Surgical Aspects of Brain Metastases and Avoiding Complications
Neurosurgeon Princess Alexandra Hospital Brisbane
Metastatic brain cancer arises in 10-40% of patients with cancer.
Patchells landmark trial strongly supported excision of a solitary metastases. Further studies have supported up to four metastases being surgically removed. Reoperation also significantly increased survival times. En bloc resection rather than piecemeal is preferable as it has been shown to reduce the risk of leptomeningeal disease.
Surgical mortality should be less than 2% and morbidity under 6 %. Mortality and morbidity have been improved by computer navigation and brain mapping with fMRI and tractography. Surgically awake craniotomies, fluroscein, neuroendoports and direct cortical stimulation can help reduce morbidity and aid maximal resection. They all have limitations that will be discussed.
Laser interstitial tumour ablation is an exciting new surgical technology showing promise for metastases in eloquent locations. It is not currently yet available in Australia.
There have been no prospective randomised trials comparing SRS and surgery but each method would appear particularly suited to different situations and outcome similar.
Surgery can provide histological diagnosis, avoid long term steroid use, result in immediate improvement of mass effect and provides tissue samples for scientific purposes. It may be necessary if the primary disease is unknown. It is ideal for large tumours over 3cm in patients with limited comorbidities, good performance status and good systemic control. Minimally invasive brain cancer removal means patients can be discharged the following day.
53% of metastatic tumours have clinically relevant genetic alterations from the primary cancer and the importance of brain cancer metastatic tissue may in future have significant practical implications as we look more to molecular pathways.