Chordoma incidence, treatment, and survival in the 21st century: a population-based Ontario cohort study.

Objective: This study estimates the incidence, treatment patterns, and overall survival for patients with chordoma treated in Ontario.

Methods: A 17-year (2003-2019) population-based cohort study was conducted, including all patients in the Ontario Cancer Registry with histologically proven chordoma. Primary outcomes of interest were age-standardized annual incidence, overall survival, and rates of radiation therapy, chemotherapy, and open resection.

Results: A total of 208 patients were diagnosed with chordoma over the study period: 97 patients with skull base chordoma, 37 with mobile spine chordoma, and 65 with sacropelvic chordoma. A total of 133 patients were treated with either open or endoscopic surgery, of whom 99 were also treated with some form of radiation therapy. Across the 17-year study period, the average annual age-standardized incidence was 12.04 cases per 10 million (95% CI 9.31-14.78 cases per 10 million). There was no significant change in the annual incidence rate over the study period (average annual percent change 2.27, 95% CI -1.74 to 6.44; p = 0.25). The odds of receiving radiation therapy or chemotherapy significantly increased by 8% per year (95% CI 1%-16% per year, p = 0.036) over the study period. The odds of receiving open resection significantly decreased by 14% per year (95% CI 8%-20% per year, p < 0.001). The odds of receiving endoscopic surgery among patients with skull base chordoma increased by 38% per year (95% CI 22%-60% per year, p < 0.001), while the odds of patients receiving biopsy alone did not change significantly over the study period (p = 0.684). After diagnosis of chordoma, the 5-, 10-, and 15-year overall survival probabilities were 0.74 (95% CI 0.69-0.81), 0.58 (95% CI 0.51-0.67), and 0.48 (95% CI 0.40 to 0.59), respectively. There was no significant association between hazard of death and year of diagnosis (p = 0.126) or anatomical location (p = 0.712, skull base vs mobile spine chordoma; p = 0.518 skull base vs sacropelvic chordoma).

Conclusions: Chordoma is a rare disease with no significant change in the average annual incidence rate between 2003 to 2019. During this time, treatment with less invasive modalities increased, particularly for skull base chordoma. Overall survival exceeds 10 years for many patients, with no change in the hazard of death across the study period.