Conditional survival and changing risk profile in patients with chordoma: a population-based longitudinal cohort study

Abstract

Objective: To evaluate the conditional survival of patients with chordoma to potentially help physician planning of optimal cancer surveillance and guide better clinical decisions.

Methods: In total, 1942 patients with chordoma were identified and extracted from Surveillance, Epidemiology, and End Results (SEER) databases (1973-2015). The cumulative survival estimates were used to calculate the conditional survival rate, and the Greenwood formula was used to estimate the 95% CI. In addition, multivariable Cox regression analyses were used to calculate hazard ratios, according to the duration of survival.

Results: The conditional 5-year disease-specific survival in patients with regional or localized chordoma was relatively stable over time, whereas in patients with distant chordoma, there was a gradual improvement. The conditional 5-year disease-specific survival (DSS) of patients older than 60 years old and patients with a tumor size between 5 and 10 cm improved. Interestingly, for patients with a tumor larger than 10 cm, the conditional 5-year DSS decreased over time. After surviving 5 years, the hazard ratio (HR) of patients older than 60 years old decreased from 1.33 to 1.24, that of patients with a tumor size between 5 and 10 cm decreased from 1.61 to 1.52 and that of patients with distant metastasis decreased from 3.30 to 1.09. However, after surviving 5 years, the HR of patients with a tumor size larger than 10 cm increased from 2.33 to 3.77, that of patients who underwent surgical resection increased from 0.37 to 0.58 and that of patients who received radiation therapy increased from 0.81 to 1.04.

Conclusion: Age at diagnosis, tumor size and disease stage can influence conditional survival for patients with chordoma. The HR of different factors will change over the survival time. Therefore, understanding the changing risk profile and conditional 5-year DSS of chordoma is critical for accurate clinical treatment guidance.

Keywords: Changing risk profile; Chordoma; Conditional survival; Survival.

Fig. 1

Kaplan–Meier survival curves illustrating the chordoma conditional 5-year disease-specific survival

Fig. 2

Conditional 5-year disease-specific survival of patients a who were less than 60 years old and over 60 years old with chordoma; b who had localized, regional, and distant chordoma; c who had different tumor sizes; and d who underwent or did not undergo surgical therapy

Fig. 3

Hazard ratios from multivariable Cox regression analyses for prediction of disease-specific mortality with the number of years of survival stratified according to age (< 60 years old is the reference.)

Fig. 4

Hazard ratios from multivariable Cox regression analyses for prediction of disease-specific mortality with the number of years survived stratified according to tumor size (tumor size < 5 cm is the reference)

Fig. 5

Hazard ratios from multivariable Cox regression analyses for prediction of disease-specific mortality with the number of years survived stratified according to disease stage (localized tumor is the reference)

Fig. 6

Hazard ratios from multivariable Cox regression analyses for prediction of disease-specific mortality with the number of years survived stratified according to surgical therapy (surgery not performed is the reference)

Fig. 7

Hazard ratios from multivariable Cox regression analyses for prediction of disease-specific mortality with the number of years survived stratified according to radiation therapy (radiotherapy not performed is the reference)