Efficacy and Safety of CyberKnife Stereotactic Radiosurgery for Occipital Condyle Metastasis

Occipital condyle metastasis (OCM) is a rare condition characterized by severe occipital pain and neurological symptoms due to lower cranial nerve (CN) deficits, stemming from its anatomic location. Despite the widespread use of stereotactic radiosurgery (SRS) for cranial metastases, its specific impact on OCM remains underexplored. This study evaluates the efficacy and safety of CyberKnife SRS in treating OCM, focusing on occipital pain, dysfunctions of lower CNs, and local tumor control.

We retrospectively analyzed cases of OCM treated with SRS at our institute from 2012 to 2023, evaluating patient demographics, presenting symptoms, treatment parameters, and outcomes.

Eighteen patients (10 females) with a mean age of 64 years (SD: 10.4) were treated. Common presentations included occipital pain (44.4%) and lower CN deficits (27.8%). The median target volume was 6.95 cc (IQR: 4.64-21.2). The mean single-fraction equivalent dose was 18.7 Gy₁₀ (SD: 1.9). Ten tumors received 15-20 Gy in 1 fraction (50%), 2 tumors received 20-28 Gy in 2 fractions (10%), 4 tumors received 27 Gy in 3 fractions (20%), and 4 tumors received 30-40 Gy in 5 fractions (20%). Based on Kaplan-Meier estimate, SRS achieved 93.8% local tumor control rate over 3 years, with a median overall survival of 13 months (95% CI: 0-32.2). Among patients presenting with symptoms, 87.5% reported occipital pain relief (P = .04), and 80% observed improvements in CN function (P = .003). Four patients experienced local recurrence.

CyberKnife SRS is a promising treatment of OCM, offering significant pain relief and improvement in neurological symptoms, along with favorable local control rates. This noninvasive therapy provides a valuable alternative to surgery, potentially enhancing the quality of life for patients with limited treatment options due to this challenging condition.