Introduction: Stereotactic radiosurgery (SRS) is effective for most brain metastases less than 3 cm diameter (approximately 15cc). Larger metastases are well managed with surgery followed by adjuvant radiation or SRS. Patients with large metastases, who are not surgical candidates, have had few options.

Methods: Between 2002 and 2010, we treated 21 patients with solid metastases over 20 cc’s using SRS alone. We retrospectively analyzed demographics, diagnostic information, treatment parameters, and outcome data.

Results: There were 15 men and 6 women aged 22 to 94 (median 63 ± 19). Lesion volumes ranged from 20.4 to 56.7 cc (median 23.8 ± 8.3). Lesion diameter ranged from 4.1 to 8.3 cm (5.0 ± 0.1). Pathologies included melanoma (4), lung (2), renal (2), prostate (2), germ cell (2), parotid (2), nasopharyngeal (2), colon, squamous cell, adenoid cystic, teratocarcinoma, and unknown primary (2). Survival varied from 3 days to greater than 9 years (median 0.4 ± 1.9 years) with one still alive 9 years after treatment. Seven patients were noted to have an increase in tumor size or tumoral edema (31.8%). Two of these required craniotomy. Five patients had stable tumor size (23.8%) and four showed improvement in tumor size and neurologic function (19%). Six patients had no post-treatment imaging or were lost to follow-up. There were no treatment related complications or deaths.

Conclusions: Some metastases larger than 20 cc can be safely treated with SRS alone. Outcomes were best for those with a radiosensitive lesion, those with locally invasive lesions, and those with high pretreatment Karnofsky scores.

Patient Care: Patients who could not previously be treated using SRS may benefit from improvement of symptoms and palliation.

Learning Objectives: Participants should be able to describe the benefits of treating larger lesions with SRS.

References: Yang, H., H.et al (2011). What factors predict the respone of larger brain metastases to readiosurgery? Neurosurgery. 68:682-690. Muacevic, A. Et al (2010). Feasibility, safety and outcome of frameless image-guided robotic radiosurgery for brain metastases. J Neurooncology. 97:267-274.