Experience of Gamma Knife radiosurgery for treatment of brain metastases in pregnancy with literature review

Brain metastases during pregnancy poses complex conundrum in management. Stereotactic radiosurgery (SRS) offers valuable option to clinicians in this scenario. We reviewed and described the safety and effectiveness of Gamma Knife (GK) SRS in treating a solitary cerebellar metastasis in a patient with recurrent breast cancer at 28 weeks of gestation. Following multidisciplinary discussion, she consented for urgent single session GK SRS to the brain metastasis with 2 cycles of 3-weekly paclitaxel chemotherapy prior to planned delivery at term. Prior to the frame-based treatment, a trial run with dosimeters placed on the superior and inferior parts of foam knee support showed radiation exposure of 3.12 mSv and 1.06 mSv respectively. A prescription dose of 16 Gy at the 50% isodose was delivered using 24 isocentres over 39.7' of beam on time. The treatment plan had 98% coverage, 89% selectivity and a gradient index of 2.98. Dosimeters placed near the uterine fundus and suprapubic region (consistent with location of fetal head) during the actual treatment recorded 2.83 mSv and 0.27 mSv, which is lower than the trial dosimeter readings. The patient successfully completed SRS treatment and gave birth to a healthy baby two months later. Follow-up MRI at three months interval showed total resolution of the lesion. GK SRS is known for the lowest extracranial dose compared to other SRS modalities. This report and literature review confirmed that GK is a sharp and effective, yet gentle and safe treatment for pregnant patients with brain metastases.