Re-evaluation of prophylactic cranial irradiation in limited-stage small cell lung cancer: a propensity score matched analysis

Efficacy evaluation of prophylactic cranial irradiation for limited stage small‑cell lung cancer in the magnetic resonance imaging era: A meta‑analysis

The role of prophylactic cranial irradiation (PCI) in patients with limited-stage small-cell lung cancer (LS-SCLC) remains controversial in the era of magnetic resonance imaging (MRI). The present study aimed to evaluate the effectiveness of PCI in the treatment of LS-SCLC in the era of MRI. The PubMed, EMBASE and Cochrane Library databases were searched from the time of database creation until May 24, 2023, to identify clinical studies that evaluated the effectiveness of PCI in patients with LS-SCLC in the MRI era. The references of the obtained studies were also reviewed to identify clinical studies that were not discovered in the initial search. All studies were screened in accordance with the inclusion criteria, and the data were extracted and subjected to meta-analysis using STATA17.0. In total, 21 studies were included in the analysis. Notably, 10 studies only used brain MRI at baseline to confirm the absence of brain metastases (BMs; pre-chemoradiotherapy MRI group), 7 studies used brain MRI prior to PCI to confirm the absence of BMs (pre-PCI MRI group) and 4 studies used active surveillance in the form of brain MRI following PCI (MRI surveillance group). The results of the meta-analysis demonstrated that for all included patients, PCI was associated with a significant improvement in overall survival time [OS; hazard ratio (HR), 0.61; confidence interval (CI), 0.53-0.70] and progression-free survival (HR, 0.69; CI, 0.61-0.79), as well as a significant decrease in the rate of BM (HR, 0.59; CI, 0.50-0.70). Subgroup analyses revealed that PCI remained effective in improving OS and reducing the rate of BM in patients with LS-SCLC who did not have BMs confirmed via brain MRI performed at baseline or prior to PCI. However, in the MRI surveillance group, PCI failed to significantly improve the OS (HR, 0.65; CI, 0.41-1.05), despite significantly reducing the BM rate (HR, 0.6; CI, 0.45-0.8) of LS-SCLC. Collectively, the results of the present study demonstrated that PCI remained effective in improving OS and reducing the rate of BM in patients with LS-SCLC who had the absence of BM confirmed via brain MRI at baseline or prior to PCI. Additionally, in patients with LS-SCLC who had undergone active surveillance using brain MRI following PCI, the incidence of BM was reduced, while the OS was not significantly improved. However, additional randomized controlled clinical studies are required to verify these findings.

Efficacy of Prophylactic Cranial Irradiation According to the Risk of Extracranial Recurrence in Limited-Stage Small Cell Lung Cancer

PURPOSE

We aimed to evaluate the effectiveness of prophylactic cranial irradiation (PCI) for "early brain metastasis", which occurs before extracranial recurrence (ECR), and "late brain metastasis", which occurs after ECR, in limited-stage small cell lung cancer (LS-SCLC).

Materials and Methods

We retrospectively analyzed 271 LS-SCLC patients who underwent definitive chemoradiation. All patients were initially staged with brain magnetic resonance imaging and positron emission tomography. Intracranial recurrence (ICR), ECR, progression-free rate (PFR), and overall survival (OS) were analyzed as clinical endpoints. The competing risk of the first recurrence with ICR (ICRfirst) was evaluated. Significantly associated variables in multivariate analysis of ECR were considered as ECR risk factors. Patients were stratified according to the number of ECR risk factors.

RESULTS

The application of PCI was associated with higher PFR (p=0.008) and OS (p=0.045). However, PCI was not associated with any of the clinical endpoints in multivariate analysis. The competing risk of ICRfirst was significantly decreased with the application of PCI (hazard ratio, 0.476; 95% confidence interval, 0.243 to 0.931; p=0.030). Stage III disease, sequential, and stable disease after thoracic radiation were selected as ECR risk factors. For patients without these risk factors, the application of PCI was significantly associated with increased OS (p=0.048) and a decreased risk of ICRfirst (p=0.026).

CONCLUSION

PCI may play a role in preventing early brain metastasis rather than late brain metastasis after ECR, suggesting that only patients with a low risk of ECR may currently benefit from PCI.

Prophylactic cranial irradiation-related lymphopenia affects survival in patients with limited-stage small cell lung cancer

Background

The study aimed to identify the relations of the absolute lymphocyte count (ALC) nadir during prophylactic cranial irradiation (PCI) and patient outcomes in limited-stage small cell lung cancer (LS-SCLC).

Methods

We analyzed 268 L S-SCLC patients who underwent PCI from 2012 to 2019. ALC values were collected prior, during, and 3 months post PCI. Kaplan-Meier and Cox regression analyses were performed to assess the relation of ALC to patient prognosis. Two nomograms were developed on the basis of clinical variables for survival prediction.

Results

Compared with the ALC before PCI (1.13 × 10⁹ cells/L), the ALC nadir during PCI was significantly reduced by 0.68 × 10⁹ cells/L (P < 0.001) and raised to 1.02 × 10⁹ cells/L 3 months post PCI. Patients with a low ALC nadir during PCI (<0.68 × 10⁹ cells/L) had inferior progression free survival (PFS) (median PFS: 17.2 m vs. 43.7 m, P = 0.019) and overall survival (OS) (median OS: 29.0 m vs 39.1 m, P = 0.012). Multivariate Cox analysis revealed that age, smoking history, clinical stage, and ALC nadir were independent OS (P = 0.006, P = 0.005, P < 0.001 and P = 0.027, respectively), as well as independent PFS predictors (P = 0.032, P = 0.012, P = 0.012 and P = 0.018, respectively). After internal cross-validation, the corrected concordance indices of the predictive nomograms for PFS and OS were 0.637 and 0.663, respectively.

Conclusion

LS-SCLC patients with a low ALC nadir during PCI likely have worse survival outcomes. Dynamic evaluation of the ALC during PCI is recommended for LS-SCLC patients.