Radiation Oncology/Sarcoma/Hemangiopericytoma

Hemangiopericytoma Overview Malignant vascular tumor Tumor cells appear like smooth muscle cells, but don't arise from endothelial cells Cell of origin not clear, possibly derived from pericytes Most commonly in pelvic, proximal femur, humerus, and vertebral bodies Median age in 4th and 5th decade Typically slow growing Radiography not definitive Easily confused with meningioma. No calcifications or hyperostosis on CT (where as meningiomas have these features) larger lesions will show flow voids on MRI. Treatment frequently surgical, role of chemo and RT not clear, although small series show lower rates of recurrence with addition of radiotherapy. Heidelberg, 2005 (Germany) (1984-2004) 16222690 — "Precision radiotherapy for hemangiopericytomas of the central nervous system." (Combs SE et al. Cancer. 2005 Dec 1;104(11):2457-65.) Retrospective. 25 patients. 23 surgical resection. Treated with fractionated stereotactic RT or IMRT for tumors of the CNS and spine. Median dose 54 (in 1.8-2 Gy/fx) OS: 5-years 100%, 10-years 64%. 5-year PFS 61% Conclusion: "High precision" RT effective and safe SEER Analysis, 2013 (1990-2008) 22867893 - The Role of Postoperative Radiation Therapy in the Treatment of Meningeal Hemangiopericytoma—Experience From the SEER Database (Stessin AM et al. Int J Radiat Oncol Biol Phys. 2013 Mar 1;85(3):784-90.) SEER analysis from 1990-2008 of 76 patients in, of these 38 (50%) underwent gross total resection (GTR), whereas the other half underwent subtotal resection (STR), with a mean follow-up time is 7.9 years (95 months). There were Postoperative RT was administered to 42% (16/38) of the patients in the GTR group and 50% (19/38) in the STR group. The 1-year, 10-year, and 20-year cause-specific survival rates were 99%, 75%, and 43%, respectively. On multivariate analysis, postoperative RT was associated with significantly better survival (HR = 0.269, 95% CI 0.084-0.862; P=.027), in particular for patients who underwent STR (HR = 0.088, 95% CI: 0.015-0.528; P<.008). Conclusion: Based on the current literature, the practical approach is to deliver limited field RT to doses of 50-60 Gy while respecting the normal tissue tolerance, especially for cases of STR.