Introduction: Single session treatments have been the mainstay of stereotactic radiosurgery (SRS) for patients with metastatic cerebral tumors. However, patients with tumors that are large and/or in eloquent locations may not be candidates for this method. Alternatively, multiple session SRS may confer radiobiologic treatment advantages in the eradication of metastatic cerebral tumors. We compared the results of single and multiple session SRS for metastatic tumors.
Methods: We reviewed all patients from our institution who were treated with SRS for cerebral metastases between January 2010 and December 2011. Collected data included diagnosis, tumor location, lesion volume, and SRS dose.
Results: 132 patients with 249 lesions underwent SRS. 178 lesions (71%) were followed from 423 serial MRIs ranging from 0.2–28.2 months (6.19±5.95 months). 52 lesions had treatment volumes greater than 3cc. Of these, 28 lesions underwent single session SRS and 24 were treated in 3 sessions (case displayed). Median prescription doses for single and multiple SRS were 18 and 24 Gy, respectively. Tumor progression was noted in 6 lesions from 5 patients treated with a single session (3 lesions with biopsy proven progression), compared with progression in only 1 lesion treated with 3 sessions. Fractionated SRS patients were more likely to have local tumor control at a median of 4 months after SRS (p=0.040, Kaplan-Meier displayed). Lesion volume following multiple session SRS decreased by 55.5%, vs. 21.5% after single session (p=0.017).
Conclusions: Multiple session SRS for patients with large brain metastases yielded improved local tumor control compared with single session SRS. The radiobiological advantage of hypofractionation for metastatic tumors may reflect the ability to give a more potent prescription dose for larger lesions. These preliminary results have encouraged us to continue evaluating the efficacy of multiple session SRS for patients harboring large cerebral metastases.
Patient Care: Patients with metastatic cerebral tumors that are large and/or in eloquent locations can benefit from multiple session stereotactic radiosurgery treatments.
Learning Objectives: By the conclusion of this session, participants should be able to:
1) Describe the importance of multiple session SRS in the treatment of large and/or eloquently located cerebral metastatic lesions.
2) Discuss, in small groups the radiobiologic treatment advantages of multiple session SRS in the eradication of metastatic cerebral tumors.
3) Identify an effective treatment dose regimen for large and/or eloquently located cerebral metastatic lesions.