Elsevier

World Neurosurgery

Volume 91, July 2016, Pages 409-418
World Neurosurgery

Original Article
Proposal and Validation of a Basic Progression Scoring System for Patients with Skull Base Chordoma

https://doi.org/10.1016/j.wneu.2016.04.073Get rights and content

Objective

To propose and further validate a basic progression scoring system for patients with skull base chordoma.

Methods

All patients (n = 170) undergoing operation for skull base chordoma were classified randomly into a training (n = 113) or validation set (n = 57). In the training set, adverse factors for progression were analyzed by univariate and multivariate analyses. Significant independent factors were included into the scoring system. Scores for each risk category were allocated 1 point and each protection category 0 point. Three prognostic groups were formed on the basis of total score. The same scoring and grouping dispositions were made in the validation set. Analyses of the differences among the 3 groups in individual sets with regard to recurrence and the comparisons between the corresponding prognostic groups of both sets were all carried out by the Kaplan-Meier method.

Results

In the training set, age, treatment history, preoperative Karnofsky performance scale, pathology, and features on magnetic resonance imaging were all significant independent factors and were included into the scoring system. According to the total score, 3 prognostic groups were formed, group A (0–1 points), group B (2–3 points), and group C (3–4 points), respectively. The pairwise comparisons between every 2 of 3 groups in the training set showed significance with P < 0.001, whereas in validation set, a log-rank test showed significance, P ≤ 0.001 (log-rank test). The comparisons between the corresponding prognostic groups of both sets did not show significance.

Conclusions

The basic progression scoring system for patients with skull base chordoma is valid and reproducible.

Introduction

Chordoma is a rare low-grade but local invasive bone malignancy that arises from persistent notochordal elements.1 The annual incidence of chordoma is 0.084 per 100,000 individuals, the prevalence is 0.4 per 100,000, and cranial chordoma represents 32% of the total incidence.2, 3, 4 The extremely low incidence and gradually progressing clinical course of chordoma lead to difficulties in early detection and delayed diagnosis and treatment. Its apparent tendency to recur locally but not metastasize highlights the importance of local control.

To date, the most valued method of treating cranial chordoma is safely and maximally resecting the tumor. Because it is difficult to completely remove the entity because of the limited space and its proximity to vital structures in the skull base, particle beam irradiation, rather than conventional radiotherapy techniques, also plays an important role in tumor control despite of the low-grade evidence.5, 6, 7, 8 No drugs have shown a statistically significant effect on treating chordoma, even though some clinical trials and case reports reported encouraging findings that 44% of advanced tumors could be controlled for more than 16 weeks.9 The median duration of progression-free survival (PFS) in a group of patients was 9 months.10

With a duration of PFS ranging from several months to decades, it is very complicated to predict when a tumor will recur. It is important for researchers to evaluate the effect of drug therapy on the basis of PFS. A reliable endpoint of clinical trial is needed desperately, which highlights the importance of predicting tumor progression. Moreover, once progression is well predicted, follow-ups could be more accurately scheduled to reduce the frequency of imaging and abate the emotional burden of patients.

Many researchers have focused on the prognostic factors of tumor recurrence or progression and made some findings. Despite some controversy, age, sex, resection degree, tumor location, tumor volume, previous treatment history, pathology, and adjuvant radiotherapy have shown statistically significant associations with tumor progression in respective studies.11, 12, 13, 14 No prognostic scale, however, was designed to systematically evaluate the PFS of patients with skull base chordoma. On the basis of the huge population of China and our specialty clinic for cranial tumors, a great number of patients with skull base chordoma have been admitted to our hospital, which gave us a chance to try to fill in this gap.

Section snippets

Patients and Methods

This study was approved by the Institution Review Board of the Beijing Tiantan Hospital affiliated with the Capital Medical University. Inclusion criteria included: 1) patients who received surgery between January 1, 2008, and December 31, 2013; 2) tumor's pathologic type was verified as chordoma by experienced neuropathologists. Exclusion criteria included: 1) patients who died within 3 months after operation; 2) patients without preoperative magnetic resonance imaging (MRI) scans; 3) patients

Results

Among 170 patients, 34 patients were ≤22 years of age, and 136 patients were older than 22 years old (median, 40 years of age; range, 5–67 years). The majority of patients were men (55.9%), and the ratio of men to women was 1.27. The volume of tumor ranged from 2.14 cm3 to 139.14 cm3, with a median volume of 22.61 cm3. The Pre-KPS of 12.9% of patients was less than 70. Among the whole series, 25 patients received adjuvant therapy within 6 months after operation. In the training set, 13 patients

Discussion

In this study, we found that age, treatment history, Pre-KPS, pathology, and MRI features were independent prognostic factors for tumor progression of patients with chordoma. The BPSC was well proposed and validated. Patients in the high-risk group showed the worst tumor control. To the best of our knowledge, this study is the first to analyze so many potential prognostic factors and design a progression scoring system for patients with skull base chordoma.

Conclusions

Age ≥22 years, treatment history, preoperative KPS <70, classical chordoma, and RCE/RT1 ≥1.7 and RT2/RT1 ≤4.3 of MRI features are risk factors for tumor progression of skull base chordoma. The BPSC is valid and reproducible. It can be used to counsel individual patients and screen high-risk patients for clinical trials of drug therapies.

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    Conflict of interest statement: This study was supported in part by the National Natural Science Foundation of China (NSFC; grant no. 81472370 and 81541146), the Natural Science Foundation of Beijing Municipality (Beijing Natural Science Foundation; grant no. 7142052) and Beijing Municipal Science and Technology Commission (grant no. Z131107002213179).

    Jun-Peng Ma and Kai-Bing Tian are co–first authors.

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