Early symptoms of thyroid cancer: First, differentiated thyroid cancer often exhibits no symptoms in its early stages, only accidentally discovered nodules that vary in size and texture on the front of the neck. Some patients are only diagnosed during routine physical exams or through imaging studies, with clinical symptoms being relatively rare. However, more symptoms and signs may appear in the later stages. Second, medullary thyroid cancer presents some unique symptoms, such as persistent diarrhea, typically watery, and a syndrome involving the endocrine system. Patients may exhibit facial flushing, elevated blood pressure, and decreased blood calcium levels, accompanied by other conditions, such as parathyroid adenomas, multiple mucosal neuromas, and pheochromocytomas, which also manifest specific symptoms.