be pneumonia, lung infection, tuberculosis or fungal infection of lung. If there is blood in sputum, there may be fever, cough, yellow sputum, CT scan of lungs can find flaky shadows in lungs, yellow sputum and blood in sputum will disappear after anti-infection treatment, and flaky shadows in lungs will disappear, and then the diagnosis of lung infection will be clear. Tuberculosis can be treated with anti-tuberculosis therapy and the blood in the sputum will disappear, and the course of treatment will take about six months to a year. Fungal infections can also be characterized by cavitary lesions in the lungs and blood in the sputum, accompanied by fever, which can be detected on CT scanning of the lungs. Anti-fungal treatment can be used to treat fungal infections in the lungs, and the blood in sputum will disappear quickly, and the course of anti-fungal treatment should be at least three months. Lung cancer can present with blood in sputum, but CT is a soft tissue mass in the lungs, and pathologic puncture biopsy or fiberoptic bronchoscopy can find cancer cells and make a clear diagnosis.