Nose odor is usually not a harbinger of lung cancer. Nose odor may be related to atrophic rhinitis, diabetic ketoacidosis and other diseases, and when there are persistent or progressive symptoms of nose odor, one should consult doctor in time to find out the cause. Lung cancer is a primary malignant tumor of the lungs originating from bronchial mucosa or glands, and its main clinical manifestations are cough, sputum, wheezing, chest pain, fever, emaciation, etc., and the symptom of bad smell from the nose does not usually occur. Atrophic rhinitis is mainly related to endocrine disorders, vitamin deficiency, high concentration of harmful dust, gas on the nasal cavity of the continuous stimulation, etc., the patient may appear nasal congestion, nasal dryness, nosebleeds and other symptoms, the serious cases can appear when exhaling a special rotten odor, the patient feels that the nose has a bad smell. Nose odor may also be caused by diabetic ketoacidosis. Diabetic ketoacidosis is a serious metabolic disorder syndrome, due to the lack of insulin in the body, which can lead to fat decomposition to produce a large number of acidic ketone bodies, exhaling rotten apple flavor, but also can appear deep and fast breathing, drinking, eating, urinating, dry skin mucous membranes and other symptoms. In addition, sinusitis, nasal polyps and other diseases can also lead to nose odor, but this symptom alone is not enough to diagnose the disease, such as symptoms can not be relieved should be timely consultation, identify the cause of the disease, if necessary, by the doctor for targeted treatment.