CSPG4 as a prognostic biomarker in chordoma

Background: There are currently no generally accepted biomarkers used in the clinical treatment of chordoma tumors. CSPG4 has been associated with disease severity in other tumors.

Purpose: This study aimed to characterize the frequency of CSPG4 expression in chordoma tumors and to correlate it with disease severity and clinical outcome.

Study design: A retrospective review of clinical outcomes and immunohistochemical staining using tissue micro-array was carried out.

Patient sample: The sample comprised 86 patients treated for chordoma at a single center (1985-2007).

Outcome measures: Survival and incidence of metastases were the outcome measures.

Methods: Pathologic specimens of chordoma tumors were evaluated for the expression of CSPG4 by immunohistochemical staining with mAbs. Chi-square testing and Cox proportional hazard regression analysis were used to evaluate the impact of CSPG4 expression on survival and incidence of metastases, while controlling for patient age, sex, and surgical margins.

Results: Average patient age at the time of presentation was 59.8 years (standard deviation [SD] 13.7). Average follow-up was 6.5 years (SD 4.8). Twenty (23%) patients developed metastatic disease. At the time of final follow-up, 57 patients (66%) had died. Chordoma tumors from 62 patients (72%) stained positive for CSPG4. CSPG4 expression more than doubled the risk of death (hazard ratio [HR] 2.3; 95% CI 1.04, 5.17). CSPG4 positive tumors were also associated with an increased risk of metastatic disease (31% for CSPG4 positive tumors vs. 0% in CSPG4 negative, p=.02).

Conclusions: Results presented here support the consideration of using CSPG4 as a biomarker establishing the prognosis for chordoma tumors. A positive CSPG4 stain may be associated with an increased risk of metastasis and mortality from disease.