Survival in cancer is improving with some reports of patients surviving longer than 1 - 2 years following treatment. The Cleveland Clinic reported 2.5% survival rate at ≥ 5 years. 15 of 1300 patients had intracranial recurrences. The ACR suggests that a growing number of patients may live to re-develop intracranial metastases requiring retreatment. University of Wisconsin researchers have investigated re-irradiation of intracranial tumors in the setting of prior radiation and re-irradiation of intracranial primaries (GBM) has been undertaken in desperation with GBM recurrence and its uniformly poor outcomes.
Follow up imaging requirements are indeterminant and sometimes it is difficult to tell treatment response from recurrence. The median time of new metastases after SRS has been reported at 8.8 months after initial SRS. This study's authors recommended repeat imaging at 3 months from treatment to identify new metastases and determine best further course. Patients with ≥ 3 lesions were more likely to develop additional mets, and be more likely to benefit from closer surveillance.
Retreatment after brain recurrence may be required following a variety of prior treatments including surgery, whole brain irradiation, radiosurgery, chemotherapy and combinations of these treatments. The treatment modality of choice in an intracranial recurrence will depend on many factors including, but not limited to:
Re-irradiation of the brain has been reported, but little toxicity data is available. BID radiation does not appear to have a place as radiobiologic time to repair may be longer than 6 hours. Response to first course radiation therapy did affect survival time after re-irradiation, but interval between initial and repeat RT and age did not affect survival time. The ACR feels there may be a role for WBRT for re-treatment of brain metasteses.
SRS is an option for recurrent brain mets following initial course WBRT if the size and number permit, similar to primary SRS treatment parameters. Local control has been reported as high as 91% at 1 year down to 68%. 2 year local control ranges from 86% to 58% Repeat Gamma Knife treatment to previously treated (SRS) sites did increase the risk of radionecrosis. A recent review of 10 series treated with surgery followed by SRS showed local control rates of 79% and median survival of 14.2 months, with a 52% rate of new metastases following SRS.
Surgery may be indicated for palliation of mass effect from progressive or hemmorrhagic brain metastases. It can also yield a tissue diagnosis where needed. Surgery may be indicated in prior RT with a KPS > 60, stable or absent extracranial disease. Crude local control rates range from 69& - 79%.
Chemotherapy has been used for some tumors. Small molecule inhibitors (lapatinib for HER2/neu positive tumors), erlotinib, gefitinib, temozolomide and capcitabine have been used.
Best supportive care is an option for recurrent intracranial metastases.