Limited-stage small cell lung cancer: Outcomes associated with prophylactic cranial irradiation over a 20-year period at the Princess Margaret Cancer Centre

Real-world predictors of survival in patients with limited-stage small-cell lung cancer in Manitoba, Canada

Background

Although therapy for limited-stage small-cell lung cancer (LS-SCLC) is administered with curative intent, most patients relapse and eventually die of recurrent disease. Chemotherapy (CT) with concurrent radiotherapy (RT) remains the standard of care for LS-SCLC; however, this could evolve in the near future. Therefore, understanding the current prognostic factors associated with survival is essential.

Objective

This real-world analysis examines factors associated with long-term survival in patients with LS-SCLC treated with CT in Manitoba, Canada.

Methods

A retrospective cohort study was conducted using Manitoba Cancer Registry and CancerCare Manitoba records. Eligible patients were aged >18 years and had cytologically confirmed LS-SCLC diagnosed between January 1, 2004, and December 31, 2018, for which they received CT ± RT. Baseline patient, disease, and treatment characteristics and survival duration, characterized as short (<6 months), medium (6-24 months), and long term (>24 months), were extracted. Overall survival (OS) was estimated at one, two, and five years and assessed using Kaplan-Meier methods and Cox proportional hazards models.

Results

Over the 15-year study period, 304 patients met the eligibility criteria. Long-term survivors comprised 39.1% of the cohort; at diagnosis, this subgroup was younger, more likely to have Eastern Cooperative Oncology Group Performance Status (ECOG PS) 0, and have normal lactate dehydrogenase, sodium, and hemoglobin levels. OS estimates for the entire cohort at one, two, and five years were 66%, 38%, and 18%, respectively. In the ECOG PS 0 subgroup, OS estimates at one, two, and five years were 85%, 52%, and 24%, respectively; OS estimates were 60%, 35%, and 17%, respectively, for ECOG PS 1-2 and were 47%, 23%, and 10%, respectively, for ECOG PS 3-4. OS was significantly higher among patients with normal serum sodium and hemoglobin levels than those with abnormal levels. Univariable hazard regression models found that ECOG PS, age at diagnosis, receipt of prophylactic cranial irradiation (PCI), and thoracic RT were associated with survival. On multivariable hazard regression, ECOG PS and receipt of PCI were associated with survival.

Conclusion

Survival for greater than two years in patients with LS-SCLC treated with CT ± RT was associated with ECOG PS and receipt of 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.

An Overview of the Role of Radiotherapy in the Treatment of Small Cell Lung Cancer - A Mainstay of Treatment or a Modality in Decline?

AIMS

Small cell lung cancer (SCLC) accounts for about 15% of all lung cancers. Chemotherapy, immunotherapy and radiotherapy all play important roles in the management of SCLC. The aim of this study was to provide a comprehensive overview of the role and evidence of radiotherapy in the cure and palliation of SCLC.

MATERIALS AND METHODS

The search strategy included a search of the PubMed database, hand searches, reference lists of relevant review articles and relevant published abstracts.

CLINICALTRIALS

gov was also queried for relevant trials.

RESULTS

Thoracic radiotherapy improves overall survival in limited stage SCLC, but the timing and dose remain controversial. The role of thoracic radiotherapy in extensive stage SCLC with immunotherapy is the subject of several ongoing trials. Current evidence supports the use of prophylactic cranial irradiation (PCI) for limited stage SCLC but the evidence is equivocal in extensive stage SCLC. Whole brain radiotherapy is well established for the treatment of brain metastases but evidence is rapidly accumulating for the use of stereotactic radiosurgery. Further studies will define the role of PCI, whole brain radiotherapy and hippocampal avoidant PCI in the immunotherapy era.

CONCLUSION

Radiotherapy is an essential component in the multimodality management of SCLC. Technological advances have allowed safer delivery of radiotherapy with reduced toxicities. Discussion at multidisciplinary team meetings is important to ensure radiotherapy is considered and offered in appropriate patients.

Prophylactic cranial irradiation (PCI) versus active surveillance in patients with limited-stage small cell lung cancer: a retrospective, multicentre study

Background

The recommendation of PCI for limited-stage small cell lung cancer (LS-SCLC) is primarily based on evidence from the pre-magnetic resonance imaging (MRI) era. However, as MRI accuracy improves and stereotactic radiosurgery advances, the role of PCI for LS-SCLC has become uncertain. This study aims to compare the contemporary survival outcomes of patients with LS-SCLC treated with PCI versus active surveillance.

Methods

We conducted a retrospective cohort study in which 1068 patients with LS-SCLC who achieved a good response to first-line chemoradiotherapy were consecutively enrolled from 5 tertiary medical centres between June 2009 and June 2019. Of these patients, 440 received PCI, while 628 received surveillance without PCI. Propensity score matching with a 1:1 ratio was performed to balance the baseline characteristics of the two cohorts. The endpoints were overall survival (OS) and the incidence of brain metastasis (BM).

Results

In total, 648 patients were matched. The baseline characteristics were generally well balanced. At a median follow-up of 64.5 months (range 2–190), patients who underwent PCI had a significantly lower risk for BM than those who underwent surveillance. The 3-year cumulative incidence rate of BM was 28.2% (95% CI 22.5–33.8%) in the PCI cohort and 38.5% (32.6–44.5%) in the surveillance cohort (Gray’s p = 0.002). However, the lower incidence of BM in the PCI cohort did not translate into a significant extension of OS. The median OS was 35.8 months (95% CI 27.6–44.0 months) in the PCI cohort versus 32 months (26.4–37.6 months) in the surveillance cohort (HR 0.90, 95% CI 0.74–1.10, p = 0.29). Multivariable analysis showed that disease stage, chemoradiotherapy sequence, and response to chemoradiotherapy were independent prognostic factors for BM or OS.

Conclusions

Overall, PCI reduces the risk for BM but does not substantially prolong OS compared with active surveillance. A phase 3, prospective clinical trial (NCT04829708) we initiated is currently underway, which is expected to corroborate our results.

The overall survival impact of prophylactic cranial irradiation in limited-stage small-cell lung cancer: a systematic review and meta-analysis

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PCI for LS-SCLC patients has become more controversial.

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Literature search on PCI impact on overall survival in LS-SCLC yielded 28 studies.

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Meta-analysis of adjusted HRs revealed pooled HR of 0.62 (95% CI: 0.57–0.69).

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Findings support PCI in current practice while awaiting prospective trial results.

Background

Prophylactic cranial irradiation (PCI) for limited-stage small-cell lung cancer (LS-SCLC) patients has become more controversial. Since the publication of the systematic review by Aupérin et al. in 1999, no randomized controlled trials regarding PCI in LS-SCLC have been completed. The aim of this study was to systematically review and meta-analyze the effect of PCI on overall survival (OS) in patients with LS-SCLC.

Methods

A systematic search was conducted in the databases of MEDLINE (PubMed), Embase and the Cochrane library. Only studies that reported an adjusted hazard ratio (aHR), indicating the effect of PCI versus no PCI on OS (adjusted for confounders) in patients with LS-SCLC were included for critical appraisal and meta-analysis. A pooled aHR estimate was calculated using a random-effects model.

Results

Pooling of 28 retrospective studies including a total of 18,575 patients demonstrated a significant beneficial effect of PCI versus no PCI on OS with a pooled aHR of 0.62 (95% CI: 0.57–0.69). Substantial heterogeneity of reported aHRs among studies was observed (I² = 65.9%). Subgroup analyses revealed that this heterogeneity could partly be explained by study sample size. The pooled aHR among 7 versus 21 studies with a sample size of > 300 versus ≤ 300 patients was 0.79 (95% CI: 0.64–0.97) versus 0.56 (95% CI: 0.46–0.69; p < 0.001), respectively.

Conclusions

This meta-analysis demonstrates a significant beneficial effect of PCI on OS in patients with LS-SCLC. Larger studies reported a milder beneficial effect, possibly due to a decreased risk of model overfitting. Serious risk of selection and confounding bias were of concern due to the lack of prospective trials. These results support the role of PCI in standard clinical practice in patients with LS-SCLC while awaiting results of prospective trials on alternative strategies.

One Cycle of Concurrent Chemotherapy vs. Two Cycles of Concurrent Chemotherapy With Radiation Therapy in Patients With Limited-Stage Small Cell Lung Cancer

Background

The optimal number of concurrent chemotherapy cycles during thoracic radiotherapy (RT) in patients with limited stage-small cell lung cancer (LS-SCLC) is not well defined. The purpose of this study was to evaluate the impact of the number of concurrent chemotherapy cycles on prognosis of LS-SCLC.

Material and Methods

Patients with LS-SCLC treated with concurrent chemo-radiotherapy from May 2008 to December 2020 in our hospital were retrospectively analyzed. The prescribed radiation dose was 60Gy administrated with conventional RT in 30 fractions within 6 weeks. The prognostic role of cycle number of chemotherapy administrated concurrently with RT were analyzed. All patients were followed up at one month after the treatment, then once every three months until two years after the treatment, and every six months thereafter. Propensity score matching (PSM) was performed to reduce confounding factors. The primary endpoint was overall survival (OS). Survival analysis was performed with Kaplan-Meier and multivariate analysis was performed with Cox regression model.

Results

Among the 370 patients who received radical radiotherapy, 206 patients received concurrent chemo-radiotherapy and were included for the analysis. Multivariate analysis showed that stage and PCI were independent prognostic factors for OS. The median OS in patients who received one cycle and two cycles of chemotherapy concurrently with RT were 32.9 months and 31.6 months, respectively (P = 0.241). And the median PFS were 20.6 months and 18.4 months, respectively (P = 0.764). After PSM, no statistical differences in OS and PFS were observed between patients who received one cycle and those who received two cycles of concurrent chemotherapy.

Conclusion

Two cycles of concurrent chemotherapy during RT were not necessarily superior compared to one cycle in LS-SCLC. The optimal cycle number of concurrent chemotherapy during RT needs to be further studied.

Limited-Stage Small-Cell Lung Cancer: Current Progress and the Next Frontier

Limited-stage (LS) small-cell lung cancer (SCLC) is defined as disease confined to a tolerable radiation portal without extrathoracic metastases. Despite clinical research over two decades, the prognosis of LS-SCLC patients remains poor. The current standard of care for LS-SCLC patients is concurrent platinum-based chemotherapy with thoracic radiotherapy (RT). Widespread heterogeneity on the optimal radiation dose and fractionation regimen among physicians highlights the logistical challenges of administering BID regimens. Prophylactic cranial irradiation (PCI) is recommended to patients following a good initial response to chemoradiation due to improved overall survival from historical trials and the propensity for LS-SCLC to recur with brain metastases. However, PCI utilization is being debated due to the greater availability of magnetic resonance imaging (MRI) and data in extensive-stage SCLC regarding close MRI surveillance in lieu of PCI while spurring novel RT techniques, such as hippocampal-avoidance PCI. Additionally, novel treatment combinations incorporating targeted small molecule therapies and immunotherapies with or following radiation for LS-SCLC have seen recent interest and some concepts are being investigated in clinical trials. Here, we review the landscape of progress, limitations, and challenges for LS-SCLC including current standard of care, novel radiation techniques, and the integration of novel therapeutic strategies for LS-SCLC.