Calcitonin as a marker for bronchogenic cancer: a prospective study

Calcitonin-secreting neuroendocrine neoplasms of the lung: a systematic review and narrative synthesis

Calcitonin-secreting neuroendocrine neoplasms of the lung are rare, with few cases reported in the literature. Differentiating between medullary thyroid carcinoma and an ectopic source of calcitonin secretion can represent a complex diagnostic conundrum for managing physicians, with cases of unnecessary thyroidectomy reported in the literature. This manuscript reports a case of ectopic hypercalcitonaemia from a metastatic neuroendocrine neoplasm of the lung with concurrent thyroid pathology and summarises the results of a systematic review of the literature. Medical Literature Analysis and Retrieval System Online, Excerpta Medica, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov and SCOPUS databases were systematically and critically appraised for all peer reviewed manuscripts that suitably fulfilled the inclusion criteria established a priori. The protocol for this systematic review was developed according to the Preferred Reporting Items for Systematic review and Meta-Analysis Protocols, and followed methods outlined in The Cochrane Handbook for Systematic Reviews of Interventions. This systematic review is registered with PROSPERO. It is vital to consider diagnoses other than medullary thyroid carcinoma when presented with a patient with raised calcitonin, as it is not pathognomonic of medullary thyroid carcinoma. Lung neuroendocrine neoplasms can appear similar to medullary thyroid carcinoma histologically, they can secrete calcitonin and metastasize to the thyroid. Patients with medullary thyroid carcinoma may show stimulated calcitonin values over two or more times above the basal values, whereas calcitonin-secreting neuroendocrine neoplasms may or may not show response to stimulation tests. The present review summarises existing evidence from cases of ectopic hypercalcitonaemia to lung neuroendocrine neoplasms.

Procalcitonin as Marker of Recurrent Medullary Thyroid Carcinoma: A Systematic Review and Meta-Analysis

BACKGROUND

Calcitonin measurement is pivotal in the management of medullary thyroid carcinoma (MTC), but several pitfalls can affect its reliability. Other potential markers have been proposed, and procalcitonin (ProCT) has been reported as promising. The present study was undertaken to summarize the published data and provide more robust estimates on the reliability of ProCT as marker in the management of patients with MTC.

METHODS

The systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The sources comprised studies published through May 2018. Journal Articles that reported series of MTC patients undergone ProCT during postoperative follow-up were searched. A random-effects model was used for statistical pooling of the data. The I² index was used to quantify the consistency among the studies. The Egger test evaluated the possible presence of significant publication bias. Quality assessment of the studies was performed according to Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2).

RESULTS

According to inclusion and exclusion criteria five papers, reporting 296 MTC patients undergone ProCT evaluation, were finally selected. The number of MTC with recurrence was 140. The pooled sensitivity of ProCT in detecting recurrence was 96% (95% confidence interval [CI], 92% to 99%), with neither heterogeneity (I²=0%) nor publication bias (Egger test, 3.16; P=0.99). The pooled specificity was 96% (95% CI, 87% to 100%) with mild heterogeneity (I²=66.6%), while Egger test was not calculable.

CONCLUSION

The present meta-analysis provides evidence that ProCT is reliable to manage MTC patients during their postoperative follow-up.

Plasma Calcitonin and Tumors

Plasma levels of calcium, phosphorus, immunoreactive calcitonin (iCT), immunoreactive parathyroid hormone (iPTH), and carcinoembryonic antigen (CEA) were measured in patients affected by tumors of various organs: 22 breast, 41 lung, 23 kidney, 16 gastrointestinal tract, and 8 other types. iCT plasma level was elevated in 53.6% of patients with bronchogenic cancer, in 31.8% with breast cancer, in 65.3% with renal cancer, in 31.2% with gastrointestinal cancer, and in 62.5% with other tumors. Blood calcium level was increased in 6 patients suffering from lung cancer; iCT plasma level was increased in all but one of these subjects. iPTH plasma level, measured in 35 patients, was elevated only in one case, in which normo-calcemia was present. Our results demonstrate that plasma iCT is increased in a high percentage of cancer patients and that it is probably a good tumor marker. The simultaneous measurement of CEA increases the diagnostic probability of the individual marker. The incidence of laboratory findings suggestive of primary or ectopic hyperparathyroidism was very low in our series of patients.

Procalcitonin as a marker of severe bacterial infection in children in the emergency department

Procalcitonin, the prohormone of calcitonin, is a relatively new and innovative marker of bacterial infection that has multiple potential applications in the pediatric emergency department. In healthy individuals, circulating levels of procalcitonin are generally very low (<0.05 ng/mL), but in the setting of severe bacterial infection and sepsis, levels can increase by hundreds to thousands of fold within 4 to 6 hours. Although the exact physiologic function of procalcitonin has not been determined, the consistent response and rapid rise of this protein in the setting of severe bacterial infection make procalcitonin a very useful biomarker for invasive bacterial disease. In Europe, serum procalcitonin measurements are frequently used in the diagnosis and the management of patients in a variety of clinical settings. To date, the use of procalcitonin has been limited in the United States, but this valuable biomarker has many potential applications in both the pediatric emergency department and the intensive care unit. The intent of this article is to review the history of procalcitonin, describe the kinetics of the molecule in response to bacterial infection, describe the laboratory methods available for measuring procalcitonin, examine the main causes of procalcitonin elevation, and evaluate the potential applications of procalcitonin measurements in pediatric patients.

Procalcitonin: a marker for the diagnosis and follow-up of patients with medullary thyroid carcinoma

CONTEXT

Calcitonin (CT) is the main medullary thyroid carcinoma (MTC) tumor marker. However, it has several limitations, including a concentration-dependent biphasic half-life, sensitivity to rapid in vitro degradation, and the presence of different isoforms/fragments. Procalcitonin (PCT), the prohormone of calcitonin, is free of these limitations but is currently used only as a sepsis marker.

OBJECTIVES

The objective of the study was to determine whether PCT is suited as a MTC tumor marker by comparing the diagnostic performance of PCT with that of CT in MTC.

DESIGN

PCT and CT were measured in a total of 835 subjects, including normal volunteers (n = 197) and patients with active-MTC (n = 91), cured-MTC (n = 42), neuroendocrine tumors (n = 225), mastocytosis (n = 48), follicular cell-derived thyroid carcinoma (cured = 120, persistent/recurrent = 55), and benign thyroid disease (n = 57).

RESULTS

PCT levels were significantly higher in the active-MTC patients (mean 126.4 ng/ml) than the cured-MTC patients (mean <0.1 ng/ml). The overall concordance between the two markers was 95.7% (kappa = 0.81). Receiver-operating characteristic curve analysis showed no significant difference in diagnostic performance between CT and PCT. PCT's diagnostic sensitivity and specificity were 91 and 96%, respectively. The corresponding values for CT were 99 and 98%. Analyte stability studies showed that CT is very unstable in vitro with a decrease of 35-50% from the original value 24 h after the blood draw, whereas PCT levels did not significantly change during this time.

CONCLUSIONS

A strong correlation was observed between PCT and CT levels in patients with MCT. Given PCT's greater analytical stability, we conclude that it represents a promising complementary MTC tumor marker.

Procalcitonin assay in systemic inflammation, infection, and sepsis: clinical utility and limitations

OBJECTIVE

The use of procalcitonin (ProCT) as a marker of several clinical conditions, in particular, systemic inflammation, infection, and sepsis, will be clarified, and its current limitations will be delineated. In particular, the need for a more sensitive assay will be emphasized. For these purposes, the medical literature comprising clinical studies pertaining to the measurement of serum ProCT in various clinical settings was examined.

DATA SOURCE AND SELECTION

A PubMed search (1965 through November 2007) was conducted, including manual cross-referencing. Pertinent complete publications were obtained using the MeSH terms procalcitonin, C-reactive protein, sepsis, and biological markers. Textbook chapters were also read and extracted.

DATA EXTRACTION AND SYNTHESIS

Available clinical and other patient data from these sources were reviewed, including any data relating to precipitating factors, clinical findings, associated illnesses, and patient outcome. Published data concerning sensitivity, specificity, and reproducibility of ProCT assays were reviewed.

CONCLUSIONS

Based on available data, the measurement of serum ProCT has definite utility as a marker of severe systemic inflammation, infection, and sepsis. However, publications concerning its diagnostic and prognostic utility are contradictory. In addition, patient characteristics and clinical settings vary markedly, and the data have been difficult to interpret and often extrapolated inappropriately to clinical usage. Furthermore, attempts at meta-analyses are greatly compromised by the divergent circumstances of reported studies and by the sparsity and different timing of the ProCT assays. Although a high ProCT commonly occurs in infection, it is also elevated in some noninfectious conditions. Thus, the test is not a specific indicator of either infection or sepsis. Moreover, in any individual patient, the precipitating cause of an illness, the clinical milieu, and complicating conditions may render tenuous any reliable estimations of severity or prognosis. It also is apparent that even a febrile septic patient with documented bacteremia may not necessarily have a serum ProCT that is elevated above the limit of functional sensitivity of the assay. In this regard, the most commonly applied assay (i.e., LUMItest) is insufficiently sensitive to detect potentially important mild elevations or trends. Clinical studies with a more sensitive ProCT assay that is capable of rapid and practicable day-to-day monitoring are needed and shortly may be available. In addition, investigations showing that ProCT and its related peptides may have mediator relevance point to the need for evaluating therapeutic countermeasures and studying the pathophysiologic effect of hyperprocalcitonemia in serious infection and sepsis.

Evaluation of serum procalcitonin and interleukin-6 levels as markers of liver metastasis

OBJECTIVES

Procalcitonin (PCT) and interleukin-6 (IL-6) are established markers of tissue inflammation and injury. The aim of the present study was to investigate the possible correlation of PCT and IL-6 with liver metastasis.

DESIGN AND METHODS

The study consisted of fifteen healthy controls (group A), twenty-one patients with solid tumors without metastases (group B), eleven patients with liver metastasis only (group C) and eleven patients with generalized metastatic disease (group D).

RESULTS

Serum PCT levels were significantly increased in group D compared to groups A (p<0.001) and B (p=0.004), but no difference was observed in PCT levels between groups C and B or C and D. IL-6 serum levels were markedly elevated in group C compared to group A (p<0.001) or to groups B (p<0.001) and D (p=0.02). A positive correlation was observed between PCT and IL-6 serum levels (r=0.357, p=0.019).

CONCLUSIONS

PCT levels are related to disease stage in cancer patients, whereas IL-6 concentration seems to be a more specific marker of liver metastasis.

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.

Tumor markers in bronchogenic carcinoma. Superiority of tissue polypeptide antigen to carcinoembryonic antigen and carbohydrate antigenic determinant 19-9

One hundred six patients with histologically proven bronchogenic carcinoma were tested for carcinoembryonic antigen (CEA), tissue polypeptide antigen (TPA), and carbohydrate antigenic determinant 19-9 (CA19-9). A total of 349 CEAs, 350 TPAs, and 317 CA19-9s were measured. In addition, sera were assayed from 57 patients with pulmonary benign diseases and their CEA, TPA, and CA19-9 levels were used as negative controls for specificity and accuracy. One hundred twenty healthy subjects provided our normal CA19-9 reference value. Sensitivity, specificity, and accuracy were obtained for CEA, TPA, and CA19-9, respectively. Significant intermarker correlations were found both at diagnosis and during follow-up, CEA and CA19-9 being the most closely related substances. The percentage of patients with elevated levels of TPA increased significantly according to tumor load. Individual values of TPA related significantly to the stage of disease. Concentrations of CEA, TPA, and CA19-9 varied significantly during the course of the illness in relation to treatment response; however, TPA showed the closest relationship to the clinical status assessments of the follow-up period. Abnormal pretreatment levels of TPA were significantly associated with a poor outcome. Biomarker combinations were clinically evaluated by calculating the mean of the percentage of the reference value for each combined marker. Using this method, any association of TPA with CEA and/or CA19-9 revealed neither a greater diagnostic accuracy nor a more reliable predictive capacity for the above clinical variables than TPA evaluated on its own. The authors believe that a single TPA assay should be added to the initial and subsequent clinical assessments of patients with bronchogenic carcinoma.

Clinical value of a multiple biomarker assay in patients with bronchogenic carcinoma

In 98 newly diagnosed patients with histologically proven bronchogenic carcinoma seen at Cuneo Hospital of Chest Diseases from July 1983 to December 1984, multiple biomarker assays were performed. Fiftynine cases had more than one carcinoembryonic antigen (CEA) and/or tissue polypeptide antigen (TPA) assay during the course of the disease, at 3- to 12-week intervals. A total of 209 CEA (91 pretreatment), 170 TPA (80 pretreatment), 62 human chorionic gonadotropin (HCG)-beta subunits and 60 lactate dehydrogenase (LDH) was assayed. In addition, serum samples were taken from 141 blood donors and their TPA values were used as a control. The percentages of elevated values were, respectively, 37%, 52%, 18%, and 25%. In 85% of the patients at least one biomarker was found to be higher than normal. Neither significant differences between mean biomarker levels in tumors of various histologic types nor positive intermarker correlations were found. The number of patients with elevated CEA, TPA, and LDH serum levels and their mean values increased significantly according to the disease extent. Among evaluated markers TPA showed the highest accordance to tumor burden. The raising of two markers was never associated with Stage I-II disease, except in one patient. Both CEA and TPA concentrations changed significantly during the course of the illness in relation to the clinical status assessment. Abnormal pretreatment levels of CEA, LDH, and particularly, TPA were independently and significantly associated with a poor outcome. Patients with abnormal levels of TPA and LDH and, to a lesser degree, TPA and beta-HCG had shorter survival as compared with patients with high TPA values, irrespective of the LDH and beta-HCG levels, although not significantly so.

Lung tumour cell lines synthesizing peptide hormones established from tumours of four histological types: characterization of the cell lines and analysis of their peptide hormone production

Thirty permanent and more than 60 primary tumour cell lines were established from pleural and pericardial exudates or wedge biopsies from human bronchial carcinoma. The permanent cell lines have their origin in 6 small cell, 5 large cell, 9 squamous and 5 adeno carcinomas of the lung. Tumour cells were purified from non tumour cells by direct cloning in fluid cultures or by soft agar cloning. In vitro secretion of ACTH, bombesin, calcitonin, and neurotensin was demonstrated for lung tumour cells belonging to the four major histological types. Cell suspensions of peptide hormone secreting permanent cell cultures were grown to solid tumours after xenotransplantation into nude mice. Comparative ultrastructural examination of the primary tumour and of cells grown in tissue culture and in xenografts demonstrated the preservation of most tumour type specific structural criteria in the ex vivo/in vitro systems. The present data show that not only tumour cells from small cell carcinoma but also from other histological types are capable of synthesizing a broad spectrum of immunoreactive peptide hormones. This result might be interpreted as indicating a common expression of hormone biosynthesis and secretion by all lung tumours.

Comparison of tumour markers in malignant mesothelioma and pulmonary adenocarcinoma

Immunohistological methods were used to investigate the presence of carcinoembryonic antigen, beta 1 pregnancy specific glycoprotein, beta subunit of human chorionic gonadotrophin, human placental lactogen, calcitonin, and keratin in formalin fixed tissue from 29 malignant mesotheliomas and 27 pulmonary adenocarcinomas. Malignant mesotheliomas were negative for tumour markers except for the beta subunit of human chorionic gonadotrophin and keratin, one and 13 cases respectively being positive for these. Pulmonary adenocarcinomas, however, were frequently positive for tumour markers--namely, carcinoembryonic antigen, beta 1 pregnancy specific glycoprotein, beta subunit of human chorionic gonadotrophin, human placental lactogen, calcitonin, and keratin. The presence of carcinoembryonic antigen and beta 1 pregnancy specific glycoprotein within an intrathoracic tumour is strong evidence against its being of mesothelial origin.

Collaborative study for the evaluation of multiple simultaneous markers in lung cancer

The search for tumor markers suitable for use in diagnosis and management of patients with lung cancer has met with limited success because each available marker lacks sufficient sensitivity and specificity. We have begun a collaborative study to evaluate multiple simultaneous serum markers to determine whether there is a combination that will increase both sensitivity and specificity to the degree that noninvasive serologic tests might provide a means for managing patients with lung cancer. The National Cancer Institute, Bethesda, Maryland, has established a Serum Bank which can supply identical aliquots of the same serum sample to several different laboratories to perform quantitative assays for a number of markers. The results of these assays will serve as a data base to be analyzed for selection of the optimal grouping of markers for the different types of lung cancer and for evaluation of different biostatistical techniques to maximize the benefit derived by multiple marker determination. The evaluation of multiple markers will be carried out in several separate steps: (a) determination of a combination of markers that discriminate advanced lung cancer from benign lung disease; (b) demonstration of the ability of that combination to define early or localized lung cancer; (c) selection of a combination that best separates lung cancer from cancer of other sites; (d) testing of combined markers for the ability to predict response to therapy, including detection of early recurrence before clinical signs appear; and (e) evaluation of the combination(s) for effectiveness in detecting lung cancer in asymptomatic individuals. The experimental design and selection of markers will be presented and discussed.

Calcitonin secretion by continuous cultures of small cell carcinoma of the lung: incidence and immunoheterogeneity studies

A study was made of immunoreactive calcitonin (iCT) secretion by continuous cultures of small cell carcinoma of the lung (SCCL). Using an antiserum region specific for the midportion of the molecule, 9/12 cultures were found to secrete iCT. Gel filtration studies were performed on both supernatant fluid (SF) and cell pellet (CP) extract from a culture secreting high levels of iCT. Multiple iCT fractions were found in the SF with the major fraction being of high molecular weight (MW). In contrast, the CP had apparently monomeric CT as its principal iCT fraction. These studies demonstrate frequent iCT secretion by SCCL cultures and significant disparities between the iCT moieties found extra- and intracellularly.

The detection and evaluation of human tumor metastases

Many biochemical indices are purported to have clinical utility in the detection and management of neoplasia. Experience gained during the past decade tends to indicate their having a more important role in the detection and monitoring of metastases than of the primary lesion. From this present review of some of the commoner human tumours, it is concluded that such marker substances are important adjuncts in the management of germ cell and certain endocrine and endocrine-related tumours. The carcinoembryonic antigen (CEA) provides a marker for many gastrointestinal cancers, but there are no presently available substances with clinical usefulness for either breast or lung neoplasms. Alternative approaches to the detection of metastases are also presented. The particular use of antibody probes at an immunohistochemical level has been claimed to be able to detect micrometastastic disease in bone marrow or tumour-related monoclonal antibody probes may have application to other cancers in the future.

Hypothesis: the bronchial Kulchitsky (K) cell as a source of humoral biologic activity

The bronchial Kulchitsky cells are scattered specific cells which lie close to the basement membrane of the bronchi and bronchioles. Electron microscopy reveals that they contain electron-dense granules similar to that seen in cells with a known endocrine function. In addition, experimentally induced degranulation of the K cell suggestive of a secretory process, and the likelihood that these cells are precursors of small cell lung carcinoma (which often elaborates humoral substances) has led to the postulate that this bronchial cell serves a humoral role of either a paracrine or endocrine nature. We have found that the bronchial K cell of man contains a calcitonin-like polypeptide which, immunologically and chemically, is not dissimilar to the hormone produced by the C cells of human thyroid. This finding may help explain the persistence of serum immunoreactive calcitonin (iCT) after total thyroidectomy, the fact that thyroidectomized man does not manifest any profound alteration of calcium metabolism, and why small cell cancer of the lung is frequently associated with hypercalcitonemia. In addition, the finding of K cell hyperplasia in chronic bronchitis and emphysema may explain the occurrence of hypercalcitonemia in patients with these diseases and some lung cancers of cell types other than the small cell variety. Further studies are needed to elucidate the role of K cell iCT, and to determine what other hormones might also be elaborated by this diffuse system of bronchial cells.

A study of immunoreactive calcitonin (CT), adrenocorticotropic hormone (ACTH) and carcinoembryonic antigen (CEA) in lung cancer and other malignancies

Levels of immunoreactive ACTH and calcitonin (CT), as well as CEA, were determined serially in 144 patients with lung cancer and in 62 patients with metastatic carcinoma to the lungs. Patients with neoplasms not involving the lungs, with nonmalignant blood dyscrasias, and with chronic obstructive pulmonary disease were studied, as were normal control subjects. In 55-91% of lung cancer patients, elevated values of CT were detected; the frequency of elevation varied with cell type and stage. The highest values (mean 1346 +/- 2534 pg/ml) were found in patients with extensive small cell lung carcinoma (SCLC) and were significantly greater than the values for patients with SCLC confined to one hemithorax (196 +/- 287.7 pg/ml, P less than 0.005). ACTH levels were elevated less frequently (24-46%) and were highest (192 +/- 200.9 pg/ml) in patients with extensive small cell carcinoma, although Cushing's syndrome was observed only once. Agreement between all three tumor markers was seen in 25-50% of lung cancer patients; the percentage depended on cell type. Calcitonin levels paralleled changes in the clinical status and tumor burden in 89% of SCLC patients, while ACTH levels reflected the clinical course in 67%. In six patients with small cell carcinoma in remission, rising levels of CT, ACTH, and CEA preceded clinical evidence of relapse, in oe patient, by as long as five months. Among 129 patients with conditions other than primary lung cancer, CT levels were highest (232 +/- 328 pg/ml) in those with cancer metastatic to the lungs and/or pleura; there was no; association between CT levels and the presence of bone metastases.

Increased serum and urinary calcitonin levels in patients with pulmonary disease

Serum and urinary calcitonin levels were measured in patients with acute and chronic inflammatory diseases of the lung. Using both carboxyl terminal and midportion antisera, the incidence of increased immunoreactive values of this hormone was 68 percent for patients with emphysema, 59 percent for tuberculosis, and 89 percent for acute bacterial pneumonitis. In order to determine the source of the high levels of calcitonin, immunoperoxidase stains were made of sections of human lung; the hormone was found within the bronchial Kultschitzky cell (K cell). This suggests a specific endocrine role for the K cell, and may explain not only the high calcitonin levels in patients with inflammatory lung disease, but also the high levels associated with both carcinoid tumor and small cell carcinoma, which may originate from K cells. It is apparent that moderately high levels of calcitonin in a patient with pulmonary disease cannot always be associated with tumor.

Purification and partial characterization of high-molecular-weight forms of ectopic calcitonin from a human bronchial carcinoma cell line

Studies on the high-molecular-weight immunoreactive calcitonin produced ectopically in culture by an epidermoid bronchial carcinoma cell line are reported. In cell-exposed medium, the principal component has a molecular weight of 40000 and molecules of mol.wts. 13000 and 10000 also occur. Only a trace amount of material co-eluting with 35000-mol.wt. human calcitonin is detectable. None of the calcitonins show cross-reactivity with anti-corticotropin serum. The 40000-mol.wt. immunoreactive calcitonin is readily proteolysed to the 13000- and 10000-mol.wt. components, but the 10000-mol.wt. component behaves as a comparatively stable 'core' molecule. By using immunoprecipitation and high-pressure liquid chromatography (h.p.l.c.), it is possible to prepare radiochemically homogeneous 10000-mol.wt. immunoreactive calcitonin from cells grown in the presence of individual 35S- or 3H-labelled amino acids. Peptide mapping of enzymic digests of this material by h.p.l.c. shows that it contains peptides in common with synthetic human calcitonin.