HER2 is generally referred to as HER2, short for Human Epidermal Growth Factor Receptor 2, and HER2-negative means that the prognosis is good for patients with breast or stomach cancer. HER2 negative means that the gene is not expressed, which is a good sign. It means that breast cancer or stomach cancer patients have better late treatment, good prognosis and higher late survival rate. If the HER2 gene is negative, there is no need to take targeted drug therapy for HER2 gene. HER2 positive means that the patient’s cancer cells have a higher degree of malignancy and are prone to recurrence and metastasis. Strictly follow the doctor’s instructions and cooperate with the relevant treatment. Formulate a treatment plan to avoid adverse consequences.