Further analysis of patients with EOC showed that the expression of B2M had no association with clinicopathological features, such as age (≤45 vs. >45), tumour size (≤2 cm vs. >2 cm), multifocal tumours, lymph node metastasis, and clinical stages (Table 2) (all P > 0.05). Here, B2M is linked to metastatic malignant neoplasm in the lymph nodes.