Role of endoscopic transnasal surgery for skull base chondrosarcoma: a retrospective analysis of 19 cases at a single institution

Abstract

OBJECTIVE Skull base chondrosarcoma is one of the most intractable tumors because of its aggressive biological behavior and involvement of the internal carotid artery and cranial nerves (CNs). One of the most accepted treatment strategies for skull base chondrosarcoma has been surgical removal of the tumor in conjunction with proactive extensive radiation therapy (RT) to the original tumor bed. However, the optimal strategy has not been determined. The goal of this study was to evaluate the early results of endoscopic transnasal surgery (ETS). METHODS The authors retrospectively analyzed 19 consecutive patients who underwent ETS at their institution since 2010. Adjuvant stereotactic radiosurgery (SRS) was performed only for the small residual tumors that were not resected to avoid critical neurological complications. Histological confirmation and evaluation of the MIB-1 index was performed in all cases. The Kaplan-Meier method was used to determine the actuarial rate of tumor-free survival. RESULTS The median tumor volume and maximal diameter were 14.5 cm (range 1.4-88.4 cm) and 3.8 cm (range 1.5-6.7 cm), respectively. Nine patients (47%) had intradural extension of the tumor. Gross-total resection was achieved in 15 (78.9%) of the 19 patients, without any disabling complications. In 4 patients, the surgery resulted in subtotal (n = 2, 11%) or partial (n = 2, 11%) resection because the tumors involved critical structures, including the basilar artery or the lower CNs. These 4 patients were additionally treated with SRS. The median follow-up duration was 47, 28, and 27 months after the diagnosis, ETS, and SRS, respectively. In 1 patient with an anterior skull base chondrosarcoma, the tumor relapsed in the optic canal 1 year later and was treated with a second ETS. Favorable tumor control was achieved in all other patients. The actuarial tumor control rate was 93% at 5 years. At the final follow-up, all patients were alive and able to perform independent activities of daily living without continuous neurological sequelae. CONCLUSIONS These preliminary results suggest that ETS can achieve sufficient radical tumor removal, resulting in comparative resection rates with fewer neurological complications to those in previous reports. Although the follow-up periods of these cases were relatively short, elective SRS to the small tumor remnant may be rational, achieving successful tumor control in some cases, instead of using proactive extensive RT. Thus, the addition of RT should be discussed with each patient, after due consideration of histological grading and biological behavior. To determine the efficacy of this strategy, a larger case series with a longer follow-up period is essential. However, this strategy may be able to establish evidence in the management of skull base chondrosarcoma, providing less-invasive and effective options as an initial step of treatment.

ICAR: endoscopic skull‐base surgery

“…In fact, ESBS is probably a useful addition to the surgical armamentarium for the treatment of skull‐base chondrosarcoma and might allow satisfactory tumor resection or decompression in appropriately selected cases. Some authors have reported the successful use of a staged surgical strategy combining an EEA and a transcranial approach to achieve GTR …”

“…Analysis of the reported tumor control data is limited by short follow‐up (only 1 study reporting a mean duration of follow‐up >60 months) and a low number of patients in each cohort. Nonetheless, PFS rates reported in the included series are comparable to previous studies on skull‐base chondrosarcomas (70 to 81% at 5 years) …”

“…The cumulative recurrence‐free survival rate was 83.7% and 80.8% at 3 and 5 years, respectively. Hasegawa et al . reported on a series of 19 patients with skull‐base chondrosarcoma operated exclusively through an ESBS (although 6 patients had previous transcranial surgeries).…”

“…Only retrospective case series and case reports were identified, with a corresponding level of evidence according to the Oxford LOE classification of 4 and 5, respectively. Among the included studies, only 3 were focused solely on ESBS for skull‐base chondrosarcoma, with 3 additional studies including also chordoma cases along with chondrosarcoma operated through an ESBS . The studies published by Carlson et al., Cho et al., and Raza et al .…”

“…In the larger studies included in this review, the rate of new postoperative CN deficit was low. On the contrary, a significant proportion of patients actually had improvement of their preoperative CN deficits . However, this review is limited by significant heterogeneity among the included studies.…”