Epidemiology of unknown primary tumours

Local Treatment Efficacy for Single-Area Squamous Cell Carcinoma of the Unknown Primary Site

The prognosis for cancer of unknown primary site (CUP) is poor, and squamous cell carcinoma of the unknown primary site (SCCUP) is a rare histological type. CUP is often treated with aggressive multimodal treatments, while the treatment of single-area localized CUP remains controversial. We retrospectively reviewed the medical records of patients with CUP. SCCUP in women was classified according to several definitions. Based on the histologic type and site, they were classified into favorable and unfavorable subsets. We further divided SCCUP into two types (single and multiple areas) and reviewed treatment and efficacy. Among the 227 female CUP patients, 36 (15%) had SCCUP. The median age was 59.9 years (range, 31-90 years). Most patients (61.1%) had a good performance status. Of the SCCUP patients, 22 had cancer in a single area, and 14 in multiple areas. Single-area SCCUP was further divided into favorable (16 cases) and unfavorable subsets (6 cases). In the favorable subset, local treatment was predominant, and almost all cases had a good prognosis. Even in the unfavorable subset, local therapy was combined with systemic chemotherapy in only two cases, and four cases showed no recurrences. Local treatment may be effective for single-area SCCUP, even in the unfavorable subset.

Confirmation of lung adenocarcinoma as the primary cancer with detection of EML4-ALK rearrangement using next-generation sequencing: a case study

We report a female patient, who presented as a carcinoma of unknown primary site with multiple tumors in breast, lung, stomach, and ovary, was confirmed to be lung adenocarcinoma as primary cancer through detecting EML4-ALK rearrangement by the next generation sequencing (NGS). The patient was treated with crizotinib and resulted in significant regression of the primary and metastatic tumors, but resistance to crizotinib was developed 5 months after the treatment. Targeted therapy was, therefore, switched to alectinib, one of the second-generation of anaplastic lymphoma kinase (ALK) inhibitors, with excellent therapeutic response till November 16th, 2021. This study suggested that NGS be recommended to detect ALK rearrangement in the patients with carcinoma of unknown primary site, and that resistance to targeted therapy with ALK inhibitors should be considered for personalized precision medicine.

Tumor Genomic Profiling to Determine Tissue Origin of Cancers of Unknown Primary: A Single Institute Experience With its Utility and Impact on Patient Management

Tumor genomic profiling represents a promising tool in diagnosis and management of cancer of unknown primary. We report our experience on the impact of genomic profiling in elucidating primary tumor site, correlation with pathologic findings and patient management. Tissue or cytology specimens from 22 cancers of unknown primary were referred for genomic profiling. Reports were available to review in 18 cases; 3 samples were inadequate for analysis. Of the remaining 15 cases, primary tumor site was suggested in 12 cases (80%), whereas it remained indeterminate in 3 (20%). Of the 12 cases, molecular profiling was concordant with light microscopy findings in 3 patients, whereas in 2 cases molecular testing identified a sarcoma, contradicting light microscopy and immunohistochemistry findings. The suggested primary was confirmed by additional immunohistochemistry in 1 case and by endoscopic biopsy in another. In 5 cases, follow-up biopsy or additional testing were not considered necessary for patient management. Three patients received palliative care and 12 received various chemotherapy regimens. Five patients died within a year, whereas 9 were alive more than a year after diagnosis, 3 of who were alive >3 years after diagnosis. In conclusion, genomic profiling helped confirm the original diagnosis and suggested primary sites in two third of our cases. Although many patients may be at a disease stage too advanced to withstand further investigations or underg aggressive therapy, molecular testing improves diagnostic accuracy and may thus assist in selection of the most appropriate therapy.

Sarcoma of unknown primary: myth or reality?

BACKGROUND

Sarcoma of unknown primary (SUP) designates an enigmatic entity with histologic confirmation of a metastatic tumor without an identifiable primary after a thorough diagnostic workup. The term "unknown primary" is heavily debatable given that sarcomas can arise from any tissue that harbors its histological structure. In this review, we discuss the validity of SUP as a distinct entity. Medline/PubMed and Google Scholar were searched from 1990 until April 2020 for publications in the English language reporting on SUP. We excluded articles reporting on cases with sarcomas from known organ sites such as lung or uterine sarcomas as well as synovial sarcomas. The Kaplan-Meier method was used to compute the median overall survival. A total of 26 patients with SUP were identified. The median age at diagnosis was 17.5 years with a similar prevalence among men and women. The tumors most commonly reported were alveolar rhabdomyosarcoma and rhabdomyosarcoma not otherwise specified. Almost two-thirds of the patients were reported to have more than one metastatic site. Among the 13 patients with survival data, the median overall survival was 10.0 months. Two patients underwent autopsy and had their primary culprit identified in the chest wall and paravertebral.

CONCLUSIONS

This review showed that SUP shares with sarcomas of known primary similar clinical features including an aggressive clinical course, generally poor response to chemotherapy, and dismal patient outcomes. Thus, SUP does not appear to display a different natural history and biological properties that would allude to a distinct entity.

Site-specific therapy in cancers of unknown primary site: a systematic review and meta-analysis

Background

Cancer of unknown primary site (CUP) is a term applied to characterize pathologically confirmed metastatic cancer with unknown primary tumor origin. It remains uncertain whether patients with CUP benefit from site-specific therapy guided by molecular profiling.

Patients and methods

A systematic search in PubMed, Web of Science, Embase, Cochrane Library, and ClinicalTrials.gov, and of conference abstracts from January 1976 to January 2021 was performed to identify studies investigating the efficacy of site-specific therapy on patients with CUP. The quality of included studies was evaluated using the Cochrane risk of bias tool and Newcastle–Ottawa scale. Eligible studies were weighted and pooled for meta-analysis. Hazard ratios (HRs) for overall survival (OS) and progression-free survival (PFS) were assessed to compare the efficacy of site-specific therapy with empiric therapy in patients with CUP. In addition, subgroup analyses were conducted.

Results

Five studies comprising 1114 patients were identified, of which 454 patients received site-specific therapy, and 660 patients received empiric therapy. Our meta-analysis revealed that site-specific therapy was not significantly associated with improved PFS [HR 0.93, 95% confidence interval (CI) 0.74-1.17, P = 0.534] and OS (HR 0.75, 95% CI 0.55-1.03, P = 0.069), compared with empiric therapy. However, during subgroup analysis significantly improved OS was associated with site-specific therapy in the high-accuracy predictive assay subgroup (HR 0.46, 95% CI 0.26-0.81, P = 0.008) compared with the low accuracy predictive assay subgroup (HR 0.93, 95% CI 0.75-1.15, P = 0.509). Furthermore, compared with patients with less responsive tumor types, more survival benefit from site-specific therapy was found in patients with more responsive tumors (HR 0.67, 95% CI 0.46-0.97, P = 0.037).

Conclusions

Our results suggest that site-specific therapy is not significantly associated with improved survival outcomes; however, it might benefit patients with CUP with responsive tumor types.

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Studies evaluating the role of site-specific therapy guided by molecular profiling in CUP provided contradictory results.

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Site-specific therapy is not significantly associated with improved survival outcomes in the overall CUP population.

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Molecularly defined site-specific therapy may improve OS only when high-accuracy assays assign CUP to responsive tumor types.

Extensive diagnostic work-up for patients with carcinoma of unknown primary

Patients with carcinoma of unknown primary (CUP) present with metastatic disease without an identified primary tumour. The unknown site of origin makes the diagnostic work-up and treatment challenging. Since little information is available regarding diagnostic work-up and treatment in daily practice, we collected and analysed these in a patient cohort with regard to the recommendations of the national CUP guideline. Data of 161 patients diagnosed with CUP in 2014 or 2015 were extracted from the Netherlands Cancer Registry (NCR) and supplemented with diagnostic work-up information from patient files and analysed. Patients underwent an average of five imaging studies during the diagnostic phase (range 1-17). From the tests as recommended in the national guideline on CUP, a chest X-ray was most commonly performed (73%), whereas a PET-CT was done in one out of four patients (24%). Biopsies were taken in 86% of the study population, with Cytokeratin 7 being the most frequently tested histopathological marker (73%). Less than half of patients received therapy (42%). CUP patients undergo extensive diagnostic work-up. The performance status did not influence the extent of the diagnostic work-up in CUP patients, but it was an important factor for receiving treatment.

Carcinoma of unknown primary with hepatic metastases: a need of judicious and contemplative diagnostic algorithm

Carcinoma of Unknown Primary presenting primarily as hepatic metastases encompasses a dismal subgroup of tumors with a median survival of 5.9 months. Adenocarcinoma is the most common histological subtype identified upon biopsy and the primary tumor remains undetectable in the majority of cases despite extensive workup. It is important to have a validated and standardized algorithm to follow these tumors to avoid unnecessary tests, as the wishes and health status of the patient represent the principal concerns. The purpose of this paper is to briefly review the current literature on carcinoma of unknown primary with hepatic metastases and propose a standardized diagnostic approach.

The diagnostic challenges of patients with carcinoma of unknown primary

INTRODUCTION

Cancer of unknown primary (CUP) is a disease entity encompassing heterogeneous malignancies without a clinically-detectable anatomical primary. It is usually a poor prognosis malignancy with dismal prognosis where molecular and genetic testing were expected to be a major breakthrough.

AREAS COVERED

In this review, we provide an overview of the advances in the understanding of the carcinogenesis, biology, diagnosis and treatment of patients with CUP. This review focuses on the advantages and inconveniences of immunohistochemistry and CUP classifiers in assessing the progress in the management of CUP.

EXPERT OPINION

CUP classifiers were expected to gradually replace the classical multistep approach in identifying the culprit tumors to guide site-specific therapy. Immunohistochemistry staining led to the prediction of a single tissue of origin in 10.8-51%. CUP classifiers identified the primary site in 61-89% of these cases and were concordant with immunohistochemistry in 57.1-100%. Immunohistochemistry is cheap, fast and broadly available whereas CUP classifiers are less widely available and have not been validated in randomized control trials. The diagnostic recommendations consist of a standard pathology evaluation based on morphology and algorithmic immunohistochemistry assessment. Physicians should weigh in the input of the CUP classifier to the clinical picture and pathology investigations before performing additional investigations.

The Quest for Improving Treatment of Cancer of Unknown Primary (CUP) Through Molecularly-Driven Treatments: A Systematic Review

Background: Carcinomas of unknown primary (CUP) account for 3–5% of all malignancy and, despite a reduction in incidence, the overall survival has not improved over the last decade. Chemotherapy regimens have not provided encouraging results. New diagnostic technologies, such as next generation sequencing (NGS), could represent a chance to identify potentially targetable genomic alterations in order to personalize treatment of CUP and provide insights into tumor biology.

Methods: A systematic review of studies of patients with CUP, whose tumor specimen was evaluated through a NGS panel, has been performed on June 10th, 2019 according to PRISMA criteria from PubMed, ASCO meeting library and Clinicaltrial.gov. We have identified potentially targetable alterations for which approved/off-label/in clinical trials drugs are available. Moreover, we have included case reports about CUP patients treated with targeted therapies driven by NGS results in order to explore the clinical role of NGS in this setting.

Results: We have evaluated 15 publications of which eleven studies (9 full-text articles and 2 abstracts) have analyzed the genomic profiling of CUPs through NGS technology, with different platforms and with different patients cohorts, ranging from 16 to 1,806 patients. Among all these studies, 85% of patients demonstrated at least one molecular alteration, the most frequent involving TP53 (41.88%), KRAS (18.81%), CDKN2A (8.8%), and PIK3CA (9.3%). A mean of 47.3% of patients harbored a potentially targetable alteration for which approved/off-label/in clinical trials drugs were available. Furthermore, we have identified 4 case reports in order to evaluate the clinical relevance of a specific targeted therapy identified through NGS.

Conclusions: NGS may represent a tool to improve diagnosis and treatment of CUP by identifying therapeutically actionable alterations and providing insights into tumor biology.

Progress in refining the clinical management of cancer of unknown primary in the molecular era

Cancer of unknown primary (CUP) is an enigmatic disease entity encompassing heterogeneous malignancies without a detectable primary tumour, despite a thorough diagnostic workup. A minority of patients with CUP (15-20%) can be assigned a putative primary tissue of origin according to clinical and histopathological findings and typically have a more favourable prognosis with the use of corresponding tumour type-specific therapies. Thus, the majority of patients with CUP have disease that cannot be assigned to a culprit primary tumour, are treated with empirical chemotherapy and have a poor prognosis. In the molecular era, the use of (epi)genomic or transcriptomic CUP classifiers and DNA or RNA sequencing offers two, sometimes overlapping, therapeutic strategies: tumour type-specific therapy and biomarker-guided therapy. Published data reveal that the accuracy of site-of-origin predictions made using CUP classifiers ranges between 54% and 98% when compared with the assignment made according to the recommended clinicopathological criteria. These advances have led to promising results in non-randomized prospective studies evaluating the efficacy of tumour type-specific therapy; however, the favourable outcomes were not confirmed in randomized controlled studies comparing this approach with standard empirical chemotherapy. Currently, the evidence supporting the use of biomarker-guided therapies is limited to case reports and small case series. In this Review, we discuss the clinical management of CUP in the era of precision medicine. We focus on the advances in understanding the biology of CUP, the implications for the diagnosis and classification of CUP according to the tissue of origin and the shift away from empirical therapy towards tailored therapy.

Molecular Profiles of Brain and Pulmonary Metastatic Disease in Cancer of Unknown Primary

Cancers of unknown primary (CUP) are histologically confirmed malignancies but for which further investigation cannot identify a primary site. Improvements in histopathologic modalities for diagnosis have lessened the frequency of CUPs to 3%-5% of all malignancies compared with historical estimates of 5%-10%. Despite this, there is an ongoing debate as to whether CUPs are malignancies where the primary is not found or if they are otherwise a fully separate entity. Improvements in molecular analysis holds promise for improved identification and treatment of CUPs with mixed preliminary results. Here we present a woman with CUP and metastases in her brain and lung. We performed genomic profiling to compare the molecular makeup of each site in order to establish treatment targets. KEY POINTS: Cancer of unknown primary remains a diagnostic and therapeutic challenge. Molecular analysis may provide improvements in diagnosis and novel treatment options. Different sites of metastatic disease have subtle variations in molecular profile. Sequencing of different sites may offer therapeutic options that are either already approved or available in clinical trial.

Carcinoma of unknown primary abuts left clavicle: Case report and review of the literature

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Carcinoma of unknown primary clinical manifestations usually associated with head and neck region.

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Painless cervical Lymphadenopathy is the most common symptom of the disease.

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Laboratory tests usually do not identify the primary disease.

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Limited data exists about management and the role of surgery in carcinoma of unknown primary if a single neck mass exists without evidence of lymph node implication.

Introduction

Carcinoma of unknown primary is a well-recognized clinical syndrome which accounts for the 3–5% of all the malignancies. Patients with carcinoma of unknown primary usually present with late stage disease without having identified the primary source of the tumour despite an extensive diagnostic work-up.

Presentation of case

A 60 years old male presented to the clinic complaining of a neck mass to the left lateral neck. Patient’s history was unremarkable without evidence of any malignant disease. Clinical and radiological examination revealed a cystic mass extending from the lower one third of the neck to the left clavicle causing periostal reaction. Mass biopsy and PET-CT was unspecific for the primary origin of the mass. However in the context of tumour immunohistochemistry, HPV status, neck location and basaloid cell differentiation, the tumour mass was considered as carcinoma of unknown primary with possible oropharyngeal primary location. The patient underwent surgical resection of the mass, left clavicle and the first rib. One year after the operation the patient is disease free.

Discussion

Although CUP usually presents with cervical lyphadenopathy, in our case there was no evidence of lymph node tissue infiltration in the neck region. Surgical resection of the mass showed that the location was extending within the cervical soft tissues and upper thorax. Taking into consideration the absence of lymphadenopathy this is an uncommon location of carcinoma of unknown primary in the neck.

Conclusion

This is an uncommon location of CUP with possible implications in survival and management.

Somatic substitution signature as an innovative tool in lung cancer diagnosis

Diagnosis of lung cancer can sometimes be challenging and is of major interest since effective molecular-guided therapies are available. Compounds of tobacco smoke may generate a specific substitutional signature in lung, which is the most exposed organ. To predict whether a tumor is of lung origin or not, we developed and validated the EASILUNG (Exome And SIgnature LUNG) test based on the relative frequencies of somatic substitutions on coding non-transcribed DNA strands from whole-exome sequenced tumors. Data from 7,796 frozen tumor samples (prior to any treatment) from 32 TCGA solid cancer groups were used for its development. External validation was carried out on a local dataset of 196 consecutive routine exome results. Eight out of the 12 classes of substitutions were required to compute the EASILUNG signature that demonstrated good calibration and good discriminative power with a sensitivity of 83% and a specificity of 72% after recalibration on the external validation dataset. This innovative test may be helpful in medical decision-making in patients with unknown primary tumors potentially of lung origin and in the diagnosis of lung cancer in smokers.

The Incidence of Nonmalignant Diseases among Patients with Suspected Carcinoma of Unknown Primary Site

Objective Few reports have analyzed the diagnostic process of carcinoma of unknown primary site (CUP) or have focused on the frequency of nonmalignant lesions among patients with suspected malignant diseases. The aim of this study was to investigate the incidence and characteristics of nonmalignant diseases that tend to be mistaken for malignant diseases. Patients We retrospectively analyzed the medical records of patients with suspected CUP who were referred to the National Cancer Center Hospital (Tokyo, Japan) between April 2007 and December 2014. All patients underwent a thorough history and physical examination as well as radiological and ultrasonography imaging tests for the CUP diagnostic work up. Results Among 830 patients with suspected CUP, 46 were diagnosed with nonmalignant diseases, and 780 were diagnosed with a malignant neoplasm (409 neoplasms with detected primary site and 371 CUP neoplasms). Four patients discontinued the diagnostic workup because they refused further examinations or had a poor general status. The final diagnosis of the 46 patients with nonmalignant disease comprised 10 benign tumors, 10 benign diseases, and 26 with no evidence of disease. The nonmalignant tumors comprised three hemangiomas, two schwannomas, two uterine myomas, two pseudomyxoma peritonei, one lymphangioma, one meningioma, and one poroma. Conclusion The incidence of nonmalignant diseases among patients with suspected CUP was 46 out of 830 patients in our institution. It is important to perform a thorough pathological examination in the CUP diagnostic workup. To confirm a diagnosis, some patients may need to visit specialized institutions, especially those with liver and bone lesions.

Inter-observer variability of clinical target volume delineation in definitive radiotherapy of neck lymph node metastases from unknown primary. A cooperative study of the Italian Association of Radiotherapy and Clinical Oncology (AIRO) Head and Neck Group

BACKGROUND

This study, promoted by Italian Association of Radiotherapy and Clinical Oncology (AIRO) Head and Neck Group, aimed to assess the current national practice of target volume delineation on a case of neck lymph node metastases from unknown primary evaluating inter-observer variability, in a setting of primary radiotherapy.

MATERIALS AND METHODS

A case of metastatic neck lymph node from occult primary was proposed to 17 radiation oncologists. A national reference RT center was identified and considered as benchmark. Participants were requested to delineate target volumes. A structured questionnaire was administered. A comparison between following parameters of the CTVs was performed: centroids distances, Dice similarity index (DSI), Jaccard index and mean distance to agreement (MDA). Volume expressed in cubic centimeters and CTVs cranio-caudal extension were evaluated.

RESULTS

Sixteen of 17 radiation oncologists recommended three CTVs dose levels. (CTV HD, CTV ID and CTV LD); CTV ID was not delineated by one of the participants and by the reference center. The distance between the reference centroid and the mean centroid of CTVs HD was 1.09 cm (0.36-3.99 cm); for CTV LD, a mean centroids distance of 2.45 (0.27-4.83 cm) was found, and for CTV HD, mean DSI is 0.48 and mean Jaccard index is 0.32 and MDA was 8.89 mm. CTV LD showed a mean DSI of 0.46, mean Jaccard index of 0.31 and MDA of 14.87 when compared to the reference.

CONCLUSION

Many aspects concerning treatment optimization of cervical nodes metastases from occult primary remain unclear, and we found a notable heterogeneity of global radiotherapy management reporting discordances both in target volume delineation and volume prescription.

[2018 Consensus statement by the Spanish Society of Pathology and the Spanish Society of Medical Oncology on the diagnosis and treatment of cancer of unknown primary]

Cancer of unknown primary is defined as a heterogeneous group of tumours that present with metastasis, and in which attempts to identify the original site have failed. They differ from other primary tumours in their biological features and how they spread, which means they can be considered a separate entity. There are several hypotheses regarding their origin, but the most plausible explanation for their aggressiveness and chemoresistance seems to involve chromosomal instability. Depending on the type of study done, cancer of unknown primary can account for 2-9% of all cancer patients, mostly 60-75 years old. This article reviews the main clinical, pathological and molecular studies conducted to analyse and determine the origin of cancer of unknown primary. The main strategies for patient management and treatment, by both clinicians and pathologists, are also addressed.

Liquid biopsy: a new diagnostic, predictive and prognostic window in cancers of unknown primary

Cancer of unknown primary (CUP) is a heterogeneous group of metastatic cancers characterised by early dissemination of metastases in the absence of any identifiable primary site. Most patients with CUP have poor prognosis with the traditional diagnostic and treatment modalities. Recognising the putative primary tumour is hypothesised to ameliorate the prognosis of patients with CUP by guiding treatment decisions. The active efforts in molecular oncology have shown that gene expression profiling is able to identify the primary tumour site and to determine targetable mutations. In this regard, liquid biopsy opens a new diagnostic, predictive and prognostic window in CUP that may lead to substantial improvement in the management of patients with CUP.

Cancer of unknown primary-Epidemiological trends and relevance of comprehensive genomic profiling

Background

Cancer of unknown primary (CUP) is a distinct clinicopathological entity with poor prognosis, frequently resistant to chemotherapy. Comprehensive genomic profiling (CGP) by next‐generation sequencing potentially identifies novel treatment options for CUP patients. The objective of this study was to determine incidence and survival trends and to discuss the value of CGP in CUP patients.

Methods

Age‐standardized incidence rates (ASR) per 100 000 were calculated for 2935 CUP patients from 1981 to 2014 using cancer registry data of the canton of Zurich, Switzerland. Kaplan–Meier survival curves were estimated for sex, age, and histological groups. Cox proportional hazards regression models were used to estimate adjusted hazard ratios (HR). A literature review was conducted to assess the current use of CGP in CUP patients.

Results

ASR of CUP increased from 10.3 to 17.6 between 1981 and 1997 and decreased to 5.8/100 000 in 2014. Mean overall survival remained stable. Mortality was significantly lower for patients with squamous cell carcinoma (HR 0.48 [95% CI, 0.41‐0.57]) and neuroendocrine carcinoma (0.75 [0.63‐0.88]) and higher for unclassified neoplasms (1.25 [1.13‐1.66]) compared to adenocarcinomas. The literature review identified 10 studies using CGP of CUP tissue. Clinically relevant mutations were identified in up to 85% of CUP patients, of which 13%‐64% may benefit from currently available drugs.

Conclusions

CUP incidence decreased probably due to improved diagnostics, but mortality did not improve over the last 34 years. CGP testing may help to identify molecular signatures in CUP patients and enable targeted treatment.

2018 consensus statement by the Spanish Society of Pathology and the Spanish Society of Medical Oncology on the diagnosis and treatment of cancer of unknown primary

Cancer of unknown primary (CUP) is defined as a heterogeneous group of tumours that present with metastasis, and in which attempts to identify the original site have failed. They differ from other primary tumours in their biological features and how they spread, which means that they can be considered a separate entity. There are several hypotheses regarding their origin, but the most plausible explanation for their aggressiveness and chemoresistance seems to involve chromosomal instability. Depending on the type of study done, CUP can account for 2–9% of all cancer patients, mostly 60–75 years old. This article reviews the main clinical, pathological, and molecular studies conducted to analyse and determine the origin of CUP. The main strategies for patient management and treatment, by both clinicians and pathologists, are also addressed.

Neuroendocrine tumors of unknown primary site: Gold dust or misdiagnosed neoplasms?

Aims and background

Neuroendocrine tumors of an unknown primary site are rarer than other neuroendocrine tumors (0.6–2% of all neuroendocrine tumors) and have a poor prognosis. The aim of the study was to review the cases of unknown primary site neuroendocrine tumors encountered at the Istituto Nazionale Tumori of Milan between 1984 and 2008 in order to verify their incidence and evaluate their characteristics and prognosis.

Methods and study design

During the study period, 750 neuroendocrine tumor patients attended our Institute, 82 of whom (10.9%) were diagnosed as having neuroendocrine tumors of an unknown primary site. The data from their medical records were analyzed descriptively, and survival probabilities were calculated using the Kaplan-Meier method and the logrank test, considering patient, tumor and treatment-related characteristics.

Results

The 82 patients with neuroendocrine tumors of an unknown primary site (34 males) had a median age of 60 years; 57 (69.5%) had histologically well-differentiated tumors, 3 (3.7%) poorly differentiated tumors, and 22 (26.8%) had tumors that could not be classified. Of the 52 patients (62.2%) who underwent Octreoscan(®) (Bykgulden Italia SpA), 40 (78.4%) showed a pathological uptake and 11 (21.6%) were negative. Thirty-one patients (37.8%) underwent metastatic site surgery, which was radical in 11 cases (35.4%). Forty-eight patients (58.5%) received somatostatin analogues, and 41 (50.0%) underwent chemotherapy. At the end of the study period, 59 patients (72.0%) had died, 31 (53.0%) because of disease progression, and 23 (28.0%) were still alive.

Conclusions

Neuroendocrine tumors of an unknown primary site are difficult to identify but their incidence is higher than previously reported, and the prognosis remains unfavorable.

Predictors of care for patients with cancer of unknown primary site in three Australian hospitals

AIM

Cancer of unknown primary site (CUP) is a medically challenging malignancy with a poor prognosis. We describe an incident tertiary CUP patient cohort and identify factors predictive of specific types of health care.

METHODS

We reviewed the medical records of 217 patients diagnosed with CUP (2006-2011) in three public hospitals in New South Wales, Australia. We systematically abstracted data and performed multivariable logistic regression to identify factors predictive of tumor biopsy, surgery, chemotherapy, radiotherapy and palliative care.

RESULTS

The median age at CUP diagnosis was 75 years (range 23-98) and 52% were male. The most common mode of presentation was emergency department admission (57%). Serum tumor markers were performed in 42%, fine needle aspiration alone in 15% and core biopsy in 52%. Younger age, health service referral, oncologist review and a family history of cancer predicted receipt of a biopsy (77%). Cancer-related surgery (17%) was more likely in younger patients, those presenting with pain, and those with single lymph node metastases. Younger age and good performance score predicted receipt of chemotherapy (22%). The location of metastases predicted receipt of radiotherapy (28%). Older age, emergency presentation, poor performance score and no oncology review predicted receipt of palliative care only (52%); 77% were referred for palliative care during hospitalization.

CONCLUSION

The determinants of care were generally consistent with international CUP clinical guidelines. Areas of future research include potential underinvestigation and undertreatment of older patients, overuse of certain low-value diagnostic tests, suboptimal use of immunohistochemistry and mammography and underreferral to palliative care.

Diagnostic and treatment modalities for patients with cervical lymph node metastases of unknown primary site - current status and challenges

Background and Purpose

This review aims to provide a comprehensive overview of the literature and elucidate open questions for future clinical trials concerning diagnostics and treatment modalities for cervical cancer of unknown primary (CUP).

Methods

A literature search for head and neck CUP was performed with focus on diagnostics and therapies as well as molecular markers.

Results

High level evidence on CUP is limited. However, it seems that a consensus exists regarding the optimal diagnostic procedures. The correct implementation of biomarkers for patient stratification and treatment remains unclear. An even greater dispute dominates about the ideal treatment with publications ranging from sole surgery to surgery with postoperative bilateral radiotherapy with inclusion of the mucosa and concomitant chemotherapy.

Conclusions

Cervical CUP represents a very heterogeneous malignant disease. On this account many aspects concerning treatment optimization remain unclear, despite a considerable number of publications in the past. Future research in form of prospective randomized trials is needed in order to better define patient stratification criteria and enable tailored treatment.

Development and validation of a gene expression tumour classifier for cancer of unknown primary

Accurate identification of the primary tumour in cancer of unknown primary (CUP) is required for effective treatment selection and improved patient outcomes. The aim of this study was to develop and validate a gene expression tumour classifier and integrate it with histopathology to identify the likely site of origin in CUP.RNA was extracted from 450 formalin fixed, paraffin embedded samples of known origin comprising 18 tumour groups. Whole genome expression analysis was performed using a bead-based array. Classification of the tumours made use of a binary support vector machine, together with recursive feature elimination. A hierarchical tumour classifier was developed and incorporated with conventional histopathology to identify the origins of metastatic tumours.The classifier demonstrated an accuracy of 88% for correctly predicting the tumour type on a validation set of known tumours (n = 94). For CUP samples (n = 49) having a final clinical diagnosis, the classifier improved the accuracy of histology alone for both single and multiple predictions. Furthermore, where histology alone could not suggest any specific diagnosis, the classifier was able to correctly predict the primary site of origin.We demonstrate the integration of gene expression profiling with conventional histopathology to aid the investigation of CUP.

Health service utilisation and investigations before diagnosis of cancer of unknown primary (CUP): A population-based nested case-control study in Australian Government Department of Veterans' Affairs clients

BACKGROUND

Population-based data on the use of health services and diagnostic investigations for patients with cancer of unknown primary (CUP) is scarce. It is uncertain whether the pathways to diagnosis are different for CUP compared to other cancers.

METHODS

We performed a population-based nested matched case-control study using linked routinely collected records for Australian Government Department of Veterans' Affairs clients, 2004-2007. We compared health care consultations, hospitalisations, emergency department visits, and diagnostic procedures in the three months prior and the month of diagnosis for 281 clients registered with a diagnosis of CUP (C809) and 1102 controls randomly selected from clients registered with a first diagnosis of metastatic cancer of known primary.

RESULTS

Overall, the median age at cancer diagnosis was 83 years. CUP patients were slightly older and had significantly more comorbidities prior to diagnosis than those with known primary. Compared to known primary, a diagnosis of CUP was significantly more likely after an emergency department visit, less specialist input, fewer invasive diagnostic procedures such as resection or endoscopy, and more non-invasive procedures such as magnetic resonance imaging. There were no differences in primary care or allied health consultations and hospitalisations.

CONCLUSIONS

This health care pathway suggests delayed recognition of cancer and scope for improvement in the medical management of high-risk individuals presenting to primary care. The pattern of diagnostic investigations reveals under-investigation in some CUP patients but this is likely to reflect recognition of limited treatment options and poor prognosis and is consistent with clinical guidelines.

Neuroendocrine cell carcinoma of unknown primary arising in long standing history of multiple sclerosis

Multiple sclerosis (MS) is a chronic autoimmune disease that targets myelinated axons in the central nervous system (CNS). Cancer of unknown primary site (CUP) is a well-recognised clinical disorder, accounting for 3–5% of all malignant epithelial tumors. CUP is clinically characterised as an aggressive disease with early dissemination. Studies of cancer risk in MS patients have shown inconsistent findings. An increased risk of malignancy in patients with MS has been suggested, but recently serious questions have been raised regarding this association. Use of disease-modifying therapies might contribute to an increased cancer risk in selected MS patients. The concurrence of MS and CUP is exceptionally rare. Here we describe the case of a neuroendocrine carcinoma of unknown primary diagnosed in a male patient with a nine-year history of MS. The discussion includes data from all available population-based register studies with estimates of certain malignancies in patients with MS.

Patients with cancer of unknown primary: a retrospective analysis of 223 patients with adenocarcinoma or undifferentiated carcinoma

BACKGROUND

Cancer of unknown primary (CUP) now accounts for 2-3% of all fatal cases of cancer in Germany. Histologically, most of these tumors are either adenocarcinoma or undifferentiated carcinoma. Scant data on their clinical features and prognosis are now available, and the published survival times are highly variable. In this article, we document and analyze our own experience with CUP to date.

METHOD

We took all 223 patients with CUP (adenocarcinoma or undifferentiated carcinoma) whom we saw in our CUP clinic from 2006 to 2010 as an unaltered sample for retrospective analysis of clinical data and overall survival. We performed the analysis with Kaplan-Meier plotting, log-rank testing, and Cox regression.

RESULTS

With a median follow-up time of 32.9 months, the median survival from the time of diagnosis was 16.5 months. Metastases were most commonly found in the lymph nodes, followed by the liver, bones, and lungs. The main pre-treatment prognostic variables that remained significant after adjustment for multiple testing were the Eastern Cooperative Oncology Group (ECOG) score for overall state of health and the number of organ systems involved. These variables were used to construct a practice-oriented risk stratification.

CONCLUSION

In patients with adeno- or undifferentiated CUP syndrome, the ECOG score and the number of organ systems involved are important risk factors.

[Cancer of unknown primary. Epidemiology and pathogenesis]

DEFINITION

The term cancer of unknown primary (CUP) describes by definition epithelial malignancies for which no primary tumor can be found after primary diagnostics have been performed.

EPIDEMIOLOGY

The CUP syndrome constitutes 2-3% of all fatal cases of malignancies in both men and women. The proportion of women has increased in parallel to the increase of tobacco consumption in women.

PATHOGENESIS

The most frequent origin appears to lie in the lungs or upper abdominal organs, while notable differences can be found between older autopsy findings and recent gene expression data with respect to identified primary tumors or tissue assignation. The fact that a primary tumor cannot be identified is probably based on various reasons: a complete regression of a primary tumor in isolated cases seems to be just as plausible as the misclassification of a primary tumor as a metastasis.

CONCLUSION

In combination with the fact that a primary tumor cannot be identified by autopsy in more than 20 % of cases, the important conclusion can be drawn that curative approaches seem appropriate for localized CUP cases.

Metabolic profiles are principally different between cancers of the liver, pancreas and breast

Molecular profiling of primary tumors may facilitate the classification of patients with cancer into more homogenous biological groups to aid clinical management. Metabolomic profiling has been shown to be a powerful tool in characterizing the biological mechanisms underlying a disease but has not been evaluated for its ability to classify cancers by their tissue of origin. Thus, we assessed metabolomic profiling as a novel tool for multiclass cancer characterization. Global metabolic profiling was employed to identify metabolites in paired tumor and non-tumor liver (n=60), breast (n=130) and pancreatic (n=76) tissue specimens. Unsupervised principal component analysis showed that metabolites are principally unique to each tissue and cancer type. Such a difference can also be observed even among early stage cancers, suggesting a significant and unique alteration of global metabolic pathways associated with each cancer type. Our global high-throughput metabolomic profiling study shows that specific biochemical alterations distinguish liver, pancreatic and breast cancer and could be applied as cancer classification tools to differentiate tumors based on tissue of origin.

Deep neck abscess as the predominant initial presentation of carcinoma of unknown primary: A case report

Malignancies, which present as deep neck abscesses are uncommon and may result in a delayed diagnosis or potentially a misdiagnosis. The present study describes a patient who exhibited a deep neck abscess as the initial manifestation of carcinoma of unknown primary (CUP). The aim of the present study was to raise awareness of this unusual presentation of CUP and emphasize the importance of repeating targeted fine-needle aspiration cytology or biopsies in patients presenting with a deep neck abscess suspicious for malignancy.

Causes of death in patients with extranodal cancer of unknown primary: searching for the primary site

BACKGROUND

Cancer of unknown primary (CUP) is a fatal cancer, accounting for 3-5% of all diagnosed cancers. Finding the primary site is important for therapeutic choices and we believe that the organ which is designated as the cause of death may give clues about the primary site.

METHODS

A total of 20,570 patients with CUP were identified from the Swedish Family-Cancer Database. Causes of death--as reported in the death certificate--were investigated, analyzing reported metastatic sites and histological subtypes separately. Survival was compared with metastatic cancer with a known primary tumor.

RESULTS

An organ-specific cancer could be identified as a cause of death in approximately 60% of all CUP patients with adenocarcinoma or undifferentiated histology. In adenocarcinoma, lung cancer was the most frequent cause of death (20%), followed by pancreatic cancer (14%), and ovarian cancer (11%). Lung cancer was the most common cause of death in patients with CUP metastases diagnosed in the nervous system (69%), respiratory system (53%), and bone (47%), whereas ovarian cancer was the most common cause of death when CUP was diagnosed in the pelvis (47%) or the peritoneum (32%). In CUP diagnosed in the liver, liver and pancreatic cancers accounted for 26% and 22% of deaths, respectively. Also in squamous cell CUP, lung cancer was the most common cause of death (45%).

CONCLUSIONS

According to the causes of death, the primary site appeared frequently to be either the organ where CUP metastases were diagnosed or an organ which may be traced through the known metastatic patterns of different cancer types.

Annexin A10 is an immunohistochemical marker for adenocarcinoma of the upper gastrointestinal tract and pancreatobiliary system

AIMS

Annexin A10 (ANXA10) is a calcium- and phospholipid-binding protein expressed normally in the gastric mucosa. In this study, we evaluated the potential use of ANXA10 as a diagnostic marker.

METHODS AND RESULTS

We observed ANXA10 expression in the gastric mucosa, the Brunner gland of the duodenum and the urothelium, but absence of expression in other normal organs. Following the screening of 1327 primary carcinomas of major organs, we identified ANXA10 expression in 46% of gastric, 72% of ampullary, 78% of pancreatic and 33% of biliary adenocarcinomas. ANXA10 was expressed in 83% of non-invasive urothelial carcinomas, but was expressed in only 9% of invasive urothelial carcinomas. ANAX10 was rarely expressed in carcinomas of other organs. Of 227 metastatic adenocarcinomas, ANXA10 was expressed in 83% of metastatic pancreatic and 47% of metastatic gastric adenocarcinomas, but was expressed in only 2% of metastatic adenocarcinomas from other organs. In the liver, the sensitivity and specificity for identifying the pancreas as the primary site of metastatic adenocarcinoma were 83 and 95%, respectively.

CONCLUSION

Our study results indicate that the inclusion of ANXA10 in an immunohistochemical panel will be helpful in the differential diagnosis of adenocarcinoma of an unknown primary site.

The yield and cost of colonoscopy in patients with metastatic cancer of unknown primary

BACKGROUND

Although gastroenterologists are asked to perform colonoscopy in patients with metastatic cancer of unknown primary (MCUP), studies evaluating this practice are lacking.

AIM

To determine the yield and cost of colonoscopy in patients referred for colonoscopy with an indication of MCUP.

METHODS

We prospectively and retrospectively assessed colonoscopies performed from 2000 to 2011 at a county, a university, and a Veterans Administration medical centre to identify patients referred for colonoscopy for the indication of MCUP. Exclusion criteria included overt or occult bleeding, iron-deficiency anaemia, familial-colon-cancer syndrome, prior colon cancer, imaging suggesting colorectal lesion, and palpable rectal mass. Outcomes were the number of primary colon cancers and costs based on 2012 Medicare reimbursements.

RESULTS

Two (1%) of the 160 patients meeting enrollment criteria had a primary colon cancer identified, and both died within 1 month after diagnosis without receiving therapy targeted at colon cancer. One patient without colon cancer had a perforation because of colonoscopy, which required surgery and colostomy. The cost of a strategy of routinely performing colonoscopy in patients referred with MCUP was $84 736 per colon primary identified.

CONCLUSIONS

Primary colon cancer was rarely identified at colonoscopy in patients with MCUP and no standard indications for diagnostic colonoscopy. Furthermore, the cost to diagnose one additional colon primary was very high. Those with colon cancer had advanced disease and were unable to benefit from targeted therapy. Routine colonoscopy for MCUP cannot be recommended at present.

The role of 18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography in the management of patients with carcinoma of unknown primary

Purpose

Carcinoma of unknown primary is one of the ten most frequent cancers worldwide. Its median survival time is less than 10 months. Detecting primary tumour locations and/or occult metastatic lesions may inform definitive treatment and improve patients’ prognosis. We aimed to determine: (1) the sensitivity, specificity and accuracy of 18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography; (2) its detection rate of primary tumour locations and occult metastases and (3) factors associated with improved survival times.

Methods

We retrospectively reviewed all cases in the West of Scotland for the period 1 December 2007 to 31 May 2011 that met all our selection criteria: (1) diagnosis of carcinoma of unknown primary; (2) a thorough but negative ‘work-up’ and (3) 18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography report. Statistical methods included frequencies, Kaplan-Meier graphs and log-rank tests to compare survival times.

Results

18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography detected primary tumour sites in 19/51 (37.3%) and occult metastases in 28/51 (54.9%) of eligible patients. Its sensitivity, specificity and accuracy were 79.2%, 70.4% and 74.5%, respectively; 20/51 (39.2%) patients died during the study period with a median survival of 8.4 months (range 21.4, SD ± 6.2). The number of metastatic locations was strongly associated with survival ( p = 0.002), but detection of a primary tumour site ( p = 0.174) or histopathology ( p = 0.301) was not.

Conclusion

18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography detected occult metastatic sites in the majority and a primary cancer location in a substantial minority of patients. Our results were comparable with international literature and may indicate that 18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography have an early role to improve the accuracy of cancer staging and to optimise carcinoma of unknown primary management.

Cervical squamous cell lymph node metastases from an unknown primary site: survival and patterns of recurrence after radiotherapy

Introduction

The purpose of the present retrospective study was to review outcome and patterns of failure of patients who were treated with radiotherapy for cervical lymph node metastases from an unknown primary site (CUP).

Patients and Methods

Between 2000 and 2009, 34 patients diagnosed with squamous cell CUP were admitted to radiotherapy in curative intent. In 26 of 34 patients (76%) neck dissection was performed prior to radiotherapy, extracapsular extension (ECE) was seen in 20 of 34 patients (59%). Target volumes included the bilateral neck and panpharyngeal mucosa. Concomitant chemotherapy was applied in 14 of 34 patients (41%).

Results

After a median follow-up of 45 months for the entire group, 2 of 34 patients (6%) presented with an isolated regional recurrence, another 2 of 34 patients (6%) developed both local and distant recurrence, and 6 of 34 patients (18%) had distant failure only. Estimated overall survival after 2- and 5 -years was 78% and 63%. All patients with N1 or N2a disease (n=6) were disease free after 5 years. ECE, concomitant chemotherapy and involvement of neck levels 4 and 5 were associated with worse overall survival on univariate analysis.

Conclusion

Radiotherapy of the panpharynx and bilateral neck leads to excellent local control while distant metastases are the most frequent site of failure and prognostically limiting. Therefore intensified concomitant or sequential systemic therapies should be evaluated in future trials.

Evaluation of survival benefits by platinums and taxanes for an unfavourable subset of carcinoma of unknown primary: a systematic review and meta-analysis

Background:

Although chemotherapeutic regimens containing a taxane or platinum agent have been widely recommended for unfavourable carcinoma of unknown primary (CUP), no evidence exists for the superiority of any administered regimens. To date, the efficacy has been mostly assessed in the limited setting of phase II trials, and few attempts have been made to synthesise all available data for survival outcomes.

Methods:

Electronic databases were searched from 1980 to 2011. Survival results were combined for each pre-specified category of regimens using a random-effects model, and meta-regression models were used to adjust for heterogeneity in some known prognostic factors.

Results:

A total of 32 studies were included for meta-analysis. Tendency towards better survival outcome by platinums or taxanes was indicated. After adjustment for important prognostic factors, however, the difference between the platinum-based and non-platinum regimens became no longer significant. Survival benefits by the taxane-based regimens remained significant, with a prolonged median survival time of 1.52 months (P=0.03) and a higher 1-year survival rate of 6.25% (P=0.05), but the benefit did not sustain for 2 years.

Conclusion:

Although no effective therapies have been established, this meta-analysis helps to fill an important gap of evidence. However, caution should still be taken because of the potential unmeasured confounding.

Multisite validation study to determine performance characteristics of a 92-gene molecular cancer classifier

PURPOSE

Accurate tumor classification is essential for cancer management as patient outcomes improve with use of site- and subtype-specific therapies. Current clinicopathologic evaluation is varied in approach, yet standardized diagnoses are critical for determining therapy. While gene expression-based cancer classifiers may potentially meet this need, imperative to determining their application to patient care is validation in rigorously designed studies. Here, we examined the performance of a 92-gene molecular classifier in a large multi-institution cohort.

EXPERIMENTAL DESIGN

Case selection incorporated specimens from more than 50 subtypes, including a range of tumor grades, metastatic and primary tumors, and limited tissue samples. Formalin-fixed, paraffin-embedded tumors passed pathologist-adjudicated review between three institutions. Tumor classification using a 92-gene quantitative reverse transcriptase polymerase chain reaction (RT-PCR) assay was conducted on blinded tumor sections from 790 cases and compared with adjudicated diagnoses.

RESULTS

The 92-gene assay showed overall sensitivities of 87% for tumor type [95% confidence interval (CI), 84-89] and 82% for subtype (95% CI, 79-85). Analyses of metastatic tumors, high-grade tumors, or cases with limited tissue showed no decrease in comparative performance (P = 0.16, 0.58, and 0.16). High specificity (96%-100%) was showed for ruling in a primary tumor in organs commonly harboring metastases. The assay incorrectly excluded the adjudicated diagnosis in 5% of cases.

CONCLUSIONS

The 92-gene assay showed strong performance for accurate molecular classification of a diverse set of tumor histologies. Results support potential use of the assay as a standardized molecular adjunct to routine clinicopathologic evaluation for tumor classification and primary site diagnosis.

Update on the diagnosis of cancer of unknown primary (CUP) origin

The cancer of unknown primary (CUP) concept encompasses a heterogeneous group of cancers that are difficult to diagnose and that show diverse clinical and histopathological features. Currently, CUP is the fifth most frequent cancer diagnosis in women and the eighth in men. The ongoing development of new therapies specific to the various cancer types makes mandatory the identification of the primary tumour in CUP patients, so that they may benefit from advances in therapy and improvements in prognosis. Molecular detection techniques provide very useful tools in the prediction of primary tumour types and must be used together with clinical, histopathological and IHC diagnostic techniques. Steady collaboration and fluid communication between oncologists and pathologists is of the utmost importance for the correct interpretation of tests and the personalised approach required by each individual case. Work in multidisciplinary teams will result in significant changes in the diagnosis and treatment of these patients.

Carcinomas of an unknown primary origin--diagnosis and treatment

Carcinomas of an unknown primary origin (CUP) account for 3-5% of all malignancies and are thus among the ten most-frequent cancers worldwide. Having a specific and unique phenotype of early and usually aggressive metastatic dissemination with no identifiable primary tumor, CUP are a challenge for physicians. The diagnostic workup of patients with CUP includes a careful clinical and extensive histopathological examination, as well as the use of imaging techniques. CUP can be divided into favorable and unfavorable subsets. Patients with unfavorable CUP subsets have a poor prognosis with a median survival of approximately 8 months; the optimal chemotherapy regimen for these patients remains to be determined. Although studies have focused on the introduction of new cytotoxic agents with broad-spectrum clinical activity (such as gemcitabine, irinotecan, and taxanes), no randomized trial has provided clear evidence of a survival benefit. Molecular targeted therapies that are approved for other solid tumors are now considered for the treatment of patients with CUP. Molecular diagnostic tools, such as DNA microarray analysis, could help in the search for 'lost' CUP origins. In this Review, we describe the clinical evaluation of patients with CUP, and discuss treatment strategies and outcomes of patients with various CUP subsets.

MicroRNA profiling for the identification of cancers with unknown primary tissue-of-origin

Cancer of unknown primary (CUP) represents a common and important clinical problem. There is evidence that most CUPs are metastases of carcinomas whose primary site cannot be recognized. Driven by the hypothesis that the knowledge of primary cancer could improve patient's prognosis, we investigated microRNA expression profiling as a tool for identifying the tissue of origin of metastases. We assessed microRNA expression from 101 formalin-fixed, paraffin-embedded (FFPE) samples from primary cancers and metastasis samples by using a microarray platform. Forty samples representing ten different cancer types were used for defining a cancer-type-specific microRNA signature, which was used for predicting primary sites of metastatic cancers. A 47-miRNA signature was identified and used to estimate tissue-of-origin probabilities for each sample. Overall, accuracy reached 100% for primary cancers and 78% for metastases in our cohort of samples. When the signature was applied to an independent published dataset of 170 samples, accuracy remained high: correct prediction was found within the first two options in 86% of the metastasis cases (first prediction was correct in 68% of cases). This signature was also applied to predict 16 CUPs. In this group, first predictions exhibited probabilities higher than 90% in most of the cases. These results establish that FFPE samples can be used to reveal the tissue of origin of metastatic cancers by using microRNA expression profiling and suggest that the approach, if applied, could provide strong indications for CUPs, whose correct diagnosis is presently undefined.

PET and PET/CT for unknown primary tumors

Carcinoma of unknown primary (CUP) is defined as histologically proven metastatic disease that, after a complete diagnostic work-up, yields no primary detectable tumor. CUP is one of the ten most frequent cancers, with overall poor outcome. Detection of the unknown primary tumor is of crucial importance in this scenario, since it might help to select and offer definitive treatment, which, in turn, may improve patient prognosis. Additional diagnostic work-up, usually consisting of a combination of several radiological and endoscopic investigations and serum tumor marker studies, can be time consuming, expensive, and pose a significant burden to the patient. The final diagnostic yield of these tests is often limited. Combined positron emission tomography/computed tomography (PET/CT), using the radiotracer (18)F-fluoro-2-deoxyglucose (FDG), may be of great value in the management of patients with CUP for the detection of primary tumors. This chapter gives a brief introduction to the syndrome of CUP, followed by an outline of the rationale, use, and utility of FDG-PET/CT in CUP, and concludes with a discussion on the challenges and future directions in the diagnostic management of patients with CUP.

Hypoxia-related protein expression and its clinicopathologic implication in carcinoma of unknown primary

Carcinoma of unknown primary (CUP) is a heterogeneous entity with different clinical and histological features. The aim of this study was to investigate the clinicopathological features and expression of proteins associated with carcinogenesis and tumor environment in different histological subtypes of CUP. Sixty-nine cases of CUP were subjected to immunohistochemistry for EGFR, phospho-EGFR, HER-2, phospho-HER-2, p53, ERCC1, RRM1, REDD1, HIF1α, COX-2, GLUT-1, 14-3-3σ, Phospho-mTOR, Phospho-S6, AMPKα1, Phospho-Akt, PDGF-β receptor, and caveolin-1, and fluorescence in situ hybridization for HER-2 gene amplification. Fourteen (20.3%) cases were poorly differentiated carcinoma, 24 (34.8%) were adenocarcinoma (AD), 17 (24.6%) were squamous cell carcinoma (SC), and 14 (20.3%) were undifferentiated carcinoma (UD). AD were mostly carcinomatosis type, while SC and UD were mostly nodal type (p < 0.001). SC showed more frequent EGFR overexpression (p < 0.001) and Glut-1 (p = 0.001). AD (p = 0.001) and carcinomatosis (p < 0.001) types showed shorter overall survival. SCs expressing Glut-1, HIF1α, and COX2 showed a poor prognosis (p = 0.048, 0.029, and 0.042, respectively). CUP shows various clinicopathological features according to the histological subtypes. SC is mainly associated with nodal metastasis in the head and neck, and frequent EGFR overexpression and Glut-1 expression. Glut-1, HIF1α, and COX2 expression in SC is associated with a poor prognosis.