Radiation necrosis (RN) is a serious complication of stereotactic radiosurgery (SRS) impacting quality of life. Some literature reports an increased risk of developing RN in patients treated with SRS and immunotherapy (IT). The authors sought to determine whether SRS combined with systemic therapy with/ without whole brain radiotherapy (WBRT) results in an increased incidence of RN in patients treated for intracranial metastatic disease.
A retrospective review of 128 patients who underwent SRS for treatment of brain metastasis at our centre between May 2014 and June 2016 was conducted. Systemic therapy was classified as IT, targeted therapy (TT) and chemotherapy (CT). The influence of WBRT and timing of systemic therapies in relation to SRS was also considered. Logistic regression analysis was used to determine the likelihood of developing RN for each treatment type.
Preliminary results show that of 128 patients, 18 (14%) developed RN. RN rates were 33.3% for patients receiving IT alone, 5.3% for those receiving CT alone, 10.3% for those receiving TT alone, and 9% for patients not receiving any systemic therapy during SRS. RN rates were significantly increased for patients receiving IT only when compared to CT alone, TT alone, or no systemic therapy (OR 3.85 [95%CI 1.14–13.02] p = <0.05) during SRS. Of the 18 patients who developed RN, a higher proportion 27.8% were on IT alone compared to 5.6% for CT alone and 16.7% for IT alone. Final results and conclusions will be presented at the conference.
Patients who received IT appeared to be at higher risk to develop RN during SRS compared to patients who received CT or TT. This suggests a possible benefit to withhold IT in patients undergoing SRS for intracranial metastatic disease.