Second tumors after radiosurgery: tip of the iceberg or a bump in the road?

OBJECTIVE: Radiosurgery-associated second tumors have been reported in four isolated patients during the past 2 years. In our own experience, we are aware of two additional patients. The purpose of this report is to call attention to this potentially emerging problem.
METHODS: A review of the English-language literature concerning patients with radiosurgery-associated second tumors was performed. In addition, we report on two patients in our own practice who were treated in the past year.
RESULTS: Four patients were found in the literature, and two additional patients were seen by the authors. Malignant tumors occurred as early as 6 years after radiosurgery. The pathological findings in three of these four malignant tumors were glioblastoma multiforme. Benign tumors developed between 16 and 19 years later. Tumors developed both within the full-dose prescription volume and in the lower-dose periphery. Of interest, three of the six patients experienced complications of the radiosurgery treatment before developing second tumors.
CONCLUSION: Although patients will increasingly be reported with second tumors after radiosurgery in the future, the overall incidence seems quite low and should not alter current radiosurgical practice. However, continual surveillance of treated patients should be considered.