WBRT Plus Radiation Boost Improves Survival Outcomes for Small Cell Lung Cancer With Brain Metastases

Compared with whole brain radiotherapy alone, the addition of local radiation boost to whole brain radiotherapy improved overall survival and progression-free survival among patients with small cell lung cancer and brain metastases.

Whole brain radiotherapy (WBRT) plus local radiation boost improved survival over WBRT alone for patients with small cell lung cancer (SCLC) with brain metastases, according to data from a study published in Frontiers in Oncology.

After a median follow up of 40 months, the median overall survival (OS) for the patient population was 17 months, with 1- and 2-year OS rates of 63.3% and 20.6%, respectively. In the WBRT plus boost group, the median OS was 20 months compared with 14 months in the WBRT alone group. The 1- and 2-year OS rates were 74.3% and 28.0% in the WBRT plus boost group and 54.1% and 14.3% in the WBRT alone group.

“Our study showed a significant improvement in survival outcomes by introducing WBRT plus boost,” the investigators wrote. “High [biologically effective doses] for WBRT plus boost may be a preferred strategy for SCLC patients with brain metastases.”

In order to be eligible for the study, patients were required to have pathologically confirmed SCLC and brain metastasis identified via initial contrast-enhanced MRI. Other eligibility criteria included completed treatment with follow-up information and treatment with WBRT or WBRT plus radiation boost for brain metastases. Those who did not undergo initial brain MRI or who did not complete treatment were not eligible to enroll on the study. Those who had other primary malignant tumors, who underwent prophylactic cranial irradiation or surgery, or who were loss to follow-up were also ineligible.

A total of 180 patients were eligible for treatment, 98 of whom underwent WBRT alone and 82 underwent WBRT plus radiation. The mean patient age was 60 ± 8 years (range, 34-87) at the time of initial brain metastasis diagnosis and 79.4% of patients were male.

The median intracranial progression-free survival (iPFS) was 12 months for the overall population, with 1- and 2-year iPFS rates of 48.3% and 12.8%, respectively. Specifically, for the WBRT plus radiation group, median iPFS was 16 months and 1- and 2-year iPFS rates were 59.8% and 19.5%. The median iPFS for the WBRT alone group was 10 months, with 1- and 2-year iPFS rates of 38.8% and 7.1%.

Separate analyses found that age (P = .038), number of brain metastases (P = .013), and radiotherapy treatment (P = .014) were significant prognostic factors associated with OS.

Moreover, WBRT plus radiation treatment was independently associated with improved OS for patients (HR = 0.69; 95% CI, 0.50-0.96; P = .028). Notably, having more than 5 brain metastases was associated with worsened OS (HR = 1.49; 95% CI, 1.02-2.17; P = .039).

For the WBRT plus radiation group, significant differences in OS were observed between the high-BED group (23 months) and the low-BED group (17 months; P = .002). Similar results were found when analyzing iPFS between the high-BED (17 months) and low-BED groups (10 months; P = .002).

“Further validation in large randomized controlled trials is required to facilitate the individual options and minimize neurotoxicities when conducting WBRT plus boost with a BED of at least 58.35 Gy,” the investigators concluded.

Reference

Li H, Li W, Qi C, et al. Optimizing whole brain radiotherapy treatment and dose for patients with brain metastases from small cell lung cancer. Front Oncol. Published October 25, 2021. doi:10.3389/fonc.2021.726613