Clinicopathologic characteristics of patients with nonsmall cell lung carcinoma with elevated serum progastrin-releasing peptide levels

Clinical significance of progastrin-releasing peptide, neuron-specific enolase, chromogranin a, and squamous cell cancer antigen in pulmonary neuroendocrine tumors

Background/aim

It is not always easy to diagnose pulmonary neuroendocrine tumors (PNETs). The aim of the present study is to make a differential diagnosis by studying the same markers in patients with non-small-cell lung carcinoma (NSCLC), patients with benign lung disease (chronic obstructive pulmonary disease and pneumonia), and healthy volunteers to determine the roles of these markers in pulmonary neuroendocrine tumor diagnosis and to identify their power.

Materials and methods

A total of 100 participants including 23 PNET patients and 28 NSCLC patients who were pathologically diagnosed but not yet treated, 25 participants with benign disease, and 24 healthy volunteers were included in this cross-sectional study.

Results

No significant difference was found between the chromogranin A (CgA) and squamous cell carcinoma antigen 1 (SCCA1) values among the groups (PNET, NSCLC, benign, healthy volunteers), but the difference in progesterone-releasing peptide (ProGRP), neuron-specific enolase (NSE), and adjusted NSE was statistically significant (P values were respectively ProGRP, P = 0.006; NSE, P = 0.015; NSE adjusted, P = 0.09). In a comparison of the PNET and NSCLC groups, having a ProGRP value higher than 84.6 pg/mL revealed PNET with 60.9% sensitivity and 89.3% specificity (P = 0.001).

Conclusion

The ProGRP value is the only indicator that distinguishes the PNET group from the other 3 groups.

Meta-Analysis of Serum Gastrin-Releasing Peptide Precursor as a Biomarker for Diagnosis of Small Cell Lung Cancer

Background:

The serum level of gastrin-releasing peptide precursor (proGRP) is generally? elevated in patients with small cell lung cancer (SCLC). However, the diagnostic sensitivity and specificity of serum proGRP in SCLC cases remains controversial. The study aimed to assess the diagnostic value of this biomarker by meta-analysis.

Materials and Methods:

The Cochrane, Clinical trials, Pubmed, Web of Science and Embase databases were searched and diagnostic values were calculated or extracted. Statistical analysis was accomplished with RevMan 5.3 and STATA 12.0 software.

Results:

A total of 27 studies with 7268 participants were included. The pooled sensitivity, specificity, PLR, NLR and DOR were 0.754 (95% CI: 0.700-0.802), 0.945 (95% CI: 0.916-0.965), 13.804 (95% CI: 9.096-20.948), 0.260 (95% CI: 0.213-0.317) and 53.101 (95% CI: 34.327-82.145) respectively. The AUC was 0.910 (95% CI: 0.880-0.930). Significant publication bias was not found (P =0.622).

Conclusions:

The meta-analysis indicated that serum proGRP is indeed a useful biomarker with goodsensitivity and high specificity for diagnosis of SCLC. Therefore proGRP can be expected to be widely applied in the clinic for identification of lung cancer patients.

New ARCHITECT plasma pro-gastrin-releasing peptide assay for diagnosing and monitoring small-cell lung cancer

Background:

Progastrin-releasing peptide (ProGRP) is a potential marker for small-cell lung cancer (SCLC) in serum; however, it may be more stable in plasma. We investigated a new plasma assay (ProGRPp) and its usefulness in diagnosing and monitoring SCLC.

Methods:

The marker concentrations were determined on the ARCHITECT i system.

Results:

The assay could distinguish SCLC from non-small-cell lung cancer (NSCLC: area under the curve 0.931, 95% CI 0.893–0.969; cross-validated accuracy 0.813; sensitivity 84.0%, specificity 96.3% at 140 pg ml⁻¹ cutoff). The probability of SCLC when ProGRPp was >140 pg ml⁻¹ was 91.8%, after adjusting for age, gender, and renal dysfunction. The NSCLC patients with ProGRPp >140 pg ml⁻¹ were at high risk (odds ratio=37.0, P<0.001) for tumours with neuroendocrine features. False negatives in SCLC were associated with a lack of thyroid transcription factor-1 (P<0.001). A decrease of ProGRPp to <140 pg ml⁻¹ during chemotherapy was significantly associated with the image-based response (P<0.001), and independently affected progression-free survival (PFS, relative risk=2.51, P=0.04) and overall survival (OS, relative risk=4.38, P=0.003), after adjustment for imaging response, performance status, and stage.

Conclusions:

The ProGRPp assay is specific and sensitive for diagnosing SCLC. Changes in ProGRPp during chemotherapy are significantly associated with image-based response, PFS, and OS.

Neuropeptides as lung cancer growth factors

This manuscript is written in honor of the Festschrift for Abba Kastin. I met Abba at a Society for Neuroscience meeting and learned that he was Editor-in-Chief of the Journal Peptides. I submitted manuscripts to the journal on "Neuropeptides as Growth Factors in Cancer" and subsequently was named to the Editorial Advisory Board. Over the past 30 years I have published dozens of manuscripts in Peptides and reviewed hundreds of submitted manuscripts. It was always rewarding to interact with Abba, a consummate professional. When I attended meetings in New Orleans I would sometimes go out to dinner with him at the restaurant "Commanders Palace". When I chaired the Summer Neuropeptide Conference we were honored to have him receive the Fleur Strand Award one year in Israel. I think that his biggest editorial contribution has been the "Handbook of Biologically Active Peptides." I served as a Section Editor on "Cancer/Anticancer Peptides" and again found that it was a pleasure working with him. This review focuses on the mechanisms by which bombesin-like peptides, neurotensin and vasoactive intestinal peptide regulate the growth of lung cancer.

Large cell neuroendocrine carcinoma of the lung: is it possible to diagnose from biopsy specimens?

OBJECTIVE

We have recently proposed new diagnostic criteria for high-grade non-small cell neuroendocrine carcinoma, i.e. possible large cell neuroendocrine carcinoma, in biopsy specimens and have started a clinicopathological comparative study of high-grade neuroendocrine carcinomas in an advanced stage. This study aimed to elucidate the usefulness of our diagnostic criteria for inoperable advanced large cell neuroendocrine carcinoma and to know the true incidence of large cell neuroendocrine carcinoma among lung cancers.

METHODS

We reviewed all cancer lesions (1040 specimens) obtained by transbronchial lung biopsies in our hospital from 2002 to 2009 and selected 38 biopsy specimens that satisfied our diagnostic criteria for high-grade non-small cell neuroendocrine carcinoma. All 38 cases were clinicopathologically investigated and all biopsy specimens were precisely studied for their morphological characteristics.

RESULTS

Clinicopathological information about the selected 38 cases was very similar to the clinicopathological characteristics of large cell neuroendocrine carcinoma reported. Of 38 cases, six were at Stage I, II or IIIA, underwent surgery, and the diagnosis was confirmed to be large cell neuroendocrine carcinoma using surgical tumor specimens. In the 38 biopsy specimens, features of neuroendocrine morphology such as organoid nesting, peripheral palisading and rosette formation were not frequent histological features and the majority of tumor cells contained nuclei with a fine chromatin pattern. Mitoses were difficult to find; however, immunohistochemical Ki-67/MIB1 labeling indices were quite useful for evaluating proliferative activity, which ranged from 43.4 to 99.0%.

CONCLUSIONS

Our study showed the diagnostic potential of using biopsy specimens for large cell neuroendocrine carcinoma, and we herein proposed more simplified diagnostic criteria for possible large cell neuroendocrine carcinoma in practical diagnostic use.

Early clinical diagnosis of synchronous multiple primary lung cancer

The diagnosis of synchronous multiple primary lung cancer (SMPLC) remains a formidable challenge. The aim of the present study was to identify useful clues for the clinical diagnosis of SMPLC, in particular for the early stages. The medical records of 10 patients diagnosed with SMPLC with different histological types were analyzed retrospectively. Chest computed tomography (CT) findings showed two pulmonary lesions in all patients. The two lesions displayed malignant characteristics of primary lung cancer. The levels of a number of tumor markers, including carcinoembryonic antigen, neuron-specific enolase, cytokeratin fragment 21-1, squamous cell carcinoma and CA125 increased in 2 patients. Auxiliary examinations of other physical sites in these patients did not show signs of neoplasm metastasis. Two tumors were separately staged and appropriate treatment was carried out based on the revised stage, which provided more benefits for SMPLC patients. The diagnosis of SMPLC might be delayed or mistaken owing to its similarity to neoplasm metastasis. A high index of awareness is required for the early diagnosis of this disease. The malignant characteristics of primary lung cancer in various lesions may be valuable clues for the diagnosis of SMPLC. Alterations in the levels of tumor markers may be a poor diagnostic tool for the detection of SMPLC. Separate biopsies for different pulmonary masses should be performed for clinical staging as soon as possible and reasonable treatment based on the stage should also be selected.

Diagnostic value of pro-gastrin-releasing peptide for small cell lung cancer: a meta-analysis

BACKGROUND

Lung cancer, of which 15%-20% is small cell lung cancer, is the leading cause of cancer mortality and shows a high incidence worldwide. While pro-gastrin-releasing peptide (ProGRP) has been reported as a predictive diagnostic factor, it has not been widely accepted because of inconsistent conclusions. The aim of this study was to systematically evaluate ProGRP as the diagnostic standard for small cell lung cancer.

METHODS

All published studies on ProGRP in the diagnosis of small cell lung cancer from January 1994 to April of 2010 were retrieved. By measuring methodological qualities, 11 papers were selected for this study. The overall diagnostic sensitivity, specificity, and area under the receiver operating characteristic curve were used to evaluate ProGRP as the diagnostic standard for small cell lung cancer using Meta DiSc statistical software.

RESULTS

There were 5146 subjects included in this meta-analysis. The sensitivity and specificity (95% confidence interval) of ProGRP was 0.716 (0.688-0.743) and 0.921 (0.909-0.932), respectively. The area under the summary receiver operating characteristic curve of ProGRP was 0.9236. The index of Q* was 0.8575.

CONCLUSIONS

ProGRP has better sensitivity and high specificity as an auxiliary indicator for the diagnosis of small cell lung cancer.

Clinicopathological findings of non-small-cell lung cancer with high serum progastrin-releasing peptide concentrations

Although progastrin-releasing peptide (proGRP) is used as a serum tumor marker for small cell lung cancer (SCLC), high serum pro-GRP concentrations are observed in some non-small-cell lung cancers (NSCLCs). The characteristics of these NSCLCs are not well known. To determine the clinicopathological features of NSCLC in patients with elevated serum proGRP concentrations, serum proGRP values were assessed in 654 advanced lung cancer patients, and positive (>46pg/mL) NSCLC specimens were subjected to cytological and histopathological reevaluation. Serum proGRP concentrations were positive in 34 of 421 NSCLC patients (8.1%) and 186 of 233 SCLC patients (80%). Histological subtypes of the 34 NSCLC patients at diagnosis were 20 adenocarcinomas, 5 squamous cell carcinomas, 4 large cell carcinomas, and 5 large cell neuroendocrine carcinomas. Six of 27 cytology specimens contained characteristic neuroendocrine morphology. Immunohistochemical analysis showed that 11 of 17 tumors were positive for neuroendocrine markers (64.7%). Twenty of 34 serum proGRP-positive NSCLC patients received platinum-based chemotherapy, and the response rate was 55.0%. These results suggest that serum proGRP-positive NSCLCs may have neuroendocrine differentiation. In addition, serum proGRP-positive NSCLCs may have clinical characteristics that are different from other NSCLCs.

Gastrin-releasing peptide: different forms, different functions

All forms of the neuropeptide gastrin-releasing peptide (GRP) are derived from the precursor proGRP1-125. Amidated GRP18-27, which together with amidated GRP1-27 was long thought to be the only biologically relevant product of the GRP gene, is involved in a multitude of physiological functions and acts as a mitogen, morphogen, and proangiogenic factor in certain cancers. Recently, GRP has been implicated in several psychiatric conditions, in the maintenance of circadian rhythm, in spinal transmission of the itch sensation, and in inflammation and wound repair. The actions of GRP are mediated by the GRP receptor. Over the last decade, nonamidated peptides derived from proGRP, such as the glycine-extended form GRP18-28 and recombinant and synthetic fragments from proGRP31-125, have been shown to be biologically active in a range of tissues and in cancer cell lines. While GRP18-28 acts via the GRP receptor, the identity of the receptor for proGRP31-125 and its fragments has not yet been established. Nonamidated fragments are also present in normal tissues and in various cancers. In fact, proGRP31-98 is the most sensitive serum biomarker in patients with small cell lung cancer and is a significant predictor of poor survival in patients with advanced prostate cancer.

Lung Cancer - Clinical Implications

Karcinom pluća je najčešće maligno oboljenje kod muškog pola, a u žena na drugom mestu (nakon raka dojke). Klinička podela na nemikrocelularni (NSCLC) i mikrocelularni (SCLC) odražava različito biološko ponašanje i sledstveno razlike u terapijskom pristupu. Od velike važnosti bi bilo postojanje biomarkera koji bi omogućili razlikovanje ova dva tipa karcinoma pluća, naročito u slučajeva kada nije izvodljiva invazivna dijagnostika kao i u praćenju efekata terapije i ranom otkrivanju relapsa bolesti. Rezultati velikih retrospektivnih ili prospektivnih studija ukazuju na izvesnu vrednost specifičnih markera ili kombinacija ovih markera za dijagnostičke i diferencijalno dijagnostičke svrhe. Merenje četiri serum tumor markera, CYFRA 21-1, CEA, NSE i ProGRP ima opravdanja da bi se identifikovao vodeći marker i na taj način predpostavio verovatni histološki tip tumora. Serijska određivanja odgovarajućeg tumor markera može takođe biti od pomoći da se utvrdi kompletnost uklanjanja tumora i utvrdi relaps bolesti u okultnom kliničkom stadijumu.

Tumor markers in detection of lung cancer

The expression of biomarkers by lung cancers is useful in the diagnosis and clinical management of patients with lung cancer. Biomarkers provide insight into histogenesis, interrelationships, and biological behavior of lung tumors. This chapter presents data on lung cancer detection, involving some of the most studied and interesting lung cancer biomarkers to date-CYFRA 21-1, NSE, ProGRP, SCC, CEA, Tumor M2-PK, as well as markers in clinical application such as CRP, LDH, tumor-suppressor genes and oncogenes, CA125, CgA, NCAM, and TPA. Biomarker profiles in combination with fuzzy logic techniques have also been addressed. Serum markers used alone or in combination with other indices might play an important role in monitoring response to therapy in early detection of tumor reactivation in new treatment strategies as well as in secondary prevention.

The prognostic significance of circulating neuroendocrine markers chromogranin a, pro-gastrin-releasing peptide and neuron-specific enolase in patients with advanced non-small-cell lung cancer

BACKGROUND

Chromogranin A (CGA), Pro-gastrin-releasing peptide (ProGRP) and neuron-specific enolase (NSE) are known as immunohistochemical tissue markers closely associated with neuroendocrine differentiation in non-small-cell lung carcinoma (NSCLC). The aim of the present study was to assess the value of serum levels of these markers in predicting response to chemotherapy and survival of patients with unresectable NSCLC.

METHODS

The study included 67 patients with advanced NSCLC treated with chemotherapy. Before treatment, serum levels of CGA, ProGRP and NSE were measured with commercial kits.

RESULTS

No association was found between serum NSE and age, gender, histology, performance status or extent of the disease. Distribution of serum CGA differed significantly according to gender and histology, with higher levels being found in men (p = 0.01) and in squamous cell carcinoma (p = 0.01). Serum ProGRP levels correlated with disease extent, being higher in patients with metastatic disease (M1) than in those with locoregional disease (M0; p = 0.02). The association of NSE, CGA and ProGRP levels with response to chemotherapy was not significant. While NSE had no impact on survival, the median survival was shorter for patients with elevated serum CGA and longer for patients with high ProGRP levels. Association with survival was significant when the Classification and Regression Tree (CART)-derived or median cutoff points were explored. On inclusion in multivariate Cox models, both CGA and ProGRP retained significance with high levels showing an opposite effect on survival [CART-derived cutoff points: CGA, relative risk (RR) -4.0; p < 0.001, and ProGRP, RR -0.4; p = 0.006, and median cutoff points: CGA, RR -1.8; p = 0.04, and ProGRP, RR -0.5; p = 0.03]. The combined use of CGA, ProGRP and NSE allowed for definition of two sets of patients with significantly different median survival times (25.2 vs. 8.8 months, p = 0.0001).

CONCLUSIONS

In the circulation, CGA and Pro-GRP appear to bear important information related to the prognosis for NSCLC patients before chemotherapy. While a high CGA before treatment was found as an unfavorable prognostic determinant, a high ProGRP conferred a survival advantage. The combined use of serum CGA, ProGRP and NSE may supply additional information to prognosis.

Complexity in the treatment of pulmonary large cell neuroendocrine carcinoma

PURPOSE

According to the World Health Organization (WHO) classification of pulmonary large cell neuroendocrine carcinoma (LCNEC), one of the neuroendocrine tumors of the lung, is considered as a variant of non-small cell lung carcinoma. The objective of this study was to investigate the treatment strategy for LCNEC.

METHODS

We retrospectively reviewed the clinical information of 12 patients with LCNEC.

RESULTS

Three patients with stage I disease underwent curative resection but all relapsed within 20 months. One with stage IIA disease underwent non-curative resection received adjuvant chemoradiotherapy (cisplatin plus etoposide) and is well with no evidence of recurrence. Two with stage IIIB disease received concurrent chemoradiotherapy. Both achieved partial response (PR) but relapsed within 2 months. One elderly patient with stage IIIA disease received vinorelbine alone and did not respond. Of five patients with stage IV disease, three received platinum-based chemotherapy but no patient achieved PR. Of five patients with gefitinib as salvage therapy, one achieved PR.

CONCLUSIONS

The prognosis of LCNEC is poor. To improve the outcome, we must evaluate the effectiveness of adjuvant or neoadjuvant therapy in patients with resectable disease. In addition, the evaluation of systemic and multimodality treatment strategies similar as in small cell lung cancer is worthy of consideration.

Prognostic implications of neuroendocrine differentiation and hormone production in patients with Stage I nonsmall cell lung carcinoma

BACKGROUND

Approximately 10-20% of nonsmall cell lung carcinomas (NSCLC) show neuroendocrine (NE) differentiation, as evaluated by panendocrine markers or ultrastructural evidence of dense-core secretory granules. However, little is known regarding the prevalence and clinical implications of NE differentiation in patients with Stage I NSCLC.

METHODS

The authors analyzed 220 consecutive patients with Stage I NSCLC (pT1-T2N0M0) among 2100 patients with primary lung carcinoma who underwent surgical treatment between 1987 and 1993. Using light microscopy and immunohistochemical staining for synaptophysin, chromogranin A, and respiratory tract-related hormones, 28 NSCLC specimens with NE differentiation (NSCLC-ND) and 11 large cell neuroendocrine carcinoma (LCNEC) specimens were identified.

RESULTS

The 28 NSCLC-ND specimens included 15 adenocarcinomas and 13 squamous cell carcinomas. Neoplastic cells with NE features never exceeded 20% in NSCLC-ND specimens, whereas neoplastic cells amounted to 20-90% in LCNEC specimens. NSCLC-ND specimens with > 5% NE-differentiated tumor cells showed increased Ki-67 labeling index (P = 0.007) and invasive phenotype, as evaluated by fascin immunoreactivity (P = 0.021). Patients with adenocarcinoma, but not with squamous cell carcinoma, who had > 5% NE-differentiated cells had a worse clinical course compared with patients who had ordinary NSCLC, with reduced overall survival (P = 0.017) and disease free survival (P = 0.049). In multivariate analysis, NE differentiation > 5% neoplastic cells in patients with adenocarcinoma independently predicted a poorer prognosis (hazard ratio, 2.61; 95% confidence interval, 0.99-6.85). Hormone production was restricted to chromogranin positive NSCLC-ND but did not affect prognosis.

CONCLUSIONS

Stage I adenocarcinomas with >or= 5% NE tumor cells are clinically aggressive tumors, similar to LCNEC. Hormone production identifies a more fully developed neuroendocrine phenotype but is not relevant to prognosis. The identification of NE-differentiated cells in patients with NSCLC may have clinical relevance.

Large cell neuroendocrine carcinoma of the lung: a clinicopathologic study of eighty-seven cases

OBJECTIVE

Large cell neuroendocrine carcinoma of the lung is a newly recognized clinicopathologic entity. The clinical characteristics and optimal treatment of patients with large cell carcinomas are not yet established. The aim of this study was to define the clinicopathologic characteristics of large cell neuroendocrine carcinoma.

METHODS

The histologic characteristics of the patients receiving an initial diagnosis of poorly differentiated non-small cell lung carcinoma (n = 484), small cell carcinoma (n = 55), carcinoid (n = 31), and large cell neuroendocrine carcinoma (n = 12) were retrospectively reviewed according to World Health Organization criteria. Immunohistochemistry was performed to confirm the neuroendocrine phenotype. The outcomes and other clinical characteristics of those patients with large cell neuroendocrine carcinoma were retrospectively analyzed and compared with those of patients with poorly differentiated carcinoma of other histologic types.

RESULTS

A total of 87 patients were given a diagnosis of large cell neuroendocrine carcinoma after the histologic review. These patients comprised 3.1% of all patients undergoing resection for primary lung cancer during the same period. The overall 5-year survival was 57%. The 5-year survivals of patients with stage I, II, III, and IV disease were 67%, 75%, 45%, and 0%, respectively. There was no statistically significant difference between the overall survival of patients with large cell neuroendocrine carcinoma and those with other non-small cell lung cancers. There was a significant difference between the survival of patients with stage I large cell neuroendocrine carcinoma and that of patients with the same stage of other non-small cell lung carcinomas. The site of the first documented recurrence was locoregional in 12 patients (34%), distant metastases in 20 patients (57%), and both simultaneously in 3 patients. Locoregional lymph node recurrences were observed frequently. More than 80% of recurrences were found within 1 year after the operation.

CONCLUSION

In terms of prognosis, large cell neuroendocrine carcinoma is distinctly different from other non-small cell lung cancers. The prognosis of large cell neuroendocrine carcinoma was poor, even for early stage disease; the prognosis of the stage I disease of large cell neuroendocrine carcinoma was poorer than that of the same stage of other non-small cell lung cancers. Because of its aggressive clinical behavior and poor prognosis, large cell neuroendocrine carcinoma should be recognized as one of the poorest prognostic subgroups among primary lung cancers, and therefore novel therapeutic approaches should be established.

Pro-gastrin-releasing peptide, neuron specific enolase and chromogranin A as serum markers of small cell lung cancer

BACKGROUND

Small cell lung cancer (SCLC) yields neuroendocrine properties. Pro-gastrin-releasing peptide (ProGRP), neuron specific enolase (NSE) and chromogranin A (CGA) are therefore putative serum markers in this disease.

AIM

To assess any difference in the sensitivity-specificity relationship between these neuroendocrine markers regarding various control populations and disease extent.

METHOD

A total of 146 patients were prospectively assessed clinically and biologically. Serum marker titrations were performed using commercial immunoradiometric assays (NSE, CGA) or ELISA (ProGRP). Areas under receiver operating characteristic curves (AUC-ROC) were calculated in order to assess the sensitivity-specificity relationship of each marker and to compare marker accuracy. Maximum Youden indices were used to determine marker thresholds able to produce the best overall diagnostic information.

RESULTS

Assessing the sensitivity in the SCLC population and the specificity in benign lung disease, ProGRP demonstrated the best sensitivity relationship in as much as its AUC-ROC was significantly greater than the ones calculated using NSE and CGA (respective values, 0.95, 0.89, 0.70; two-tailed Z-test <0.05). The ProGRP threshold value, which offered the best sensitivity-specificity relationship was 53 pg/ml corresponding to a 0.80 sensitivity and a 0.96 specificity. In addition, when specificity was assessed in NSCLC and again the sensitivity in the whole SCLC population, ProGRP continued to demonstrate a greater AUC-ROC in comparison with other markers. Using the 53 pg/ml threshold the specificity of this marker was excellent with no false positives in NSCLC. On the other hand, none of the markers were able to discriminate limited from extensive SCLC as suggested by the fact that AUC-ROC, constructed when sensitivity was defined as a positive test in extensive disease and specificity as a true negative test in limited disease, did not reach the upper left octant (AUC 0.65, 0.71 and 0.63 for ProGRP, NSE and CGA, respectively).

CONCLUSION

ProGRP yields the best sensitivity-specificity feature in SCLC, a result deserving further studies designed to evaluate the clinical applicability of this marker.

Demonstration and diagnostic significance of pro-gastrin-releasing peptide in medullary thyroid carcinoma

The expression of pro-gastrin-releasing peptide (proGRP) in medullary thyroid carcinoma (MTC) and other histological types of thyroid carcinoma was studied by an immunohistochemical technique, using polyclonal anti-proGRP antiserum. Immunoreactivity for proGRP was detected exclusively in MTC (n = 7); other histological types (n = 12) were all negative for proGRP. In addition, serum proGRP levels were elevated in patients with primary or recurrent MTC (n = 3), and they changed in parallel with serum calcitonin (CT), and carcinoembryonic antigen (CEA). These results show that proGRP, which is considered to be a specific marker for small-cell lung carcinoma, may be also a potential tumor marker for MTC, in addition to CT and CEA.