What is the likelihood of nonpulmonary metastasis occurring in the absence of lung metastasis in bone and soft tissue sarcoma? A nested case-control from a sarcoma referral centre

Background and Objectives Nonpulmonary metastases (NPM) are rare, associated with a poorer prognosis, and maybe missed on conventional chest imaging for sarcoma surveillance. We determined (1) the proportion of NPM occurring in isolation or with synchronous or prior pulmonary metastases (PM), and (2) if initial NPM would have been recognized with a standard surveillance protocol. Methods Investigators identified patients who developed initial NPM without prior evidence of or concurrent PM from an ongoing cohort of bone and soft tissue sarcoma (STS) patients. Logistic regression at univariate level was done. Results There were 138/630 (22%) patients with metastasis and 66 (10%) had NPM: 50 (8%) patients had PM presenting first, while 16 (3%) had initial NPM. Malignant peripheral nerve sheath tumor, angiosarcoma, rhabdomyosarcoma, synovial sarcoma, and myxoid liposarcoma were six times more likely to develop initial NPM than other subtypes of STS with odds ratio = 6 (95% confidence interval: 1.93-18.65, p value < 0.01). Chest imaging and physical examination were sufficient to identify NPM in all except three bone sarcoma patients. Conclusions Patients who develop initial NPM are rare and demonstrate a predilection towards some subtypes of extremity sarcoma. They develop oligometastatic disease, which may be amenable for surgical excision. All isolated or initial NPM in STS patients were discovered by physical examination and standard chest imaging.