In chordoma, metastasis, recurrences, Ki-67 index, and a matrix-poor phenotype are associated with patients' shorter overall survival.

Purpose: To establish a chordoma tissue cohort (n = 43) and to correlate localization, size, metastasis, residual disease (R-status), recurrences, histological subtype, matrix content, and Ki-67 proliferation index with patients' overall survival (OS).
Methods and Results: We used routine histopathology supplemented by immunohistochemistry. In our patient cohort (median age 69 years, range 17 to 84 years) the median OS was 8.25 years. 24 chordomas were localized in the sacrum, 6 in lumbar vertebrae, 7 in thoracic and cervical vertebrae, 5 were limited to the clivus, and one was localized in the nasal septum. Ten patients had metastases, with pulmonary, nodal, and hepatic involvement. 23 patients had recurrent disease. 23 chordomas were classified as 'not otherwise specified' (NOS). Besides NOS, we found the following differentiation patterns: renal cell cancer like in six cases, chondroid in four cases, hepatoid differentiation in three cases, and anaplastic morphology in six cases. Ki-67 index of ≥10 %, presence of metastasis, and the low content of extracellular matrix were statistically linked to poor OS (p < 0.05). The matrix-poor phenotype had a higher Ki-67 index (p < 0.05). Furthermore, presence of metastasis was associated with a higher Ki-67 index in the primary lesion, a positive resection margin, and multiple recurrences (p < 0.05 each).
Conclusion: We propose to include these parameters in the final pathologic report of the resected chordoma.