PURPOSE The role of chemotherapy (CT) and radiotherapy (RT) for management of extraskeletal osteosarcoma (ESOS) remains controversial. We examined disease outcomes for ESOS patients and investigated the association between CT/RT with recurrence and survival. PATIENTS AND METHODS Retrospective review at 25 international sarcoma centers identified patients ≥18 years old treated for ESOS from 1971 to 2016. Patient/tumour characteristics, treatment, local/systemic recurrence, and survival data were collected. Kaplan-Meier survival and Cox proportional-hazards regression and cumulative incidence competing risks analysis were performed. RESULTS 370 patients with localized ESOS treated definitively with surgery presented with mainly deep tumours (n = 294, 80%). 122 patients underwent surgical resection alone, 96 (26%) also received CT, 70 (19%) RT and 82 (22%) both adjuvants. Five-year survival for patients with localized ESOS was 56% (95% CI 51%-62%). Almost half of patients (n = 173, 47%) developed recurrence: local 9% (35/370), distant 28% (102/370) or both 10% (36/370). Considering death as a competing event, there was no significant difference in cumulative incidence of local or systemic recurrence between patients who received CT, RT, both or neither (local p = 0.50, systemic p = 0.69). Multiple regression Cox analysis showed a significant association between RT and decreased local recurrence (HR 0.46 [95% CI 0.26-0.80], p = 0.01). CONCLUSION Although the use of RT significantly decreased local recurrences, CT did not decrease the risk of systemic recurrence, and neither CT, nor RT nor both were associated with improved survival in patients with localized ESOS. Our results do not support the use of CT; however, adjuvant RT demonstrates benefit in patients with locally resectable ESOS.

中文翻译：

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化学疗法和放射疗法在局部骨骼外骨肉瘤中的作用。

目的化学疗法（CT）和放射疗法（RT）在骨骼外骨肉瘤（ESOS）管理中的作用仍存在争议。我们检查了ESOS患者的疾病结局，并研究了CT / RT与复发和生存之间的关系。患者与方法在1971年至2016年间，对25个国际肉瘤中心的回顾性研究确定了≥18岁的ESOS患者。收集了患者/肿瘤特征，治疗，局部/全身复发和生存数据。进行了Kaplan-Meier生存率和Cox比例风险回归以及累积发生率竞争风险分析。结果370例经局部手术明确治疗的ESOS患者主要表现为深部肿瘤（n = 294，80％）。仅接受手术切除的122例患者中，有96例（26％）也接受了CT检查，分别有70（19％）的RT和82（22％）的佐剂。局部ESOS患者的五年生存率为56％（95％CI 51％-62％）。几乎一半的患者（n = 173，47％）复发：局部9％（35/370），远处28％（102/370）或两者均10％（36/370）。考虑到死亡是竞争事件，接受CT，RT，两者或两者都不接受的患者之间局部或全身复发的累积发生率没有显着差异（局部p = 0.50，全身p = 0.69）。多元回归Cox分析显示RT与局部复发率降低之间存在显着相关性（HR 0.46 [95％CI 0.26-0.80]，p = 0.01）。结论尽管使用RT显着降低了局部复发，但CT并没有降低全身复发的风险，并且CT和RT或两者均与局部ESOS患者的生存率提高无相关性。我们的结果不支持CT的使用；然而，佐剂放疗对局部可切除ESOS的患者显示出益处。