Clinical outcome in chordoma: utility of flow cytometry in DNA determination
A retrospective review of 100 patients with chordoma of the lumbar spine and sacrum. Twenty-three patients had flow cytometry data available and a minimum follow-up period of 5 years. To determine whether DNA content and cell cycle analysis were associated with patient outcome. DNA flow cytometry has been shown to be predictive for biologic behavior of various tumors. Chordoma has been evaluated in very small numbers of patients using DNA flow cytometric analysis, and the utility of DNA patterns in predicting outcome has not been clearly demonstrated. Between January 1979 and December 1995, 100 patients underwent surgical resection for chordoma, and 23 had a minimum follow-up period of 5 years with flow cytometry data. DNA content and cell cycle analysis were determined by enzymatically staining cells with propidium iodide dye and passing them through a flow cytometer. DNA histograms were generated. Survivorship and freedom from local recurrence curves were constructed by the Kaplan-Meier method and compared by the log-rank test. The mean follow-up period was 7.3 years. For this group of 23 patients, mortality was 61% (14 patients) and local recurrence was 78% (18 patients). Eleven patients had tumors with diploid DNA content, and 12 patients had tumors with aneuploid DNA content. Metastases occurred in 4 of the 11 patients with a diploid pattern and 6 of the 12 with an aneuploid pattern. Six of the 11 patients with the diploid pattern died, in comparison with 8 of 12 patients with the aneuploid pattern. The Kaplan-Meier estimated survivorship (95% confidence interval) was 78% (66-90%) at a follow-up period of 5 years and 36% at a follow-up period of 10 years (22-50%), and no significant differences were found between patients with diploid and aneuploid patterns. Patients in whom metastases did not develop had a more favorable clinical outcome. DNA pattern was not associated with local recurrence or survival.