High-grade plasmacytoid carcinoma stage III grade C is more serious, at this time the disease has already developed to the middle and late stage, and the prognosis is mostly poor. High-grade plasmacytoid carcinoma cells are less differentiated, so it is a kind of epithelial tumor with higher malignant degree, and stage III already belongs to the middle and late stage of tumor, with larger cancer foci and lymph node or distant metastasis, so it can only be treated as palliative treatment and cannot achieve the effect of radical treatment, so the prognosis is worse, and the disease is also more serious. For patients who are found to have high-grade plasmacytoid carcinoma stage III grade C, it is recommended that they should go to regular hospitals for consultation, and choose radiotherapy, chemotherapy or palliative surgery under the guidance of doctors for active treatment, with a view to improving the quality of life and prolonging the life span.