Detection of unknown occult primary tumors using positron emission tomography

Recurrence of Cervical Lymph Node Metastasis From an Unknown Primary Site: A Report of a Case Treated Using a Multidisciplinary Approach

Metastatic cervical carcinoma from an unknown primary source poses a diagnostic and therapeutic challenge, as it involves the spread of cancer to the neck lymph nodes without a discernible primary tumor despite thorough investigation. While the diagnosis and treatment of this uncommon condition lack definitive evidence, a review of existing literature offers some clinical guidance. A comprehensive diagnostic evaluation, which includes multiple imaging and endoscopic studies, is essential. Surgery is preferred whenever feasible due to its ability to offer more precise staging. This treatment entails an excisional biopsy, neck dissection, and tonsillectomy, but advanced cases necessitate a combination of treatments. This case report underscores this complexity, where, despite radical neck dissection on the affected side, recurrence manifested after two months with no discernible primary site. We emphasize the urgency for continued research and innovative approaches to enhance the diagnosis and management of metastatic cervical carcinoma from an unknown primary source.

Recognizing Tumor Origin for Lymphoid Tumor of Unknown Primary via Total-Body PET/CT Scan—Case Report

Localizing the site of tumor origin for patients with lymphoid tumor is fairly difficult before the definitive detection of the primary tumor, which causes redundant imaging examinations and medical costs. To circumvent this obstacle, the emergence of the world’s first total-body positron emission tomography/computed tomography (PET/CT) provides a transformative platform for simultaneously static and dynamic human molecular imaging. Here, we reported a case of lymph node metastasis from an unknown primary tumor, and the primary tumor was detected with the aid of the total-body PET/CT scanner. This patient with right neck mass was subjected to static and dynamic PET scan, as the static PET imaging found irregular thickening of the upper rectal wall and the dynamic PET imaging recognized the associations between the lymph metastasis and the rectal tumor lesions. The diagnosis by the total-body PET/CT was confirmed by pathological examination.

Broadband diffuse optical spectroscopy of absolute methemoglobin concentration can distinguish benign and malignant breast lesions

SIGNIFICANCE

Noninvasive diffuse optical spectroscopy (DOS) is a promising adjunct diagnostic imaging technique for distinguishing benign and malignant breast lesions. Most DOS approaches require normalizing lesion biomarkers to healthy tissue since major tissue constituents exhibit large interpatient variations. However, absolute optical biomarkers are desirable as it avoids reference measurements which may be difficult or impractical to acquire.

AIM

Our goal is to determine whether absolute measurements of minor absorbers such as collagen and methemoglobin (metHb) can successfully distinguish lesions. We hypothesize that metHb would exhibit less interpatient variability and be more suitable as an absolute metric for malignancy. However, we would expect collagen to exhibit more variability, because unlike metHb, collagen is also present in the healthy tissue.

APPROACH

In this retrospective clinical study, 30 lesions with breast imaging reporting and database system score   (  BIRADS  )    >    =  3 (12 benign and 18 malignant) measured with broadband quantitative DOS were analyzed for their oxyhemoglobin (HbO), deoxyhemoglobin (HHb), water, lipids, collagen, metHb concentrations, and optical scattering characteristics. Wilcoxon rank sum test was used to compare benign and malignant lesions for all variables in both normalized and absolute forms.

RESULTS

Among all absolute DOS parameters considered, only absolute metHb was observed to be significant for lesion discrimination (0.43  ±  0.18  μM for benign versus 0.87  ±  0.32  μM for malignant, p  =  0.0002). Absolute metHb concentration was also determined to be the best predictor of malignancy with an area under the curve of 0.89.

CONCLUSIONS

Our findings demonstrate that lesion metHb concentration measured by DOS can improve noninvasive optical diagnosis of breast malignancies. Since metHb concentration found in normal breast tissue is extremely low, metHb may be a more direct indicator of malignancy that does not depend on other biomarkers found in healthy tissue with significant variability. Furthermore, absolute parameters require reduced measurement time and can be utilized in cases where healthy reference tissue is not available.

Melanoma With an Unknown Primary in an Asymptomatic Elderly Male With Unilateral Lymphadenopathy

Melanoma with an unknown primary (MUP) is an uncommon metastatic melanoma without an obvious primary site. MUP has a higher prevalence in men in their fifth decade of life. The pathogenesis of MUP is still unknown but several hypotheses have been proposed including the predominant regression theory, occult cutaneous, or visceral location, or by the presence of ectopic melanocytes. Proper physical examination, imaging, and histopathological review are needed to diagnose MUP. Patients with MUP must be aggressively treated and monitored for recurrence. We present a case of MUP occurring in an asymptomatic 61-year-old male with axillary lymphadenopathy. We hope to raise awareness that melanoma of unknown primary can present in lymph nodes without external structural changes.

FDG PET/CT for metastatic squamous cell carcinoma of unknown primary of the head and neck

OBJECTIVE

The role of FDG PET/CT is uncertain in squamous cell carcinoma of unknown primary (SCCUP). Published data are limited by heterogeneity of pathology, varied diagnostic criteria, and small sample size.

MATERIALS/METHODS

This retrospective study was conducted in 40 patients who had FDG PET/CT for SCCUP. Prior to PET/CT, patients had underwent standard clinical evaluations including flexible rhinolaryngoscopy. The majority of the patients had anatomic imaging. All subjects had histopathological investigations, and follow-up data after PET/CT.

RESULTS

FDG PET/CT detected the primary in 16 of 40 patients (40%), and the most common locations of the primary were in the base of the tongue, palatine tonsil, and hypopharynx. There were 10 false positive and 6 false negative PET/CT scans. There was no difference in the mean SUVs of the suspected primary lesions between true and false positive groups. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy of FDG PET/CT for SCCUP in this patient cohort were 72.7% (16/22), 44.4% (8/18), 61.5% (16/26), 57.1% (8/14), and 60% (24/40), respectively. The tonsil was the site with the most false positive and false negative findings.

CONCLUSIONS

FDG PET/CT might be an effective single shot of whole-body imaging for detection of the primary in SCCUP. Low specificity remained the most notable weakness of FDG-PET in work-up for SCCUP. In addition to varied physiologic uptake or inflammatory related uptake in the common locations of the primary, the image indication bias might be another significant contributor of high false positive rate.

Detection of unknown primary tumor in patients presented with brain metastasis by F-18 fluorodeoxyglucose positron emission tomography/computed tomography

Aim:

F-18 fluorodeoxyglucose (FDG) PET/CT has several advantages in diagnosis of cancer of unknown primary with reported incremental diagnostic value. In this study, we evaluated the patients who were presented with multiple brain metastasis and unknown primary tumor.

Materials & methods:

31 patients (17 males, 14 females; mean: 56.1 ± 14.22 years old) with diagnosis of brain metastasis according to histopathology and/or MRI were included into this retrospective study.

Results:

The patients presented with hypermetabolic (n = 17; mean SUVmax: 11.6 ± 6.9) or hypometabolic brain lesions with additional different metastatic sites in 13 patients (mean SUVmax: 9.03 ± 4.02). The primary tumor was determined by FDG PET/CT in 20/26 patients (77%) (lung [n = 6], primary brain [n = 9], renal cell carcinoma [n = 2], skin [n = 1], breast [n = 1] and neuroendocrine tumor [n = 1]).

Conclusion:

New generation multislice scanners may provide higher detection ratios. The detection rate of FDG PET/CT might be higher than previously reported according to this study.

Perceptions of cancer of unknown primary site: a national survey of Australian medical oncologists

BACKGROUND

Despite being the sixth most common cause of cancer death in Australia, cancer of unknown primary (CUP) site remains poorly understood.

AIMS

To describe practices relating to the diagnosis, investigation, classification, communication and management of CUP among medical oncologists.

METHODS

We invited all members of the Medical Oncology Group of Australia to participate in a national, anonymous online survey about CUP. The survey collected data regarding diagnosis acceptance, diagnostic tests, treatment protocols and communication practices around the diagnosis of CUP.

RESULTS

Three hundred and two oncologists were invited and 86 (28%) completed the survey. Eighty (93%) respondents were directly involved in the assessment of patients with CUP. Eighty-five (99%) respondents were prepared to make a diagnosis of CUP if, after appropriate diagnostic tests, the primary location could not be ascertained. Eighty-three percent would assign a primary site to obtain Pharmaceutical Benefits Schedule funding of medical therapy. Sixty-two percent did not have a specific treatment protocol designed for CUP. The majority of oncologists used serum tumour markers and computed tomography scans in the initial work-up, while 43% indicated they would use a positron emission tomography scan in the majority of cases. The majority would arrange mammography in female patients. Thematic analysis of responses to open-ended questions about how CUP is described identified little consistency in the language being used.

CONCLUSION

The approach to diagnosis, investigation and management of CUP by medical oncologists in Australia is variable. Many preferred to estimate the primary site and treat accordingly. Pharmaceutical Benefits Schedule restrictions may encourage the practice of 'best guessing'.

Synchronous, bilateral tonsillar carcinomas: Patient characteristics and human papillomavirus genotypes

INTRODUCTION

The incidence of oropharyngeal squamous cell carcinoma (OPSCC) is increasing, but data on the incidence of synchronous, bilateral tonsillar squamous cell carcinomas (BiTSCCs) is sparse. In this study, we report the incidence and tumour characteristics of BiTSCCs in a population-based, consecutive cohort of OPSCCs.

METHODS

We identified all patients diagnosed with tonsillar squamous cell carcinoma (TSCC) in eastern Denmark during a 15-year period to detect the incidence of synchronous BiTSCCs. The tumours were assessed for p16^Ink4a expression, the presence of HPV DNA and HPV genotypes. Furthermore, we systematically reviewed the literature examining BiTSCCs.

RESULTS

Of the total of 1119 TSCCs diagnosed in eastern Denmark from 2000 to 2014, we identified 12 BiTSCCs, nine of which initially presented as a cancer of unknown primary (CUP) in the neck. Nine cases were bilaterally HPV16 positive (HPV16+), while two cases were HPV16+ in one tonsil and respectively, HPV33 and HPV35 positive in the contralateral tonsil. One case was bilaterally HPV-negative. We also identified an increase in the incidence of BiTSCCs after 2012 when histological examination of the entire tonsil tissue became routine, suggesting that BiTSCCs might be underdiagnosed. In the literature, we identified 15 studies from six countries, encompassing 25 cases in total.

CONCLUSIONS

BiTSCCs were primarily HPV16+ and were most often diagnosed as part of the diagnostic work-up for CUP. We found an incidence of 9% BiTSCCs in patients with TSCC after 2012 and we therefore recommend focusing on putative BiTSCC with total embedding and histological examination of tonsils harvested by bilateral tonsillectomies.

Clinical Practice in PET/CT for the Management of Head and Neck Squamous Cell Cancer

OBJECTIVE

The purpose of this article is to summarize the evidence for the value of PET/CT for the management of patients with head and neck squamous cell cancer and suggest best clinical practices.

CONCLUSION

FDG PET/CT is a valuable imaging tool for identifying unknown primary tumors in patients with known cervical node metastases leading to management change and is the standard of care for the initial staging of stage III and IV head and neck squamous cell carcinomas (HNSCCs), for assessing therapy response when performed at least 12 weeks after chemoradiation therapy, and for avoiding unnecessary planned neck dissection. Neck dissection is avoided if PET/CT findings are negative-regardless of the size of the residual neck nodes-because survival outcomes are not compromised. FDG PET/CT is valuable in detecting recurrences and metastases during follow-up when suspected because of clinical symptoms and serves as a prognostic marker for patient survival outcomes, for 5 years. Using FDG PET/CT for routine surveillance of HNSCC after 6 months of treatment without any clinical suspicion should be discouraged.

Fluorodeoxyglucose Imaging Using a Coincidence Gamma Camera to Detect Head and Neck Squamous Cell Carcinoma and Response to Chemotherapy

This prospective study was performed to evaluate the ability of a dual-head gamma camera with fluorine-18 fluorodeoxyglucose coincidence detection emission tomography (FDG-CDET) to detect primary tumor and cervical lymph nodes in head and neck squamous cell carcinoma (HNSCC), and to show the response of the carcinoma to chemotherapy. The findings were compared with those of physical examination, computed tomography (CT), and histopathology, before treatment in 61 patients, and after induction chemotherapy in 34 of them. Before treatment, the primary was detected in 93%, 79%, and 95% of cases on panendoscopy, CT, and FDG-CDET, respectively. After chemotherapy, 34 patients were evaluable for response of the primary tumor. Surgical resection was performed in 23 of them: agreement with histopathologic results for response to treatment was 74%, 69%, and 78% for panendoscopy, CT, and FDG-CDET, respectively. No surgical resection was performed in 11 of the 34 patients, but biopsies were performed before radiotherapy, and their rates of agreement with histopathologic results for response to treatment were 75%, 75%, and 67% on panendoscopy, CT, and FDG-CDET, respectively. For cervical lymph nodes, 245 sites were resected in 41 patients, and FDG-CDET appeared competitive with CT in detecting metastatic neck disease, especially after neoadjuvant chemotherapy; the accuracy was 93%. These results demonstrated the ability of FDG-CDET to detect primary tumors and cervical lymph nodes in HNSCC and to show its response to chemotherapy, as compared to the ability of CT and panendoscopy. It may be a complementary tool to evaluate residual disease after induction chemotherapy, although higher sensitivity would be required for FDG-CDET to be considered as a staging modality.

The Accuracy of 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in the Evaluation of Bone Lesions of Undetermined Origin

The aim of the current study was to determine the diagnostic accuracy of whole-body fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in detecting carcinoma of unknown primary (CUP) with bone metastases. We evaluated 87 patients who were referred to FDG-PET/CT imaging and reported to have skeletal lesions with suspicion of malignancy. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated. The median survival rate was measured to evaluate the prognostic value of the FDG-PET/CT findings. In the search for a primary, FDG-PET/CT findings correctly diagnosed lesions as the site of the primary true positive (TP) in 64 (73%) cases, 4 (5%) findings diagnosed no site of a primary, and none were subsequently proven to be true negative (TN); 14 (16%) diagnoses were false positive (FP) and 5 (6%) diagnoses were false negative (FN). Life expectancy was between 2 months and 25 months. Whole-body FDG-PET/CT imaging may be a useful method in assessing the bone lesions with suspicion of bone metastases.

Carcinoma of unknown primary in the head and neck: The evaluation of the effectiveness of (18)F-FDG-PET/CT, own experience

AIM

The aim of the present study was to estimate the clinical effectiveness of (18)F-FDG-PET/CT in the detection of the primary tumor in patients with histologically proven squamous cell carcinoma cervical lymph nodes metastasis from an unknown primary.

BACKGROUND

(18)F-fluorodeoxyglucose positron emission tomography combined with CT ((18)F-FDG-PET/CT) is believed to be very helpful in localization of primary tumor in CUP Syndrome patients.

MATERIAL AND METHOD

41 patients referred to Poznan Medical University Department of Head and Neck Surgery from January 2010 to December 2013 with CUP Syndrome were included in the study. All patients presented fine-needle biopsy proven squamous cell carcinoma metastasis of the upper-, or mid neck lymph nodes. The final results were obtained from the histopathologic reports of tissue samples from anatomical regions suspected for primary tumor, additional imaging exams as well as clinical follow-up data.

RESULTS

The (18)F-FDG-PET/CT successfully detected primary tumor in 7 out of 41 patients (17%). In two more cases the primary tumor was indicated in the lung. 24 of 41 patients (58.5%) analyzed in our study remained without evidence of a primary tumor. In 4 cases (9.75%) we did not reveal any pathology within the localizations indicated by PET/CT on panendoscopy. In 4 cases we obtained histological confirmation of neoplasm on panendoscopy despite the negative results of PET/CT examinations.

CONCLUSION

We may suppose a relatively high usefulness of (18)F-FDG-PET/CT in the diagnosis process of CUP Syndrome patients. High NPV may indicate patients with no symptoms of primary tumor, which allows to avoid extensive resection or extra imaging.

Correlation of fine-needle aspiration with fluorodeoxyglucose positron emission tomography and ultrasonography imaging in head and neck lymph nodes

INTRODUCTION

Fluorodeoxyglucose positron emission tomography (FDG-PET) is a well-established tracer technique, particularly useful for oncologic conditions. However, in the head and neck region, this modality may have limitations due to the complex anatomy and high frequency of normal variants in FDG-PET uptake resulting in diagnostic errors. Hence, FDG-PET results often require additional diagnostic investigations including ultrasonography (US), and guided fine-needle aspirations (FNAs) in order to improve diagnosis and patient care.

MATERIALS AND METHODS

A total of 87 cases of head and neck lymph node FNA were accessioned in the cytopathology laboratory between 2010 and 2013, 75 cases with corresponding standard uptake values (SUVs) were selected to form the current study cohort. Patient demographics, primary tumor site, size of the biopsied lymph node, PET SUV, and US findings, as well as FNA diagnoses and surgical follow-ups were reviewed. SUVs were grouped into 5 ranges: A (2.2-2.9), B (3.0-4.9), C (5.0-6.9), D (7.0-9.9), and E (10.0 +).

RESULTS

The SUV cutoff of 5.0 was seen in the groups C, D, and E, which increased the probability of malignancy in the FNA specimens from 67% to 100%. The average size of the lymph nodes was 18.57 mm (range 6-41 mm); it was 13.4, 14.2, 19.7, 18.4, and 20.2 for groups A, B, C, D, and E, respectively. The lymph node measurements represented similarities in groups A and B (13.4, 14.2), and groups C, D, and E (19.7, 18.4, 20.2). Albeit a few exceptions, an increase in the lymph node size 14.2 to 19.7 (ie, from groups A and B to groups C, D, and E) correlated with SUV and US abnormalities. Abnormal US findings were pronounced (100%) in group E, and ranged between 67% and 73% of the cases in other groups.

CONCLUSIONS

This study documents the usefulness of SUV range in FDG-PET results and not an absolute "cutoff" number for diagnosing suspicious head and neck lymph nodes due to an overlap in the SUVs between malignant and benign lesions. False positive and negative results may occur in hyperplastic and necrotic lymph nodes. An increase in the lymph node size generally compares well with SUVs and US abnormalities; use of US-guided FNAs in these cases can be helpful to achieve definite diagnosis.

Detection of occult primary tumors in patients with cervical metastases of unknown primary tumors: comparison of (18)F FDG PET/CT with contrast-enhanced CT or CT/MR imaging-prospective study

PURPOSE

To assess diagnostic accuracy of fluorine 18 ((18)F) fluorodeoxyglucose (FDG) combined positron emission tomography (PET) and computed tomography (CT) in the detection of occult primary tumors and determination of optimal care in patients with cervical metastasis of an unknown primary tumor (CUP) compared with contrast material-enhanced CT alone or combined contrast-enhanced CT and magnetic resonance (MR) imaging (CT/MR imaging).

MATERIALS AND METHODS

Institutional review board approval and written informed consent were obtained. In total, 56 patients with initially undetected tumors after endoscopic or physical examination were prospectively assessed with (18)F FDG PET/CT and contrast-enhanced CT or contrast-enhanced CT/MR imaging. The contrast-enhanced CT/MR images were read in combination. Results of guided biopsy with general anesthesia served as the reference standard. Diagnostic values of (18)F FDG PET/CT, contrast-enhanced CT, and contrast-enhanced CT/MR imaging were compared with the McNemar test.

RESULTS

Primary tumors were detected at 32 sites in 31 (55%) of 56 patients. There were 26 tumors in the palatine tonsil, two in the hypopharynx, two in the base of the tongue, and two in the nasopharynx. PET/CT depicted 22 (69%) of 32 primary tumors, but it failed to depict primary tumors in 10 (31%) of 32 cases. Overall, sensitivity of PET/CT (69%) in detection of primary tumors was higher than that of contrast-enhanced CT (16%) (P < .001) or contrast-enhanced CT/MR imaging (41%) (P = .039), while specificity of these methods did not differ (88%, 76%, and 59% for PET/CT, contrast-enhanced CT, and contrast-enhanced CT/MR imaging, respectively; P > .4). Diagnostic performance (area under the receiver operating characteristics curve [AUC] = 0.759) of PET/CT in tumor detection was significantly better than that of contrast-enhanced CT alone (AUC = 0.531) (P = .001) or contrast-enhanced CT/MR imaging (AUC = 0.537) (P = .036). PET/CT depicted primary tumors in eight (50%) of 16 cases of false-negative CT/MR imaging findings, one distant metastatic case, and two cases of synchronous cancer.

CONCLUSION

(18)F FDG PET/CT is more sensitive in detection of primary tumors than is contrast-enhanced CT or contrast-enhanced CT/MR imaging in patients with CUP; therefore, it may lead to improved therapeutic planning in these patients.

Assessing tumor contrast in radiographically dense breast tissue using Diffuse Optical Spectroscopic Imaging (DOSI)

Introduction

Radiographic density adversely affects the performance of X-ray mammography and can be particularly problematic in younger and high-risk women. Because of this limitation, there is significant ongoing effort to develop alternative cancer screening and detection strategies for this population. This pilot study evaluates the potential of Diffuse Optical Spectroscopic Imaging (DOSI) to image known tumors in dense breast tissue.

Methods

We performed a retrospective analysis on 24 radiographically dense breast cancer subjects measured with DOSI over a four-year period (Breast Imaging Reporting and Data System - BI-RADS, category 3 and 4, average age = 39 ± 7.6, average maximum size 31 ± 17 mm). Two previously-described DOSI contrast functions, the tissue optical index (TOI) and the specific tumor component (STC), which are based upon the concentrations and spectral signatures of hemoglobin, water and lipids, respectively, were used to form 2D optical images of breast tumors.

Results

Using TOI and STC, 21 out of 24 breast tumors were found to be statistically different from the surrounding highly vascularized dense tissue and to be distinguishable from the areolar region. For these patients, the tumor to normal contrast was 2.6 ± 1.2 (range 1.3 to 5.5) and 10.0 ± 7.5 (range 3.3 to 26.4) for TOI and STC, respectively. STC images were particularly useful in eliminating metabolic background from the retroareolar region which led to identification of two out of four retroareolar tumors.

Conclusions

Using both the abundance and the disposition of the tissue chromophores recovered from the DOSI measurements, we were able to observe tumor contrast relative to dense breast tissue. These preliminary results suggest that DOSI spectral characterization strategies may provide new information content that could help imaging breast tumors in radiographically dense tissue and in particular in the areolar complex.

Non-spine bone metastasis as an initial manifestation of cancer in Korea

Non-spine bone metastasis accounts for approximately 20% of all skeletal metastases, but little data have been published that focused on bone metastasis to the pelvis and extremities as an initial manifestation of cancer. We determined 1) clinicopathologic characteristics of patients who presented with non-spine bone metastasis of unknown primary malignancy, and 2) process by which the diagnosis of primary cancer was made. We retrospectively reviewed 84 patients with bone metastasis of unknown primary cancer site at the time of presentation. The study population consisted of 56 men and 28 women, with a mean age of 59.1 yr (17.5-85.6 yr). The average follow-up period was 20.8 months (1-120 mo). Primary cancer site was identified in 79 patients (94.0%), and was determined to be the lung (46.4%), kidney (13.1%), liver (9.5%), thyroid (8.3%), and prostate (4.8%). Five-year overall survival rate was 28.0%. Multiple bone metastases, distant organ metastasis, and multiple bone with organ metastases were the significant prognostic factors in univariate analysis. Multiple bone metastases remained significant after multivariate analysis (P = 0.008). Lung cancer is the most common site of primary cancer, and patients with multiple bone metastases have a poor prognosis, possibly due to disseminated cancer and a greater tumor burden.

CT and PET-CT of a dog with multiple pulmonary adenocarcinoma

A 10-year-old, intact female Yorkshire terrier had multiple pulmonary nodules on thoracic radiography and ultrasonography with no lesions elsewhere. Computed tomography (CT) and positron emission tomography and computed tomography (PET-CT) using 18F-fluorodeoxyglucose (FDG) were performed to identify metastasis and undetected primary tumors. On CT examination, pulmonary nodules had a hypoattenuating center with thin peripheral enhancement, suggesting ischemic or necrotizing lesion. In PET-CT at 47 min after intravenous injection of 11.1 MBq/kg of FDG, the maximum standardized uptake value of each pulmonary nodule was about from 3.8 to 6.4. There were no abnormal lesions except for four pulmonary nodules on the CT and PET-CT. Primary lung tumor was tentatively diagnosed, and palliative therapy using 2 mg/kg tramadol and 2.2 mg/kg carprofen twice per day was applied. After the dog’s euthanasia due to deteriorated clinical signs and poor prognosis, undifferentiated pulmonary adenocarcinoma was diagnosed through histopathologic and immunochemistry examination. To the best of the authors’ knowledge, this is the first study of CT and PET-CT features of canine pulmonary adenocarcinoma. In this case, multiple pulmonary adenocarcinoma could be determined on the basis of FDG PET-CT through screening the obvious distant metastasis and/or lymph node invasions and excluding unknown primary tumors.

The Outline of Prognosis and New Advances in Diagnosis of Oral Squamous Cell Carcinoma (OSCC): Review of the Literature

Objective. Oral squamous cell carcinoma (OSCC) has a remarkable incidence over the world and a fairly strenuous prognosis, encouraging further research on the prognostic factors and new techniques for diagnosis that might modify disease outcome. Data Sources. A web-based search for all types of articles published was initiated using Medline/Pub Med, with the key words such as oral cancer, prognostic factors of oral cancer, diagnostic method of oral cancer, and imaging techniques for diagnosis of oral cancer. The search was restricted to articles published in English, with no publication date restriction (last update April, 2013). Review Methods. In this paper, I approach the factors of prognosis of OSCC and the new advances in diagnostic technologies as well. I also reviewed available studies of the tissue fluorescence spectroscopy and other noninvasive diagnostic aids for OSCC. Results. The outcome is greatly influenced by the stage of the disease (especially TNM). Prognosis also depends or varies with tumour primary site, nodal involvement, tumour thickness, and the status of the surgical margins. Conclusion. Tumour diameter is not the most accurate when compared to tumour thickness or depth of invasion, which can be related directly to prognosis. There is a wide agreement on using ultrasound guided fine needle aspiration biopsies in the evaluation of lymph node metastasis.

The added value of18F-fluorodeoxyglucose positron emission tomography computed tomography in patients with neck lymph node metastases from an unknown primary malignancy

Background:

The search for a primary malignancy in patients with a metastatic cervical lymph node is challenging yet ultimately of utmost clinical importance. This study evaluated the efficacy of positron emission tomography computed tomography in detecting the occult primary, within the context of a tertiary referral centre head and neck cancer multidisciplinary team tumour board meeting.

Methods:

Thirty-two patients (23 men and 9 women; mean and median age, 61 years) with a metastatic cervical lymph node of unknown primary origin, after clinical examination and magnetic resonance imaging, underwent positron emission tomography computed tomography.

Results:

The primary tumour detection rate was 50 per cent (16/32). Positron emission tomography computed tomography had a sensitivity of 94 per cent (16/17) and a specificity of 67 per cent (10/15). Combining these results with those of 10 earlier studies of similar patients gave an overall detection rate of 37 per cent.

Conclusion:

Positron emission tomography computed tomography has become an important imaging modality. To date, it has the highest primary tumour detection rate, for head and neck cancer patients presenting with cervical lymph node metastases from an unknown primary.

Peritonealkarzinose: Präoperative Diagnostik und Patientenselektion

<b><i>Hintergrund: </i></b>Die zytoreduktive Chirurgie und die hypertherme intraperitoneale Chemotherapie spielen inzwischen eine zunehmend wichtige Rolle in der Therapie der Peritonealkarzinose bei zahlreichen Tumorentitäten. <b><i>Methode: </i></b>Die wichtigsten Selektionskriterien werden erläutert. <b><i>Ergebnisse: </i></b>Neben dem Alter und Allgemeinzustand sowie der Auswahl geeigneter Tumorentitäten spielt die Tumorlast, die möglichst exakt bereits vor der Operation abgeschätzt werden sollte, eine entscheidende Rolle. <b><i>Schlussfolgerung: </i></b>Entscheidend ist eine Selektion geeigneter Patienten, um den onkologischen Benefit zu steigern und die Morbidität zu verringern.

¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography as an effective diagnostic workup in cervical metastasis of carcinoma from an unknown primary tumor

PURPOSE

The purpose of this study is to assess the potential of ¹⁸F-fluorodeoxyglucose (¹⁸FDG) positron emission tomography/computed tomography (PET/CT) imaging for the diagnosis of cervical metastasis of carcinoma of an unknown primary tumor (CUP) and to determine whether the maximum standardized uptake value (SUV(max)) is a prognostic factor.

METHODS

Twenty-five consecutive patients with cervical metastasis of CUP were retrospectively analyzed by PET/CT between July 2007 and July 2011.

RESULTS

FDG PET/CT suggested a primary tumor in 21 out of 25 patients (84.0%). The sensitivity of FDG PET/CT in detecting the primary tumor was 73.3% (11 of 15), and the positive predictive value was 52.4% (11 of 21). The median follow-up duration of survival patients was 10.4 months (range: 0-30 months). The estimated 2-year overall survival rate of all patients was 50.0%. Univariate analyses did not reveal a significant difference in overall survival between the group of 11 patients identified by pathology and the 14 patients not identified by pathology (overall survival was 57.1% and 49.1%, respectively; p=0.468). The median SUV(max) was 7.6. In the log-rank test, patients with a low SUV(max) (≤ 7.0) in cervical lymph nodes had a significantly higher survival rate at 2 years (87.5% vs. 21.2%; p=0.007) than patients with a high SUV(max) (>7.0).

CONCLUSIONS

Although our study was inconclusive due to the small sample size, our results suggest that FDG PET/CT may be an effective diagnostic workup in the cervical metastasis of carcinoma from an unknown primary tumor (UPT). In the present study, SUV(max) of PET/CT in the cervical lymph node may serve as a prognostic factor of cervical metastasis of carcinoma from a UPT based on the limited number of patients. Further studies are needed to confirm these findings.

Positron emission tomography in the detection of occult primary head and neck carcinoma: a retrospective study

Background

The management of cervical lymph node metastases from an unknown primary tumor remains a controversial subject. Recently, Positron Emission Tomography (PET) has proved useful in the detection of these tumors, even after an unsuccessful conventional diagnostic workup. This study was performed to assess the role of PET in the detection of occult primary head and neck carcinomas.

Methods

A retrospective analysis of a four year period at a tertiary referral oncology hospital was conducted.

Results

Of the 49 patients with cervical metastases of carcinoma from an unknown primary, PET detected a primary in 9 patients and gave 5 false positive and 4 false negative results. Detection rate, sensitivity, specificity and accuracy were of 18.4%, 69.2%, 86.1% and 81.6%, respectively. PET was also of substantial benefit in detecting distant metastatic disease and, thus, altered therapeutic strategies in a significant amount of patients.

Conclusions

Therefore, PET is a valuable tool in the management of patients with occult primary head and neck carcinoma, not only because it provides additional information as to the location of primary tumors, but also due to the fact that it can detect unexpected distant metastases.

Occult colon cancer with initial cutaneous metastatic manifestation: PET/CT detection

Skin metastasis as initial clinical presentation of occult internal organ malignancy is of rare occurrence, predominantly encountered in breast and lung cancer. The search for the occult causative primary malignancy is usually difficult with conventional anatomy-based cross-sectional imaging. The authors present a case of cecal cancer with thoracic and abdominal cutaneous metastasis demonstrated by PET/CT.

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.

PET/CT in Neuroendocrine Tumors: Evaluation of Receptor Status and Metabolism

In-111 Octreoscan is considered the gold standard for imaging of neuroendocrine tumors (NET). However, in the absence of morphologic imaging correlation, the exact localisation of the tumor is often difficult. Also the sensitivity of PET imaging is more than Gamma camera (SPECT) imaging. Ga-68 labelled somatostatin analogs (SMS-R) are interesting radiopharmaceuticals for PET receptor imaging of NET. Some other radiopharmaceuticals e.g. F-18 DOPA can also be used to assess metabolism and functional status of NET. The importance of these radiopharmaceuticals, especially SMS-R increases in the absence of any specific biochemical marker or clinical parameter for follow-up of patients after therapy (eg peptide receptor radionuclide therapy, surgery, chemoembolisation, etc). New criteria based on molecular, metabolic and morphologic imaging needs to be developed for correct assessment of response to therapy for these slow-growing, solid tumors.

Mucinous adenocarcinoma of lung presenting as oral metastases: a case report and literature review

BACKGROUND

Metastasis of a malignant tumor to the oral cavity is rare and can indicate an unknown primary tumor.

METHODS

Described is a case of metastatic tumor in the right jaw. The patient was a 50-year-old woman who consulted her dentist with complaints of tooth pain and an abscess. The clinical examination showed an abscess around the mandibular right first molar and second premolar tooth. Teeth were extracted and two periapical, nontypical cystic lesions were excised.

RESULTS

The histopathological analysis revealed mucinous malignant cells embedded in an inflammatory infiltration and fibrinous tissue. The diagnosis was metastatic mucinous adenocarcinoma. The lesion at the apex of teeth was the initial presenting site of the patient's lung cancer. There was no other site of metastasis.

CONCLUSIONS

There are typical dental apical cysts that do not usually require a histopathological examination, but mucinous and nontypical cysts must be sent for a histopathological examination. The case emphasizes the important role of dentists in diagnosing metastatic oral lesions and shows that even apparently benign atypical lesions in healthy patients need to be examined histopathogically.

Evaluation of clinical problems associated with bone metastases from carcinoma from unknown primary sites

INTRODUCTION

This study focused on the evaluation of data concerning the clinical features of patients who were initially diagnosed with bone metastases of carcinoma from unknown primary sites that could not be detected, even using state of-the-art diagnostic modalities.

METHOD

The oncologic outcome of these patients is discussed.

PATIENTS

The clinical records of seven patients who had presented with bone metastases of carcinoma from unknown primary sites were retrospectively reviewed. Clinical features, treatment and outcome were analyzed. Extraskeletal metastases were located in the lymph nodes, liver, skeletal muscle, kidney, adrenal gland, and pleura. Six cases were observed in the pelvis, three in the femur, three in the skull, two in the rib, two in the cervical spine, two in the thoracic spine, two in the lumbar spine, one in the humerus, one in the radius, one in the clavicle, one in the scapula and one in the sternum. Four patients received systemic chemotherapy including platinum.

RESULTS

At the last follow-up time of average 272 days, six patients were dead of disease and one patient was alive with disease. Although considerable progress has been made in the development of diagnostic modalities, including more recently FDG-PET, the primary tumor site cannot always be identified. Multiple bone and visceral organ metastases are often present in patients whose primary tumor was not detected.

CONCLUSION

In the present study, it was found that systemic chemotherapy can appreciably increase the survival time of the patients with carcinoma metastases from unknown primary sites.

FDG PET imaging of head and neck cancers

In initial staging of head and neck cancers, the addition of FDG PET to conventional imaging improves the accuracy for cervical nodal metastases. The sensitivity of FDG PET is, however, limited in nodes <1 cm and in completely necrotic nodes. In the posttherapy setting, PET scans obtained at least 10 weeks after radiotherapy have an excellent predictive value to rule out residual disease. Due to the limited positive predictive value of FDG PET after radiation therapy, a positive PET scan needs to be confirmed before management decisions are made.

Role of 18F-FDG PET in detecting primary site in the patient with primary unknown carcinoma

The aim of this study was to verify the effectiveness of positron emission tomography (PET) in detecting primary sites in carcinoma of unknown primary (CUP) patients. In this study, CUP represented a group of heterogeneous tumors that shared the clinical manifestation of metastatic carcinoma with no obvious primary site at the time of first diagnosis, which included clinical investigations, computed tomography, magnetic resonance imaging and panendoscopy. We reviewed the records of 24 patients with CUP between January 1995 and December 2009. The patients who demonstrated additional tracer uptake sites other than previously known metastatic lesions by PET scan were done direct biopsies for the sites of accumulation. Patients who had a negative PET scan or for whom the primary site could not be identified by direct biopsies underwent examination under anesthesia of the at-risk occult tumor sites. PET scan demonstrated focal accumulation suspicious for primary tumor in 12 (50.0%) of 24 patients: tonsil 5, nasopharynx 3, hypopharynx 1, tongue 1, larynx 1, and maxillary sinus 1. A subsequent biopsy of these sites revealed primary cancer in 9 (37.5%) of 24 patients: tonsil 5, nasopharynx 1, hypopharynx 1, tongue 1, and maxillary sinus 1. In the remaining three patients, no malignant cells were found by the biopsy of the accumulated area: nasopharynx 2, larynx 1. PET scans increase the yield of primary tumor by 37.5%. The sensitivity, specificity for PET scan were 80.8, 76.9%, respectively. PET scanning is useful in detecting primary cancer of CUP patients.

A study of patients with brain metastases as the initial manifestation of their systemic cancer in a Chinese population

To investigate the clinical characteristics of patients with brain metastases as the initial manifestation of their systemic cancer in a Chinese population, a retrospective study of 254 such patients admitted to Huashan Hospital, Fudan University, Shanghai, China between January 1, 2003 and December 30, 2008 was performed. Data were collected to determine the features of this group (i.e., manifesting signs and symptoms, imaging studies, extracerebral metastases, primary tumor sites, initial diagnosis, and survival data). Common symptoms included headache and motor impairment. The distribution of brain metastases paralleled blood flow, and the majority of brain metastases were located in the cerebral hemispheres. Magnetic resonance imaging (MRI) was more sensitive than computed tomography (CT) for confirming presence of brain lesions. This distinct clinical entity exhibited high rates of misdiagnosis at initial presentation. Pathology varied, and adenocarcinomas were most commonly observed. Underlying primary tumors were identified in 84.2% of patients, most often located in lung (71.7%), followed by digestive tract. Chest CT had high yield. Sixty-two patients presented with silent extracerebral metastases at initial presentation. Median survival time was 15 months (95% confidence interval, 12.2-17.8 months). Survival rates for 1, 2, and 5 years were 59.2%, 23.2%, and 15.1%, respectively. Contrast-enhanced MRI had high yield for detection of brain metastases. Adenocarcinoma was the most common histologic type. Given the high frequency of primary lung tumors and the sensitivity of chest CT, chest CT should be a part of the initial screen of primary site with brain metastases as the initial manifestation. Metastatic dissemination of malignancy to the brain as the initial manifestation is generally associated with dismal prognosis, with the exception of a minority who experience long survival.

Contribution of positron emission tomography in pleural disease

INTRODUCTION

Positron emission tomography (PET) now plays a clear role in oncology, especially in chest tumours. We discuss the value of metabolic imaging in characterising pleural pathology in the light of our own experience and review the literature.

BACKGROUND

PET is particularly useful in characterising malignant pleural pathologies and is a factor of prognosis in mesothelioma. Metabolic imaging also provides clinical information for staging lung cancer, in researching the primary tumour in metastatic pleurisy and in monitoring chronic or recurrent pleural pathologies.

CONCLUSIONS

PET should therefore be considered as a useful tool in the diagnosis of liquid or solid pleural pathologies.

Detection of unknown primary neuroendocrine tumours (CUP-NET) using (68)Ga-DOTA-NOC receptor PET/CT

PURPOSE

This bi-centric study aimed to determine the role of receptor PET/CT using (68)Ga-DOTA-NOC in the detection of undiagnosed primary sites of neuroendocrine tumours (NETs) and to understand the molecular behaviour of the primarily undiagnosed tumours.

METHODS

Overall 59 patients (33 men and 26 women, age: 65 + or - 9 years) with documented NET and unknown primary were enrolled. PET/CT was performed after injection of approximately 100 MBq (46-260 MBq) of (68)Ga-DOTA-NOC. The maximum standardised uptake values (SUV(max)) were calculated and compared with SUV(max) in known pancreatic NET (pNET) and ileum/jejunum/duodenum (SI-NET). The results of PET/CT were also correlated with CT alone.

RESULTS

In 35 of 59 patients (59%), (68)Ga-DOTA-NOC PET/CT localised the site of the primary: ileum/jejunum (14), pancreas (16), rectum/colon (2), lungs (2) and paraganglioma (1). CT alone (on retrospective analyses) confirmed the findings in 12 of 59 patients (20%). The mean SUV(max) of identified previously unknown pNET and SI-NET were 18.6 + or - 9.8 (range: 7.8-34.8) and 9.1 + or - 6.0 (range: 4.2-27.8), respectively. SUV(max) in patients with previously known pNET and SI-NET were 26.1 + or - 14.5 (range: 8.7-42.4) and 11.3 + or - 3.7 (range: 5.6-17.9). The SUV(max) of the unknown pNET and SI-NET were significantly lower (p < 0.05) as compared to the ones with known primary tumour sites; 19% of the patients had high-grade and 81% low-grade NET. Based on (68)Ga-DOTA-NOC receptor PET/CT, 6 of 59 patients were operated and the primary was removed (4 pancreatic, 1 ileal and 1 rectal tumour) resulting in a management change in approximately 10% of the patients. In the remaining 29 patients, because of the far advanced stage of the disease (due to distant metastases), the primary tumours were not operated. Additional histopathological sampling was available from one patient with bronchial carcinoid (through bronchoscopy).

CONCLUSION

Our data indicate that (68)Ga-DOTA-NOC PET/CT is highly superior to (111)In-OctreoScan (39% detection rate for CUP according to the literature) and can play a major role in the management of patients with CUP-NET.

Radiosurgery for brain metastases from unknown primary cancers

PURPOSE

We evaluated the role of Gamma Knife stereotactic radiosurgery in the multidisciplinary management of brain metastases from an undiagnosed primary cancer.

METHODS AND MATERIALS

Twenty-nine patients who had solitary or multiple brain metastases without a detectable primary site underwent stereotactic radiosurgery between January 1990 and March 2007 at the University of Pittsburgh. The median patient age was 61.7 years (range, 37.9-78.7 years). The median target volume was 1.0 cc (range, 0.02-23.6 cc), and the median margin radiosurgical dose was 16 Gy (range, 20-70 Gy).

RESULTS

After radiosurgery, the local tumor control rate was 88.5%. Twenty four patients died and 5 patients were living at the time of this analysis. The overall median survival was 12 months. Actuarial survival rates from stereotactic radiosurgery at 1 and 2 years were 57.2% and 36.8%, respectively. Factors associated with poor progression-free survival included large tumor volume (3 cc or more) and brainstem tumor location.

CONCLUSIONS

Radiosurgery is an effective and safe minimally invasive option for patients with brain metastases from an unknown primary site.

Fluorodeoxyglucose-positron-emission tomography imaging of head and neck squamous cell cancer

The hybrid technique of PET/CT has significantly impacted the imaging and management of HNSCC since its introduction in 2001 and has become the technique of choice for imaging of this cancer. Diagnostic FDG-PET/CT is useful for identification of an unknown primary tumor, delineation of extent of primary tumor, detection of regional lymph node involvement even in a normal-sized node, detection of distant metastases and occasional synchronous primary tumor, assessment of therapy response, and long-term surveillance for recurrence and metastases. The role of PET/CT is evolving in radiation therapy planning. Combined diagnostic PET/CT provides the best anatomic and metabolic in vivo information for the comprehensive management of HNSCC.

Role of functional imaging in head and neck squamous cell carcinoma: fluorodeoxyglucose positron emission tomography and beyond

Positron emission tomography (PET) has emerged as an integral diagnostic tool in the management of head and neck squamous cell carcinoma (HNSCC). This article reviews the usefulness and ongoing dilemmas of fluorine-18 fluorodeoxyglucose (18-F FDG) PET and FDG PET/CT in HNSCC. In addition, it examines the potential role of novel markers and biologic characterization of disease, which in the future may assist in targeted therapeutic strategies.

Exploring the epidemiological characteristics of cancers of unknown primary site in an Australian population: implications for research and clinical care

OBJECTIVES

To investigate incidence, mortality and case survival trends for cancer of unknown primary site (CUP) and consider clinical implications.

METHOD

South Australian Cancer Registry data were used to calculate age-standardised incidence and mortality rates from 1977 to 2004. Disease-specific survivals, socio-demographic, histological and secular predictors of CUP, compared with cancers of known primary site, and of CUP histological types, using multivariable logistic regression were investigated.

RESULTS

Incidence and mortality rates increased approximately 60% between 1977--80 and 1981--84. Rates peaked in 1993--96. Male to female incidence and mortality rate ratios approximated 1.3:1. Incidence and mortality rates increased with age. The odds of unspecified histological type, compared with the more common adenocarcinomas, were higher for males than females, non-metropolitan residents, low socio-economic areas, and for 1977--88 than subsequent diagnostic periods. CUP represented a higher proportion of cancers in Indigenous patients. Case survival was 7% at 10 years from diagnosis. Factors predictive of lower case survival included older age, male sex, Indigenous status, lower socio-economic status, and unspecified histology type.

CONCLUSION

Results point to poor CUP outcomes, but with a modest improvement in survival. The study identifies socio-demographic groups at elevated risk of CUP and of worse treatment outcomes where increased research and clinical attention are required.

Role of fluorodeoxyglucose-PET versus fluorodeoxyglucose-PET/computed tomography in detection of unknown primary tumor: a meta-analysis of the literature

The objectives of this study were to evaluate the diagnostic accuracy of fluorodeoxyglucose (FDG)-PET and FDG-PET/computed tomography (CT) in the detection of primary tumors in patients presenting with carcinoma of unknown primary (CUP) unidentified by conventional workup, and to compare the statistical difference between the FDG-PET and FDG-PET/CT. Twenty-eight studies (involving a total of 910 patients) published between 1990 and 2007 were reviewed. These studies evaluated the role of FDG-PET and FDG-PET/CT in the detection of unknown primary tumors after physical examination and conventional workup failed to detect a primary tumor. Systematic methods were used to identify, select, and evaluate the methodological quality of the studies as well as to summarize the overall findings of sensitivity, specificity, and detection capacity of the primary tumor. The overall sensitivity and specificity of FDG-PET in detecting unknown primary tumors were 0.78 [95% confidence interval (CI): 0.72-0.84)] and 0.79 (95% CI: 0.74-0.83), respectively. Furthermore, FDG-PET detected 28.54% of tumors that were not apparent after CUP failed to be detected by conventional workup. Data were collected on the locations of primary tumors detected by FDG-PET in 17 studies and detected by FDG-PET/CT in seven studies. Tumors from the base of the tongue accounted for 20.7% (six of 29) of all false-positive FDG-PET scans, corresponding to a false-positive rate of 28.6% (six of 29), much higher than tumors from the others. FDG-PET exhibited a lower sensitivity with respect to the tumors at the base of the tongue and tonsils, which was 68.2 and 76.7%, respectively. In the eight studies with 430 patients diagnosed with CUP by FDG-PET/CT, 31.4% (n=135) of primary tumors were detected. The pooled sensitivity and specificity were 0.81 (95% CI: 0.74-0.87) and 0.83 (95% CI: 0.78-0.87), respectively. FDG-PET and FDG-PET/CT can detect primary tumors that went undetected by physical examination and conventional workup. FDG-PET exhibited lower sensitivity with respect to the tumors at the base of the tongue and the tonsils.

New directions in head and neck imaging

Computerized tomography (CT) and magnetic resonance imaging (MRI), positron emission tomography (PET) and the hybrid modality of PET/CT are sensitive and reliable tools for detection and staging of head and neck cancers. This article describes the role of PET/CT in initial staging of head and neck squamous cell carcinoma, the utility of CT/MR perfusion imaging in qualitative analysis of tumor tissue, and the usefulness of diffusion weighted MR and dynamic contrast-enhanced MR imaging in head and neck oncological imaging.

Prospective study of 18FDG-PET in the detection and management of patients with lymph node metastases to the neck from an unknown primary tumor. Results from the DAHANCA-13 study

BACKGROUND

The benefit of a complementary fluorodeoxyglucose-positron emission tomography (FDG-PET) scan to standard workup for carcinoma of unknown primary (CUP) and metastatic neck lesions was prospectively studied.

METHODS

Sixty-seven patients underwent standardized diagnostic workup according to national guidelines including panendoscopies, multiple mucosal biopsies, and diagnostic CT/MRI scans. Median follow-up was 40 months (range, 2-65 months).

RESULTS

In 60 eligible patients, FDG-PET indicated a primary tumor or metastatic disease in 30 patients (50%). Additional investigations confirmed a primary tumor in 18 patients: hypopharynx in 5, oropharynx in 5, nasopharynx in 2, lung in 1, axilla in 1, bone in 1, rectum in 1, as well as multiple metastatic lesions from CUP in 2 patients. In retrospect, MRI was able to detect 1 of the PET-detected primaries, leading to an overall detection rate of PET of 29% in CUP. A therapeutic change of treatment was made in 25% as a consequence of FDG-PET. PET before panendoscopy demonstrated fewer false-positive pathological foci.

CONCLUSION

FDG-PET is a valuable tool in addition to conventional extensive workup in CUP and neck metastases. Consequently, FDG-PET is now recommended as an early diagnostic modality in the workup of these patients.