In addition to age and gender, tumor size, presence of extraperitoneal invasion and multifocal lesions are also several factors that affect prognosis. 1.Tumor size Whether the size of TMC is a factor affecting prognosis is still controversial. However, a study has compared the maximum diameter of microscopic carcinoma 0.5-1.0 cm with that of <0.5 cm, and found that the incidence of lymph node metastasis was 59.0% in the former and 13.0% in the latter; the incidence of extraperitoneal invasion was 10.0% in the former and only 3.0% in the latter. Although patients with tumor diameter ≥0.5 cm were prone to recurrence after surgery in the univariate analysis, the results of multivariate analysis showed that tumor size was not an independent factor affecting prognosis. Extraperitoneal invasion is one of the important risk factors affecting the prognosis of thyroid cancer. 2.0% to 21.0% of the patients with TMC had extraperitoneal invasion. According to the extent of invasion, it should be T3, T4a or T4b according to TNM staging, and should be treated actively according to the staging. 3. Multifocal lesions Multifocal lesions tend to increase the risk of lesions in the contralateral glandular lobe and may increase the incidence of regional lymph node metastasis, so the risk of lymph node recurrence in the contralateral glandular lobe and lateral cervical area should be paid attention to during the follow-up of patients with multifocal TMC.