Comparison of the Effectiveness of “Late” and “Early” Prophylactic Cranial Irradiation in Patients with Limited-Stage Small Cell Lung Cancer

Prevention of Brain Metastases: A New Frontier

This review discusses the topic of prevention of brain metastases from the most frequent solid tumor types, i.e., lung cancer, breast cancer and melanoma. Within each tumor type, the risk of brain metastasis is related to disease status and molecular subtype (i.e., EGFR-mutant non-small cell lung cancer, HER2-positive and triple-negative breast cancer, BRAF and NRAF-mutant melanoma). Prophylactic cranial irradiation is the standard of care in patients in small cell lung cancer responsive to chemotherapy but at the price of late neurocognitive decline. More recently, several molecular agents with the capability to target molecular alterations driving tumor growth have proven as effective in the prevention of secondary relapse into the brain in clinical trials. This is the case for EGFR-mutant or ALK-rearranged non-small cell lung cancer inhibitors, tucatinib and trastuzumab-deruxtecan for HER2-positive breast cancer and BRAF inhibitors for melanoma. The need for screening with an MRI in asymptomatic patients at risk of brain metastases is emphasized.

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.

Prophylactic cranial irradiation in SCLC

Prophylactic cranial irradiation (PCI) has well established place in therapy for patients with limited-disease small cell lung cancer who responded to treatment. The data from randomized trials document that PCI reduces brain metastases rate from approximately 60% to 30%, and increases 3-year overall survival by approximately 5%. Currently, the dose of 25 Gy in 10 fractions is considered as standard. In attempt to reduce neuropsychological sequelae attributable to PCI hippocampal sparing techniques are employed. The existing studies suggest the benefit of hippocampal sparing in limiting memory and higher neurocognitive function losses, but with a risk of failures in the spared region. Ongoing studies will further validate the role of hippocampal sparing, both in terms of toxicity reduction and metastases prevention. PCI for patients who have undergone resection for stage I small cell lung cancer (SCLC) is not recommended, PCI may be, however, associated with a favourable outcome in SCLC patients who have undergone complete surgery in stages II−III. The role of PCI in extensive-disease (ED) SCLC has been evolving. Most recent evidence indicate that PCI is controversial in ED patients with response to initial chemotherapy and absence of brain metastases confirmed by contrast-enhanced MRI. The patients who do not receive PCI, must, however, receive periodic MRI examination during follow-up, i.e., remain under active surveillance with access to radiotherapy at brain relapse. The assessment of safety and effectiveness of hippocampal-sparing PCI, with or without drug neuroprotection in consideration of diverse combinations of radiotherapy, chemotherapy and immunotherapy create a background for future directions of research.

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.

Association of Twice-Daily Radiotherapy With Subsequent Brain Metastases in Adults With Small Cell Lung Cancer

IMPORTANCE

Although thoracic twice-daily radiotherapy (TDRT) is one of the standards of care for small cell lung cancer, its association with brain metastases remains unknown.

OBJECTIVE

To investigate the association of TDRT vs once-daily radiotherapy (ODRT) with brain metastases after prophylactic cranial irradiation in patients with small cell lung cancer.

DESIGN, SETTING, AND PARTICIPANTS

In this multicenter cohort study, data on 778 consecutive patients with small cell lung cancer who had undergone thoracic radiotherapy (609 received ODRT and 169 received TDRT), chemotherapy, and prophylactic cranial irradiation were retrieved from the databases of 8 hospitals in China between July 1, 2003, and June 30, 2016. A 1:1 propensity score matching approach was used to control for confounding between the ODRT and TDRT groups. Confounding covariates included 8 demographic variables and 8 treatment-related covariates. Data analysis was conducted from November 1, 2017, to May 31, 2018, and reanalyzed for revision.

EXPOSURES

The ODRT group received 50 to 66 Gy given in 25 to 33 fractions. The TDRT group received 45 Gy given in 30 fractions.

MAIN OUTCOMES AND MEASURES

The primary end point was brain metastases. Secondary end points included progression-free survival and overall survival.

RESULTS

Of the 778 patients (median age, 55 years [interquartile range, 48-61 years]), 204 were women and 574 were men. At a median follow-up of 23.6 months (interquartile range, 14.2-38.2 months), 131 patients (16.8%) experienced brain metastases. The rate of brain metastasis at 3 years in the TDRT group was significantly higher than in the ODRT group (26.0% vs 16.9%; hazard ratio, 1.55; 95% CI, 1.06-2.26; P = .03). Of the 338 matched patients (169 in the ODRT group vs 169 in the TDRT group), 60 (17.8%) experienced brain metastases, with a rate at 3 years of 14.9% in the ODRT group vs 26.0% in the TDRT group (hazard ratio, 1.71; 95% CI, 1.02-2.88; P = .04). Progression-free survival was similar in both the whole cohort and the matched cohort. Median overall survival in the ODRT group tended to be significantly longer than in the TDRT group after matching (47.2 vs 32.8 months; hazard ratio, 1.41; 95% CI, 0.99-2.01; P = .06).

CONCLUSIONS AND RELEVANCE

In this study, patients with small cell lung cancer who received thoracic TDRT appeared to have a higher risk of brain metastases than those who received ODRT, which supports the need for further prospective randomized clinical trials, especially in China and other parts of Asia.

Outcomes of stereotactic radiosurgery of brain metastases from neuroendocrine tumors

Background

Stereotactic radiosurgery (SRS) is an established treatment for brain metastases, yet little is known about SRS for neuroendocrine tumors given their unique natural history.

Objective

To determine outcomes and toxicity from SRS in patients with brain metastases arising from neuroendocrine tumors.

Methods

Thirty-three patients with brain metastases from neuroendocrine tumors who underwent SRS were retrospectively reviewed. Median age was 61 years and median Karnofsky performance status was 80. Primary sites were lung (87.9%), cervix (6.1%), esophagus (3%), and prostate (3%). Ten patients (30.3%) received upfront SRS, 7 of whom had neuroendocrine tumors other than small cell lung carcinoma. Kaplan-Meier survival and Cox regression analyses were performed to determine prognostic factors for survival.

Results

With median follow-up after SRS of 5.3 months, local and distant brain recurrence developed in 5 patients (16.7%) and 20 patients (66.7%), respectively. Median overall survival (OS) after SRS was 6.9 months. Patients with progressive disease per Response Assessment in Neuro-Oncology-Brain Metastases (RANO-BM) criteria at 4 to 6 weeks after SRS had shorter median time to developing recurrence at a distant site in the brain and shorter OS than patients without progressive disease: 1.4 months and 3.3 months vs 11.4 months and 12 months, respectively (both P < .001). Toxicity was more likely in lesions of small cell histology than in lesions of other neuroendocrine tumor histology, 15.7% vs 3.3% (P = .021). No cases of grade 3 to 5 necrosis occurred.

Conclusions

SRS is an effective treatment option for patients with brain metastases from neuroendocrine tumors with excellent local control despite slightly higher toxicity rates than expected. Progressive disease at 4 to 6 weeks after SRS portends a poor prognosis.

Simultaneous integrated prophylactic cranial irradiation in sino-nasal cancer

Therapy for small cell cancer and high grade neuroendocrine tumours of the paranasal sinuses is extrapolated from the treatment of small cell lung cancer and paranasal cancer of different histologies. Prophylactic cranial irradiation has proven survival benefit in small cell lung cancer. Two patients with aggressive cancer of the paranasal sinuses received radiotherapy with simultaneous integrated prophylactic brain irradiation, using two sequential plans. Chemotherapy was given before, during and after radiotherapy. None of the patients had intracranial recurrence. One patient experienced severe, but transient encephalitis-like symptoms that could only be attributed to radiotherapy. No long term side effects in the CNS were observed. The treatment was feasible, but with possible severe, but transient side effects. It should be considered in cases with head and neck cancer, with a high risk of intracerebral metastasis, as well as a significant overlap between the primary irradiated volume and the brain.

Frequency of Silent Brain Metastasis Before Prophylactic Cranial Irradiation in Small Cell Lung Cancer

OBJECTIVES

Prophylactic cranial irradiation (PCI) decreases incidence of brain metastasis and improves survival in patients with limited disease-small cell lung cancer (LD-SCLC) who achieved complete response (CR) after treatment. There is no satisfactory evidence about the necessity of new brain imaging for asymptomatic metastasis immediately prior to PCI. The present study aimed to evaluate the frequency of brain metastasis in SCLC patients without neurological symptoms who are candidates for PCI.

MATERIAL AND METHODS

The data files of 243 patients with SCLC referred for cranial irradiation were retrospectively reviewed. The patients with following characteristics were enrolled to the study; 1) LD-SCLC patients with CR after chemoradiotherapy who are candidates for PCI. 2) No neurological signs or symptoms of brain metastasis after chemoradiotherapy. 3) Having brain imaging at initial diagnosis and before PCI.

RESULTS

Ninety-nine patients (83 male, 83.3%) were included in this study. Median age was 60 years. Time interval between initial and reevaluation for brain metastasis was median 5.5 months (range; 4.7-7.1). Asymptomatic brain metastasis rate was 20.2% (18/99).

CONCLUSION

Even if local disease is under control, asymptomatic brain metastasis is not rare. Therefore, patients who are candidates for PCI after completion of chemoradiotherapy should be reimaged for brain metastasis before PCI.

Prophylactic cranial irradiation in 399 patients with limited-stage small cell lung cancer

The benefit of prophylactic cranial irradiation (PCI) in limited-stage small-cell lung cancer (LS-SCLC) was established in a meta-analysis performed in 1999. Since then, considerable progress has been made in the diagnosis, staging and treatment of LS-SCLC, including chemotherapy and radiotherapy, which led to a longer survival time in patients. Therefore, the magnitude of the benefit of PCI should be re-evaluated. Furthermore, the optimum timing of PCI for LS-SCLC treatment has not been established and more data is required to demonstrate this. In the present retrospective study, the cases of patients that were diagnosed with LS-SCLC between March 2005 and December 2010 were reviewed. The main eligibility criteria of patients were a diagnosis of LS-SCLC and the achievement of a complete response (CR) or near CR subsequent to receiving ≥3 cycles of cisplatin-based chemotherapy, with or without advanced thoracic radiotherapy. Early and late PCI groups were separated using the median time interval between the start of primary chemotherapy and the start of PCI. In total, 80 patients were excluded from the analysis, including 9 patients that developed brain metastases, 2 during primary chemotherapy and 7 during radiotherapy. The remaining 399 patients were deemed eligible. PCI was administered to 185 patients; 92 patients were in the early PCI group and 93 were in the late PCI group. PCI significantly decreased the incidence of brain metastases [P<0.001; HR, 0.24; 95% confidence interval (CI), 0.15-0.39] and improved the overall survival time of the patients (median survival time, 21.5-38.8 months; P<0.001; HR, 0.60; 95% CI, 0.45-0.79). However, no significant difference was identified between the early and late PCI groups, either in the incidence of brain metastases (P=0.875) or the overall survival time (P=0.361). Multivariate analysis revealed that PCI (P=0.004) and thoracic radiotherapy (P=0.023) were the only 2 independent favorable prognostic factors of overall survival time. The present study demonstrates that PCI may be of considerable benefit to increase the survival rate and time of patients, and early PCI is as effective as late PCI. However, the present study recommends that PCI should be offered as soon as primary chemotherapy is completed, since there is a greater risk of developing brain metastases during thoracic radiotherapy.

Limited disease of extra-pulmonary small cell carcinoma. Impact of local treatment and nodal status, role of cranial irradiation

PURPOSE

As extra-pulmonary small cell carcinoma (EPSCC) is a rare entity of tumors, the available treatment recommendations are mainly based on retrospective analyses and deduction from treatment of small cell lung cancer. The aim of this study was to provide a detailed analysis concerning prognostic factors and treatment modalities.

PATIENTS AND METHODS

A total of 20 patients with limited disease (LD) of EPSCC treated at our institution from 1999–2009 were retrospectively analyzed. Data were gathered from chart review. Localization, lymph node involvement, as well as local and systemic treatment were documented and their impact on pattern of failure and survival times statistically evaluated.

RESULTS

With a median follow-up of 21 months, the estimated median overall- and disease-free survival were 59 and 25 months, respectively. Local control was excellent with 100% at 2 years. Nodal involvement was observed in 74% (n = 14/19) of evaluable patients. However, outcome was not altered by this parameter. Local treatment consisted of surgery in 10 cases, radiotherapy in 7 cases, and a combination of both in 3 cases. Only 3 patients (15%) developed hematogenous central nervous system metastases, while none of the patients received prophylactic cranial irradiation.

CONCLUSION

Nodal involvement did not worsen prognosis. Local control was excellent irrespective of local treatment modality and the leading cause of failure was distant metastasis. Therefore, systemic treatment should not be omitted. Prophylactic cranial irradiation might be dispensable but discussed for head and neck malignancies.

Prophylactic cranial irradiation in patients with small cell lung cancer. A retrospective study of recurrence, survival and morbidity

BACKGROUND

Prophylactic cerebral irradiation (PCI) is a standard treatment for all small cell lung cancer (SCLC) patients with response to chemotherapy. The aims of this study were: to evaluate patients undergoing PCI with regard to cerebral recurrence rate, site of recurrence, and overall survival (OS) and to investigate the influence of steroid dose on acute toxicity.

MATERIALS AND METHODS

From 2007 to 2010 a total of 118 consecutive patients underwent PCI (25 Gray in 10 fractions). In total, 114/118 received full PCI dose, all 118 were included in the study. Data were analyzed retrospectively with regard to disease stage, treatment, date of PCI, steroid dose during PCI, toxicity, time to recurrence, site of recurrence and time of death. The median follow up time was 16.6 months (range 3-54 months).

RESULTS

Of the 118 patients undergoing PCI, 74 had limited disease (LD-SCLC) and 44 had extensive disease (ED-SCLC). The median age was 65 years (range 46-80 years). The median overall survival of all patients from the time of diagnosis was 16.0 months (CI 95% 13.0-19.0), in LD-SCLC it was 24.0 months (CI 95% 19.6-28.3), and in ED-SCLC it was 12.0 months (CI 95% 9.6-14.4). Twenty-one patients (17.8%) were diagnosed with cerebral recurrence. Five of these presented with metastatic disease within the limbic system. Of these five patients, four had miliary cerebral disease and one had non-oligometastatic disease. The time from PCI to cerebral recurrence ranged from 4 to 27 months. Prednisolone administration varied from 0 to 100 mg/day. Forty-eight patients were not treated with steroids, 64.6% of these patients reported acute toxicity. Of the 36 patients receiving 50 mg prednisolone, only 22.2% had side effects. The most common symptoms during PCI were nausea and headache.

CONCLUSIONS

Twenty-one patients out of 118 developed brain metastases after PCI: five of the twenty-one had metastases located in the limbic system. The study showed that prophylactic steroid use might reduce acute toxicity to PCI. Survival data and recurrence rates are comparable to other clinical studies.

Cerebral metastases in extrapulmonary cell carcinoma. Implications for the use of prophylactic cranial irradiation

BACKGROUND AND PURPOSE

Extrapulmonary small cell carcinoma (EPSCC) is a rare disease. Standard treatment is performed in analogy to small cell lung cancer; however, due to the differences in rates of cerebral metastases (CM), prophylactic cranial irradiation (PCI) is not routinely used. Therefore, we evaluated the characteristics of all patients developing brain metastases in a population of EPSCC patients and calculated a number needed to treat (NNT) for the prevention of cerebral metastases by PCI.

PATIENTS, METHODS, AND RESULTS

Of 51 patients treated at our institution from 1999-2011 for EPSCC, 11 presented with CM, 5 at initial diagnosis, 6 in the course of their disease. Median overall survival after primary diagnosis of EPSCC was 12 months. Overall survival after diagnosis of CM was significantly in favor of primarily cerebrally metastasized patients with 9 compared to 2 months for secondary CM (p = 0.04), median survival for all patients being 4 months. The NNT calculation was based on the 6 patients with secondary brain metastases in our series and a relative risk reduction of 60% observed in the studies of PCI for small cell lung cancer (SCLC), resulting in an NNT of 13.

CONCLUSION

Although the frequency of brain metastases in EPSCC was lower than in SCLC, the NNT of 13 for the prevention of CM, as well as the poor median survival after diagnosis of secondary brain metastases of 2 months might be a reason to discuss and evaluate PCI for EPSCC patients responding to initial therapy.

Chemoradiotherapy duration correlates with overall survival in limited disease SCLC patients with poor initial performance status who successfully completed multimodality treatment

BACKGROUND AND PURPOSE

Limited data concerning treatment-related prognostic factors in limited disease (LD) small-cell lung cancer (SCLC) patients with poor initial performance status (PS) who successfully completed chemoradiotherapy (CRT) are available.

PATIENTS AND METHODS

A total of 125 patients with initial PS WHO 2-3 who successfully completed CRT were retrospectively reviewed. Thoracic radiation therapy (TRT) was applied in the concurrent (group 1) or sequential (group 2) mode. Influence of treatment type, time from diagnosis to start of TRT, number of chemotherapy cycles, prophylactic cranial irradiation (PCI), occurrence of brain metastases (BMs), and duration of CRT on overall survival (OS) were analyzed.

RESULTS

Median duration of CRT was 156 days in group 1 and 195 days in group 2 (p < 0.001). Median progression-free survival and OS were 11.6 (95% confidence interval (CI) 10-13.2) and 14.9 (95% CI 11.7-17.6) months with no difference between the groups. The 2- and 3-year survival rates were 37.9 ± 6.9% and 22.7 ± 6.3% in group 1 and 22.4 ± 4.9% and 15.2 ± 4.3% in group 2, respectively. Duration of CRT was only treatment-related factor predicting OS in the uni- (p < 0.014) and multivariate (p < 0.025) analyses. Short dose-dense CRT was associated with improved OS.

CONCLUSION

Duration of CRT affects OS in LD SCLC patients with poor initial performance status who successfully completed multimodality treatment.