Impact of tumor volume doubling time on post-metastatic survival in bone or soft-tissue sarcoma patients treated with metastasectomy and/or radiofrequency ablation of the lung

Metastasectomy represents the standard treatment for improving survival in patients with lung metastases (LMs) from bone (BS) or soft-tissue sarcoma (STS). Recently, radiofrequency ablation (RFA) of the LMs has been proved to be a useful option which can promise the similar effect to metastasectomy. The aim of this study was to determine prognostic factors, including tumor volume doubling time (TVDT), for post-metastatic survival in BS and STS patients treated with metastasectomy and/or RFA of the lung. Forty-eight patients with LMs were retrospectively reviewed. The mean age of the patients at the time of LMs was 56 years. The cohort comprised 27 male and 21 female patients. Eight of the 48 patients had LMs at the point of initial presentation. The mean follow-up period after commencing the treatment for LMs was 37 months. The mean maximum diameter of the initial LMs was 11 mm. The mean number of LMs was 4. The TVDT was calculated using a method originally described by Schwartz. At last follow-up, 5 patients had no evidence of disease, 3 patients were still alive with disease, and 32 patients had died of disease. The 3-year and 5-year post-metastatic survival rates were 32% and 16.8%, respectively. In a Cox univariate analysis, the size (P= 0.04) and number of LMs (P < 0.001), disease-free interval (P=0.04), curability of the initial LMs (P <0.001), and TVDT (P <0.001) were significantly identified as factors which affect prognosis. In the multi-variate analysis, TVDT (P <0.001) and curability of the initial LMs (P <0.001) were confirmed as independent predictors of survival. There was a significant association between the number and curability of the initial LMs (P <0.001). In conclusion, metastasectomy and/or RFA of LMs is recommended for improving survival. However, TVDT and the curability of the LMs should be taken into consideration.