Changes in morphologic and biochemical characteristics of small cell carcinoma of the lung. A clinicopathologic study

Chemotherapy-induced PDL-1 expression in cancer-associated fibroblasts promotes chemoresistance in NSCLC

OBJECTIVES

A cure for cancer is out of reach for most patients due to chemoresistance. Cancer-associated fibroblasts (CAFs) play a vital role in cancer chemoresistance, but detailed understanding of the process particularly in chemoresistant lung cancer is lacking. In this study, we investigated programmed death-ligand 1 (PDL-1) as a potential biomarker for CAF-induced chemoresistance and evaluated its role and the underlying mechanisms of chemoresistance in non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

A systemic search of gene expression profiles of multiple tissues in NSCLC was carried out to determine the expression intensities of traditional fibroblast biomarkers and CAF-secreted protumorigenic cytokines. PDL-1 expression in CAFs was analyzed by ELISA, Western blotting, and flow cytometry. Human cytokine array was used to identify specific cytokines secreted from CAFs. Role of PDL-1 in NSCLC chemoresistance was assessed using CRISPR/Cas9 knockdown and various functional assays including MTT, cell invasion, sphere formation, and cell apoptosis. In vivo experiments were conducted using a co-implantation xenograft mouse model with live cell imaging and immunohistochemistry.

RESULTS

We demonstrated that chemotherapy-stimulated CAFs promoted tumorigenic and stem cell-like properties of NSCLC cells, which contribute to their chemoresistance. Subsequently, we revealed that PDL-1 expression is upregulated in chemotherapy-treated CAFs and is associated with poor prognosis. Silencing PDL-1 expression suppressed CAFs' ability to promote stem cell-like properties and invasiveness of lung cancer cells, favoring chemoresistance. Mechanistically, an upregulation of PDL-1 in chemotherapy-treated CAFs led to an increase in hepatocyte growth factor (HGF) secretion, which stimulates cancer progression, cell invasion, and stemness of lung cancer cells, while inhibiting apoptosis.

CONCLUSION

Our results show that PDL-1-positive CAFs modulate stem cell-like properties of NSCLC cells by secreting elevated HGF, thereby promoting chemoresistance. Our finding supports PDL-1 in CAFs as a chemotherapy response biomarker and as a drug delivery and therapeutic target for chemoresistant NSCLC.

Lung adenocarcinoma relapse with emerging EGFR mutation following complete response of small cell lung cancer warrants routine re-biopsy: A case report

Transformation of small cell lung cancer (SCLC) to lung adenocarcinoma (LUAD) is rarely reported. Here, we report a case initially presented with SCLC and was diagnosed as LUAD when the lesion relapsed at the same site. A 56-year-old patient with SCLC who received etoposide and cisplatin chemotherapy combined with radiotherapy achieved a complete radiological response. After 28 months of stable disease, a computed tomography scan revealed a new lesion at the same site as the primary tumor. Pathological examination suggested a LUAD with an emerging EGFR exon 19 deletion. The patient was then treated with icotinib and achieved a near-complete radiological response. Nineteen months later, the patient developed resistance caused by EGFR T790M mutation and received treatment with osimertinib. At the last follow-up in January 2022, the patient was symptom-free. This case warrants re-biopsy and genetic testing as a routine operation when SCLC relapses at the same site as the primary tumor for an extended period, and prospective investigation is required.

Transformational Changes Between Non-Small Cell and Small Cell Lung Cancer-Biological and Clinical Relevance-A Review

During the course of therapy, patients with small cell lung cancer have been noted to develop transformation to non-small cell lung cancer and conversely, patients with non-small cell lung cancer have had transformation to small cell lung cancer or other non-small cell histologies. Transformation may occur after prior tyrosine kinase inhibitors, chemotherapy, immunotherapy or radiation therapy. These changes reflect on the overlapping biology of these cell types and the clinical need for re-biopsy at times of disease progression. The optimum therapy after transformation will depend upon prior therapies received, the functional capacity of the patient, and further research to define the best therapy options.

State of the art management of metastatic gastroesophageal cancer

The anatomical locations of upper gastrointestinal (GI) tumors have changed remarkably in the western world and reflect the increasing impact of obesity and gastroesophageal (GE) reflux rather than infectious etiologies. Incidence rates of GE tumors are rising rapidly and survival rates for patients with metastatic disease remain poor. Traditionally, cytotoxic chemotherapy has had some survival advantages but increasingly complex combination regimens are limited by toxicities. The advent of molecularly targeted therapy has provided additional options for patients with advanced disease including trastuzumab and ramucirumab. There has also been detailed molecular characterization of upper GI tumors which hopefully will result in improved tailoring of clinical trial design accounting for the heterogeneity inherent in GE tumors. While numerous targeted therapies are currently being studied in clinical trials, there is much excitement regarding the role of immunotherapy in GE cancers. Although further investigation is warranted, it represents a promising avenue for patients with advanced GE tumors.

From molecular classification to targeted therapeutics: the changing face of systemic therapy in metastatic gastroesophageal cancer

Histological classification of adenocarcinoma or squamous cell carcinoma for esophageal cancer or using the Lauren classification for intestinal and diffuse type gastric cancer has limited clinical utility in the management of advanced disease. Germline mutations in E-cadherin (CDH1) or mismatch repair genes (Lynch syndrome) were identified many years ago but given their rarity, the identification of these molecular alterations does not substantially impact treatment in the advanced setting. Recent molecular profiling studies of upper GI tumors have added to our knowledge of the underlying biology but have not led to an alternative classification system which can guide clinician's therapeutic decisions. Recently the Cancer Genome Atlas Research Network has proposed four subtypes of gastric cancer dividing tumors into those positive for Epstein-Barr virus, microsatellite unstable tumors, genomically stable tumors, and tumors with chromosomal instability. Unfortunately to date, many phase III clinical trials involving molecularly targeted agents have failed to meet their survival endpoints due to their use in unselected populations. Future clinical trials should utilize molecular profiling of individual tumors in order to determine the optimal use of targeted therapies in preselected patients.

Neuroendocrine tumors of the lung

Neuroendocrine tumors may develop throughout the human body with the majority being found in the gastrointestinal tract and bronchopulmonary system. Neuroendocrine tumors are classified according to the grade of biological aggressiveness (G1-G3) and the extent of differentiation (well-differentiated/poorly-differentiated). The well-differentiated neoplasms comprise typical (G1) and atypical (G2) carcinoids. Large cell neuroendocrine carcinomas as well as small cell carcinomas (G3) are poorly-differentiated. The identification and differentiation of atypical from typical carcinoids or large cell neuroendocrine carcinomas and small cell carcinomas is essential for treatment options and prognosis. Pulmonary neuroendocrine tumors are characterized according to the proportion of necrosis, the mitotic activity, palisading, rosette-like structure, trabecular pattern and organoid nesting. The given information about the histopathological assessment, classification, prognosis, genetic aberration as well as treatment options of pulmonary neuroendocrine tumors are based on own experiences and reviewing the current literature available. Most disagreements among the classification of neuroendocrine tumor entities exist in the identification of typical versus atypical carcinoids, atypical versus large cell neuroendocrine carcinomas and large cell neuroendocrine carcinomas versus small cell carcinomas. Additionally, the classification is restricted in terms of limited specificity of immunohistochemical markers and possible artifacts in small biopsies which can be compressed in cytological specimens. Until now, pulmonary neuroendocrine tumors have been increasing in incidence. As compared to NSCLCs, only little research has been done with respect to new molecular targets as well as improving the classification and differential diagnosis of neuroendocrine tumors of the lung.

A functional role for tumor cell heterogeneity in a mouse model of small cell lung cancer

Small cell lung cancer (SCLC) is the lung neoplasia with the poorest prognosis, due to its high metastatic potential and chemoresistance upon relapse. Using the previously described mouse model for SCLC, we found that the tumors are often composed of phenotypically different cells with either a neuroendocrine or a mesenchymal marker profile. These cells had a common origin because they shared specific genomic aberrations. The transition from neuroendocrine to mesenchymal phenotype could be achieved by the ectopic expression of oncogenic Ras(V12). Crosstalk between mesenchymal and neuroendocrine cells strongly influenced their behavior. When engrafted as a mixed population, the mesenchymal cells endowed the neuroendocrine cells with metastatic capacity, illustrating the potential relevance of tumor cell heterogeneity in dictating tumor properties.

Neuroendocrine tumors of the lung: an update

CONTEXT

The 2004 World Health Organization (WHO) classification recognizes 4 major types of lung neuroendocrine tumors: typical carcinoid, atypical carcinoid, small cell lung cancer, and large cell neuroendocrine carcinoma. Markedly different prognostic implications and treatment paradigms for these tumors underscore the importance of accurate pathologic diagnosis.

OBJECTIVE

To detail the clinical and pathologic features of lung neuroendocrine tumors, with emphasis on diagnostic criteria, differential diagnoses, and application of immunohistochemistry. The emerging evidence for the utility of Ki-67 (MIB1) in the diagnosis of lung neuroendocrine tumors, particularly in small biopsy and cytology, is emphasized.

DATA SOURCES

The 2004 WHO classification, other published literature, and primary material from the author's institution.

CONCLUSIONS

The current WHO classification of neuroendocrine tumors is based on morphologic features in combination with precisely defined mitotic rate and absence or presence of necrosis. Ki-67 (MIB1) is emerging as a useful ancillary tool in the diagnosis of these tumors. Continued research efforts are needed to identify additional immunohistochemical and molecular biomarkers that can serve as ancillary diagnostic tools and as potential therapeutic targets for these diseases.

On the need for biopsy confirmation at suspected first recurrence of cancer

At the time of suspected first recurrence of cancer, it is unclear whether biopsy confirmation is routinely performed, although this is a very common clinical situation. First, 20 oncologists were surveyed to ascertain the pattern of practice in our community. A questionnaire with hypothetical typical cases suspected of having recurrent cancer was distributed. Second, eligibility criteria were reviewed from investigational protocols from the National Cancer Institute (NCI) and the Eastern Cooperative Oncology Group to see whether confirmation of recurrence was specifically required in these research studies. Third, 64 cases from our own practice were reviewed retrospectively to determine our patterns and results in performing biopsies to document suspected recurrence. Finally, criteria were developed that might suggest the need for biopsy confirmation of recurrence and then retrospectively tested against our cases. There was no clear consensus among oncologists regarding the need for tissue confirmation in patients with solid tumor with suspected recurrences, although rebiopsy was routinely requested for recurrent lymphoma. Published Eastern Cooperative Oncology Group and NCI protocols reviewed did not require biopsy proof specifically of recurrence. Retrospective review of our own cases suggested that, in the absence of one of the proposed indicators, the risk of making an erroneous diagnosis without biopsy confirmation is low. It is suggested that biopsy is not routinely necessary for confirmation of recurrence in all cases of suspected recurrent solid tumors, but criteria are proposed that would help to reduce the possibility of misdiagnosis when biopsy of suspected recurrence is not performed.

Protein kinase C-epsilon promotes survival of lung cancer cells by suppressing apoptosis through dysregulation of the mitochondrial caspase pathway

The serine/threonine protein kinase C (PKC) has been implicated in the regulation of drug resistance and cell survival in many types of cancer cells. However, the one or more precise mechanisms remain elusive. In this study, we have identified and determined the mechanism by which PKC-epsilon, a novel PKC isoform, modulates drug resistance in lung cancer cells. Western blot analysis demonstrates that expression of PKC-epsilon, but not other PKC isoforms, is associated with the chemo-resistant phenotype of non-small cell lung cancer (NSCLC) cell lines. Northern blotting and nuclear run-on transcription analysis further reveals that the failure of expression of PKC-epsilon in the chemo-sensitive phenotype of small cell lung cancer (SCLC) cells results from transcriptional inactivation of the gene. Importantly, forced expression of PKC-epsilon in NCI-H82 human SCLC cells confers a significant resistance to the chemotherapeutic drugs, etoposide and doxorubicin. Resistance is characterized by a significant reduction in apoptosis in PKC-epsilon-expressing cells. Treatment of NCI-H82 cells with etoposide induces a series of time-dependent events, including the release of cytochrome c from the mitochondria to the cytosol, activation of caspase-9 and caspase-3, and cleavage of poly(ADP-ribose) polymerase (PARP). All of these events are blocked by PKC-epsilon expression. Furthermore, caspase-specific inhibitors, z-VAD-fmk and z-DEVD-fmk, significantly attenuate the accumulation of sub-G(1) population and block the PARP cleavage in response to etoposide. These results suggest that PKC-epsilon prevents cells from undergoing apoptosis through inhibition of the mitochondrial-dependent caspase activation, thereby leading to cell survival. Finally, down-regulation of PKC-epsilon expression by the antisense cDNA in NSCLC cells results in increased sensitivity to etoposide. Taken together, our findings suggest an important role for PKC-epsilon in regulating survival of lung cancer cells.

A phase II study of all-trans-retinoic acid plus cisplatin and etoposide in patients with extensive stage small cell lung carcinoma: an Eastern Cooperative Oncology Group Study

BACKGROUND

The dysregulation of both myc gene expression and retinoid signaling pathways commonly occurs in small cell lung carcinoma (SCLC). Because preclinical data showed that all-trans-retinoic acid (RA) inhibited SCLC growth, altered myc expression, and blocked transition to a treatment-resistant phenotype, a Phase II trial was designed to determine the effects of the combination of RA, cisplatin, and etoposide in patients with SCLC.

METHODS

Patients with untreated, extensive stage SCLC were treated with up to 8 cycles of cisplatin, 60 mg/m2, intravenously (i.v.) on Day 1 and etoposide, 120 mg/m2, i.v. on Days 1-3 in addition to up to 1 year of oral RA, 150 mg/m2/day.

RESULTS

Of 22 assessable patients 1 had a complete response and 9 had a partial response, for an overall response rate of 45% (95% confidence interval, 24-68%). The median survival was 10.9 months and the 1-year survival was 41%. The median duration of chemotherapy was 6 cycles and the median duration of RA treatment was 2.8 months. Thirteen patients discontinued RA prematurely due to toxicity and only 4 responders were receiving RA at the time of recurrence. Toxicity-limiting RA treatment mainly was comprised of mucocutaneous changes and headaches.

CONCLUSIONS

RA at a dose of 150 mg/m2/day was tolerated poorly in combination with cisplatin plus etoposide, leading to early discontinuation of RA in the majority of patients. The hematologic toxicity, response rate, and survival were similar to those associated with cisplatin and etoposide in prior trials. Further studies with more active and less toxic agents will be required to determine the role of retinoids in the treatment of SCLC.

Combined carcinoid tumor of the lung: a combination of carcinoid and adenocarcinoma

Combined small cell carcinoma is an uncommon but well described diagnostic category of neuroendocrine lung tumors. The prognosis of these tumors appears to be similar to that of pure small cell carcinoma, although it is believed that the non-small cell components of these tumors are less chemo-responsive than the small cell components. We report a case of a 60-year-old male smoker with a 2-cm nodule that, on subsequent lobectomy, was a combination of carcinoid and adenocarcinoma. A lymph node metastasis to an ipsilateral hilar node was comprised of only the well differentiated adenocarcinoma component. The biologic behavior of such tumors is not well described and their place within, what may be described as, a spectrum of combined neuroendocrine tumors is discussed.

Neurologic disorders in 203 consecutive patients with small cell lung cancer. Results of a longitudinal study

BACKGROUND

Neurologic complications of small cell lung cancer (SCLC) are manifold. The incidence and course of the various metastatic and nonmetastatic neurologic disorders were studied prospectively in a cohort of SCLC patients.

METHODS

The 203 patients underwent neurologic examinations on a regular basis, prior to therapy, during and after treatment, from 1983 through 1994. Routine computer tomography or magnetic resonance imaging of the brain was performed before therapy and after 2 years' survival. Other auxiliary diagnostic tests were performed as required.

RESULTS

The majority of the 174 neurologic disorders, diagnosed in 132 patients, were associated with metastases. A total of 79 patients developed brain metastases. The cumulative risk of brain metastases reached 47% for limited and 69% for extensive disease patients at 2 years from diagnosis. Survival following the diagnosis of brain metastases was significantly longer for patients with brain metastases at the initial diagnosis of SCLC than for patients with delayed brain metastases (P < 0.01, long rank test). The most frequent paraneoplastic syndrome with neurologic symptoms was that of inappropriate secretion of antidiuretic hormone (SIADH), which was diagnosed in 11 patients. Antibody-mediated paraneoplastic neurologic syndromes were diagnosed in five patients. Chemotherapy for SCLC caused SIADH to subside in most patients. In contrast, the antibody-mediated syndromes did not respond to SCLC therapy. Adverse effects of treatment included peripheral neuropathy, encephalopathy, radiation plexopathy, and steroid myopathy. However, unlike the other complications, peripheral neuropathy was reversible.

CONCLUSIONS

This clinical investigation confirmed the frequency of central nervous system metastatic involvement as well as the diversity of the neurologic complications in SCLC. The high frequency of brain metastases justifies a reappraisal of prophylactic cranial irradiation in this patient group.

Histologic changes in small cell lung carcinoma after treatment

BACKGROUND

Small cell lung carcinoma (SCLC) has been divided into three subtypes: pure SCLC, mixed small cell/large cell carcinoma (mixed SC/LC), and combined SCLC. Patients with mixed SC/LC show a worse prognosis than those with pure SCLC.

METHODS

Persistence of histologic subtype in SCLC in the primary sites during the course of treatment or in the different organs at autopsy was examined. For this purpose, biopsy or cytologic specimens before chemotherapy, and autopsy specimens from 175 patients with SCLC were reviewed. They included 147 (84%) men and 28 (16%) women with an age range of 29-83 (median, 65) years.

RESULTS

The frequency of mixed SC/LC in the primary sites was statistically higher in autopsy (14.3%) than that in biopsy or cytology specimens (8.6%) (P < 0.05). At autopsy, involved organs were categorized into two groups according to frequency of appearance of mixed SC/LC, i.e., a higher frequency group, including the liver (31 of 85; 36.4%), adrenal gland (15 of 56; 26.8%), brain (6 of 9; 66.7%), and extrathoracic lymph nodes (17 of 59; 28.8%) and a lower frequency group, including the lung (metastatic sites) (12 of 102; 11.8%), pleura (8 of 74; 10.8%), and intrathoracic lymph nodes (12 of 94; 12.8%). The difference in frequency between these two groups was statistically significant (P < 0.05).

CONCLUSIONS

These findings suggest that primary pure SCLC can progress to mixed SC/LC with an increased potential for distant metastasis.

Increased radioresistance of an in vitro transformed human small cell lung cancer cell line

After 4-6 months in continuous culture the human small cell lung cancer (SCLC) cell line, U-1906, changed its radiobiological characteristics spontaneously. The cell line became more radioresistant indicating an increased repair capacity. This change was accompanied by a more adherent growth pattern, a higher clonogeneity, a decrease in the cytokeratin (tissue polypeptide antigen) content and increased glucagon and neuron-specific enolase (NSE) production. Other parameters such as the estramustine-binding protein (EMBP) and the proliferation associated antigen Ki-67 were unaltered. This spontaneous transformation in vitro of U-1906 may reflect a clinically important in vivo phenomenon of SCLC, which frequently develops resistance both to radio- and chemotherapy.

Evolution of chromosomal alterations and biologic features in two small cell lung carcinoma cell lines established from one patient during the course of the disease

Two small cell lung cancer (SCLC) cell lines were established from metastases of a patient during the course of the disease. SCLC 74A was derived from biopsy material obtained at the time of diagnosis and SCLC 74B was from a biopsy specimen of a relapsed tumor obtained after treatment. A transition occurred from SCLC 74A, an intermediate form with 5% large cells to SCLC 74B, a standard mixed form with 20% of large cells, with a decrease in neuroendocrine markers and a substantial increase in P-glycoprotein, a multidrug resistance marker. For both cell lines, R-banding and FISH indicated a del(1)(p35pter) also found in other neural-crest-derived tumors, the loss of regions with suspected tumor suppressor genes at 3p, 5q, and 17p, and a recurrent translocation of the 6q24-6qter region to 10p14. Further genetic modifications in SCLC 74B affected chromosomes 2, 3, 5, 10, 11, 14, and 15. The main observations were a der(2)t(2;5)(p16;q?); a der(3;11)(q10;p10) in SCLC 74A which became der(3;14)(q10;p10) and der(11;14)(p10;q10) in SCLC 74B; and the insertion of the 5q13-5q31 region in the der(10)t(6;10). The finding of the same structural abnormalities in both cell lines suggests a monoclonal origin for both metastases. Hypotetraploid cells were in the same proportion as large cells whose number was a characteristic feature of each cell line. They possessed twice the same chromosomal alterations observed in the hypodiploid cells. This suggests a permanent process of tetraploidization.

A prospective randomized trial to determine the benefit of surgical resection of residual disease following response of small cell lung cancer to combination chemotherapy

Three hundred twenty-eight patients with limited stage small cell lung cancer were enrolled in a trial to evaluate surgical treatment for such patients responding to chemotherapy. Cyclophosphamide, doxorubicin, and vincristine were administered every 21 days for five cycles. Patients achieving at least partial response who had confirmation of pure small cell histologic features by pathology review and who were fit enough for thoracotomy were randomized to undergo or not to undergo pulmonary resection. All randomized patients received radiotherapy to the chest and brain. Two hundred seventeen (66%) of the patients achieved objective response (90 complete response; 127 partial response). One hundred forty-six patients were randomized (66% of responders, 44% of all patients): 70 to surgery and 76 to no surgery. Results of surgery were 83% resection rate, 19% pathologic complete remission rate, and 9% with residual non-small cell histologic features only, for a total of 28% eradication of small cell lung cancer. The survival curves for the two arms are not different (log rank p = 0.78). Median survivals were 12 months for all enrolled patients and 16 months for those who were randomized. Actuarial 2-year survival is 20%. The results of this trial do not support the addition of pulmonary resection to the multimodality treatment of small cell lung cancer.

Preferential localization of c-kit product in tissue mast cells, basal cells of skin, epithelial cells of breast, small cell lung carcinoma and seminoma/dysgerminoma in human: immunohistochemical study on formalin-fixed, paraffin-embedded tissues

Eighteen hundred and eighty-four cases of human solid tumours and 833 samples of normal human tissues, formalin-fixed and paraffin-embedded, were examined immunohistochemically for expression of c-kit oncogene product using polyclonal antibody against synthesized c-kit peptide. Seminoma/dysgerminoma and small cell lung carcinoma (SCLC) show preferential c-kit expression at 92% and 36% frequency, respectively, whereas only sporadic cases of cervical carcinoma and non-SCLC lung carcinoma show c-kit positivity. A normal tissue counterpart positive for c-kit product is detected in the testis (spermatocyte) and ovary (oocyte) but not in the lung or the cervix. In contrast, normal epithelial cells of the breast, skin basal cells and tissue mast cells harbour c-kit product, but transformed cells of the former two are largely deficient in the c-kit protein. One hundred and thirty-nine neuroendocrine tumours and 39 non-pulmonary small cell carcinomas were all negative, except for two cases of neuroblastoma. This indicates a distinct character for SCLC in c-kit expression. The c-kit product may be a useful marker in diagnostic pathology of seminoma/dysgerminoma and SCLC among human solid tumours, and in distinction of SCLC from non-pulmonary small cell carcinoma.

Small cell lung cancer: etiology, biology, clinical features, staging, and treatment

Lung cancer is the leading cause of cancer death in the United States. Small cell lung cancer (SCLC) accounts for 20% to 25% of all bronchogenic carcinoma and is associated with the poorest 5-year survival of all histologic types. SCLC differs in its etiologic, pathologic, biologic, and clinical features from non-SCLC, and these differences have translated to distinct approaches to its prevention and treatment. Compared with other histologic types of lung cancer, exposures to tobacco smoke, ionizing radiation, and chloromethyl ethers pose a substantially greater risk for development of SCLC. The histologic classification of SCLC has been revised to include three categories: (1) small cell carcinoma, (2) mixed small cell/large cell, and (3) combined small cell carcinoma. Ultrastructurally, SCLC displays a number of neuroendocrine features in common with pulmonary neuroendocrine cells, including dense core vesicles or neurosecretory granules. These dense core vesicles are associated with a variety of secretory products, cell surface antigens, and enzymes. The biology of SCLC is complex. The activation of a number of dominant proto-oncogenes and the inactivation of tumor suppressor genes in SCLC have been described. Dominant proto-oncogenes that have been found to be amplified or overexpressed in SCLC include the myc family, c-myb, c-kit, c-jun, and c-src. Altered expression of two tumor suppressor genes in SCLC, p53 and the retinoblastoma gene product, has been demonstrated. Cytogenetic and molecular evidence for chromosomal loss of 3p, 5q, 9p, 11p, 13q, and 17p in SCLC has intensified the search for other tumor suppressor genes with potential import in this malignancy. Bombesin/gastrin-releasing peptide, insulin-like growth factor I, and transferrin have been identified as autocrine growth factors in SCLC, with a number of other peptides under active investigation. Several mechanisms of drug resistance in SCLC have been described, including gene amplification, the recently described overexpression of multi-drug resistance-related protein (MRP), and the expression of P-glycoprotein. The classic SCLC staging system has been supplanted by a revised TNM staging system where limited disease and extensive disease are equivalent to the TNM stages I through III and stage IV, respectively. Therapeutically, recent strategies have attained small improvements in survival but significant reductions in the toxicities of chemotherapeutic regimens. Presently, the overall 5-year survival for SCLC is 5% to 10%, with limited disease associated with a significantly higher survival rate.(ABSTRACT TRUNCATED AT 400 WORDS)

Small-cell lung carcinoma: inhibition of proliferation by vasoactive intestinal peptide and helodermin and enhancement of inhibition by anti-bombesin antibody

Small-cell lung cancer (SCLC) is a common and highly fatal malignancy for which there is no satisfactory treatment. The amphibian peptide bombesin and its mammalian counterpart, gastrin-releasing peptide, serve as autocrine growth factors for the SCLC cells, but little is known about endogenous substances that inhibit the growth and proliferation of these tumor cells. We report that the neuropeptide vasoactive intestinal peptide (VIP) markedly inhibits the growth and multiplication of SCLC cell lines NCI-H345 and NCI-H69, and that the closely related peptide helodermin inhibits the proliferation of NCI-H345 cells with even higher efficacy. In the latter cells, the inhibition by VIP and isobutyl methyl xanthine paralleled their ability to stimulate cyclic adenosine monophosphate production within the cells. The peptide-induced suppression of SCLC proliferation is enhanced in the presence of an anti-bombesin monoclonal antibody. The antimitogenic activities of VIP and helodermin, and their enhancement by anti-bombesin antibody, offer the potential for a new approach to the pharmacologic control of SCLC.

Extrapulmonary and pulmonary small-cell carcinoma: tumor biology, therapy, and outcome

Extrapulmonary small-cell cancer is a distinct clinicopathological entity from small-cell anaplastic carcinoma of the lung. Approximately 1,000 cases have been projected annually in the United States, which represents an overall incidence of between 0.1% and 0.4% of all cancer. Not surprisingly then, little information is available regarding the treatment of this disease, which presents a challenge to the clinician when it is regionally confined. The majority of patients with extrapulmonary small-cell neoplasms have only been treated with local modalities of therapy, surgery, radiation, or a combination of both. Prolonged survival is not infrequent, which is in contrast to the experience for small-cell lung cancer and surprising given our current systemic approach to patients with this disease. This report will summarize the similarities and differences in biology, natural history, and clinical characteristics of patients with extrapulmonary small-cell cancer and small-cell anaplastic carcinoma of the lung. The histogenesis of small-cell cancer is briefly reviewed. A general therapeutic approach to patients with small-cell lung cancer is reported. Lastly, recommendations for therapy of patients with regionally confined extrapulmonary small-cell cancer by primary site are outlined.

Immunohistochemical detection of two small cell lung carcinoma-associated antigens defined by MAbs F12 and 123C3 in bronchoscopy biopsy tissues

We have studied MAbs* for their ability to detect SCLC and differentiate this tumor type from the other lung tumor histotypes in cryostat sections of biopsy specimens taken at bronchoscopy from patients with suspected primary lung tumor disease. MAb F12, specific for the ganglioside fucosyl-GM1, reacted with 58% of the cases with SCLC (n = 19) and with less than 3% of those with non-SCLC (n = 38). MAb 123C3, specifically reactive with NCAM, reacted with 78% of the SCLC cases (n = 23). With this MAb no positive staining was seen in the non-SCLC cases (n = 41). None of the two MAbs reacted with tissue sections without tumor. In combined analysis with MAbs F12 and 123C3, all SCLC cases (n = 15) were positive with either and 47% with both of the MAbs. Our results show that both MAbs F12 and 123C3 are highly specific for SCLC in bronchoscopic biopsy tissue specimens, whereas the sensitivity for this histotype tends to be higher with MAb 123C3 than with F12 (P = 0.14). When used in combination, all SCLC cases could be identified. These MAbs may therefore be valuable as complements to current histopathologic characterization and differentiation of lung cancer.

Small cell lung carcinoma: clinicopathological, immunohistochemical, and ultrastructural study

Sixty-seven cases of small cell lung carcinoma (SCLA) in Tri-Service General Hospital (TSGH) during the past 16 years were studied. For patients with extensive stage of disease, the mean survival time and 2-year survival rate were 7.2 months and 3.1% versus 13.4 months and 16.7% for patients with limited stage. A better prognosis was obtained by treatment with a combination of intensive chemotherapy and radiotherapy. Immunohistochemical studies were performed by the peroxidase-antiperoxidase method. The positive rates in descending order were bombesin (80%), synaptophysin (74.3%), neurofilament (68.6%), neuron-specific enolase (60%), low molecular weight cytokeratin (54.3%), high molecular weight cytokeratin (25.7%), chromogranin-A (22.9%), adrenocorticotrophic hormone (0). Seven cases were examined and found to be ultrastructure; only 3 cases were found to contain neurosecretory granules. We emphasize that electron microscopy is not necessary as a routine diagnostic procedure, while light microscopy should be employed whenever possible; the immunohistochemical study should be considered within this context.

Selection of radioresistant cells by vitamin A deficiency in a small cell lung cancer cell line

Radiation sensitivity of a human small cell lung cancer cell line, Lu-134-B cells, cultured in serum-supplemented medium and of cells transferred to and cultured in delipidized serum-supplemented (vitamin A-deficient) medium was studied. The cells cultured in serum-supplemented medium showed the phenotype of classic small cell lung cancer sensitive to radiation, while cells transferred to delipidized serum-supplemented medium showed partial squamous cell differentiation and became resistant to radiation. These results suggest that some small cell lung cancer cells in vitro change their morphology and radiosensitivity depending on the culture conditions. The change in radiosensitivity was reproducible, and was not reversible by culture of the radioresistant cells in delipidized serum-supplemented medium with addition of retinoic acid (vitamin A-sufficient medium) for two months, although squamous cells disappeared. Acquisition of radioresistancy was considered to occur as the result of clonal selective growth in delipidized medium of a minor cell population in the original cell culture, based on a study of chromosome number. It was also found that there was no association of myc-family oncogenes with the changes of radiosensitivity in this cell line.

Atypical carcinoid tumor of the lung, associated with giant-cell transformation in bone metastasis

A case of neuroendocrine lung tumor located beneath the pleura in a 71-year-old woman is reported. At autopsy, the tumor was found to have metastasized to the bones and liver without involving the hilar lymph nodes. Histologically, the tumor cells at the primary site and in the liver metastasis exhibited a carcinoid-like organoid structure, whereas pleomorphic giant cells were noted in the bone metastasis. The argyrophilic tumor cells were immunoreactive for neuron-specific enolase, chromogranin A, serotonin, calcitonin, calcitonin gene-related peptide, gastrin-releasing peptide, neuropeptide Y, gastrin, pancreatic polypeptide, glicentin, the alpha-subunit of human chorionic gonadotropin, keratin, epithelial membrane antigen, Leu M1 and carcinoembryonic antigen. Electron microscopy revealed abundant neurosecretory granules in the cytoplasm. This was considered to be a rare case of neuroendocrine lung tumor showing carcinoid-like histology at the primary site and large-cell transformation in bone metastasis.

v-rasH induces non-small cell phenotype, with associated growth factors and receptors, in a small cell lung cancer cell line

Small cell lung cancer (SCLC) tumor progression can involve partial or complete conversion to a more treatment-resistant non-small cell (NSCLC) phenotype. In a cell culture model of this phenomenon, we have previously demonstrated that insertion of the viral Harvey ras gene (v-Ha-ras) into SCLC cell lines with amplification and overexpression of the c-myc gene induced many NSCLC phenotypic features. We now report that the v-Ha-ras gene can also induce morphologic, biochemical, and growth characteristics consistent with the NSCLC phenotype in an N-myc amplified SCLC cell line, NCI-H249. We show that v-Ha-ras has novel effects on these cells, abrogating an SCLC-specific growth requirement for gastrin-releasing peptide, and inducing mRNA expression of three NSCLC-associated growth factors and receptors, platelet-derived growth factor B chain, transforming growth factor-alpha (TGF-alpha), and epidermal growth factor receptor (EGF-R). TGF-alpha secretion and EGF-R also appear, consistent with the induction of an autocrine loop previously shown to be growth stimulatory for NSCLC in culture. These data suggest that N-myc and v-Ha-ras represent functional classes of genes that may complement each other in bringing about the phenotypic alterations seen during SCLC tumor progression, and suggest that such alterations might include the appearance of growth factors and receptors of potential importance for the growth of the tumor and its surrounding stroma.

Chemo-radioresistance of small cell lung cancer cell lines derived from untreated primary tumors obtained by diagnostic bronchofiberscopy

New cell lines of small cell lung cancer (SCLC) were established from specimens of untreated primary tumors biopsied by diagnostic bronchofiberscopy. The advantage of this method was ease of obtaining specimens from lung tumors. Establishment of cell lines was successful with 4 of 13 specimens (30%). Clinical responses of the tumors showed considerable variation, but were well correlated with the in vitro sensitivity of the respective cell lines to chemotherapeutic drugs and irradiation. One of the cell lines was resistant to all drugs tested and irradiation, while another was sensitive to all of them. Although the acquired resistance of SCLC is the biggest problem in treatment, the natural resistance to therapy is another significant problem. Either acquired or natural, resistance mechanisms of SCLC may be elucidated by the use of such cell lines derived from untreated tumors. This method and these SCLC cell lines are expected to be useful for the serial study of biologic and genetic changes of untreated and pre-treated tumors, or primary and secondary tumors.

Long-term outcome of small cell lung cancer

Long-term survival (greater than or equal to 3 years) is possible in a small proportion of patients with SCLC, particularly if the disease is limited in extent. The influence of thoracic irradiation on the long-term outcome of limited stage patients is controversial, although there is a suggestion of benefit. Despite the use of irradiation, thoracic recurrence is the single most important site of treatment failure. Further experience will be necessary to determine if radiotherapeutic strategies to enhance thoracic control can improve long-term survival. Prophylactic cranial irradiation (PCI) may influence long-term survival of limited stage patients who achieve a complete response to therapy and remain controlled in the chest. However, this is not clearly established and must be considered in the light of the contribution of PCI to neurotoxicity occurring in survivors. Reduction in the radiation fraction size and the omission of chemotherapeutic agents which cause neurotoxicity, either alone or by synergism with PCI, are reasonable approaches to pursue in an attempt to prevent this complication. A small proportion of NSCLC occurring after treatment of SCLC may be preventable by attempts to eradicate NSCLC components present in the original SCLC. Leukemogenic chemotherapy agents may contribute to the development of secondary ANL, and should probably not be used in view of the availability of alternative equally effective agents.

Small cell lung cancer

Lung cancer is the most common cause of cancer death in the United States, with approximately 135,000 men and women dying each year. While much has been learned about the etiologic risk factors, less progress has been made in therapy. Five-year survival rates remain at less than 10%. However, there has been some progress in the therapy of one histological subtype of lung cancer, small cell lung cancer. Totaling around 20% of lung cancer cases, small cell lung cancer is distinct from the other histologic subtypes in its biologic behavior and responsiveness to therapy. In the 1960s, the median survival for patients with small cell lung cancer was approximately 3 months. With combination chemotherapy and radiotherapy median survivals now range from 1 to 2 years, and there is evidence for a curative potential since approximately 10% of patients who initially present with limited disease survive greater than 2 years. The unique clinical aspects of this histological subtype potentially relate to its underlying cell of origin. This behavior is reflected in the numerous paraneoplastic syndromes that frequently accompany small cell lung cancer. Its propensity for early dissemination have made staging the extent of disease an important part of the clinical evaluation. Since small cell lung cancer is sensitive to both chemotherapy and radiation therapy, there have been multiple clinical trials evaluating drug/radiotherapy combinations. This article will briefly describe the unique aspects of small cell lung cancer as opposed to other histological subtypes of lung cancer and give an overview of the current clinical approach and treatment of this disease.

Surgical treatment of patients with small cell carcinoma of the lung: a histochemical and immunohistochemical study

Thirty-three patients with small cell carcinoma of the lung were treated surgically, and immunohistochemistry of the cell differentiations was examined in detail. The overall 5-year survival rate was 38% and the rates in patients with stage I or stage III were 57% and 11%, respectively (P less than 0.05). Survival rates in patients with the oat cell type and intermediate type were 24% and 44%, respectively, but with no significant difference. This carcinoma seemed to originate from primitive multipotential stem cells, i.e., those of a neuroendocrine or epithelial nature. Histochemically and immunohistochemically, argyrophilic granules and neuron-specific enolase, neuroendocrine markers, were detected more frequently in the oat cell type rather than in the intermediate type. In contrast, keratin, epithelial membrane antigen, and carcinoembryonic antigen, epithelial origin markers, were present more frequently in the intermediate type than in oat cell type. However, the difference was significant only in case of detection of argyrophilic granules and the carcinoembryonic antigen (P less than 0.05). Our current recommendation is that surgical resection should be done in the earlier stage in both subtypes. A more favorable prognosis can be expected when adjuvant chemotherapy is prescribed.

What's new in lung tumor heterogeneity?

The categorization of lung tumors into histologically defined groups and subtypes is based on morphometric criteria, on various degrees of tumoral differentiation and growth patterns. Light microscopic examination of different sections of one and the same tumor reveals in more than 30% of the cases investigated a qualitative and quantitative heterogeneous cell and tumor growth pattern, which is further proved by additional immunohistochemical, electronmicroscopic and DNA-flow cytometry studies. According to observations on the ultrastructural level mixed or combined morphologic features signaling abnormal differentiation patterns in preneoplastic lesions of the bronchial mucosa were visible. So-called amphicrine cells containing mucous vacuoles as well as granules of neurosecretory type were found in basal cell and goblet cell hyperplasia. Squamous-type cells predominate in epidermoid metaplasia and in dysplasia. Cells containing mucous granules or tonofilaments and scant granules of dense core-type suggestive of squamous neurosecretory differentiation were present in all lesions. The ultrastructural features were correlated with the bronchial carcinoma cell heterogeneity and histogenesis.

Radiosensitivity related to neuroendocrine and endodermal differentiation in lung carcinoma lines

A panel of human lung carcinoma lines was studied with respect to hormone production and intermediate filament expression to distinguish between endodermal and neuroendocrine differentiation. An index of the degree of neuroendocrine differentiation of each line was derived from the presence or absence of hormone production, cytokeratins, neurofilaments and an embryonic endodermal cell marker, which allowed identification of three groups showing high, intermediate or low neuroendocrine expression. This grouping correlated well with the in vitro radiosensitivity of the lines, those expressing pure neuroendocrine features being significantly more radiosensitive than those with an endodermal phenotype, with the intermediate group having intermediate sensitivity. Use of such an index might predict those patients likely to benefit from the use of radiotherapy in their management.

v-Ha-ras oncogene insertion: a model for tumor progression of human small cell lung cancer

Small cell lung cancer (SCLC) manifests a range of phenotypes in culture that may be important in understanding its relationship to non-SCLCs and to tumor progression events in patients. Most SCLC-derived cell lines, termed "classic" SCLC lines, have properties similar to SCLC tumors in patients, including high expression of neuroendocrine markers and low c-myc oncogene expression. A significant number of SCLC lines characterized as "biochemical or morphologic variant" SCLC lines have decreased levels of endocrine differentiation markers associated with increased proliferative indices, amplification of the c-myc oncogene, and growth patterns and biochemical markers more typical of non-SCLCs. To delineate further the relationships between these phenotypes and the molecular events involved, we have inserted the v-Ha-ras gene in SCLC cell lines with (biochemical variant) and without (classic) an amplified c-myc gene. These two SCLC subtypes had markedly different phenotypic responses to similar levels of expression of v-Ha-ras RNA. No biochemical or morphologic changes were observed in classic SCLC cells. In contrast, in biochemical variant SCLC cells, v-Ha-ras expression induced features typical of large cell undifferentiated lung carcinoma, including adherent monolayer growth patterns, increased cloning efficiency, increased levels of non-SCLC cell markers, ultrastructural characteristics and an acquired resistance to polyamine depletion typical of large cell carcinoma, but not SCLC, in vitro. Expression of v-Ha-ras in biochemical variant SCLC cells directly demonstrates that important transitions can occur between phenotypes of human lung cancer cells and that these may play a critical role in tumor progression events in patients. The findings provide a model system to study molecular events involved in tumor progression steps within a series of related tumor types.

The prognostic implication of histopathologic subtyping of pulmonary adenocarcinoma according to the classification of the World Health Organization. An analysis of 259 consecutive patients with advanced disease

The prognostic impact of subtyping pretreatment histologic material in adenocarcinoma of the lung (ACL) according to WHO was evaluated in 259 consecutive, inoperable, Stage III patients. One hundred thirty patients (50%) had acinar adenocarcinoma, 23 (9%) had papillary adenocarcinoma, 13 (5%) had bronchioloalveolar carcinoma, and 32 (12%) had solid carcinoma with mucus formation; five patients (2%) had other types of lung cancer. Subtyping was impossible due to cytology or insufficient histologic material in 56 patients (22%). Bronchioloalveolar carcinoma had the longest median duration of response to chemotherapy (47 weeks), time to progression (33 weeks), and median survival (40 weeks). Corresponding values for solid carcinoma with mucus formation were 8, 12, and 22 weeks. Acinar and papillary adenocarcinoma were intermediate. Survival curves and response rates were similar (P greater than 0.05). Bronchioloalveolar carcinoma had 46% 1-year survivors compared to 16% to 22% for other subtypes. The subtypes may have an impact on the prognosis of ACL, but further evaluation is required.

Enzymatic determination of serum neuron-specific enolase in small cell lung cancers. Utility of the serum neuron-specific enolase/serum nonneuronal enolase ratio

Increasing interest is shown in the determination of the serum neuron-specific enolase for the diagnosis and the follow-up studies of small cell lung cancers. We report results obtained by an enzymatic procedure that permits the simultaneous determination of the neuron and nonneuron-specific enolase and the calculation of the ratio of these two components. The utility of this ratio which characterizes elevations of the serum neuron-specific enolase from a poor or rich source of this component was tested in 38 patients with small cell lung carcinoma and in 57 subjects suffering from other bronchogenic cancers. The control group consisted of 37 blood donors and 56 patients with respiratory disease. For the diagnosis, the sensitivity and the specificity of the enzymatically determined neuron-specific enolase compared well with published results obtained by radioimmunoassay and enzymoimmunoassay. The use of the ratio clearly increases the specificity of the test, since only 5.3 percent of false positive results are found when bronchogenic tumors other than small cell carcinoma are studied. The sensitivity was 76 and 100 percent in diagnosis of limited and extensive forms, respectively. The use of this ratio in the follow-up of the patients and for the determinations in hemolyzed samples is set out.

Altered metastatic behavior of small cell carcinoma of the lung after chemotherapy and radiation

Heterogeneity of malignant neoplasms is a recognized phenomenon now, but the implications of this with respect to the responsiveness of carcinomas to different modes of therapy are not known. To examine this question, we reviewed the clinical and pathologic features of 85 autopsied patients with small cell carcinoma of the lung. Patients who were treated with chemotherapy plus radiation survived significantly longer than all other patients (P less than 0.005), but there were no significant differences in the mean number of metastatic sites or overall tumor burden at autopsy. Patients who were treated with chemotherapy only had significantly more frequent (P less than 0.05) and more extensive (P less than 0.005) metastases to the leptomeninges, more frequent metastases to other sites within the lungs (P less than 0.05), and less frequent metastases to the adrenal glands (P less than 0.01) and pancreas (P less than 0.05). The patients who were treated with radiation only had more extensive metastases to the adrenal glands (P less than 0.005), and more frequent metastases to the pancreas (P less than 0.001), colon (P less than 0.01), and cerebral white matter (P less than 0.05). The patients who were treated with both chemotherapy and radiation had more frequent and more extensive metastases to the gastrointestinal tract (P less than 0.05) and serosal surfaces (P less than 0.01), but not to any site within the central nervous system (CNS). The latter suggests that prophylactic treatment of the CNS may not be necessary to prolong survival when patients are treated with both chemotherapy and radiation. The results also suggest that although chemotherapy and radiation may prolong survival in patients with small cell carcinoma of the lung, these forms of treatment change the biologic behavior of the tumors by eliminating certain clones that are distinguishable by their metastatic patterns.

Membrane antigens of human bronchial epithelial cells identified by monoclonal antibodies

Subpopulations of normal bronchial epithelial cells were identified using a series of murine monoclonal antibodies. These antibodies were used to stain intact bronchial epithelial cells in culture by indirect immunofluorescence. LAM 2 reacted with 80%, LAM 6 with 75%, LAM 7 with 60%, and LAM 8 with 5% of these cells. Sections of human bronchial epithelium were also stained with these antibodies by immunoperoxidase methods. LAM 2 was found to bind with 80%, LAM 6 with 65%, LAM 7 with 50%, and LAM 8 with less than 1% of bronchial epithelial cells. LAM 2 stained both columnar epithelial cells and basal cells; LAM 6 stained mainly basal cells and only a small proportion of columnar cells; LAM 7 showed specificity for basal cells; LAM 8 distinctly stained single cells in the basal cell layer. These antibodies were previously shown to react with the surface membrane of human lung carcinomas, ranging from the broad reactivity of LAM 2 with small cell and non-small cell lung cancers to the highly restricted reactivity of LAM 8 with small cell carcinomas of the lung. Thus, membrane antigens have been identified in bronchial epithelial cells by monoclonal antibodies which exhibit a similar range of cellular reactivity in vitro as in vivo. Inasmuch as these antibodies recognize subsets of cells which could not be easily distinguished by morphologic characteristics, these reagents may be useful in classifying bronchial epithelial cells.

Postchemotherapy resection of residual tumor in limited stage small cell lung cancer

To determine the feasibility of post-chemotherapy resection of residual tumor in small cell lung cancer, 24 selected patients with limited-stage disease were evaluated for exploratory thoracotomy. All 24 patients achieved partial or complete clinical response to chemotherapy and were considered adequate medical candidates for surgical resection. Fifteen patients underwent a lobectomy or pneumonectomy, 13 of whom had residual tumor in the resected specimen. Of the nine remaining patients, seven had no tumor found on biopsy at thoracotomy and two had unresectable mediastinal node involvement. No chemotherapy was administered postoperatively in any patient until disease progression or relapse was documented. Median survival for the entire group was 19 months and did not differ according to the surgical procedure performed. Nineteen patients had relapse. Patients undergoing biopsy only recurred locally in six of seven cases a median of five months post-thoracotomy (range one to six months). Two "biopsy only" patients were tumor free at 34+ and 56+ months. Local recurrence was observed in six of 12 resected patients, while six patients experienced only extrathoracic metastases. Median time to recurrence for resected patients was also five months. Four resected patients experienced late recurrence 16 to 36 months postoperatively and were alive with tumor at 29+ to 42+ months. Two resected patients were tumor-free at 13+ and 37+ months. Post-chemotherapy surgical resection was feasible in limited-stage patients and improved local control of disease.