Prophylactic cranial irradiation or no prophylactic cranial irradiation in metastatic small cell lung cancer: is it a relevant question once again?

Factors affecting survival and prognosis in extensive stage small cell lung cancer

Although chemotherapy significantly improves the quality of life and prolongs survival in patients with extensive-stage small cell lung cancer (ES-SCLC), relapse is almost inevitable, with only 5% of patients surviving two years after the initial diagnosis. Prophylactic cranial irradiation (PCI) is considered for patients who achieve a complete response, as it has been shown to improve survival rates in this population. Recent studies have also demonstrated that adding PD-L1 inhibitors, such as atezolizumab or durvalumab, to chemotherapy in first-line treatment significantly enhances survival compared to chemotherapy alone. Our study was conducted retrospectively at a single center, including 280 patients with ES-SCLC who began therapy at our institution between July 2009 and February 2023. Patients who underwent thoracic residual radiotherapy (p< 0.001) and PCI (p< 0.001) showed statistically significant improvements in OS. In the first-line treatment group, the median overall survival (OS) for patients receiving cisplatin+etoposide was 12.0 months (10.71 - 13.28), while those treated with carboplatin+etoposide had a median OS of 7.0 months (4.58 - 9.41). For patients receiving carboplatin+etoposide+atezolizumab, the median OS was 35.0 months (21.32 - 48.67), and a statistically significant difference was observed (p< 0.001). In our study, the median OS was 7 months in patients who received ≤ 4 cycles of treatment in the first line and 14 months in patients who received > 4 cycles of treatment. After first-line treatment, the proportion of patients with progression-free survival (PFS) between 0 - 3 months was 21%, and between 3 - 6 months was 24%. PFS was notably worse in those with bone, liver, or brain metastases at diagnosis in the first-line treatment. Multivariate analysis revealed that carboplatin+etoposide+atezolizumab in the first line and cisplatin+etoposide in the second line reduced the risk of both progression and death, while PCI reduced the risk of death. In conclusion, ES-SCLC remains one of the most challenging malignancies, characterized by poor survival rates and short progression-free intervals. Multiple factors influence OS and PFS, some of which are intrinsic to the patient and disease at diagnosis. In contrast, others, such as treatment modalities, the number of treatment cycles, and the application of radiotherapy, can be modified by clinicians.

Prophylactic Cranial Irradiation for Extensive-Stage Small-Cell Lung Cancer: A Controversial Area

Small-cell lung cancer (SCLC) is a highly aggressive malignant tumor that is prone to lead to the development of brain metastases (BM). The application of prophylactic cranial irradiation (PCI) has been regarded as an important technological advance made in cancer therapy to reduce the occurrence of BM and improve patient survival. The benefits of PCI in the treatment of limited-stage SCLC have been confirmed. However, there has been continuous controversy about the indications and advantages of PCI for extensive-stage SCLC (ES-SCLC) because of the conflicting results from two prospective trials. In this review, we aimed to discuss the relevant controversy and progress made in the clinical application of PCI in ES-SCLC.

Prophylactic Cranial Irradiation for Limited-Stage Small-Cell Lung Cancer Patients: Secondary Findings From the Prospective Randomized Phase 3 CONVERT Trial

INTRODUCTION

The impact of the dose and fractionation of thoracic radiotherapy on the risk of developing brain metastasis (BM) has not been evaluated prospectively in limited stage SCLC patients receiving prophylactic cerebral irradiation (PCI).

METHODS

Data from patients treated with PCI from the CONVERT trial were analyzed.

RESULTS

Four hundred forty-nine of 547 patients (82%) received PCI after completion of chemoradiotherapy. Baseline brain imaging consisted of computed tomographic scans in 356 of 449 patients (79%) and magnetic resonance imaging in 83 of 449 (18%) patients. PCI was delivered to 220 of 273 participants (81%) in the twice-daily (BD) group and 229 of 270 in the once-daily (OD) group (85%; p = 0.49). Total median PCI dose was 25 Gy in both the BD and OD groups (p = 0.74). In patients who received PCI, 75 (17%) developed BM (35 [8%] in OD and 40 [9%] in BD) and 173 (39%) other extracranial progression. In the univariate analysis, gross tumor volume (GTV) was associated with an increased risk of BM (p = 0.007) or other radiological progression events (p = 0.006), whereas in a multivariate analysis both thoracic GTV (tGTV) and ECOG performance score were associated with either progression type. The median overall survival (OS) of patients treated with PCI was 29 months. In the univariate analysis of OS, PCI timing from end of chemotherapy, weight loss of more than 10%, and tGTV were prognostic factors associated with OS. In the multivariate analysis, only tGTV was associated with OS. Delay between end of chemotherapy and PCI was not associated with OS.

CONCLUSIONS

Patients receiving OD or BD thoracic radiotherapy have the same risk of developing BM. Larger tumors are associated with a higher risk of BM.

Prophylactic cranial irradiation in small-cell lung cancer: update on patient selection, efficacy and outcomes

Over 10% of small-cell lung cancer (SCLC) patients have brain metastases (BM) at initial diagnosis; more than 50% will develop BM within 2 years. BM are detected in up to 80% of all patients at autopsy. After primary treatment, prophylactic cranial irradiation (PCI) has been established as standard of care in SCLC patients responding to initial therapy. Based on level I evidence, PCI significantly decreases the risk of intracranial relapse and shows a modest survival benefit after 3 years. However, the role of PCI in defined patient subgroups such as resected SCLC, elderly and extensive stage patients with access to magnetic resonance imaging surveillance and stereotactic radiotherapy is yet to be fully clarified. Furthermore, strategies to effective prevention of neurocognitive decline after PCI remain unclear. All these factors significantly impact treatment decision making and should be evaluated in prospective settings. New concepts such as hippocampal avoidance and drug neuroprotection prevent chronic neurocognitive effects reducing treatment-related side effects of PCI. The aim of this review is to present a summary and update of the latest evidence for patient selection, efficacy and outcome of PCI.

The Role of Prophylactic Cranial Irradiation in Patients With Extensive Stage Small Cell Lung Cancer: A Systematic Review and Meta-Analysis

INTRODUCTION

The role of prophylactic cranial irradiation (PCI) is controversial in patients with extensive stage small cell lung cancer. The aim of this study was to determine the impact of PCI in these patients.

METHODS

We performed a systematic review and meta-analysis in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. A systematic literature search was conducted in MEDLINE, EMBASE, and the Cochrane Central Register. The primary outcome was overall survival (OS).

RESULTS

We identified five studies comprising 984 patients, of whom 448 received PCI and 536 did not receive PCI. In pooled estimates, PCI did not statistically improve OS compared with controls (hazard ratio [HR] = 0.82; 95% confidence interval [CI]: 0.60-1.11; I² = 77%; p = 0.19). However, the PCI group had a significant advantage in 1-year survival compared to the no-PCI group (37.1% versus 27.1%; risk ratio = 0.87; 95% CI: 0.80-0.95; I² = 47%; p = 0.002), and the pooled estimates indicated that progression-free survival and the risk of brain metastasis were associated with significant benefit in the PCI group (HR = 0.83; 95% CI: 0.70-0.98; I² = 22%; p = 0.03; and HR = 0.34; 95% CI: 0.23-0.50; I² = 0%; p < 0.001, respectively).

CONCLUSIONS

Our findings suggest that PCI in patients with extensive stage small cell lung cancer may lead to a significant benefit in 1-year survival, progression-free survival, and the risk of brain metastasis, despite the lack of a significant advantage in OS.