Prophylactic Cranial Irradiation in Extensive Stage Small Cell Lung Cancer: Outcomes at a Comprehensive Cancer Centre

Prophylactic cranial irradiation in patients with resected small-cell lung cancer: A systematic review and meta-analysis

Prophylactic cranial irradiation (PCI) was recommended for limited-stage small-cell lung cancer (SCLC) patients with complete or partial response to primary chemoradiotherapy. But it is still controversial regarding its role in SCLC patients who have had radical resection. This meta-analysis aims to evaluate the efficacy of PCI in resected SCLC patients. We searched PubMed, EMBASE, Web of Science, CENTRAl, and ClinicalTrials for controlled trials and cohort studies regarding PCI in postoperative SCLC patients. The correlation between PCI and post-operative outcomes in SCLC patients, including survival and brain metastasis rate (BMR), was examined using hazard ratios (HRs) and risk ratios with corresponding 95% confidence intervals. Quality of studies was assessed by the Newcastle-Ottawa Scale (NOS), and publication bias was assessed by Begg's test. Meta-analysis of eight studies with 2688 patients in total showed PCI was associated with improved overall survival (OS) for resected SCLC (HR: 0.65, 95% CI: 0.57-0.75, p < 0.01). In addition, subgroup analysis on three studies including 923 patients confirmed the protective role of postoperative PCI in N0 SCLC patients (HR: 0.79, 95% CI: 0.61-0.97, p < 0.05). There was also a significant reduction in BMR in the PCI group pooled from six studies (HR: 0.58, 95% CI: 0.40-0.85, p < 0.01). The use of PCI delayed brain recurrence and improved OS in patients with resected, stage I-III SCLC. Importantly, patients with N0 SCLC can also benefit from postoperative PCI. In future studies, PCI's role in patients with resected N0 SCLC at different T stage may need to be explored.

Feasibility and long-term outcomes of post-chemotherapy-based consolidation radiotherapy in extensive stage small-cell lung cancer

Background

The target definition of consolidation radiotherapy (RT) for extensive stage small-cell lung cancer (ES-SCLC) has not been standardized. This study aimed to demonstrate the feasibility of post-chemotherapy based consolidation RT in ES-SCLC.

Methods

All ES-SCLC patients without initial brain metastases who completed ≥ 4 cycles of systemic therapy at Department of Radiation and Medical Oncology, Zhongnan Hospital of Wuhan University from 2012 to 2021 were included in this retrospective study. We correlated the site of first recurrence to the post-chemotherapy-based radiation volume (small-field). Relapse pattern, progression-free survival (PFS) and overall survival (OS) were compared between those received and did not receive consolidation RT.

Results

A total of 152 patients were followed up for a median of 31.7 months (interquartile range [IQR], 23.9-39.6 months). The median PFS and OS of the cohort were 8.3 months (IQR, 6.1-11.2 months) and 16.2 months (IQR, 9.9-24.9 months), respectively. Thoracic consolidation RT served not only as an independent prognostic factor for improved PFS in the entire cohort, but also significantly prolonged OS in the subgroup without synchronous liver metastases. Small-field consolidation RT markedly reduced in-field recurrences (hazard ratio [HR], 0.28 [95% CI, 0.12-0.38]; P < 0.001) without increasing out-of-field recurrences (HR, 0.40 [95% CI, 0.13-1.16]; P = 0.080). No relapse was observed at the margin of the targets. Treatment-related toxicities were moderate, with grade 3 acute radiation pneumonia, radiation esophagitis, and bone marrow suppression rates of 8.3%, 3.1%, and 12.5%, respectively. No grade 5 toxicity occurred.

Conclusion

Small-field consolidation RT based on post-chemotherapy volume is safe and can significantly improve local control in ES-SCLC.

Use of radiation therapy among patients with Extensive-stage Small-cell lung cancer receiving Immunotherapy: Canadian consensus recommendations

OBJECTIVES

Thoracic radiation therapy (TRT) and prophylactic cranial irradiation (PCI) are commonly used in the management of extensive-stage small-cell lung cancer (ES-SCLC); however, Phase III trials of first-line immunotherapy often excluded these options. Guidance is needed regarding appropriate use of TRT, PCI, and magnetic resonance imaging (MRI) surveillance while new data are awaited.

MATERIALS AND METHODS

In two web-based meetings, a pan-Canadian expert working group of five radiation oncologists and four medical oncologists addressed eight clinical questions regarding use of radiation therapy (RT) and MRI surveillance among patients with ES-SCLC receiving immunotherapy. A targeted literature review was conducted using PubMed and conference proceedings to identify recent (January 2019-April 2022) publications in this setting. Fifteen recommendations were developed; online voting was conducted to gauge agreement with each recommendation.

RESULTS

After considering recently available evidence across lung cancer populations and clinical experience, the experts recommended that all patients with a response to chemo-immunotherapy, good performance status (PS), and limited metastases be considered for consolidation TRT (e.g., 30 Gy in 10 fractions). When considered appropriate after multidisciplinary team discussion, TRT can be initiated during maintenance immunotherapy. All patients who respond to concurrent chemo-immunotherapy should undergo restaging with brain MRI to guide decision-making regarding PCI versus MRI surveillance alone. MRI surveillance should be conducted for two years after response to initial therapy. PCI (e.g., 25 Gy in 10 fractions or 20 Gy in 5 fractions) can be considered for patients without central nervous system involvement who have a response to chemo-immunotherapy and good PS. Concurrent treatment with PCI and immunotherapy or with TRT, PCI, and immunotherapy is appropriate after completion of initial therapy. All recommendations were agreed upon unanimously.

CONCLUSIONS

These consensus recommendations provide practical guidance regarding appropriate use of RT and immunotherapy in ES-SCLC while awaiting new clinical trial data.

Outcome of immune checkpoint inhibitors in patients with extensive-stage small-cell lung cancer and brain metastases

Objectives

Brain metastases (BMs) are common in extensive-stage small-cell lung cancer (SCLC) and are underrepresented in pivotal clinical trials that demonstrate the efficacy of immune checkpoint inhibitors (ICIs). We conducted a retrospective analysis to assess the role of ICIs in BM lesions in less selected patients.

Materials and methods

Patients with histologically confirmed extensive-stage SCLC who were treated with ICIs were included in this study. Objective response rates (ORRs) were compared between the with-BM and without-BM groups. Kaplan-Meier analysis and the log-rank test were used to evaluate and compare progression-free survival (PFS). The intracranial progression rate was estimated using the Fine-Gray competing risks model.

Results

A total of 133 patients were included, 45 of whom started ICI treatment with BMs. In the whole cohort, the overall ORR was not significantly different for patients with and without BMs (p = 0.856). The median progression-free survival for patients with and without BMs was 6.43 months (95% CI: 4.70-8.17) and 4.37 months (95% CI: 3.71-5.04), respectively (p =0.054). In multivariate analysis, BM status was not associated with poorer PFS (p = 0.101). Our data showed that different failure patterns occurred between groups, with 7 patients (8.0%) without BM and 7 patients (15.6%) with BM having intracranial-only failure as the first site progression. The cumulative incidences of brain metastases at 6 and 12 months were 15.0% and 32.9% in the without-BM group and 46.2% and 59.0% in the BM group, respectively (Gray's p<0.0001).

Conclusions

Although patients with BMs had a higher intracranial progression rate than patients without BMs, the presence of BMs was not significantly associated with a poorer ORR and PFS with ICI treatment in multivariate analysis.

Risk Factors for Brain Metastases in Patients With Small Cell Lung Cancer: A Systematic Review and Meta-Analysis

The use of prophylactic cranial irradiation (PCI) for small cell lung cancer (SCLC) patients is controversial. Risk factors for brain metastasis (BM) development are largely lacking, hampering personalized treatment strategies. This study aimed to identify the possible risk factors for BM in SCLC.We systematically searched the Pubmed database (1 January 1995 to 18 January 2021) according to the PRISMA guidelines. Eligibility criteria: studies reporting detailed BM data with an adequate sample size (randomized clinical trials [RCTs]: N ≥50; non-RCTs: N ≥100) in patients with SCLC. We summarized the reported risk factors and performed meta-analysis to estimate the pooled hazard ratios (HR) if enough qualified data (i.e., two or more studies; the same study type; the same analysis method; and HRs retrievable) were available. In total, 61/536 records were eligible (18 RCTs and 39 non-RCTs comprising 13,188 patients), in which 57 factors were reported. Ten factors qualified BM data for meta-analysis: Limited stage disease (LD) (HR = 0.34, 95% CI: 0.17-0.67; P = 0.002) and older age (≥65) (HR = 0.70, 95% CI: 0.54-0.92; P = 0.01) were associated with less BM; A higher T stage (≥T3) (HR = 1.72, 95% CI: 1.16-2.56; P = 0.007) was a significant risk factor for BM. Male sex (HR = 1.24, 95% CI: 0.99-1.54; P = 0.06) tended to be a risk factor, and better PS (0-1) (HR = 0.66, 95% CI: 0.42-1.02; P = 0.06) tended to have less BM. Smoking, thoracic radiotherapy dose were not significant (P >0.05). PCI significantly decreased BM (P <0.001), but did not improve OS in ED-SCLC (P = 0.81). A higher PCI dose did not improve OS (P = 0.11). The impact on BM was conflicting between Cox regression data (HR = 0.59, 95% CI: 0.26-1.31; P = 0.20) and competing risk regression data (HR = 0.74, 95% CI: 0.55-0.99; P = 0.04). Compared to M0-M1a, M1b was a risk factor for OS (P = 0.01) in ED-SCLC, but not for BM (P = 0.19). As regular brain imaging is rarely performed, high-quality data is lacking. Other factors such as N-stage and blood biomarkers had no qualified data to perform meta-analysis. In conclusion, younger age, higher T stage, and ED are risk factors for BM, suggesting that PCI should be especially discussed in such cases. Individual patient data (IPD) meta-analysis and well-designed RCTs are needed to better identify more risk factors and further confirm our findings. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021228391, identifier CRD42021228391.

Radiation therapy for extensive-stage small-cell lung cancer in the era of immunotherapy

Unlike non-small-cell lung cancer (NSCLC), the progression of small-cell lung cancer (SCLC) is slow. Extensive-stage SCLC (ES-SCLC) is a serious threat to human health, with a 5-year survival rate of <7%. Chemotherapy has been the first-line treatment for the past 30 years. The anti-PD-L1 checkpoint blockades durvalumab and atezolizumab have greatly prolonged overall survival and have become the standard first-line therapy for ES-SCLC since the CASPIAN and IMpower133 trials. In the era of chemotherapy, radiation therapy (RT), including thoracic radiation therapy (TRT) and brain radiation therapy (BRT), has shown clinical effects in randomized and retrospective studies on ES-SCLC. RT-immunotherapy has shown exciting synergistic effects in NSCLC. For ES-SCLC, the clinical effects of combining TRT/BRT with immunotherapy have not yet been systematically explored. In this review, we found that studies on RT-immunotherapy in ES-SCLC are relatively few and limited to early phase studies focusing on toxicity. The efficacy and safety profiles of early phase studies encourage prospective clinical trials. In this review, we discuss the best population, optimum TRT dose, proper TRT time, and strategies for reducing radiation-induced neurotoxicity. Furthermore, we suggest that biomarkers and patient performance status should be fully assessed before RT-immunotherapy treatment. Prospective trials are needed to provide more evidence for RT-immunotherapy applications in ES-SCLC.

Impact of Hippocampal Avoidance - Prophylactic Cranial Irradiation in Small Cell Lung Cancer Patients

BACKGROUND/AIM

Prophylactic cranial irradiation (PCI) is a well-established treatment of small cell lung cancer (SCLC) patients following response to initial chemoradiotherapy. The benefit of PCI does, however, come at the cost of cognitive decline. This has been attributed to radiation-induced toxicity at the hippocampus, a crucial anatomic area for cognition. Modern radiotherapy techniques allow dose reduction at the hippocampal region. In this review, the safety profile, effect on cognition, and changes on brain imaging modalities of hippocampal avoidance-PCI (HA-PCI) will be presented, aiming to identify a potential clinical rationale for SCLC patients.

MATERIALS AND METHODS

A systematic review of the literature was performed in Pubmed, Cochrane library databases and ClinicalTrials.gov with no past date limitations until 07/01/2022. Principles as outlined in the preferred reporting items for systematic reviews and meta-analysis (PRISMA) statement were followed.

RESULTS

Eight studies published from 2015 to 2021 were included.

CONCLUSION

HA-PCI is safe, yet its effect on neurocognition and imaging remains unclear, as studies have shown contradictory results.

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.

Treatment and Prevention of Brain Metastases in Small Cell Lung Cancer

Central nervous system (CNS) metastasis will develop in 50% of small cell lung cancer (SCLC) patients throughout disease course. Development of CNS metastasis poses a particular treatment dilemma due to the accompanied cognitive changes, poor permeability of the blood-brain barrier to systemic therapy and relatively advanced state of disease. Survival of patients with untreated SCLC brain metastases is generally <3 months with whole brain radiotherapy used as first-line management in most SCLC patients. To prevent development of CNS metastasis prophylactic cranial irradiation (PCI) is recommended in limited stage disease, after response to chemotherapy and radiation, while PCI may be considered in extensive stage disease after favorable response to upfront treatment. Neurocognitive toxicity with whole brain radiotherapy and PCI is a concern and remains difficult to predict. The mechanism of toxicity is likely multifactorial, but a potential mechanism of injury to the hippocampus has led to hippocampal sparing radiation techniques. Treatment of established non-small cell lung cancer CNS metastases has increasingly focused on using stereotactic radiotherapy (SRS) and it is tempting to extrapolate these results to SCLC. In this review, we explore the evidence surrounding the prediction, prevention, detection, and treatment of CNS metastases in SCLC. We further review whether existing evidence supports extrapolating less toxic treatments to SCLC patients with CNS metastases and discuss trials that may shed more light on this question.

Hippocampal avoidance in prophylactic cranial irradiation for small cell lung cancer: benefits and pitfalls

Small cell lung cancers (SCLC) are a group of cancers that are clinically and pathologically different from other lung cancers. They are associated with high recurrence rates and mortality, and many patients present with metastatic disease. Approximately ten percent of SCLC patients have brain metastases at time of diagnosis, and the cumulative incidence of brain metastases increases to more than fifty percent at two years, even with optimal treatment. Hence, in patients without brain metastases at presentation, prophylactic cranial irradiation (PCI) is an important component of treatment along with systemic chemotherapy and radiotherapy. The goal of PCI is to decrease the incidence of subsequent symptomatic brain metastases in patients who show an initial response to the systemic treatment. Various clinical trials have evaluated the utility of PCI and found substantial benefit. Unfortunately, the long-term toxicity associated with PCI, namely the neuro-cognitive impairment that may develop in patients as a result of the radiation toxicity to the hippocampal areas of the brain, has raised concern both for patients and their treating physicians. Various techniques have been tried to ameliorate the neuro-cognitive impairment associated with PCI, including pharmacological agents and highly conformal hippocampal avoidance radiation. All of these have shown promise, but there is a lack of clarity about the optimal way forward. Hippocampal avoidance PCI appears to be an excellent option and a number of groups are currently evaluating this technique. Although there is clear benefit with this specialized radiation treatment, there are also concerns about the risk of disease recurrence in the undertreated hippocampal areas. This review attempts to compile the available data regarding the benefits and pitfalls associated with hippocampal avoidance PCI in the setting of SCLC.

Prophylactic cranial irradiation or MRI surveillance for extensive stage small cell lung cancer

The treatment paradigm for extensive stage small cell lung cancer (ES-SCLC) is evolving. Prophylactic cranial irradiation (PCI) has long been considered a component of standard treatment in patients with extensive stage disease who respond to chemotherapy. However, in the modern era of magnetic resonance imaging, the role of PCI has become an area of controversy following conflicting level I evidence. Due to conflicting data and toxicity concerns, the routine use of PCI has declined. Recent improvements in systemic disease control with the use of immunotherapy and reductions in the toxicity attributable to PCI with hippocampal avoidance and memantine have reignited the discussion. As such, we present here a narrative review of PCI with a focus on historical milestones, randomized data, risk mitigation and future directions.

Prophylactic cranial irradiation for extensive-stage small cell lung cancer: Analysis based on active brain MRI surveillance

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The value of PCI remains controversial in ES-SCLC.

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Under the active brain MRI surveillance, PCI improve the PFS and BSS for ES-SCLC.

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PCI reduce the incidence of BM for ES-SCLC.

Background and purpose

The value of prophylactic cranial irradiation (PCI) for extensive-stage small-cell lung cancer (ES-SCLC) has recently been challenged. This study was conducted to evaluate the role of PCI for ES-SCLC under active brain magnetic resonance imaging (MRI) surveillance.

Materials and methods

Patients with ES-SCLC who showed any responses after first-line chemotherapy and no initial brain metastasis (BM) were retrospectively included. Active brain MRI surveillance was performed for all patients. Progression-free survival (PFS) and overall survival (OS) were compared between PCI and non-PCI patients. The time-related hazard of BM was evaluated in non-PCI patients.

Results

One hundred and eighteen consecutive patients were included in the study. The median follow-up time was 26.5 months (3–72 months). The median PFS and OS were better in the PCI cohort than in the non-PCI group. Multivariate analyses revealed first-line chemotherapy cycles (> 4 vs. ≤ 4 cycles, HR: 0.29; 95% CI: 0.15–0.55, P < 0.01) and PCI (Yes vs. No, HR: 0.54; 95% CI: 0.29–0.99, P = 0.04) were independent prognostic factors for disease progression. In the non-PCI group, 47.4% (46/97) of the patients developed BM and the hazard of BM increased continuously in three-quarters of the first year since diagnosis.

Conclusion

Under active brain MRI surveillance, PCI could be beneficial for patients with ES-SCLC who show good responses after first-line chemotherapy.

Radiation Therapy for Small Cell Lung Cancer: An ASTRO Clinical Practice Guideline

PURPOSE

Several sentinel phase III randomized trials have recently been published challenging traditional radiation therapy (RT) practices for small cell lung cancer (SCLC). This American Society for Radiation Oncology guideline reviews the evidence for thoracic RT and prophylactic cranial irradiation (PCI) for both limited-stage (LS) and extensive-stage (ES) SCLC.

METHODS

The American Society for Radiation Oncology convened a task force to address 4 key questions focused on indications, dose fractionation, techniques and timing of thoracic RT for LS-SCLC, the role of stereotactic body radiation therapy (SBRT) compared with conventional RT in stage I or II node negative SCLC, PCI for LS-SCLC and ES-SCLC, and thoracic consolidation for ES-SCLC. Recommendations were based on a systematic literature review and created using a consensus-building methodology and system for grading evidence quality and recommendation strength.

RESULTS

The task force strongly recommends definitive thoracic RT administered once or twice daily early in the course of treatment for LS-SCLC. Adjuvant RT is conditionally recommended in surgically resected patients with positive margins or nodal metastases. Involved field RT delivered using conformal advanced treatment modalities to postchemotherapy volumes is also strongly recommended. For patients with stage I or II node negative disease, SBRT or conventional fractionation is strongly recommended, and chemotherapy should be delivered before or after SBRT. In LS-SCLC, PCI is strongly recommended for stage II or III patients who responded to chemoradiation, conditionally not recommended for stage I patients, and should be a shared decision for patients at higher risk of neurocognitive toxicities. In ES-SCLC, radiation oncologist consultation for consideration of PCI versus magnetic resonance surveillance is strongly recommended. Lastly, the use of thoracic RT is strongly recommended in select patients with ES-SCLC after chemotherapy treatment, including a conditional recommendation in those responding to chemotherapy and immunotherapy.

CONCLUSIONS

RT plays a vital role in both LS-SCLC and ES-SCLC. These guidelines inform best clinical practices for local therapy in SCLC.

Risk stratification of symptomatic brain metastases by clinical and FDG PET parameters for selective use of prophylactic cranial irradiation in patients with extensive disease of small cell lung cancer

PURPOSE

To identify risk factors for developing symptomatic brain metastases and evaluate the impact of prophylactic cranial irradiation (PCI) on brain metastasis-free survival (BMFS) and overall survival (OS) in extensive disease small cell lung cancer (ED-SCLC).

MATERIALS AND METHODS

Among 190 patients diagnosed with ED-SCLC who underwent FDG PET/CT and brain Magnetic Resonance Imaging (MRI) prior to treatment, 53 (27.9%) received PCI while 137 (72.1%) did not. Prognostic index predicting a high risk of symptomatic brain metastases was calculated for the group without receiving PCI (observation group, n = 137) with Cox regression model.

RESULTS

Median follow-up time was 10.6 months. Multivariate Cox regression showed that the following three factors were associated with a high risk of symptomatic brain metastases: the presence of extrathoracic metastases (p = 0.004), hypermetabolism of bone marrow or spleen on FDG PET (p < 0.001), and high neutrophil-to-lymphocyte ratio (p = 0.018). PCI significantly improved BMFS in high-risk patients (1-year rate: 94.7% vs. 62.1%, p = 0.001), but not in low-risk patients (1-year rate: 100.0% vs. 87.7%, p = 0.943). However, PCI did not improve OS in patients at high risk for symptomatic brain metastases (1-year rate: 65.2% vs. 50.0%, p = 0.123).

CONCLUSION

Three prognostic factors (the presence of extrathoracic metastases, hypermetabolism of bone marrow or spleen on FDG PET, and high neutrophil-to-lymphocyte ratio) were associated with a high risk of symptomatic brain metastases in ED-SCLC. PCI was beneficial for patients at a high risk of symptomatic brain metastases in terms of BMFS, but not OS. Thus, selective use of PCI in ED-SCLC according to the risk stratification is recommended.

Non-coplanar whole brain radiotherapy is an effective modality for parotid sparing

Background

The purpose of this study was to evaluate the efficacy and feasibility of non–coplanar whole brain radiotherapy (NC–WBRT) for parotid sparing.

Methods

Fifteen cases, previously treated with WBRT were selected. NC–WBRT plans were generated. The beam arrangement for the non–coplanar plans consisted of superior anterior, right, and left beams. After generation of the non–coplanar plans a field–in–field technique was applied to the bilateral parallel opposed beams in order to reduce maximum dose and increase dose homogeneity. The NC–WBRT plans were subsequently compared with the previously generated bilateral WBRT (B–WBRT) plans. A field–in–field technique was also used with the B–WBRT plans according to our departmental protocol. As per our institutional practice a total dose of 30 Gy in 10 fractions of WBRT was administered 5 days a week.

Results

The mean dose to the parotid gland for the two different plans were 16.2 Gy with B–WBRT and 13.7 Gy with NC–WBRT (p<0.05). In the NC–WBRT plan, the V_5Gy, V_10Gy, V_15Gy, V_20Gy, and V_25Gy of the parotid were significantly lower (p<0.05) than those of the B–WBRT plan. The D_max of the lens was also lower by 10% with NC–WBRT.

Conclusion

The use of NC–WBRT plans could be a simple and effective method to reduce irradiated volumes and improve the dose–volume parameters of the parotid gland.

Adoption of prophylactic cranial irradiation (PCI) for extensive stage small cell lung cancer (ES-SCLC): a population based outcome study

Background

The survival benefit of PCI in ES-SCLC reported by a European randomized trial (RCT) in 2007 was not replicated by a Japanese RCT published in 2017. This study aimed to evaluate the uptake of PCI before and after publication of the European RCT and its association with survival in ES-SCLC.

Methods

We identified eligible patients in the only two Singapore national cancer centres from 2003 to 2010. We linked their electronic medical records to the national death registry. We described the utilization of PCI in patients diagnosed from 2003 to 2006 (pre-adoption cohort) with patients diagnosed from 2007 to 2010 (post-adoption cohort). We performed univariable and multivariable Cox regression analysis to assess the association between PCI and survival.

Results

We identified 224 patients with ES-SCLC with no brain metastases. Among the 71 patients who had at least stable disease after first line chemotherapy, there was an increase in the use of PCI from the period 2007 to 2010 compared with 2003 to 2006 (32% versus 10%, P = 0.044). PCI was associated with improved OS (hazard ratio 0.22, 95% CI 0.10 to 0.47, P < 0.001) compared to no PCI in the multivariable analysis.

Conclusion

There was an increase in the adoption of PCI for ES-SCLC since 2007. PCI was associated with improved survival in patients who did not have mandatory MRI brain imaging prior to PCI and had stable disease or better after first line chemotherapy, suggesting that the results of the European RCT are reproducible in the real-world practice.

Extracranial metastatic burden in extensive-stage small cell lung cancer: implications for prophylactic cranial irradiation

Background

Patients with extensive-stage small cell lung cancer (ES-SCLC) often develop brain metastases. There is significant controversy regarding the benefit of prophylactic cranial irradiation (PCI) for patients with ES-SCLC. Our objective is to identify ES-SCLC patients who might be most likely to benefit from PCI.

Methods

We retrospectively reviewed 173 patients with ES-SCLC treated between 2010-2015. Of these, 117 patients were initially diagnosed without brain metastases and received systemic chemotherapy. Following exclusion of patients who received PCI and less than 2 cycles of platinum doublet therapy, 93 patients remained. Patient records were reviewed for clinical and radiographic features previously identified as relevant risk factors. Primary outcome was brain metastasis-free survival (BMFS). Kaplan-Meier analysis, log-rank tests and Cox multivariate models were used to compare outcomes.

Results

Median follow-up was 10.7 months (range, 3-58 months). Thirty-eight (40.9%) patients developed brain metastases. Three or more metastatic sites was associated with inferior BMFS on univariable (1-year estimate 43.8% vs. 61.3%; P=0.020) and multivariable (MVA) analysis [hazard ratio (HR) 2.33, 95% CI: 1.08-5.01; P=0.03).

Conclusions

Our results suggest that extracranial metastatic burden is associated with an increased risk for brain metastases in patients with ES-SCLC. As there is no clear standard regarding delivery of PCI in this patient population, utilizing the number of metastatic disease sites as a clinical indicator may help to improve selection of patients who benefit from PCI.