Treating Chordomas with Stereotactic Radiosurgery

Stereotactic Radiosurgery Used in Upfront Setting

Chordomas are rare but relentless tumors of the skull base, mobile spine, and sacrum. To date, the best available treatment is a procedure called en bloc resection with wide margins, which involves excision of the entire tumor without violation of the tumor capsule and with a cuff of healthy tissue remaining around the tumor. While they are generally slow-growing tumors, chordomas have a high propensity to recur in the absence of wide-margin resection and have proven to be highly resistant to conventional radiation therapies and available chemotherapy. Wide-margin resection generally involves extensive surgery that requires a highly experienced team of surgeons and extended recovery periods. In case of recurrence, surgery, radiation, and chemotherapy have all proven to be ineffective tumor control options.

The experience of Memorial Sloan Kettering physicians has shown that high-dose stereotactic radiosurgery (SRS) provides durable and consistent tumor control regardless of tumor size, histology, and previous treatment. These data lead to the use of SRS in the treatment of recurrent and inoperable chordomas to improve the likelihood of local tumor control in the absence of meaningful treatment options.

The promising results in the treatment of recurrent chordomas lead to the implementation of single-fraction SRS in the preoperative setting to decrease the risk of postoperative recurrence. To date, we have treated 24 patients with either preoperative or postoperative SRS, with only one patient showing evidence of tumor progression. Furthermore, SRS was administered without unexpected side effects. Two patients experienced isolated nerve toxicity, but this was expected based on the known nerve invasion by the tumor.

Chordomas are known to be slow growing, and long-term follow-up is required to elucidate the efficacy of new treatments. Currently, the median follow-up in this group of patients is two years. At this point, we have established that high-dose single-fraction SRS can be safely administered to patients with chordomas of the mobile spine and the sacrum without unexpected toxicity. Furthermore, these data provide hope that SRS may serve as an effective treatment in patients with chordoma regardless of previous treatment history and may improve the chances of local control in the future.