Intensity-Modulated Radiation Therapy in Treating Patients Undergoing Surgery for Stage IB, Stage II, or Stage III Soft Tissue Sarcoma

DISEASE CHARACTERISTICS: * Histologically confirmed soft tissue sarcoma (STS) for which neoadjuvant or adjuvant radiotherapy is considered standard care * Stage IB-III disease * Primary or locally recurrent disease * The following chemotherapy-sensitive STS histologies are excluded: * Primitive neuroectodermal tumor * Desmoplastic small round cell tumor * Synovial sarcoma * Myxoid round cell liposarcoma * Angiosarcoma * No sarcomas for which surgical staging and adjuvant radiotherapy are considered standard care (e.g., uterine sarcomas, including leiomyosarcoma, malignant mixed Müllerian tumors, and endometrial stromal sarcoma) * No retroperitoneal STS PATIENT CHARACTERISTICS: * ECOG performance status 0-2 * Able to complete the self-assessment questionnaires (may use translator service) * Willing and able to undergo pre-treatment core needle biopsies * Negative pregnancy test * No known HIV positivity PRIOR CONCURRENT THERAPY: * Prior adjuvant chemotherapy for STS allowed provided patient has locally recurrent disease * At least 1 year since prior adjuvant chemotherapy * No prior radiotherapy to the site of present STS * No other concurrent cytotoxic chemotherapy, targeted therapy, or investigational agents