On the cutting edge of intensity modulated radiotherapy and simultaneous integrated boost (IMRT-SIB): The case of a patient with 8 brain metastases

Abstract

Background

Patients with multiple brain metastases, especially those with more than 3 lesions, usually undergo to palliative whole brain (WB) radiotherapy (RT).

Methods

A breast cancer patient with 8 brain metastases was treated on the brain by a radical RT regimen. Prescription doses were according to the simultaneous integrated boost-intensity modulated radiation therapy (SIB-IMRT) technique with all lesions as well brain irradiated simultaneously in 20 daily fractions. Doses of 40.0[[ce:hsp sp="0.25"/]]Gy (2.0[[ce:hsp sp="0.25"/]]Gy/fraction) and 50.0[[ce:hsp sp="0.25"/]]Gy (2.5[[ce:hsp sp="0.25"/]]Gy/fraction) were prescribed to the whole brain and to eight individual metastases, respectively.

Results

Mean volume of the eight metastases was 8.1[[ce:hsp sp="0.25"/]]cc (range: 3.8–10.1[[ce:hsp sp="0.25"/]]cc). For all lesions, the volume receiving 95% of prescribed dose was 100% and dose homogeneity was within 3%. Moreover, maximum doses were less than 105% of prescribed dose, while average mean dose to lesions was 50.6[[ce:hsp sp="0.25"/]]Gy (range: 49.7–51.5[[ce:hsp sp="0.25"/]]Gy). Whole brain mean dose was 45.2[[ce:hsp sp="0.25"/]]Gy. Maximum doses to brainstem and optic chiasma were limited to 44.5[[ce:hsp sp="0.25"/]]Gy and 42.9[[ce:hsp sp="0.25"/]]Gy, respectively, while maximum doses to eyes, lens and optic nerves were limited to 9.2[[ce:hsp sp="0.25"/]]Gy, 4.9[[ce:hsp sp="0.25"/]]Gy and 41.0[[ce:hsp sp="0.25"/]]Gy, respectively. From a clinical point of view, subsequent MRI brain controls showed a complete clinical response. Forty months after treatment the patient is disease free and shows no late brain and skin toxicities.

Conclusion

This case demonstrates the technical feasibility of a SIB-IMRT treatment in patients with more than 3 brain metastases.