Soft tissue sarcomas (STS) include over 100 different biopathological entities, representing less than 2 % of all cancers (WHO Classification of Tumours Online). Some particular entities (e.g. desmoid-type fibromatosis, rhabdomyosarcomas, extraosseous Ewing sarcoma …) requires specific approaches. For the vast majority of STS, at the localized stage, STS is best treated with large-en-bloc resection combined with radiotherapy; however, the role of perioperative chemotherapy remains debated. Despite optimal management, 40 % of STS cases experience distant metastases. Approximately 10 % of STS cases metastasize at the time of diagnosis (Gronchi et al., 2021). At the metastatic stage, less than 5 % of STS are amenable to a curative strategy; in case of oligometastases, particularly lung metastasis, and amenable to surgery, polychemotherapy combined with surgical resection or destruction of all metastases may be proposed (Blay et al., 2003, Carbonnaux et al., 2019). In cases of diffuse metastatic spreading, in cases of extra-pulmonary spreading, the standard of care until now remains doxorubicin-based chemotherapy for palliative intent. The objective was twofold: to slow the course of sarcoma and maintain health-related quality of life (HR-QoL).

Doxorubicin-based chemotherapy remains the standard of care for metastatic sarcoma, but the objective response rate is only 20–40 %, depending on the regimen (monotherapy versus polychemotherapy) (Judson et al., 2014, Ryan et al., 2016). As a single-agent regimen, doxorubicin is usually administered at a dose of 75 mg/m² on day 1 of 21-days cycles with a total of administered cycles usually of 6 (reaching a cumulative dose of 450 mg/m²) due to the risk of delayed cardiotoxicity. The median progression-free survival (PFS) is limited (approximately 3–4 months, with some long-term progression free survivors) in a mixed series of histotypes, although it may be shorter or longer in specific histological subtypes (Judson et al., 2014, Ryan et al., 2016). Beyond the 1s-line, the therapeutic options considered active as second-line therapy are quite limited and less active than doxorubicin, with a median PFS close to 3 months (Gronchi et al., 2021). However, after 6 courses of doxorubin-based chemotherapy, the current attitude is to monitor the patient and introduce a 2nd line treatment in case of tumor progression. The choice of treatment depends on the histological subtype, for example, for liposarcomas (trabectedin or eribulin), for leiomyosarcomas (trabectedin, pazopanib, ifosfamide, gemcitabine …), for angiosarcomas (paclitaxel, pazopanib …) (Gronchi et al., 2021). Therefore, it is critical to assess the clinical utility of maintenance therapy in the minority of patients who experience an objective response or stable disease after first-line treatment. There are two kinds of maintenance therapy: (i) same regimen at a lower dose or a part of first-line regimen (“continuation maintenance therapy”), or (ii) use of another drug after administration of the first-line regimen (“switch maintenance therapy ») (Gerber and Schiller, 2013). By definition, continuation maintenance implies that the first part of the combination treatment, including the agent, is the backbone of treatment continuation. The purpose of this review was to summarize and discuss published clinical trials, directly or indirectly, raising the question of the benefits of maintenance treatment after first-line treatment for STS.