Short Course Of Preoperative Radiotherapy in Head and Neck-, Trunk- and Extremity Soft Tissue Sarcomas

Overview

Currently, soft tissue sarcomas (STS) are preoperatively irradiated in a conventionally fractionated regimen of 25 x 2 Gy in five weeks. Recent radiobiological investigations, however, suggest sensitivity to (modest) hypofractionation. Within this study, patients will be randomized to receive either the conventional schedule of 25 x 2 Gy or a shorter preoperative regimen of 14 x 3 Gy, in the hypothesis that both the postoperative wound complication rate until 30 days after surgery, as well as the local control probability at two years are comparable in both arms.

Surgery is the cornerstone in the treatment of non-metastatic sarcomas. Whenever feasible the resection should include a free surgical margin providing a rim of uninvolved tissue surrounding the tumor. In most deep located tumors however, to preserve essential neurovascular and bone structures and thus to preserve function, the margins are often limited. High grade tumors are, even with wider margins, at higher risk of local failure. Radiotherapy can reduce this risk of local failure. Preoperative radiotherapy does increase the risk for early complications due to unavoidable irradiation of the normal tissues surrounding the sarcoma mass, particularly for lower extremity lesions (6-9). Preoperative radiotherapy aims to reduce tumor vitality prior to resection, theoretically allowing more conservative surgical therapy. Postoperative RT allows histological examination of the tumor specimen, especially the margins, aiding in further treatment planning; it may also be associated with fewer early wound complications. (10, 11). In preoperative radiotherapy, as compared to postoperative radiotherapy, lower doses (50 versus 60 to 66 Gy) and smaller field sizes can be used, resulting in a reduced risk of late, often irreversible, complications. Consequently, preoperative RT is the preferred approach in many centers. Although the outcomes of combined RT and surgery are favorable, approximately 15% of the patients may relapse locally and about 30-50% distantly (dependent upon, among others, age, histopathology, size and grade), stressing the need for further improvement. These improvements should not only be sought in the domain of oncological endpoints, but also in decreasing treatment burden. A reduction in treatment duration, maintaining local control rates without increasing the rates of postoperative wound complications would serve the latter endpoints. For this purpose, quality of life questionnaires as well as patient reported outcomes measurements could come of help.Modern radiobiological investigations suggest that, on average, intermediate to high-grade soft tissue sarcomas may have α/β ratio's substantially below 10 Gy, justifying clinical studies exploring the possibility of (modest) hypofractionation. Obviously, various subtype derived cell lines exhibit different characteristics but on average an α/β ratio of 5 Gy would be a reasonable denominator for sarcomas as a group. However, it is important not to exaggerate hypofractionation in a setting where patients still need to undergo surgery.