Is local recurrence in bone and soft tissue sarcomas just a local recurrence or does it impact the overall survival, retrospective cohort from a sarcoma referral center

Background and Objectives Sarcoma local recurrence (LR) is often associated with metastasis, but it is unclear if LR can be a causal event leading to metastasis. We question if LR is best viewed as an independent oncologic event or as a worrisome harbinger threatening a patient's overall survival. Methods We identified patients with LR and/or metastasis from an ongoing cohort of 629 patients with primary sarcoma and performed a detailed review to assess the timing of metastasis resulting in the following groups: (1) Isolated LR, (2) LR before metastasis, (3) LR within 6 months of metastasis, (4) LR 6-12 months after metastasis, (5) LR >12 months after metastasis, and (6) metastasis at diagnosis. Results Overall, 43 patients met the inclusion criteria with an LR rate of 7%. Ten patients (2% of the entire cohort, 23% of LR) developed an LR before or within 6 months of metastasis. For patients without systemic disease preceding LR, 3 of 23 soft tissue sarcoma STS (13%) and 7 of 10 bone sarcoma (70%) subsequently developed metastasis (p < 0.01). Conclusion LR with subsequent metastasis is a rare event. LR appears to be best viewed as a marker of tumor aggressiveness rather than the cause of metastasis and poor survival. LR in bone sarcoma patients should warn providers of a high risk of imminent metastasis.