Hypothyroidism and thyroid cancer are two different types of thyroid diseases; hypothyroidism does not cause thyroid cancer, and there is no necessary connection between the two. Hypothyroidism refers to a decrease in thyroid function levels, caused by abnormalities in the secretion and synthesis functions of the thyroid, closely related to disorders of the endocrine system. In contrast, thyroid cancer is a change in tissue nature due to malignant transformation in thyroid tissue cells, it is not related to the thyroid's endocrine functions, and currently, there is no research indicating that hypothyroidism increases the likelihood of developing thyroid cancer. Patients with thyroid diseases should undergo dynamic thyroid ultrasonography and monitoring of thyroid function to further clarify their condition.