Dramatic response from neoadjuvant, spatially fractionated GRID radiotherapy (SFGRT) for large, high-grade extremity sarcoma

Extremity sarcomas are managed surgically with the goal of limb preservation. In order to reduce local recurrence rates, radiation treatment has been used in either the preoperative or postoperative setting for select cases [1]. This combination has proven beneficial for large, high-grade, deeply invasive, or incompletely resected tumors [2]. Due to lower long-term complications rates, neoadjuvant treatment has become favored in cases where predicted postsurgical risks are low [3]. However, high-grade sarcomas rarely completely regress after preoperative radiation [4, 5]. In addition, the median pathological treatment response for high-grade tumors is only 50 %, and patients with pathological necrosis rates less than 95 % are 2.5 times more likely to develop a local recurrence [5, 6]. Thus, very large (>8 cm) sarcomas represent an even greater clinical challenge. This has prompted the addition of chemotherapy to preoperative radiation in the hopes of improving tumor response [6–8] and to evaluate effectiveness of the drugs. Although neoadjuvant chemoradiation shows greater tumor necrosis, it comes at a significant cost. One study showed a 90% risk of grades 3–4 hematologic toxicity with chemoradiation, and a multi-institutional phase II study reported increased hospitalizations and death [7, 8]. Methods