Long-Term Outcomes of Endoscopic Transnasal Surgery in Conjunction with Stereotactic Radiosurgery for Skull Base Chordoma

Skull base chordoma (SBC) is a rare cranial neoplasm and one of the most challenging targets because of its deep ventral skull base locations, tenacious recurrence, and resistance to radiation. Endoscopic transnasal surgery (ETS) is now considered as a standard modality for SBCs, though its long-term outcomes remain to be clarified.

To examine the tumor control, functional outcomes, and survival as well as factors associated with them, we conducted the present single-institution retrospective study. Patients with SBC who were treated with ETS between 2009 and 2021 were included. The rates of local control (LCR), and poor functionality (PFR: KPS of ≤ 40), and overall survival (OS) were evaluated, and compared using the log-rank test. Factors associated with the endpoints were examined using the Cox proportional hazard analysis.

Sixty-five patients with a mean follow-up period of 5 years were enrolled. The median age and tumor volume were 52 years and 12.4 mL. Nineteen (29%) patients were recurrent cases. All underwent ETS; the extent of resection (EOR) was total/near-total (≥99%) in 36 (55%) and subtotal (90–98%)/partial (< 90%) in 29 (45%). Upfront adjuvant radiosurgery was used in 20 (31%). Histologically 49 (75%) had conventional chordoma, and 16 (25%) had chondroid subtype. The 1-, 5-, and 7-year LCRs were 78, 36, and 36%, respectively. The LCRs were significantly better in primary cases (p < 0.01), those with tumor volume of ≤12 mL (p = 0.02), those in whom total/near-total removal was achieved (p < 0.01), those with K_i-67 index of ≤7% (p = 0.02). Multivariate Cox proportional hazard analysis demonstrated that recurrent case (hazard ratio [HR]: 5.2, 95% confidence interval [CI]: 2.2–12.0) and tumor volume of > 12 mL (HR 2.9, 95% CI 1.3–6.5) were significantly associated with a worse LCR. The LCRs following subtotal/partial resection was significantly improved by adding radiosurgery (45% at 4 year vs. 0% at 1 year; p < 0.01), reaching the similar level to LCR following total/near-total removal (figures).

KPS declined to ≤ 40 in 10 patients; 9 of them developed dissemination or metastatic lesions during their courses. The 3-, 5-, and 10-year PFRs were 90%, 80%, and 80%, respectively. The PFR was significantly better in primary cases (p < 0.01), those without intradural extension (p < 0.01), those in whom total/near-total removal was achieved (p < 0.01), those with KPS better than 80 (p = 0.02).

Five mortalities were observed; all of them developed dissemination or metastatic lesions. The 3-, 5-, and 10-year OSs were 97, 89, and 89%, respectively. The OS was significantly better in those without intradural extension (p = 0.04) and those in whom total/near-total removal was achieved (p = 0.04). However, no factors were significantly associated with the OS and PFR in the multivariate analyses.

Skull base chordomas remain a challenging target, and multiple interventions are likely to be needed. Recurrent case and large tumor are risk for a failed LCR. Dissemination and metastatic lesions are the leading causes of functional deterioration and mortality.

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Artikel online veröffentlicht:
01. Februar 2023