The Role of Radiation Therapy in Small Cell Lung Cancer

Time Interval to Initiation of Whole-Brain Radiation Therapy in Patients With Small Cell Lung Cancer With Brain Metastasis

Purpose

Patients with small cell lung cancer (SCLC) who have brain metastases require whole-brain radiation therapy (WBRT). When there is no emergent indication for WBRT, patients may receive systemic therapy first and WBRT afterward. In scenarios when systemic therapy is initiated first, it has not been previously investigated whether delaying WBRT is harmful.

Methods and Materials

The National Cancer Database was queried (2004-2016) for patients with SCLC with brain metastases who received 30 Gy in 10 fractions of WBRT. Patients were divided into groups based on whether they received early WBRT (3-14 days after initiation of chemotherapy) or late WBRT (15-90 days after initiation of chemotherapy). Demographic and clinicopathologic categorical variables were compared between those who had early WBRT (3-14 days) and those who had late WBRT (15-90 days). Factors predictive for late WBRT were determined. Overall survival (OS), which was defined as days from diagnosis to death, was evaluated and variables prognostic for OS were determined.

Results

A total of 1082 patients met selection criteria; 587 (54%) had early WBRT and 495 (46%) received late WBRT. Groups were similarly distributed aside from days from initiating chemotherapy to initiating WBRT (P < .001). The early WBRT group had a median of 7 days (interquartile range [IQR], 5-10 days) from initiating chemotherapy to initiating WBRT and the late WBRT group had a median of 34 days (IQR, 21-57 days). On binary logistic regression analysis, a longer time interval between diagnosis and the start of systemic therapy was predictive for later WBRT. Median OS was 8.7 months for early WBRT and 7.5 months for late WBRT (hazard ratio [HR], 1.165; P = .008). Early WBRT (P = .02), female sex (P = .045), and private insurance (P = .04) were favorable prognostic factors for OS on multivariable analysis, whereas older age (P = .006) was an unfavorable prognostic factor.

Conclusions

Patients with SCLC and brain metastases who received early WBRT were found to have a modest improvement in OS compared with patients who received late WBRT. These findings suggest that early WBRT should be offered to patients who have brain metastases, even in the absence of an indication for emergent WBRT.

Treatment time to the end of thoracic radiotherapy has more predictive power for survival than radiation dose intensity in patients with limited-stage small-cell lung cancer receiving concurrent chemoradiation of more than 45 Gy

The optimal protocol for thoracic radiotherapy (TRT) in combination with chemotherapy in patients with limited-stage small-cell lung cancer (LS-SCLC) remains elusive. The present study aimed to evaluate radiation parameters in association with survival outcomes. A total of 101 patients with LS-SCLC who completed TRT at ≥45 Gy and concurrent chemotherapy were retrospectively reviewed. The median dose and duration of TRT were 50 Gy and 38 days, respectively. The median duration from the start of either therapy to the end of TRT (SER) was 60 days. The median survival for all patients was 26.9 months. The 3-year local control (LC), progression-free survival (PFS) and overall survival (OS) rates were 52.0, 29.5 and 37.6%, respectively, and the 5-year LC, PFS and OS rates were 50.1, 28.3 and 26.7%, respectively. Univariate analysis revealed that patient age, tumor stage, timing and dose of TRT, SER, prophylactic cranial irradiation (PCI), and tumor response were significantly associated with treatment outcomes. Multivariate analysis revealed that stage was the only significant prognostic factor for LC (P=0.011), PFS (P<0.001) and OS (P<0.001). Tumor response (P=0.014), PCI (P=0.007) and SER (P=0.005) were significant predictors of OS. OS was improved in patients who achieved complete response, and their SER was ≤70 days (P<0.001). Short treatment duration (SER ≤70 days) was a significant predictor of OS in patients with LS-SCLC who completed planned TRT at ≥45 Gy with concurrent chemoradiotherapy.

miR-144-5p Enhances the Radiosensitivity of Non-Small-Cell Lung Cancer Cells via Targeting ATF2

MicroRNAs (miRNAs or miRs) regulate gene expression at the posttranscriptional level and are involved in many biological processes such as cell proliferation and migration, stem cell differentiation, inflammation, and apoptosis. In particular, miR-144-3p is downregulated in various cancers, and its overexpression inhibits the proliferation and metastasis of cancer cells. However, the role of miR-144-5p in non-small-cell lung cancer (NSCLC), especially radiosensitivity, is unknown. In this study, we found that miR-144-5p was downregulated in NSCLC clinical specimens as well as NSCLC cell lines exposed to radiation. Enhanced expression of miR-144-5p promoted the radiosensitivity of NSCLC cells in vitro and A549 cell mouse xenografts in vivo. Furthermore, we identified activating transcription factor 2 (ATF2) as the direct and functional target of miR-144-5p using integrated bioinformatics analysis and a luciferase reporter assay. In addition, restoration of ATF2 expression inhibited miR-144-5p-induced NSCLC cell sensitivity to radiation in vitro and in vivo. Our findings suggest that deregulation of the miR-144-5p/ATF2 axis plays an important role in NSCLC cell radiosensitivity, thus representing a new potential therapeutic target for NSCLC.

Analysis of risk factors for pulmonary complications in patients with limited-stage small cell lung cancer : A single-centre retrospective study

INTRODUCTION

The most effective therapy in patients with limited-stage small cell lung cancer (LS SCLC) seems to be chemotherapy (using platinum-based regimens) and thoracic radiotherapy (TRT), which is followed by prophylactic cranial irradiation.

MATERIALS AND METHODS

The analysed group comprised 217 patients who received combined treatment for LS SCLC, i.e. chemotherapy (according to cisplatin and etoposide schedule) and TRT (concurrent in 101 and sequential in 116 patients). The influence of chemoradiotherapy (ChT-RT) schedule on treatment results (frequency of complete response, survival rates, and incidence of treatment failure and complications) was evaluated, and the frequency and severity of pulmonary complications were analysed to identify risk factors.

RESULTS

The 5‑year survival rates in concurrent vs. sequential ChT-RT schedules were 27.3 vs. 11.7% (overall) and 28 vs. 14.3% (disease-free). The frequencies of adverse events in relation to concurrent vs. sequential therapy were 85.1 vs. 9.5% (haematological complications) and 58.4 vs. 38.8% (pulmonary fibrosis), respectively. It was found that concurrent ChT-RT (hazard ratio, HR 2.75), a total dose equal to or more than 54 Gy (HR 2.55), the presence of haematological complications (HR 1.89) and a lung volume receiving a dose equal to or greater than 20 Gy exceeding 31% (HR 1.06) were the risk factors for pulmonary complications.

CONCLUSION

Pulmonary complications after ChT-RT developed in 82% of patients treated for LS SCLC. In comparison to the sequential approach, concurrent ChT-RT had a positive effect on treatment outcome. However, this is a factor that can impair treatment tolerance, which manifests in the appearance of side effects.

The Role of Radiotherapy in Small Cell Lung Cancer: a Revisit

Small cell lung cancer is staged as either limited (potentially curable) or extensive (incurable), based on the extent of disease in the chest. Limited stage disease is treated with concurrent chemotherapy and thoracic radiotherapy followed by prophylactic cranial irradiation (PCI). The conventional approach to extensive disease is chemotherapy only, with radiotherapy reserved for site-specific palliation. Recent reports suggest increasing applications for radiotherapy. The administration of PCI to extensive stage patients demonstrating response to chemotherapy is now recommended due to local control and overall survival benefits. Likewise, the role of consolidation chest radiotherapy after chemotherapy for advanced disease patients has seen a resurgence of interest in light of a recent publication suggesting improved local benefits which may influence survival. Recent technical advances in radiotherapy such as stereotactic body treatment and intensity-modulated therapy may also provide new indications for radiation, to enhance delivery and minimize toxicities.

Therapeutic effects of C-28 methyl ester of 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO-Me; bardoxolone methyl) on radiation-induced lung inflammation and fibrosis in mice

The C-28 methyl ester of 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO-Me), one of the synthetic triterpenoids, has been found to have potent anti-inflammatory and anticancer properties in vitro and in vivo. However, its usefulness in mitigating radiation-induced lung injury (RILI), including radiation-induced lung inflammation and fibrosis, has not been tested. The aim of this study was to explore the therapeutic effect of CDDO-Me on RILI in mice and the underlying mechanisms. Herein, we found that administration of CDDO-Me improved the histopathological score, reduced the number of inflammatory cells and concentrations of total protein in bronchoalveolar lavage fluid, suppressed secretion and expression of proinflammatory cytokines, including transforming growth factor-β and interleukin-6, elevated expression of the anti-inflammatory cytokine interleukin-10, and downregulated the mRNA level of profibrotic genes, including for fibronectin, α-smooth muscle actin, and collagen I. CDDO-Me attenuated radiation-induced lung inflammation. CDDO-Me also decreased the Masson's trichrome stain score, hydroxyproline content, and mRNA level of profibrotic genes, and blocked radiation-induced collagen accumulation and fibrosis. Collectively, these findings suggest that CDDO-Me ameliorates radiation-induced lung inflammation and fibrosis, and this synthetic triterpenoid is a promising novel therapeutic agent for RILI. Further mechanistic, efficacy, and safety studies are warranted to elucidate the role of CDDO-Me in the management of RILI.

Cost-effectiveness of chemotherapy combined with thoracic radiotherapy versus chemotherapy alone for limited stage small cell lung cancer: A population-based propensity-score matched analysis

BACKGROUND

The addition of thoracic radiotherapy improves the outcome of limited stage small cell lung cancer (LS-SCLC), however, the cost-effectiveness of this process has never been reported. We aimed to estimate the short-term cost-effectiveness of chemotherapy combined with thoracic radiotherapy (C-TRT) versus chemotherapy alone (C/T) for LS-SCLC patients from the payer's perspective (Taiwan National Health Insurance).

METHODS

We identified LS-SCLC patients diagnosed within 2007-2009 through a comprehensive population-based database containing cancer and death registries, and reimbursement data. The duration of interest was one year within diagnosis. We included potential confounding covariables through literature searching and our own experience, and used a propensity score to construct a 1:1 population for adjustment. We used a net benefit (NB) approach to evaluate the cost-effectiveness at various willingness-to-pay (WTP) levels. Sensitivity analysis regarding potential unmeasured confounder(s) was performed.

RESULTS

Our study population constituted 74 patients. The mean cost (2013 USD) and survival (year) was higher for C-TRT (42 439 vs. 28 357; 0.94 vs. 0.88). At the common WTP level (50 000 USD/life-year), C-TRT was not cost effective (incremental NB - 11 082) and the probability for C-TRT to be cost effective (i.e. positive net benefit) was 0.005. The result was moderately sensitive to potential unmeasured confounder(s) in sensitivity analysis.

CONCLUSIONS

We provide evidence that when compared to C/T, C-TRT is effective in improving survival, but is not cost-effective in the short-term at a common WTP level from a payer's perspective. This information should be considered by clinicians when discussing thoracic radiotherapy with their LS-SCLC patients.

Silencing of poly(ADP-ribose) glycohydrolase sensitizes lung cancer cells to radiation through the abrogation of DNA damage checkpoint

Poly(ADP-ribose) glycohydrolase (PARG) is a major enzyme that plays a role in the degradation of poly(ADP-ribose) (PAR). PARG deficiency reportedly sensitizes cells to the effects of radiation. In lung cancer, however, it has not been fully elucidated. Here, we investigated whether PARG siRNA contributes to an increased radiosensitivity using 8 lung cancer cell lines. Among them, the silencing of PARG induced a radiosensitizing effect in 5 cell lines. Radiation-induced G2/M arrest was largely suppressed by PARG siRNA in PC-14 and A427 cells, which exhibited significantly enhanced radiosensitivity in response to PARG knockdown. On the other hand, a similar effect was not observed in H520 cells, which did not exhibit a radiosensitizing effect. Consistent with a cell cycle analysis, radiation-induced checkpoint signals were not well activated in the PC-14 and A427 cells when treated with PARG siRNA. These results suggest that the increased sensitivity to radiation induced by PARG knockdown occurs through the abrogation of radiation-induced G2/M arrest and checkpoint activation in lung cancer cells. Our findings indicate that PARG could be a potential target for lung cancer treatments when used in combination with radiotherapy.