Limited Disease Small Cell Lung Research Articles

1793P Treatment and outcomes of limited disease small cell lung cancer (LD-SCLC) in the Canadian small cell lung cancer database (CASCADE)

1793P Treatment and outcomes of limited disease small cell lung cancer (LD-SCLC) in the Canadian small cell lung cancer database (CASCADE)

446: Role of prophylactic cranial irradiation for patients with limited disease small cell lung cancer

446: Role of prophylactic cranial irradiation for patients with limited disease small cell lung cancer

Therapeutic Patterns and Clinical Outcomes in Limited Disease Small Cell Lung Cancer: A Decade of Analysis at a Tertiary Cancer Center.

In this study, we investigated the outcomes and factors influencing treatment efficacy in 93 patients with limited disease small cell lung cancer (LD-SCLC), with a median age of 64 years. We focused on the impact of chemotherapy regimens, prophylactic cranial irradiation (PCI), and patient-related variables. The median follow-up for OS was 17.3 months. We observed a statistically significant difference in PFS between LD-SCLC patients treated with cisplatin and etoposide (EP) and those treated with carboplatin and etoposide (CP) (PFS: EP 13.63 months vs. CP 6.54 months, p < 0.01). Patients treated with EP had better overall survival (OS) than CP-treated patients (OS: EP 26.9 months vs. CP 16.16 months, p < 0.01). Concomitant chemotherapy was associated with improved PFS (p = 0.003) and OS (p = 0.002). Patients receiving PCI showed superior OS (p = 0.05) and a trend towards improved PFS (p = 0.057). Female gender was associated with better OS (p = 0.025). Most patients had an ECOG performance status of 0 (71%). This real-world study underscores the importance of multidisciplinary LD-SCLC management, emphasizing the roles of chemotherapy, radiotherapy, and PCI. These findings inform personalized treatment strategies and emphasize the need for prospective trials to validate these results and optimize LD-SCLC treatment.

Predicting disease recurrence in limited disease small cell lung cancer using cell-free DNA-based mutation and fragmentome analyses.

Limited disease (LD) small cell lung cancer (SCLC) treated with definitive concurrent chemoradiotherapy (CCRT) potentially experience disease recurrence. We investigated the feasibility of circulating-tumor DNA (ctDNA)-based genomic and fragmentome analyses to assess the risk of recurrence. Targeted sequencing was conducted using pre-treatment and on-treatment blood samples from definitive CCRT-treated patients with LD-SCLC (n=50). Based on 12-month recurrence-free survival (RFS), patients were categorized into persistent-response (PeR, n=29) and non-PeR (n=21) groups. Fragmentome analysis was conducted using ctDNA fragments of different lengths: P1 (100-155 bp) and P2 (160-180 bp). Patients with TP53 (n=15) and RB1 (n=11) mutation in on-treatment samples demonstrated significantly shorter RFS than patients with wild-type (WT) (P=0.05, P=0.0014, respectively). Fragmentome analysis of all available on-treatment samples (n=26) revealed that the non-PeR group (n=10) had a significantly higher P1 range (P=0.003) and lower P2 range (P=0.002). The areas under the curves for P1, P2, and the fragmentation ratio (P1/P2) in distinguishing the PeR and non-PeR were 0.850, 0.725, and 0.900, respectively. Using optimal cut-off, longer RFSs were found with the low-fragmentation-ratio group than with the high-fragmentation-ratio group (not reached vs. 7.6 months, P=0.002). Patients with both WT RB1 and a low-fragmentation-ratio (n=10) showed better outcomes than patients with both mutated RB1 and a high-fragmentation-ratio (n=10; hazard ratio, 7.55; 95% confidence interval: 2.14-26.6; P=0.002). RB1 mutations and high fragmentation ratios correlated with early disease recurrence. Analyzing ctDNA could help in predicting early treatment failure and making clinical decisions for high-risk patients.

Outcome of dose-escalated intensity-modulated radiotherapy for limited disease small cell lung cancer.

An optimal once-daily radiotherapy (RT) regimen is under investigation for definitive concurrent chemoradiotherapy (CCRT) in limited disease small cell lung cancer (LD-SCLC). We compared the efficacy and safety of dose escalation with intensity-modulated radiotherapy (IMRT). Between January 2016 and March 2021, patients treated with definitive CCRT for LD-SCLC with IMRT were retrospectively reviewed. Patients who received a total dose <50 Gy or those with a history of thoracic RT or surgery were excluded. The patients were divided into two groups (standard and dose-escalated) based on the total biologically effective dose (BED, α/β = 10) of 70 Gy. The chemotherapeutic regimen comprised four cycles of etoposide and cisplatin. One hundred and twenty-two patients were analyzed and the median follow-up was 27.8 months (range, 4.4 to 76.9 months). The median age of the patients was 63 years (range, 35 to 78 years) and the majority had a history of smoking (86.0%). The 1- and 3-year overall survival rates of the escalated dose group were significantly higher than those of the standard group (93.5% and 50.5% vs. 76.7% and 33.3%, respectively; p = 0.008), as were the 1- and 3-year freedom from in-field failure rates (91.4% and 66.5% vs. 73.8% and 46.9%, respectively; p = 0.018). The incidence of grade 2 or higher acute and late pneumonitis was not significantly different between the two groups (p = 0.062, 0.185). Dose-escalated once-daily CCRT with IMRT led to improved locoregional control and survival, with no increase in toxicity.

Prognostic Value of 18F-Fluorodeoxyglucose Uptake of Bone Marrow on PET/CT in Patients with Limited Disease Small Cell Lung Cancer

Merve AYIK TURK1, Berna KOMURCUOGLU2, Ahmet YANARTAS3, Ozgur BATUM2, Yunus TURK4, Mehmet Ufuk YILMAZ5 1Izmir Bozyaka Training and Research Hospital, Department of Pulmonology, İzmir 2Dr. Suat Seren Chest Diseases and Surgery Training and Research Hospital, Department of Pulmonology, İzmir 3Dr. Suat Seren Chest Diseases and Surgery Training and Research Hospital, Department of Nuclear Medicine, İzmir 4Dr. Suat Seren Chest Diseases and Surgery Training and Research Hospital, Department of Thoracic Surgery, İzmir 5Medicana Health Groups, Department of Pulmonology, İzmir Keywords: Small cell lung cancer, Prognostic factors, Limited stage, Bone marrow FDG uptake Small cell lung cancer (SCLC) is a malignancy from the neuroendocrine tumor family, which has a poor prognosis and presents with metastases at the time of the diagnosis. The present study investigated the relationship between bone marrow fluorodeoxy-D-glucose (FDG) uptake and survival to evaluate prognosis in limited-stage SCLC. This single-center retrospective study examined a total of 220 patients diagnosed with limited-stage SCLC between January 2010 and June 2019. Bone marrow FDG uptake, serum inflammatory markers, and other factors used to determine the prognosis, as well as overall survival (OS) and progression-free survival (PFS), were recorded and retrospectively analyzed. Within physiological limits, bone marrow standardized uptake value (SUV) mean of &gt; 1.95 was identified as a good prognostic factor for PFS (p= 0.03). The multivariate analysis of OS and PFS revealed that the Eastern Cooperative Oncology Group (ECOG) performance scale (p= 0.001) was a common independent prognostic factor. Stages of the disease, albumin levels and bone marrow-to-liver ratio (BLR) [one of the positron emission tomography/computed tomography (PET/CT) parameters] of &lt; 0.8 were prognostic factors for OS. The bone marrow SUV mean was positively correlated with the primary tumor SUV max and SUV mean. The bone marrow SUV mean is a parameter that can be used to predict PFS in limited-stage SCLC. For OS, in turn, the BLR was identified as an independent factor.

171 - The end of an era? Reduction in the use of prophylactic cranial irradiation (PCI) in limited disease small cell lung cancer (LD SCLC)

171 - The end of an era? Reduction in the use of prophylactic cranial irradiation (PCI) in limited disease small cell lung cancer (LD SCLC)

Adjuvant treatment for patients with incidentally resected limited disease small cell lung cancer-a retrospective study.

BackgroundWith the exception of very early-stage small cell lung cancer (SCLC), surgery is not typically recommended for this disease; however, incidental resection still occurs. After incidental resection, adjuvant salvage therapy is widely offered, but the evidence supporting its use is limited. This study aimed to explore proper adjuvant therapy for these incidentally resected SCLC cases.MethodsPatients incidentally diagnosed with SCLC after surgery at the Shanghai Pulmonary Hospital in China from January 2005 to December 2014 were included in this study. The primary outcome was overall survival. Patients were classified into different group according to the type of adjuvant therapy they received and stratified by their pathological lymph node status. Patients’ survival was analyzed using a Kaplan-Meier analysis and Cox regression analysis.ResultsA total of 161 patients were included in this study. Overall 5-year survival rate was 36.5%. For pathological N0 (pN0) cases (n=70), multivariable analysis revealed that adjuvant chemotherapy (ad-chemo) was associated with reduced risk of death [hazard ratio (HR): 0.373; 95% confidence interval (CI): 0.141–0.985, P=0.047] compared to omission of adjuvant therapy. For pathological N1 or N2 (pN1/2) cases (n=91), taking no adjuvant therapy cases as a reference, the multivariable analysis showed that ad-chemo was not associated with a lower risk of death (HR: 0.869; 95% CI: 0.459–1.645, P=0.666), while adjuvant chemo-radiotherapy (ad-CRT) was associated with a lower risk of death (HR: 0.279; 95% CI: 0.102–0.761, P=0.013).ConclusionsPatients who incidentally receive surgical resection and are diagnosed with limited disease SCLC after resection should be offered adjuvant therapy as a salvage treatment. For incidentally resected pN0 cases, ad-chemo should be considered and for pN1/2 cases, ad-CRT should be received.

Exploratory analysis using cfDNA-based fragmentomics to predict disease recurrence in limited disease small cell lung cancer.

8569 Background: The current standard of care (SOC) for limited disease (LD) small cell lung cancer (SCLC) is definitive concurrent chemoradiotherapy (CCRT). Despite the high response rate to SOC, up to 70% of the patients potentially experience disease recurrence and fail to show the prolonged clinical benefit. We investigated the feasibility of cell-free DNA (cfDNA) based genomic alteration and fragmentomic analysis using pre-and post-treatment samples to investigate the predictive value of disease recurrence in LD-SCLC. Methods: The blood sample from fifty LD-SCLC who were treated with definitive CCRT were collected before and after the treatment. Target sequencing, AlphaLiquid scan (IMBdx, Korea), composed of 106 target genes, was conducted using cfDNA and peripheral blood mononuclear cells. Based on the recurrence-free survival (RFS) interval of 12 months, patients were categorized into group with persistent response (PeR, n = 29) and non-PeR (n = 21). Fragmentomics analyses were collected using the proportion of cfDNA fragments sized in P1 (100 – 155 bp) and P2 (160 – 180 bp) ranges. Results: Initial analysis was conducted based on the gene of interest. Patients with RB1 mutation (n = 11) detected in follow-up sample demonstrated significant shorter RFS compared to the RB1 wild type (WT) patients (n = 39) (7.9 mon. vs. NR, P = 0.002). Among the patients who were available for our fragmentomics analysis in follow up samples (n = 19), non-PeR (n = 9) group were significantly high in P1 range ( P = 0.003) and low in P2 range ( P = 0.002) compared to PeR group (n = 10). AUCs using the fragment proportion in P1, proportion in P2, and the fragmentation ratio (proportion in P1 / proportion in P2), were 0.889, 0.911, and 0.889, respectively. The survival analysis using fragmentation ratio showed significantly longer RFS in fragmentation ratio low group compared to the high group (7.6 mon. vs. NR, P = 0.002). Integrating RB1 mutation status with fragmentation ratio, patients with both RB1 WT and fragmentation ratio low (n = 9) showed the most favorable outcomes ( P = 0.006). On the contrary, patients with either RB1 mutated or high in fragmentation ratio (n = 10) showed median RFS of rest than 12 months. Conclusions: In this study, we investigated the clinical feasibility of cfDNA detected mutation and size of the fragment in disease recurrence of LD-SCLC using the sample collected before and after definitive CCRT. It is observed that patients with either RB1 mutation or high fragmentation ratio detected from cfDNA after the completion of CCRT are likely to experience early disease recurrence. Our findings suggest that cfDNA could provide supplementary information in predicting early treatment failure and support the clinical decision in selecting high-risk patients who might need intense monitoring and additional consolidative treatment.

＜Editors' Choice＞ Elective nodal irradiation versus involved field radiotherapy for limited disease small cell lung cancer: a single-institution experience.

ABSTRACTElective nodal irradiation (ENI) and involved field radiotherapy (IFRT) are definitive radiotherapeutic approaches used to treat patients with limited-disease small cell lung cancer (LD-SCLC). However, no solid consensus exists on their optimal target volume. The current study aimed to assess the clinical outcomes of patients with LD-SCLC who received definitive ENI or IFRT. A retrospective single-institution study of patients who received definitive radiotherapy between 2008 and 2020 was performed. All patients underwent whole-body positron emission tomography/computed tomography before three-dimensional conformal radiotherapy. Among the 37 patients analyzed, 22 and 15 received ENI and IFRT, respectively. The thoracic radiotherapy dose was mostly either 60 Gy in 30 fractions delivered in 2-Gy fractions once daily or 45 Gy in 30 fractions delivered in 1.5-Gy fractions twice daily. The median follow-up period was 21.4 months. A total of 12 patients (32%) experienced locoregional relapse: 10 within and 2 outside the irradiation fields. One patient in the IFRT group experienced isolated nodal failure. Differences in locoregional relapse-free, progression-free, and overall survival rates between ENI and IFRT were not significant. Overall, IFRT did not promote a significant increase in locoregional recurrence compared to ENI. Our findings suggested the utility of IFRT in standard clinical practice and support its use for patients with LD-SCLC.

P8‐63: Impact of the lung immune prognostic index (LIPI) in limited disease small cell lung cancer patients treated with chemoradiotherapy

P8‐63: Impact of the lung immune prognostic index (LIPI) in limited disease small cell lung cancer patients treated with chemoradiotherapy

Long-term survival data of patients with limited disease small cell lung cancer: a retrospective analysis.

In patients with limited disease small cell lung cancer (LD-SCLC) treated with concurrent chemoradiotherapy (CCRT), long-term survival data have not been fully evaluated. Moreover, the association between long-term prognosis and prognostic factors has not been sufficiently investigated. In this retrospective study, we evaluated the efficacy of CCRT in 120 patients with LD-SCLC with a plan for curative CRT using concurrent accelerated hyperfractionated radiotherapy. The patients had a median age of 65.5years, predominantly male (73%), and had clinical stage III disease (80%). The median follow-up time for overall survival (OS) was 72.2months, median OS was 42.5months, and the 3-year and 5-year survival rates were 52.4% and 41.8%, respectively. The median progression-free survival (PFS) was 12.5months, and the 3-year and 5-year PFS rates were 37.6% and 33.6%, respectively. The 5-year OS rates of patients who achieved PFS at each time point were 70.9%, 83.6%, and 91.9% at 12, 24, and 36months, respectively. The gradual increase in the 5-year OS rate following PFS extension and initial depression of the Kaplan-Meier curve showed disease progression frequently occurred in the first 2years after initiation of CCRT. The Cox proportional hazards model showed no significant factors correlated with long-term survival through univariate and multivariate analyses. Although the prognostic factors associated with long-term prognosis in LD-SCLC were not identified, the 5-year survival rate was 41.8%, and among patients without disease progression at 2years, the 5-year survival rate was 83.6%. These data suggested that the prognosis of patients with LD-SCLC was improving.

MA16.07 Prognostic Value of 18F-Fluorodeoxyglucose Uptake of Bone Marrow on PET/CT in Patients with Limited Disease Small Cell Lung Cancer

AİM AND OBJECTİVES: Small cell lung cancer (SCLC) is a lung malignancy from the neuroendocrine cancer family with poor prognosis and metastases at the time of diagnosis. Advanced age, cachexia, low performance status, extensive disease and high lactate dehydrogenase (LDH) values are poor prognostic factors. We investigated whether 18F-fluorodeoxyglucse (FDG) uptake of bone marrow (BM) on positron emission tomography/computed tomography (PET/CT) has implications for predicting clinical outcomes in patients with limited disease small cell lung cancer (SCLC).

Timing of Severe Toxicity from Chemotherapy in Patients With Lung Cancer.

The aim of this study was to investigate the timing of severe toxicity in lung cancer patients receiving chemotherapy. Patients with advanced non-small cell lung cancer or limited disease small cell lung cancer included in two randomized controlled trials were analysed. Severe toxicity was defined as grade 3-5 toxicity according to the Common Terminology Criteria for Adverse Events (CTCAE) v3.0. We analysed 569 patients and 433 (76.1%) experienced severe toxicity. Of these, 249 (57.5%) experienced the first episode of severe toxicity after the first, 109 (25.2%) after the second, 54 (12.5%) after the third and 18 (4.2%) after the fourth course of chemotherapy. Performance status (PS 2 vs. 0-1; p=0.046) and treatment arm were independent predictive factors for severe toxicity. Severe toxicity was most frequent after the first chemotherapy course, but some patients did not experience severe toxicity until after the fourth course. Accounting for timing might be important when studying factors predicting severe toxicity.

Once daily versus twice-daily radiotherapy in the management of limited disease small cell lung cancer – Decision criteria in routine practise

BackgroundIn limited disease small cell lung cancer (LD-SCLC), the CONVERT trial has not demonstrated superiority of once-daily (QD) radiotherapy (66 Gy) over twice-daily (BID) radiotherapy (45 Gy). We explored the factors influencing the selection between QD and BID regimens. MethodsThirteen experienced European thoracic radiation oncologists as selected by the European Society for Therapeutic Radiation Oncology (ESTRO) were asked to describe their strategies in the management of LD-SCLC. Treatment strategies were subsequently converted into decision trees and analysed for agreement and discrepancies. ResultsLogistic reasons, patients’ performance status and radiotherapy dose constraints were the three major decision criteria used by most experts in decision making. The use of QD and BID regimens was balanced among European experts, but there was a trend towards the BID regimen for fit patients able to travel twice a day to the radiotherapy site. ConclusionBID and QD radiotherapy are both accepted regimens among experts and the decision is influenced by pragmatic factors such as availability of transportation.

Study protocol: watchful observation of patients with limited small cell lung cancer instead of the PCI\u2014prospective, multi-center one-arm study

BackgroundProphylactic cranial irradiation (PCI) is a current standard of care after confirmed response to radical chemoradiotherapy for limited disease small cell lung cancer (LD-SCLC). This standard is mostly based on results of old randomized studies when brain imaging with magnetic resonance (MRI) was not available. Survival benefit of PCI in extended disease SCLC was recently challenged by the results of randomized phase III study from Japan.MethodsEighty patients with LD-SCLC after response to chest chemoradiotherapy will be enrolled. Patients will be followed up by brain MRI every 3 to 6 months up to 3 years. Neurocognitive function tests will be performed at baseline and after 12 and 24 months. Patients who develop brain metastases will be irradiated with stereotactic (SRT) or whole brain RT (WBRT). The primary endpoint is overall survival. The secondary endpoints are: response rate to radiotherapy of early detected brain metastases, analysis of efficacy of SRT and WBRT; assessment and analysis of neurocognitive functions and QoL in the studied cohorts: QLQ-C30 questionnaire and the California Verbal Learning Test, Color connection test, Benton visual retention test, and verbal fluency test will be carried out.DiscussionThe results of this trial may contribute to changing of LD-SCLC clinical management by deescalating the treatment. There is a lack of prospective, recent studies in LD-SCLC patients with omission of PCI and modern radiation therapy technologies for developed brain metastases. The comprehensive neurocognitive function testing will help to assess the impact of modern radiotherapy (SRT) compared with WBRT and no-PCI in SCLC patients. A subgroup of long-term survivors, who will not develop brain metastases, will not be exposed to unnecessary brain irradiation with its deleterious consequences. The limitation of our study is a lack of parallel randomized control arm. This is a potential source of bias; however, randomized study will be difficult to complete for two major reasons: (1) limited population of LD-SCLC eligible for the study and (2) opinions of our patients, who after information and discussion about benefits and potential harms of PCI, often choose to omit PCI in our practice.Trial registrationClinicalTrials.gov Identifier: NCT04168281, 19 Nov. 2019.

Impact of Early Prophylactic Cranial Irradiation With Hippocampal Avoidance on Neurocognitive Function in Patients With Limited Disease Small Cell Lung Cancer. A Multicenter Phase 2 Trial (SAKK 15/12)

Our purpose was to evaluate neurocognitive function (NCF) and clinical outcomes after early hippocampal avoidance (HA) prophylactic cranial irradiation (PCI) in limited disease (LD) small cell lung cancer (SCLC). In a phase 2 trial, patients with LD SCLC received HA-PCI concomitant with the second cycle of chemotherapy and thoracic radiation therapy. All patients underwent objective NCF testing at baseline, 6 weeks, and 6 and 12 months after HA-PCI. NCF tests included Hopkins Verbal Learning Test Revised, Controlled Oral Word Association, and Trail Making Tests A and B. The primary endpoint was NCF decline at 6 months after HA-PCI. We assumed ≤30% of patients with no NCF decline to be unpromising. Secondary endpoints included brain metastases-free survival (BMFS), overall survival (OS), and safety of the concomitant treatment. Among the 44 patients enrolled in the trial, 38 had evaluable NCF assessment at 6 months after HA-PCI. The proportion of evaluable patients showing no NCF decline at 6 and 12 months was 34.2% (90% confidence interval [CI], 21.6-48.8) and 48.5% (95% CI, 30.8-66.5), respectively. Median follow-up was 13.2 months (95% CI, 12.6-14.1). At 12 months, BMFS was 84.2% and OS was 87.7% (95% CI, 73.0-94.7). Four patients died of SCLC, 1 of respiratory failure, 1 of hemorrhage, and 1 for unknown reason. The most frequently reported grade ≥3 acute adverse events were anemia (21.4%), febrile neutropenia (19.1%), and fatigue (14.3%). The proportion of patients showing no NCF decline 6 and 12 months after early HA-PCI does not appear to be better than, but rather similar to, that observed in patients receiving sequential PCI without HA. Early HA-PCI in LD SCLC is feasible, with observation of promising BMFS and OS in this selected population.

EP1.12-33 Prognostic Analysis of Surgery vs. Conservative Therapy with Chemotherapy in Stage of Limited Disease Small Cell Lung Cancer

EP1.12-33 Prognostic Analysis of Surgery vs. Conservative Therapy with Chemotherapy in Stage of Limited Disease Small Cell Lung Cancer

Abstract 3137: DNA damage response and repair pathway alteration and its association with tumor mutation burden and platinum-based chemotherapy in small cell lung cancer

Abstract Background: Impairment in DNA damage response and repair (DDR) pathway is known as a predictive biomarker of platinum sensitivity in many cancer types. In the era of cancer immunotherapy, DDR alteration is re-emphasized as a predictive biomarker of immune-checkpoint inhibitor due to its positive correlation to tumor mutation burden (TMB). Patients and methods: Target gene sequencing (381 genes) was conducted from 100 extensive disease (ED) and 66 limited disease (LD) small cell lung cancer (SCLC) patients. DDR-related genes were pre-defined by literature review, and mutations were classified as double-strand breaks (DSB, n=82): homologous recombination (n=54), non-homologous end joining (NHEJ, n=19), and Fanconi anemia (FA, n=32); or single-strand breaks (SSB, n=31): mismatch repair (MMR, n=19), base excision repair (BER, n=7), and nucleotide excision repair (NER, n=6). Based on the mutation profile, correlation of TMB and survival outcomes were analyzed. Results: Compared to patients with an intact DDR pathway (n=70), a higher TMB was observed in patients with homologous recombination (P&amp;lt;0.001), NHEJ (P=0.026), MMR (P&amp;lt;0.001), BER (P=0.046), NER (P=0.017), DSB (P&amp;lt;0.001) and SSB (P&amp;lt;0.001). Survival analyses based on TMB level showed no predictive or prognostic values in ED patients. In LD patients, prolonged progression-free survival (PFS, hazard ratio [HR] 0.497, P=0.015) to platinum compound and overall survival (HR 0.383, P=0.010) were observed in those with TMB above median. Individual DDR pathway alteration showed no survival benefit in ED patients receiving platinum-based chemotherapy. In LD patients, those with mutations in the FA pathway had shorter PFS (HR 2.048, P=0.036) to initial treatment. Conclusions: DDR pathway alterations, both DSB and SSB, in SCLC have a positive correlation with high TMB. However, it has demonstrated limited value in prediction of platinum efficacy. Tumor mutation burden and its correlation with DNA damage related gene setsFAHR(-) n=131(+) n=32P(-) n=112(+) n=54PLow TMB69 (52.7%)14 (43.8%)0.47965 (58.0%)20 (37.0%)0.018High TMB62 (47.3%)18 (56.2%)47 (42.0%)34 (63.0%)NHEJBER(-) n=147(+) n=19P(-) n=156(+) n=7P*Low TMB78 (53.1%)7 (36.8%)0.27780 (51.3%)3 (42.9%)0.716High TMB69 (46.9%)12 (63.2%)76 (48.7%)4 (57.1%)MMRNER(-) n=147(+) n=19P*(-) n=157(+) n=6P*Low TMB81 (55.1%)4 (21.1%)0.00781 (51.6%)2 (33.3%)0.437High TMB66 (44.9%)15 (78.9%)76 (48.4%)4 (66.7%)DSBSSB(-) n=84(+) n=82P(-) n=135(+) n=31PLow TMB50 (59.5%)35 (42.7%)0.04476 (56.3%)9 (29.0%)0.006High TMB34 (40.5%)47 (57.3%)59 (43.7%)22 (71.0%) Citation Format: Sehhoon Park, Hayoon Lee, Boram Lee, Jong-Mu Sun, Woong-Yang Park, Jin Seok Ahn, Myung-Ju Ahn, Se-Hoon Lee, Keunchil Park. DNA damage response and repair pathway alteration and its association with tumor mutation burden and platinum-based chemotherapy in small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3137.

Effect of Pretreatment Platelet Parameters on Survival in Limited Disease Small Cell Lung Cancer.

Background:The aim of this study was to investigate the effect of platelet parameters before concurrent chemoradiotherapy (CCRT) on survival of patients with limited disease small cell lung cancer (LD-SCLC). Methods:This study consisted of patients who received CCRT due to LD-SCLC in the oncology clinic between 1997-2017. Examined platelet parameters included total platelet count (TPC), mean platelet volume, platelet distribution width, and platelet-lymphocyte ratio. The cut-off value for TPC was determined as 306x109/U (sensitivity: 62%, specificity: 75.5%), where patients below or equal to this level was classified as Group I, and those above as Group II. Results:The study included 90 patients whose mean age was 59 years (range: 42-83) and male ratio was 80.0% (n=72). Near three-fourths of patients (74.4%) were at clinical stage III. Among stage I-II patients, mOS was found as 126 months for Group I whereas it had not been reached in Group II (p=0.158). Stage III patients showed significantly lower mOS for Group 1 (16 [range: 14.1-17.8] months) compared to that in Group 2 (19.0 [range: 15.6-62.8] months; p=0.002). In multivariate analysis, Eastern Cooperative Oncology Group performance score (p=0.003), clinical stage (p<0.001), prophylactic cranial irradiation (p=0.004), and TPC (p=0.031) was determined as the most significant factors affecting survival. Conclusion:Our study suggests association of high baseline levels of TPC to improved survival in patients scheduled to undergo CCRT for LD-SCLC. Considering easiness and universal availability of TPC measurement, potential utilization of this biomarker may be promising to predict survival, albeit requiring validation by further well-designated prospective studies.