Lung metastasis in soft tissue sarcomas: survival and risk factors using the SEER database

Aim: To investigate patients with soft tissue sarcoma (STS) and evaluate (1) factors associated with lung metastases at the time of diagnosis; (2) the impact these factors had on overall survival; and (3) the impact of the metastatic site on survival. Methods: We utilized the SEER database to analyze data from 14,520 patients diagnosed with STS between 2010 and 2018. Inclusion criteria included histologically confirmed STS of the lower limb, upper limb, or pelvis. Demographic, oncologic, and survival data were extracted, including tumor size, histopathology, AJCC staging, and metastatic status. Univariable and multivariable analyses identified risk factors for lung metastasis and Kaplan-Meier survival analysis was used to assess disease-specific survival (DSS). Results: Of the 13,372 patients with STS, 7.9% had lung metastases at diagnosis. Undifferentiated pleomorphic sarcoma, leiomyosarcoma, and rhabdomyosarcoma were the most common STS presenting with lung metastasis. Patients who present with STS of the lower extremity, higher grade, and either leiomyosarcoma, spindle cell, or synovial cell sarcoma were more likely to present with lung metastases. Patients with lung metastases had worse survival than patients without metastases. However, survival was better in patients with isolated lung metastases than in those with any combination of lung, bone, brain, and/or liver metastases. Conclusion: Tumor location, grade, T score, and lymph node involvement were significant risk factors for lung metastasis. A deeper understanding of risk factors for lung metastases presents a new opportunity for investigation in management. As expected, patients who present with lung metastases have worse overall survival.