Soft-tissue sarcomas (STSs) are malignant tumors that comprise various histological subtypes and can develop in any part of the body [1]. The 5-year overall survival rate for localized STS is reportedly around 80% [2,3]. The standard treatment strategy for patients with localized STS is wide resection with oncologic margins, possibly with radiotherapy or neoadjuvant chemotherapy [4,5].

A negative surgical margin is the standard goal for localized STSs [6]. In addition, a positive macroscopic margin followed by radiotherapy is reasonable in some cases [7]. Recent advances in reconstruction surgery have made it possible to cover more extensive soft tissue defects after tumor resection, increasing the number of patients able to receive limb-sparing surgery [8,9]. However, due to critical neurovascular structures or bones, limb-sparing surgery is not feasible in some cases, so amputation surgery is still required [10].

The amputation rate is reportedly 4–10% in patients with localized extremity STS and 9–14% for patients with recurrent disease [[11], [12], [13], [14], [15]]. In some epithelioid cancers, tumors showing invasion to the main vascular or bone are classified as higher-stage cancers [[16], [17], [18]]. In contrast, whether direct invasion to critical structures such as vessels or bone affect survival remains unclear in patients with localized STS.

We therefore hypothesized that patients with localized extremity STS who received amputation surgery might show worsened survival compared to patients who underwent limb-sparing surgery. To test this hypothesis, we investigated a population-based cohort from the Surveillance, Epidemiology, and End Results (SEER) database to clarify whether localized extremity STS patients who received amputation surgery experienced worsened survival and to identify those patients for whom amputation surgery experienced worsened survival.