Main Session
Sep
27
PQA 02 - Pediatric Cancer, Sarcoma and Cutaneous Tumors, Medical Education & Professional Development, and Health Services Research
Presenter(s)
Jacob Jordan, MD, MS - Mayo Clinic Rochester, Rochester, MN
J. A. Jordan1, F. Yousefi2, N. N. Laack II1, P. D. Brown1, S. K. Ahmed3, I. A. Petersen1, E. J. Lehrer1, K. N. Lee1, M. G. Haddock1, K. Olivier1, A. Mahajan4, A. L. Stockham Jr1, A. Amundson1, P. S. Rose5, A. L. Versteeg5, M. A. Golafshar6, and M. Welliver1; 1Department of Radiation Oncology, Mayo Clinic, Rochester, MN, 2Mayo Clinic, rochester, MN, 3Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, 4Department of Radiation Oncology, Johns Hopkins, Washington, DC, 5Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, 6Department of Qualitative Health Sciences, Section of Biostatistics, Mayo Clinic, Scottsdale, AZ
Purpose/Objective(s):
Chordoma is a rare osseous sarcoma characterized by locally aggressive tumors arising from the skull base or spine. Resectable lesions merit surgery, but en block sacral resections can be morbid. An alternate treatment is definitive radiation therapy. We seek to characterize toxicity in dose-escalated RT with focus on sacral insufficiency fracture and other morbid late toxicities.Materials/Methods:
We retrospectively queried a prospectively maintained cohort of patients with sacral chordoma treated from 2015-2025 at a single institution. We identified 49 consecutive, non-metastatic patients and included them for analysis. We report radiation dose/fractionation and acute/late toxicity using CTCAE 5.0 grading. Sacral insufficiency fractures were identified based on serial MR and graded as requiring intervention (G3) or not (G1-2).Results:
49 patients were identified. 90% received proton radiation, 6% received both surgery+RT, and 94% received RT alone. Dose schemes were varied, but most (61%) patients were treated with a dose range of 69 – 73.5 Gy in 30 fx. Measures of control will be reported in detail at a future date; briefly, we observed 10 local (20%) and 9 distant (18%) failures in this group. Acute G1-2 toxicities were common (84%) and included dermatitis, fatigue, pain, neuropathy, and bowel/bladder issues. Acute G3+ toxicities were rare (6.1%) and all were G3 dermatitis. Incidence of severe late G3+ toxicity is reported in Table 1. RT-associated infection was seen in those with major surgery (3 cases), unrelated hospitalization, and impaired mobility. Infection after surgery occurred after 1) an unrelated pelvic surgery 2) definitive salvage RT for progression in patient with prior sacrectomy (i.e. surgery before RT) and 3) a sacral fracture stabilization. Sacral insufficiency fracture was seen in 14 cases, of whom 4 required intervention. Latency to sacral fracture ranged from 0.2 - 7 yr.Conclusion:
We report toxicity outcomes for a cohort of patients treated with radiation therapy for sacral chordoma. Acute toxicities were common but mild. Risk of sacral insufficiency fracture was 31% (similar to rates in a recent European study); a smaller subset of these cases warranted intervention. Time to sacral fracture can be short after RT (9 mo), with long incidence tail. Late wound infection can also impose significant morbidity and might be underreported. Patients with major pelvic surgery are at highest risk of infectious complication and merit thorough counseling. Overall, high-dose proton radiation therapy for sacral chordoma was well-tolerated with 76% of patients avoiding any G3+ toxicity.| N (%) | |
| G1 Acute Toxicity | 29/49 (59%) |
| G2 Acute Toxicity | 12/49 (24%) |
| G3+ Acute Toxicity | 3/49 (6.1%) |
| G3+ Late Toxicity | 10/49 (20%) |
| Sacral Insufficiency Fracture (G1-2) | 10/49 (20%) |
| Sacral Insufficiency Fracture (G3+) | 4/49 (8.2%) |
| Wound Healing/Infection (G3+) | 6/49 (12%) |
| Median yr (Range) | |
| Time to Sacral Fracture | 0.78yr (0.22yr — 7.01yr) |
| Time to G3+ Infection | 3.14yr (0.94yr — 6.21yr) |