Stereotactic radiosurgery feasible for multiple brain metastases

By Laura Cowen, medwireNews Reporter

Stereotactic radiosurgery is a feasible treatment option for cancer patients with up to 10 brain metastases, Japanese researchers report in The Lancet Oncology.

Current guidelines only support stereotactic radiosurgery without concurrent whole-brain radiotherapy (WBRT) for patients with up to four brain metastases, explain Masaaki Yamamoto (Katsuta Hospital Mito Gamma House, Hitachi-naka) and study co-authors.

However, they add that “debate continues as to how many tumours can or should be treated by stereotactic radiosurgery alone.”

In the present prospective observational study, Yamamoto and team compared overall survival according to the number of brain metastases in 1194 patients treated with standard stereotactic radiosurgery (22 Gy at the lesion periphery for tumours <4 mL, 20 Gy for those 4–10 mL) at 23 facilities across Japan.

The metastases mainly originated from tumours in the lung (76%), followed by the breast (10%), gastrointestinal tract (7%), kidney (3%) and other sites (3%).

The researchers found that patients with one metastasis (n=455) had significantly longer median overall survival than those with two to four metastases (n=531), at 13.9 versus 10.8 months.

However, there was no significant difference between the patients with two to four metastases and those with five to 10 (n=208), who also had a median overall survival of 10.8 months. Furthermore, the lack of difference met the predefined criteria for non-inferiority, which was set as a hazard ratio upper 95% confidence interval value of 1.30.

The team also found no difference between the two groups of patients with multiple metastases in the incidences of neurological death, deterioration of neurological function, local recurrence, appearance of new lesions, leptomeningeal dissemination, leukoencephalopathy, and use of salvage stereotactic radiosurgery, WBRT and surgery.

And there were no differences in the proportion of patients with any grade of stereotactic radiosurgery-induced adverse event, at 9% in each of the multiple metastases groups and 7% in the patients with just one metastasis. Three patients died due to complications relating to stereotactic radiosurgery (two with one metastasis and one with two to four metastases), while a fourth patient (with three to five metastases) died of status epilepticus.

“Our results suggest that stereotactic radiosurgery without WBRT in patients with five to ten brain metastases is non-inferior to that in patients with two to four brain metastases”, Yamamoto and co-authors conclude.

They add that stereotactic radiosurgery “might be a suitable alternative” to WBRT in patients with up to 10 brain metastases due to its minimally invasive nature and reduced number of side effects.

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