SCLC: Hippocampal avoidance in prophylactic cranial irradiation a potential SoC

In patients with small-cell lung cancer (SCLC), hippocampal avoidance-prophylactic cranial irradiation (HA-PCI) better preserves cognitive function and has no adverse impact on the incidence of brain metastases, overall survival (OS) and quality of life (QoL) compared with standard PCI, a phase III randomized controlled trial has shown.

Based on the findings, the investigators concluded that HA-PCI should be considered standard of care (SoC) for patients with SCLC who plan to receive PCI. [J Clin Oncol 2021;doi:10.1200/JCO.21.00639] 

In the study, 150 patients with SCLC (71.3 percent with limited disease) were randomized to receive HA-PCI (n=75; median age, 66 years; male, 69.3 percent) or standard PCI (25 Gy in 10 fractions) (n=75; median age, 63 years; male, 70.7 percent) and followed up for a median of 40.4 months.

The primary endpoint of delayed free recall on the Free and Cued Selective Reminding Test (FCSRT) at 3 months showed a significantly smaller decline in the HA-PCI group compared with the standard PCI group (5.8 percent vs 23.5 percent; odds ratio, 5; 95 percent confidence interval; 1.57 to 15.86; p=0.003). The decline in delayed free recall remained smaller in the HA-PCI vs standard PCI group at 6 months (11.1 percent vs 33.3 percent).

Total recall on FCSRT also showed a smaller decline in the HA-PCI vs standard PCI group at 3 months (8.7 percent vs 20.6 percent), 6 months (20.3 percent vs 38.9 percent) and 24 months (14.2 percent vs 47.6 percent). Likewise, total free recall declined by a smaller degree at 6 months in the HA-PCI vs standard PCI group (14.8 percent vs 31.5 percent).

The better preservation of cognitive function with HA-PCI was achieved without adverse impact on brain metastases, OS or QoL.

Among 30 patients (21.8 percent) who developed brain metastases, 17 were in the HA-PCI group, while 13 were in the standard PCI group. The cumulative incidence of brain metastases at 2 years was 22.8 percent vs 17.7 percent in the HA-PCI vs standard PCI group, while multiple brain lesions were recorded in 70.5 percent vs 84.6 percent of the patients.

After 60 months of survival follow-up, 60 percent of patients in the HA-PCI group vs 65.3 percent of those in the standard PCI group had died. Median OS was 23.4 months vs 24.9 months. Subgroup analysis of patients with limited or extensive disease showed no difference in OS between the two treatment groups.

No significant differences in QoL changes over time were observed between the treatment groups.