Risk factors for lymphatic metastasis of malignant bone and soft-tissue tumors: a retrospective cohort study of 242 patients.

Metastasis to the lymph nodes is relatively rare in malignant bone and soft-tissue tumors, and its risk factors remains unknown, except for tumors of the lymphogenous histotype, including rhabdomyosarcoma, epithelioid sarcoma, and clear cell sarcoma. The purpose of this study was to identify the risk factors for lymph node metastasis of malignant bone and soft-tissue tumors. We retrospectively reviewed 242 patients with malignant bone and soft-tissue tumors. The predictors of interest for the risk of lymph node metastasis included age, sex, histopathological diagnosis, location(s) of the primary tumor(s), local recurrence, residual tumor(s), and the size of the primary tumors. To identify the risk factors for lymph node metastasis, Cox regression analyses were performed. Among the 242 patients with malignant bone and soft-tissue tumors in the current study, 60, 29, and 28 were detected to have lung, lymph node, and bone metastases, respectively. In the univariate analyses, the lymphogenous histotype and a primary tumor invading the subcutis were the risk factors for lymph node metastasis. In the multivariate analysis, the lymphogenous histotype (P < 0.01) and a primary tumor in the subcutis (P < 0.01) remained significantly associated with a higher risk of lymph node metastasis with 5.15 and 3.48 of hazard ratios, respectively. Lymph node metastasis was detected in malignant bone and soft-tissue tumors more frequently than that has been previously reported, and the risk factors for lymph node metastasis were the lymphogenous histotype and primary tumors invading the subcutis.