Thyroid cancer often starts insidiously and is easy to be misdiagnosed. Many patients need to undergo two surgeries before it can be removed cleanly, and a few patients may need a third surgery due to residual primary foci, occult metastasis, uncleared lymph nodes and other reasons. 1. Remaining primary foci: Thyroid cancer is often indistinguishable from thyroid adenoma, nodular goiter, thyroid cyst, etc., which often leads to inappropriate choice of the first two surgeries, and inappropriate surgeries lead to too small surgical scope, and a small amount of cancer cells will inevitably remain, leading to recurrence of cancer cells after surgery, and the patient may need a third surgery. 2. Occult metastasis: it may be that the patient has already had metastasis of cancer cells before surgery, but the secondary lesion after metastasis is small and difficult to be detected by various means of examination, and after the primary lesion is removed cleanly, the secondary lesion grows rapidly, resulting in the need for the patient to undergo the second or even the third surgery. 3. Lymph nodes are not cleaned out: commonly found in papillary thyroid cancer and medullary carcinoma, if the patient has lymph node metastasis, the cancer will often recur after the first radical thyroid cancer surgery, and then the lymph node cleaning may not be cleaned out, and some patients may even have multiple recurrences, which will require another or more surgeries.