Celecoxib and Radiation Therapy in Treating Patients With Stage II or Stage III Soft Tissue Sarcoma of the Arm, Hand, Leg, or Foot That Has Been Removed by Surgery

DISEASE CHARACTERISTICS: * Histologically confirmed soft tissue sarcoma of the extremity, including the following disease types: * Liposarcoma * Leiomyosarcoma * Synovial cell sarcoma * Malignant fibrous histiocytoma * Spindle cell sarcoma * Fibrosarcoma * Chondrosarcoma * Angiosarcoma * Hemangiopericytoma * Neurofibrosarcoma * The following disease types are excluded: * Kaposi's sarcoma * Rhabdomyosarcoma * Dermatofibrosarcoma * Epithelioid cell sarcoma * Ewing's sarcoma * Osteosarcoma * Intermediate- or high-grade tumor ≥ 5.0 cm in 1 dimension (stage II or III disease) * Locally resected disease * One prior wide local excision of the sarcoma in the same location of the extremity within the past 6 months allowed * Prior neoadjuvant chemotherapy (of ≤ 3 courses), followed by a limb-sparing surgical resection of sarcoma found to have \< 90% pathological tumor necrosis allowed * Prior resection of an extremity mass that is subsequently found to be a sarcoma meeting study criteria, followed by ≤ 3 courses of chemotherapy (independent of the percentage of pathological tumor necrosis) allowed * No evidence of nodal or distant metastases PATIENT CHARACTERISTICS: * Karnofsky performance status 70-100% * WBC ≥ 3,000/mm³ * Absolute granulocyte count ≥ 1,500/mm³ * Platelet count ≥ 100,000/mm³ * Bilirubin ≤ 1.5 mg/dL * SGPT and SGOT ≤ 2.5 times upper limit of normal (ULN) * Creatinine ≤ 1.5 times ULN * Calcium ≤ 1.3 times ULN * No prior malign…