Focal Irradiation Versus Whole-Brain Radiotherapy in Small Cell Lung Cancer

Small cell lung cancer has a high risk of metastasis to the brain (spread) during the course of the disease. Most patients with this diagnosis need radiotherapy to the brain at some point during their treatment. The conventional radiotherapy approach for brain metastases of small cell lung cancer is whole-brain irradiation. In recent years, however, whether focal irradiation covering only the metastatic sites might be sufficient has been debated. The medical term for focal radiation treatment is stereotactic radiosurgery (SRS= stereotactic radiosurgery).

The main difference between SRS and conventional external radiotherapy is that the total calculated radiation dose is delivered in one or a few sessions (fractions).

Note: There are 2 types of focal radiation treatment: stereotactic radiosurgery (stereotactic radiosurgery = SRS) is used for brain tumors; stereotactic body radiotherapy (stereotactic body radiation therapy = SBRT) is used to irradiate organs outside the brain, such as the lung, bone, or liver.

• Related topic: Radiotherapy – Types of Radiation Treatment and Their Purposes

Delivering the total dose calculated for SRS treatment over a few sessions has made it possible both to achieve extensive destruction and to reduce the side effects of radiation treatment.

Radiosurgery for Brain Metastases of Small Cell Lung Cancer

A systematic review and meta-analysis in The Lancet Oncology found that stereotactic radiosurgery (SRS) was associated with “similar survival” compared with whole-brain radiotherapy in the first-line treatment of patients with small cell lung cancer (KHAK) diagnosed with brain metastases.

Although SRS has replaced whole-brain radiotherapy (TBR) as first-line treatment for brain metastases in most solid-organ cancers, TBR remains first-line treatment for brain metastatic disease in patients with small cell lung cancer, because rapid and widespread brain metastases can occur in this cancer.

This study was conducted to evaluate the effectiveness of SRS in small cell lung cancer compared with TBR.

Study Details

This meta-analysis comparing SRS and TBR included seven studies. Data on overall survival following SRS were obtained from 14 additional single-arm studies.

Across seven studies involving a total of 18,130 patients, overall survival was better in those receiving SRS (hazard ratio [HR] = 0.85, 95% confidence interval [CI] = 0.75-0.97).

Across seven different studies involving a total of 16,961 patients, overall survival was better with SRS than with TBR (HR = 0.77, 95% CI = 0.72-0.83).

Across four studies involving a total of 1,167 patients, no significant difference in overall survival was observed for TBR supplemented with SRS versus SRS (HR = 1.17, 95% CI = 0.78–1.75).

Between-study heterogeneity was high when all comparative studies were pooled.

Analysis of 14 single-arm studies involving a total of 1,682 patients showed a median overall survival of 9 months with SRS (95% CI = 7.86–10.16 months). Brain metastasis control rates at months 6 and 12 were 81% and 78%.

In conclusion, the findings of this study show that SRS can provide similar or even better survival than TBR in patients with small cell lung cancer that has metastasized to the brain, and that previous reservations about using SRS, given the perceived risk of rapid progression of brain metastases in these patients, should lessen.