Background. The purpose of this study is to clarify the latest long-term therapeutic result for cranial base chordomas. We are seeking an improvement of long term therapeutic outcome through a review of cranial base chordomas treated in our institute and of the published literature in the era of multimodality therapy.
Materials and methods. We retrospectively reviewed 13 consecutive patients with cranial base chordoma, including ten males and three females with mean age of 39.5 years (range 5–76 years).
Results. The method of initial treatment included surgery and post-operative conventional local irradiation (IR) in 9 patients, surgery and IR followed by post-operative stereotactic radiosurgery (SRS) in 2 patients, surgery as well as SRS in one patients, and surgery as well as SRS followed by IR in one patient. Subtotal removal (over 95%) was accomplished in eight patients. The mean follow-up period after completion of surgery and initial radiotherapy was 122 months (median 108 months). According to the Kaplan-Meier estimate method, the 5-year survival rate was 82.5%: 11 out of 13 patients survived longer than 5 years and five patients survived longer than 10 years. With a longer follow-up period than the previous reports, our series has provided a 5-year survival rate comparable to that of proton beam therapy. Although our series indicates a favourable outcome, surgical resection followed by IR or SRS failed to control tumour growth in five patients.
Conclusions. IR and/or SRS provided results comparable with proton beam or heavy particle therapy in our series of cranial base chordomas probably because the radiation field must have covered the target of the tumour volume sufficiently, and reduction of gross tumour volume reduced the target size for radiotherapy. Pursuit of further effective combinations of IR and stereotactic radiotherapy (SRS, proton beam, heavy particle) after tangible resection, especially for residual and recurrent lesions, will be an acceptable framework to achieve a better therapeutic outcome for cranial base chordomas than at present.
Keywords: Chordoma; cranial base; irradiation; stereotactic radio surgery; long term outcome.