Study Identifies Which Patients With SCLC May Benefit Most From SRS

A retrospective review published in the journal Advances in Radiation Oncology suggests that patients with small cell lung cancer (SCLC) who have fewer than 5 brain metastases may benefit more from stereotactic radiosurgery (SRS) than patients with more than 5 brain metastases.

Specifically, investigators found when the treatment was carried out among individuals with fewer than 5 brain metastases, it offered acceptable control rates, they wrote. However, patients with more than 5 brain metastases had high rates of brain failure.

More than 1 in 10 patients with SCLC present with brain metastases upon diagnosis, “and more than 50% become affected within two years,” authors wrote. Although whole brain radiation therapy (WBRT) and SRS are the current treatment options available for patients with non-small cell lung cancer (NSCLC), the role of SRS in individuals with SCLC remains unclear.

In addition, it had been standard for patients without the metastases to undergo treatment with prophylactic cranial irradiation (PCI). Those with brain metastases were treated with WBRT.

“More recent data have called into question the value of PCI for patients without [brain metastases] and for patients who have [brain metastases] the treatment options have begun to include SRS,” researchers explained.

Investigators assessed an SRS database and collected data recorded between April 2008 and April 2019. They also evaluated data on dates of SCLC diagnosis, brain metastases diagnoses, death, central nervous system failure, along with other metrics.

A total of 70 patients with SCLC and 337 treated brain metastases were included in the analysis. Of the included patients, 45 had underwent WBRT. Twenty-five patients were treated with SRS alone, and median patient age was 62. “For those who received WBRT before SRS, WBRT was completed at a median of 8.7 months before SRS,” authors noted.

Patients had a median survival of 4.9 months (range, 0.70-23.9), and the total number of treated brain metastases correlated with survival.

Analyses also revealed:

• Patients with fewer brain metastases had improved overall survival (P < .021)
• The number of treated brain metastases was associated with different brain failure rates; 1-year central nervous system control rates were 39.2% for 1 to 2 brain metastases, 27.6% for 3 to 5 brain metastases, and 0% for more than 5 treated brain metastases
• Patients with previous WBRT had worse brain failure rates (P < .040)
• For patients without previous WBRT, the 1-year distant brain failure rate was 48%, and median time to distant failure was 15.3 months

“In patients with 5 or fewer brain metastatic lesions, we found SRS to be safe and effective, with a 1-year control rate of 52% for patients without previous radiation,” authors wrote. They added that the control rates seen in patients with fewer than 5 brain metastases are lower than in individuals with NSCLC.

The lack of randomization means biases may have been present in the current study and affected the results. Researchers also note it is difficult to control for factors like patient frailty, degree of neurologic symptoms and social support. They did not calculate the volume of brain metastases nor were they able to control for immunotherapy.

Despite these limitations, “our results contribute to the growing information regarding SRS for SCLC [brain metastases] as being a potential treatment option. Treating SCLC [brain metastases] with SRS rather than WBRT would reduce treatment toxicity and is logistically easier for patients and caregivers,” researchers said.

“SRS alone may be a viable option for patients with SCLC with 5 or fewer [brain metastases] but that patients with more than 5 [brain metastases] are better treated with WBRT,” they concluded.

Reference

Wang VH, Juneja B, Goldman HW, et al. Stereotactic radiosurgery for brain metastases in patients with small cell lung cancer. Adv Radiat Oncol. Published online April 8, 2023. doi:10.1016/j.adro.2023.101237