For small cell lung cancer, radiation therapy to the brain is performed as prophylactic treatment when chemotherapy to the primary cancer has resulted in partial or complete response, or as palliative relief treatment for established brain metastases from either small or non-small cell lung cancer.
Based on clinical studies and autopsy data, it is known that up to 25% of all lung cancer patients develop brain metastasis within two years of the diagnosis. 10% of patients with small cell lung cancer have brain metastases at the time of diagnosis and an additional 20 % develop such during treatment.
Radiation is usually given towards the entire brain as opposing directional fields. For 1-3 metastases up to 4 cm in diameter, stereotactic radiation therapy to the tumor(s) may be appropriate. Treatment is given as a single fraction of 15–25 Gy. Total brain radiation is administrated for small cell lung cancer even with only 1–3 metastases, due to the high risk of micrometastases outside the visible metastases. Stereotactic radiation can be administered for this patient group if total brain radiation already has been delivered.
- Complete or partial response of initial therapy in small cell lung cancer
- Established brain metastasis
- Prevent brain metastasis
- Reduce the extent of metastasis
- Relieve and prevent symptoms