Proteogenomic characterization of small cell lung cancer identifies biological insights and subtype-specific therapeutic strategies.

We performed comprehensive proteogenomic characterization of small cell lung cancer (SCLC) using paired tumors and adjacent lung tissues from 112 treatment-naive patients who underwent surgical resection. Integrated multi-omics analysis illustrated cancer biology downstream of genetic aberrations and highlighted oncogenic roles of FAT1 mutation, RB1 deletion, and chromosome 5q loss. Two prognostic biomarkers, HMGB3 and CASP10, were identified. Overexpression of HMGB3 promoted SCLC cell migration via transcriptional regulation of cell junction-related genes. Immune landscape characterization revealed an association between ZFHX3 mutation and high immune infiltration and underscored a potential immunosuppressive role of elevated DNA damage response activity via inhibition of the cGAS-STING pathway. Multi-omics clustering identified four subtypes with subtype-specific therapeutic vulnerabilities. Cell line and patient-derived xenograft-based drug tests validated the specific therapeutic responses predicted by multi-omics subtyping. This study provides a valuable resource as well as insights to better understand SCLC biology and improve clinical practice.

Utility of secretagogin as a marker for the diagnosis of lung neuroendocrine carcinoma.

Small-cell lung cancers (SCLC) and large-cell neuroendocrine carcinomas (LCNEC) are two types of high-grade pulmonary neuroendocrine carcinomas (NECs). Diagnostic neuroendocrine markers commonly include synaptophysin, chromogranin A, CD56, and insulinoma-associated protein 1 (INSM1). In this study, the utility of secretagogin (SCGN) was examined in the context of pulmonary NEC diagnosis. The study included 71 pulmonary NEC cases (18 SCLCs, 13 combined-SCLCs, 23 LCNECs, and 17 combined-LCNECs). Immunohistochemical stains of SCGN, synaptophysin, chromogranin A, CD56, and INSM1 were performed on whole tumor sections. The stains were evaluated based on combined staining intensity and the proportion of positive tumor cells. At least mild staining intensity in at least 1% of the cells was considered positive. Bioinformatic studies showed specific SCGN expression in neuroendocrine cells and NECs. SCGN showed diffuse nuclear and cytoplasmic staining in NECs with intra-tumoral heterogeneity. The non-neuroendocrine components were negative. The sensitivity of SCGN was no better than the other established neuroendocrine markers based on all NECs combined or LCNECs/c-LCNECs only. However, the sensitivity of SCGN (71%) was higher than chromogranin A (68%) for SCLCs/c-SCLCs only. The average proportion of SCGN positive tumor cells was 8% higher than chromogranin A (22% versus 14%, P = 0.0332) in all NECs and 18% higher for SCLC and c-SCLC cases only (32% versus 13%, P = 0.0054). The above data showed that SCGN could be used as a supplemental neuroendocrine marker to diagnose SCLC.

[Expression of CD44 in Tumor Tissue and Serum of Small Cell Lung Cancer and Its Clinical Prognostic Significance].

BACKGROUND: Small cell lung cancer (SCLC) is a highly aggressive malignancy characterized by rapid growth, early metastasis and acquired therapeutic resistance, and the prognosis is extremely poor. Studies have proved that the stem cell marker CD44 is correlated with tumor recurrence and treatment resistance, however, there are limited reports yet concerning on the CD44 expression and its clinical prognostic significance in SCLC patients. The purpose of this study is to investigate the expression of CD44 in tumor tissues as well as serum of SCLC patients and explore its correlation with the clinical characteristics, therapeutic effect and prognosis. METHODS: The tumor tissues and serum samples of 47 newly diagnosed SCLC patients were collected. Immunohistochemistry and enzyme-linked immunosorbent assay were applied to detect CD44. The relationship between CD44 level and the clinical characteristics as well as prognosis of the patients was analyzed. RESULTS: The stem cell marker CD44 was detectable both in serum sample and tumor tissue of SCLC patients. The positive rate of CD44 in tumor tissue was significantly higher in patients with performance status (PS) 2 than that of patients with PS 0-1 (85.71% vs 30%, P=0.017). Patients were divided in to different groups according to the treatment efficacy. The CD44 immunohistochemical score and serum level in the disease progression group were significantly higher than those in the disease control group, and the differences were statistically significant (P=0.006, P=0.034), Univariate analysis depicted that the progression-free survival (PFS) of CD44 positive patients was significantly shorter than that of CD44 negative patients (5.23 mon vs 9.03 mon, P=0.036). CONCLUSIONS: The positive expression of CD44 in tumor tissues of pre-treatment SCLC patients is correlated with poor PFS. The clinical significance of CD44 is worthy to be further studied.

Distinct transcriptional programs of SOX2 in different types of small cell lung cancers.

SOX2 is recognized as an oncogene in human small cell lung cancer (SCLC), which is an aggressive neuroendocrine (NE) tumor. However, the role of SOX2 in SCLC is not completely understood, and strategies to selectively target SOX2 in SCLC cells remain elusive. Here, we show, using next-generation sequencing, that SOX2 expressed in the ASCL1-high SCLC (SCLC-A) subtype cell line is dependent on ASCL1, which is a lineage-specific transcriptional factor, and is involved in NE differentiation and tumorigenesis. ASCL1 recruits SOX2, which promotes INSM1 and WNT11 expression. Immunohistochemical studies revealed that SCLC tissue samples expressed SOX2, ASCL1, and INSM1 in 18 out of the 30 cases (60%). Contrary to the ASCL1-SOX2 signaling axis controlling SCLC biology in the SCLC-A subtype, SOX2 targets distinct genes such as those related to the Hippo pathway in the ASCL1-negative, YAP1-high SCLC (SCLC-Y) subtype. Although SOX2 knockdown experiments suppressed NE differentiation and cell proliferation in the SCLC-A subtype, they did not sufficiently impair the growth of the SCLC-Y subtype cell lines in vitro and ex vivo. The present results support the importance of the ASCL1-SOX2 axis as a main subtype of SCLC, and suggest the therapeutic potential of targeting the ASCL1-SOX2 axis.

Selective Fishing for Peptides with Antibody-Immobilized Acrylate Monoliths, Coupled Online with NanoLC-MS.

An online microfluidics-mass spectrometry platform was developed for determining proteotypic peptides from in-solution digested samples. Accelerated and selective sample cleanup was achieved by integrating proteotypic epitope peptide immunoextraction with nano liquid chromatography-tandem mass spectrometry (online IE-nanoLC-MS/MS). Ten individually prepared 180 µm inner diameter capillaries with ethylene glycol dimethacrylate- co-vinyl azlactone (EDMA- co-VDM) monoliths were immobilized with anti-protein antibodies that are used in routine immunoassays of the intact small cell lung cancer biomarker ProGRP. The resulting AB columns provided linearity correlation coefficients of 0.96-0.99 for protein amounts and concentrations of 10 pg to 5 ng and 0.5-250 ng/mL, respectively. The columns/platform gave relative peak area RSDs below 15%. The IE-nanoLC-MS/MS platform provided a limit of detection (LOD) of 520 pg/mL of ProGRP in human serum. The approach was applicable for other matrixes and proteins, i.e., primary glioblastoma cells and endogenous αV integrin chain. Thus, EDMA- co-VDM monoliths immobilized with antibodies are suited for automated peptide capture in microfluidic formats.

Biotransformation-based metabolomics profiling method for determining and quantitating cancer-related metabolites.

The discovery and identification of reliable disease biomarkers and relevant disrupted metabolic pathways is still a major challenge in metabolomics. Here, we proposed a biotransformation-based metabolomics profiling method to identify reliable disease biomarkers by simultaneous quantitation and qualification of cancer-related metabolites and their metabolic pathways via liquid chromatography-tandem mass spectrometry (LC-MS/MS). The approach was based on selecting a subset of known cancer-related metabolites from our previous metabolomics work, cancer research literature and biological significance. The metabolic profiling of pathway-related metabolites was developed by predicted multiple reaction monitoring (MRM) of ion pairs based on their chemical structures and biotransformation. Then, a high-throughput quantitative method was established. Overall, this approach enables the sensitive and accurate detection of cancer-related metabolites and the identification of other relevant metabolites, which facilitates better data quality and in-depth investigation of dysregulated metabolic pathways. As a proof of concept, the approach was applied to a small-cell lung cancer (SCLC) study. The results showed that 43 metabolites were significantly changed, and arginine metabolism was apparently disturbed, which proved the proposed approach could be a powerful tool for discovering reliable disease biomarkers and aberrant metabolic pathways.

Insulinoma-Associated Protein 1 Immunostain: A Diagnostic Tool for Pulmonary Small Cell Carcinoma in Cytology.

OBJECTIVE: Cytology plays an important role in the diagnosis of small cell carcinoma (SCLC). Application of immunohistochemical (IHC) markers improves the accuracy and reproducibility of the diagnosis of SCLC. We report the application of insulinoma-associated protein 1 (INSM1) in the diagnosis of SCLC in cytology samples. METHODS: Our pathology data system was searched for SCLC where INSM1 IHC was performed. Patients' demographics were recorded. Cytopathology specimens were reviewed. RESULTS: A total of 32 cases were identified. INSM1 was positive in 31 (97%) cases. Twenty-seven cases showed a strong/diffuse pattern (84%). Four cases were focally/weak positive (13%). One case was negative (3%). the sensitivity of INSM1 for recognition of SCLC was 97%. CD56 was performed in SCLC. Twenty cases were strongly/diffusely positive (87%). One case was negative (4%). The sensitivity was 96%. CONCLUSION: INSM1 is positive in the majority of SCLC on cytology specimens and its sensitivity is similar to that of CD56 on SCLC. This has practical implications for the diagnosis of these tumors in cytology samples.

Clinicopathological characteristics of thyroid transcription factor 1-negative small cell lung cancers.

Limitations in obtaining surgically resected or biopsy samples of small cell lung cancer (SCLC) tumors make comprehensive biological analyses difficult. The loss of thyroid transcription factor 1 (TTF-1) has been associated with the aggressive behavior of non-small cell lung cancer; however, clinicopathological features of TTF-1-negative SCLC remain unclear. This study aimed to elucidate the characteristics of TTF-1-negative SCLC. We studied the associations between the expression of TTF-1 and the clinicopathological factors associated with SCLC, including survival and expression of neuroendocrine markers (synaptophysin, chromogranin A, and CD56), neuroendocrine cell-specific transcription factors (ASCL1, BRN2), a proliferation marker (Ki-67 labeling index), and an oncogene (NF1B). Formalin-fixed and paraffin-embedded sections of SCLC tumors were subjected to immunohistochemistry and quantitative reverse-transcription polymerase chain reaction analyses. In a case-control cohort matched for basic clinical factors, expression of ProGRP, synaptophysin, chromogranin A, and ASCL1 was significantly decreased in TTF-1-negative SCLC samples. In contrast, there was no significant correlation between Ki-67 labeling index and TTF-1. In a larger serial case cohort, TTF-1-negative SCLC cases were older at diagnosis, but there was no significant difference in the overall survival of patients with TTF-1-negative and TTF-1-positive SCLC. In conclusion, TTF-1-negative SCLC showed decreased neuroendocrine differentiation, and significantly worse clinical outcomes were not observed.

Expression of Notch1 and Numb in small cell lung cancer.

Notch signaling in tumorigenesis functions as an oncogene or tumor suppressor according to the type of malignancy. Numb represses intracellular Notch signaling. Previous studies have demonstrated that Notch signaling suppresses the proliferation of small cell lung cancer (SCLC) cell lines. However, in SCLC, the association between Notch1 and Numb expression and clinicopathological factors or prognosis has remained unclear. In this study, we evaluated the expression of Notch1 and Numb in SCLC. We immunohistochemically assessed 125 SCLCs that were surgically resected at 16 institutions participating in either the Hokkaido Lung Cancer Clinical Study Group Trial (HOT) or the Fukushima Investigative Group for Healing Thoracic Malignancy (FIGHT) between 2003 and 2013. Correlations between Notch1 or Numb expression and various clinicopathological features were evaluated. Notch1 expression was associated with ECOG performance status. Numb expression was associated with age, sex, and pathological histology (SCLC or Combined SCLC). Analysis of cellular biological expression did not demonstrate a significant correlation between the expression of Notch1 and of Numb. Multivariate Cox regression analysis showed that high Notch1 expression was an independent favorable prognostic factor for SCLC(hazard ratio = 0.503, P = 0.023). High Notch1 expression, but not Numb expression, is associated with favorable prognosis in SCLC.

[Cytology of basaloid squamous cell carcinoma and small cell carcinoma of lung: a comparative study].

OBJECTIVE: To evaluate the roles of cytomorphology and immunohistochemistry in distinguishing between basaloid squamous cell carcinoma (BSC) and small cell carcinoma (SCC) of lung. METHODS: The direct smears and/or liquid-based cytology preparation (ThinPrep) of bronchial brushing/washing and fine-needle aspiration (FNA) specimens from 17 cases of biopsy-proven BSC of lung were retrospectively reviewed and compared with those from 17 cases of SCC. The cytomorphologic parameters analyzed included proportion of cohesive cell clusters, cell palisades/rosettes, adenoid cystic features, crushing artifact, nuclear maximum diameter, nuclear molding, scantiness of cytoplasm,"salt-and-pepper"nuclei, distinct nucleoli, spindly configuration, individual cell keratinization, necrosis, hyaline material, apoptosis and mitotic activity. Immunocytochemical/immunohistochemical study of 25 cases was performed. Ten FNA samples of basaloid squamous cell carcinoma were also analyzed for epidermal growth factor receptor mutations in exons 18, 19, 20 and 21 using amplification refractory mutation system. RESULTS: Most of the 17 BSC cases (15/17) showed a predominance of tightly cohesive tumor cell clusters. The proportion of isolated tumor cells was high in SCC (more than 60% in 14 cases). The nuclear maximum diameter of BSC was slightly larger than that of SCC (9 to 11 µm in BSC versus 7 to 9 µm in SCC)."Salt-in-pepper"nuclei, nuclear molding and crushing artifact were detected in all SCC cases (15/17, 17/17 and 14/17, respectively). These features were only occasionally found in BSC group. Nucleoli were present in BSC and rarely (2/17) in SCC. Only 9 of 17 BSC cases showed individual cell keratinization. The differences in the above-mentioned cytomorphologic features were statistically significance (P<0.05). The results of immunohistochemistry performed on the cell block sections and immunocytochemistry performed on the ThinPrep slides were identical to that performed on the corresponding biopsy specimens. The tumor cells in BSC were consistently positive for CK5, p40 and p63. TTF1, chromogranin A, synaptophysin and CD56 were positive in most of SCC. One of SCC cases showed focal PAX5 expression. No EGFR mutations were detected in the 10 BSC cases studied. CONCLUSIONS: Selected cytomorphologic features, including presence of cohesive cell clusters, larger nuclear size, distinct nucleoli, lack of crushing artifact, absence of nuclear molding and presence of individual cell keratinization, are helpful in diagnosing BSC on cytology specimens. Immunohistochemistry using a panel of TTF1, CK5, p40/p63 and chromogranin A/synaptophysin/CD56 provides further clues in differential diagnosis between BSC and SCC. EGFR mutation study is often negative in lung BSC.

Prodrug-based nano-drug delivery system for co-encapsulate paclitaxel and carboplatin for lung cancer treatment.

CONTEXT: Paclitaxel (PTX) and carboplatin (CBP) are widely used for the combined chemotherapy of non-small cell lung cancer (NSCLC). However, the development of multidrug resistance of cancer cells, as well as systemic toxic side effects resulting from nonspecific localization of anticancer drugs to non-tumor areas are major obstacles to the success of chemotherapy in treating cancers. OBJECTIVE: This study aimed to engineer a prodrug-based nano-drug delivery system for co-encapsulate hydrophilic (CBP) and hydrophobic anti-tumor drugs (PTX). This system was expected to resolve the multidrug resistance cause by single drug, and the dual-drug-loaded liposome was also planned to specifically target the cancer cells without obvious influence on normal cells and tissues. METHODS: In this paper, PLGA-PEG-CBP was synthesized by the conjugation between the carboxylic group of PLGA-PEG-COOH and the amino group of CBP. Then, self-assembled nanoparticles for combination delivery of PTX and PLGA-PEG-CBP (PTX/CBP NPs) were prepared by solvent displacement technique. The in vitro and in vivo anti-tumor efficacy was assessed in NCL-H460 human non-small cell lung carcinoma cell line. RESULTS: PTX/CBP NPs achieved the highest cytotoxic effect among all formulations in vitro, as compared with single drug delivery NPs. In vivo investigation on NSCLC animal models showed that co-delivery of PTX and CBP possessed high tumor-targeting capacity and strong anti-tumor activity. CONCLUSIONS: The PTX/CBP NPs constructed in this research offers an effective strategy for targeted combinational lung cancer therapy.

Diagnostic difficulties with the diagnosis of small cell carcinoma of the lung.

Small cell carcinoma of the lung (SCLC) is a well characterized form of lung cancer that is frequently already metastatic at diagnosis. Thus, patients with SCLC are usually treated with chemotherapy, and therefore emphasis has been placed on distinguishing that tumor from squamous cell carcinomas, large cell carcinomas and other pulmonary neoplasms that can more often be managed surgically. SCLC can be readily and accurately diagnosed in biopsy specimens or cytological preparations, but in selected cases, it can pose difficult diagnostic dilemmas. This review discusses selected problems encountered during the pathologic diagnosis of SCLC, including its distinction from other neuroendocrine lesions such as large cell neuroendocrine carcinoma and "carcinoid" tumors." The role of immunohistology is also considered in this context.

Synchronous primary lung cancer presenting with small cell carcinoma and adenocarcinoma.

Multiple synchronous primary lung cancers presenting with different histologic types are uncommon. Among reported cases with different histologic findings, only a few had small cell lung cancer (SCLC) and adenocarcinoma. This unusual combination of lung cancers has not been well reported. In this report, we describe two cases of synchronous primary lung cancer presenting with lymph node metastasis of SCLC and early-stage adenocarcinoma. Epidermal growth factor receptor (EGFR) mutation was not detected in either SCLC or adenocarcinoma in the two cases.

Value of thyroid transcription factor (TTF)-1 for diagnosis and prognosis of patients with locally advanced or metastatic small cell lung cancer.

BACKGROUND: The aim of this study was to analyze the frequency of Thyroid Transcription Factor (TTF)-1 expression in small cell lung cancer (SCLC) and its value for the diagnosis of SCLC, the response to first line treatment as well as the prognostic impact on overall survival (OS). METHODS: We analyzed a total of 294 patients (m, n = 184; f, n = 110) with SCLC (stage IIIA, n = 32; IIIB, n = 87; IV, n = 175) diagnosed in our institution between January 2005 and December 2008. Patient's characteristics comprising age, gender, histology and first line treatment were included into the analyses. For the follow-up of patients the governmental death registrar was used. The TTF-1 immunostaining was prospectively performed. CT scans of all patients were reviewed and response to treatment was evaluated using the Response Evaluation Criteria In Solid Tumors 1.0 (RECIST) criteria. RESULTS: A total of 221 of the 294 patients were eligible for analysis. Patients with TTF-1-positive SCLC had a median OS of 374 (95% CI 306-442) days. The OS of patients with TTF1-negative SCLC was 290 (95% CI 191-389) days, which was not significantly shorter (p = 0.254). Also stratification for tumor stage did not reveal significant difference in OS. Analyzing the disease control rate (DCR) in patients with metastatic disease (stage IV), we observed a significantly (p = 0.006) improved response to treatment in the group of patients with TTF-1-expression (DCR 86% vs. 56%). Regarding the overall response rates (ORR) in the entire population, there was no difference observed between both subgroups. (TTF-1-pos. 75.3% vs. TTF-1-neg. 71.4%; p = 0.642). CONCLUSIONS: The diagnostic information of TTF-1 in SCLC seems to be limited. TTF-1 had no prognostic value concerning OS, but may serve as a predictor for response to first line chemotherapy. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/5811254651472285.

The alternatively spliced actinin-4 variant as a prognostic marker for metastasis in small-cell lung cancer.

BACKGROUND: The alternatively spliced actinin-4 variant (ACTN4va) is expressed in small-cell lung cancer (SCLC) and is thought to be a potential diagnostic marker. However, ACTN4va expression has not been examined in transbronchial biopsy specimens. MATERIALS AND METHODS: We retrospectively examined the relationship between ACTN4va expression, clinical factors and survival in 104 consecutive newly-diagnosed SCLC patients. RESULTS: Of the 104 screened cases, 83 (median age=69 years; transbronchial biopsy, 71) were included in our study. Survival was significantly different in the group with no distant metastasis (1996 vs. 422 days, respectively; p=0.000115) but was not significantly different with regard to ACTN4va expression in the group with distant metastasis (293 vs. 254 days, respectively; p=0.678). CONCLUSION: ACTN4va expression was identifiable in small biopsy samples. ACTN4va expression was also significantly related to distant metastasis and could stratify SCLC patients according to prognosis.

Gastric metastasis from small cell lung cancer: a case report.

Small cell lung cancer (SCLC) represents a group of highly malignant tumors that give rise to early and widespread metastases at the time of diagnosis. The preferential metastatic sites are the brain, liver, adrenal glands, bone, and bone marrow. However, metastases of the gastrointestinal system, especially the stomach, are rare; most cases of stomach metastasis are asymptomatic and, as a result, are usually only discovered at autopsy. We report a case of gastric metastasis originating from SCLC. The patient was a 66-year-old man admitted to our hospital due to abdominal pain. He underwent gastroscopy, with the pathological report of the tissue biopsy proving it to be a small cell cancer. Immunohistochemistry was positive for CD56, synaptophysin, and pan-cytokeratin. These results confirmed the diagnosis of gastric metastasis of a neuroendocrine small cell carcinoma from the lung.

Peptide imprinted receptors for the determination of the small cell lung cancer associated biomarker progastrin releasing peptide.

Peptide imprinted polymers were developed for detection of progastrin releasing peptide (ProGRP); a low abundant blood based biomarker for small cell lung cancer. The polymers targeted the proteotypic nona-peptide sequence NLLGLIEAK and were used for selective enrichment of the proteotypic peptide prior to LCMS based quantification. Peptide imprinted polymers with the best affinity characteristics were first identified from a 96-polymer combinatorial library. The effects of functional monomers, crosslinker, porogen, and template on adsorption capacity and selectivity for NLLGLIEAK were investigated and optimized. Ultimately, a solid phase extraction method was developed for highly selective enrichment of the target peptide from tryptic digests.

Triple synchronous primary lung cancer.

Synchronous multiple primary lung cancer is rare and difficult to differentiate from metastatic disease. State-of-the-art diagnostic tools may contribute to discern synchronous multiple primary lung cancer from lung cancer or other primary tumors with pulmonary metastases, thus allowing implementation of curative strategies. We report the case of a 72-year-old woman with 3 synchronous primary lung cancers.

A subset of small cell lung cancer with low neuroendocrine expression and good prognosis: a comparison study of surgical and inoperable cases with biopsy.

Patients with small cell lung carcinoma (SCLC) rarely demonstrate long-term survival. We previously reported that gene expression profiling identified a subset of SCLC with good prognosis in surgical cases. To find an easier way to routinely identify SCLC belonging to this subset, we conducted the present study with a hypothesis that neuroendocrine (NE) or basaloid (BA) phenotypes may influence prognosis. To confirm the subset, we used an array platform to analyze fresh samples. Because inoperable cases may differ from surgical cases, we enrolled 51 biopsy cases and 43 resected samples. To evaluate NE and BA phenotypes, we used NE (synaptophysin, chromogranin A, and CD56) and BA (p63 and CK34ßE12) markers. To varying extents, expression profiling based on the array platform duplicated the subsets. For NE phenotypes, 77% of surgical cases and 100% of biopsy cases were positive for at least 1 marker. For BA phenotypes, only 19% of surgical cases were positive for at least 1 marker, whereas there were no positive biopsy cases. Cases undergoing surgery were categorized based on NE and BA immunoreactivity; 58% into NE+BA-, 19% into NE+BA+, 23% into NE-BA-, and 0 into NE-BA+ groups. NE- patients (n = 10) demonstrated a significantly better prognosis (P = .0306) than their NE+ counterparts (n = 33), whereas no survival difference was evident between the BA+ and BA- groups. Multivariate analyses showed that NE positivity was an independent prognostic factor. In conclusion, the SCLC subset with good prognosis is identified by low NE marker expression, which was found only in surgical cases.

Expression of p300 and CBP is associated with poor prognosis in small cell lung cancer.

PURPOSE: To investigate the correlation among p300, CBP and MLL expression and the clinicopathological characteristics in resected SCLC patients. METHODS: Two hundred and twenty-two resected SCLC patients were included in this study. We evaluated p300, CBP and MLL expression by immunohistochemistry. RESULTS: Patients with high p300 expression had shorter OS and DFS than those with low p300 expression (p = 0.01; p = 0.009, respectively). The patients with CBP-positive tumors had significantly lower OS and DFS than those with CBP-negative tumors (p = 0.005 and p = 0.007, respectively). Moreover, the p300- and CBP-positive (+) group had a significantly poor OS and DFS. The multivariate Cox regression analysis showed that high p300 and CBP expression are independent markers of poor overall survival (p = 0.006; p = 0.017, respectively) in operable SCLC patients. CONCLUSIONS: High p300 and CBP expression are independent prognostic markers of poor overall survival for resected SCLC patients. The combination of p300 and CBP expression may be useful in identifying patients with increased risks of cancer recurrence of SCLC.