Combined Treatment of Patients With Soft Tissue Sarcoma Including Preoperative Stereotactic Radiation Therapy and Postoperative Conformal Radiation Therapy

At the first step patient undergoes preoperative stereotactic radiation therapy in hypofractionation mode. Radiation therapy plan is based on topometric MRI and CT scans. Radiation therapy plan are performed after MRI and CT fusion, contouring of the target and surrounding normal tissues. At first step only tumor and, if necessary, the surrounding normal tissues, which will be removed during surgery, are exposed to radiation. GTV - determined in with the boundaries of the tumor visualised by topometric MRI and CT CTV1 - match GTV CTV2 - formed inward (to the tumor center) from GTV by 0.5-1 cm (depending on the proximity of functionally significant normal tissues (neurovascular bundles, bone tissue, skin and subcutaneous fat, etc.) PTV - 3-5 mm indent from CTV1, taking into account the proximity of functionally significant normal tissues and the planned surgery Preoperative radiation therapy is carried in 5 fractions with a single dose on PTV - 5 Gy, a single dose on CTV2 - 7 Gy.

In 14-21 days after preoperative stereotactic radiation therapy radical surgery will be performed

In 25-35 days after the surgery postoperative conformal radiation therapy is performed according to the standard protocol GTV (tumor bed) - based on the volume of the primary tumor, including the swelling zone (T2-weighted images on preoperative MRI) СTV - formed with an indent of 4 cm from GTV (without going beyond the boundaries of the involved compartment), in the transverse direction the indent could be reduced to 2 cm. PTV - formed with an indent of 0.5-1cm from CTV An important condition for planning radiation therapy is to limit the dose absorbed during both stages of radiation therapy in surrounding normal tissues that are not removed during surgery.