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

The role of non-oropharyngeal biopsies in head and neck squamous cell carcinoma of unknown primary: A systematic review

INTRODUCTION

This systematic review aims to evaluate the role of biopsies in non-oropharyngeal subsites in patients with cervical metastasis from head and neck squamous cell carcinoma of unknown primary (HNSCCUP).

METHODS

This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Articles that encompassed non-oropharyngeal biopsies in HNSCCUP as part of the diagnostic work-up were selected and analysed.

RESULTS

A comprehensive search strategy was used to search relevant literature in PubMed from inception to October 2021. Eleven articles out of 860 were included, comprising 990 patients. There are no randomised control trials comparing the outcomes of survival and or locoregional control between patients who have or have not undergone non-targeted biopsies of non-oropharyngeal sub-sites for HNSCCUP. Several retrospective studies which showed an extremely low yield from random biopsies (range of yield, 0%-9%) of non-oropharyngeal subsites. Even targeted biopsies showed a low yield (range of yield, 0.6%-16.6%) from non-oropharyngeal subsites. The primary site identified for Epstein-Barr virus (EBV) positive cervical lymph nodes with an unknown primary is mainly the nasopharynx (51.7%). Narrow band imaging (NBI) (sensitivity range, 64%-91%) helps in the detection of primaries to target biopsies in non-oropharyngeal subsites.

CONCLUSIONS

On the basis of this systematic review, it is not appropriate to offer biopsies of clinically and radiologically normal upper aerodigestive tract mucosa at non-oropharyngeal sites. Offer nasopharyngeal biopsies when the cervical node sampling reveals EBV-positive metastasis. Where available, NBI should be used to help detect and target biopsies in non-oropharyngeal subsites.

Real-Life Performance of F-18-FDG PET/CT in Patients with Cervical Lymph Node Metastasis of Unknown Primary Tumor

Background: Neoplasms in the head and neck region possess higher glycolytic activity than normal tissue, showing increased glucose metabolism. F-18-Flourodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) can identify an unknown primary tumor (CUP). Aim: The aim of this study was to assess the real-life performance of F-18-FDG-PET/CT in detecting primary sites in patients with cervical lymph node metastasis of CUP. Methods: A retrospective data analysis of 31 patients who received FDG-PET/CT between June 2009 and March 2015 in a CUP context with histologically confirmed cervical lymph node metastasis was included. Results: In 48% of the patients (15/31), PET/CT showed suspicious tracer accumulation. In 52% of the patients (16/31), there was no suspicious radiotracer uptake, which was confirmed by the lack of identification of any primary tumor in 10 cases until the end of follow-up. FDG-PET/CT had a sensitivity of 67%, specificity of 91%, PPV of 92%, and NPV of 63% in detecting the primary tumor. Additionally, PET/CT showed suspicious tracer accumulation according to further metastasis in 32% of the patients (10/31). Conclusion: FDG-PET/CT imaging is a useful technique for primary tumor detection in patients in a cervical CUP context. Furthermore, it provides information on the ulterior metastasis of the disease.

Accuracy of 18 F-FDG PET/CT in Detection of Neck Metastases of Oral Squamous Cell Carcinoma in Patients Without Large Palpable Lymph Nodes

OBJECTIVE

To measure the efficacy of positron emission tomography/computed tomography (PET/CT) in the diagnosis of neck metastases of oral squamous cell carcinoma (OSCC) in patients without enlarged lymph nodes and to determine the threshold of maximum standardized uptake values (SUV_max) in diagnosis.

STUDY DESIGN

In total, 78 OSCC patients without large palpable lymph nodes were included. PET/CT findings were compared with histopathologic neck status.

RESULTS

Neck dissection was performed in 78 patients with 98 neck sides, and 31 neck sides harbored metastases. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of PET/CT were 83.9%, 73.1%, 76.5%, 59.1%, and 90.7%, respectively. The area under the curve in receiver operating characteristic analysis was 0.76, which indicated that SUV_max of lymph nodes was useful in diagnosis of pathologic neck status. The threshold SUV_max was 2.21, which was the best diagnosis threshold of neck metastasis.

CONCLUSIONS

PET/CT is valuable in diagnosis of neck status. The probability of neck metastasis increased with increasing SUV_max values, but the threshold SUV_max should not be the sole criterion for determining the presence of neck metastases. Fluorodeoxyglucose PET/CT is recommended for evaluation of neck status in OSCC patients without large palpable lymph nodes.

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.

The Impact of a Stepwise Approach to Primary Tumor Detection in Squamous Cell Carcinoma of the Neck With Unknown Primary

OBJECTIVES/HYPOTHESIS

To examine the cumulative effect of diagnostic steps for primary tumor identification in patients with head and neck squamous cell carcinoma of unknown primary (HNSCCUP), including lingual tonsillectomy, and the impact of primary tumor identification on subsequent treatment.

STUDY DESIGN

Retrospective analysis.

METHODS

We reviewed the records of 110 patients diagnosed with HNSCCUP between 2003 and 2015. Results of diagnostic imaging (fluorodeoxyglucose-positron emission tomography/computed tomography [FDG-PET/CT]), tumor detection with direct laryngoscopy with biopsies, palatine tonsillectomy, and transoral robotic surgery (TORS) lingual tonsillectomy were recorded. Associations between demographic and treatment variables with overall survival (OS) and progression-free survival (PFS) were modeled with Cox proportional hazards models.

RESULTS

FDG-PET/CT was suspicious for a primary site in 23/77 (30%) patients. Direct laryngoscopy identified a primary tumor in 34/110 patients (31%). Forty-seven patients underwent palatine tonsillectomy, which identified 17 primaries (36%), yielding a cumulative primary tumor identification of 51/110 (46%). Fourteen patients underwent TORS lingual tonsillectomy, which identified eight primaries (57%), resulting in a cumulative identification of 59/110 (53%). The detection rate increased from 28/63 (44%) to 31/47 (66%) after the addition of TORS lingual tonsillectomy to our institutional approach. Detection rates varied by HPV status. Primary tumor identification altered subsequent radiation planning, as patients with an identified primary tumor received radiation to a smaller volume of tissue than did those without an identified primary tumor. However, there was no significant association between primary tumor identification and OS or PFS.

CONCLUSIONS

A stepwise approach to primary tumor identification identifies a primary tumor in a majority of patients.

LEVEL OF EVIDENCE

4 Laryngoscope, 129:1610-1616, 2019.

Chapter 3 The Role of PET/CT in Squamous Cell Carcinoma of the Head and Neck

Head and neck squamous cell carcinoma is an important cause of cancer morbidity worldwide and has been stratified into human papillomavirus-related and human papillomavirus-unrelated subgroups that affect prognosis and now staging. Conventional anatomical imaging methods are suboptimal for the detection of regional and distant metastases that are important prognosticators associated with poor outcomes. Functional imaging with (F18)-fluorodeoxyglucose-positron emission tomography/computed tomography (PET/CT) is a useful tool in the management of head and neck squamous cell carcinoma, providing complementary physiological and anatomical information. In this article, optimal PET/CT technique will be reviewed and the pretreatment and posttreatment applications of PET/CT will be described. A simplified approach to imaging interpretation, including review of pearls and pitfalls will be discussed. An initial framework for follow-up evaluation will be provided.

Advantages and disadvantages of F-18 fluorodeoxyglucose positron emission tomography/computed tomography in carcinoma of unknown primary

Carcinoma of unknown primary is a type of malignant disease where the primary carcinoma cannot be identified by conventional examination, which presents challenges in diagnosis and therapy. This study aims to evaluate the detailed clinical value and indications of using fluorine-18-2-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (F-18 FDG PET/CT) in a large sample. A total of 449 patients who were selected under strict standards were retrospectively included in this study. F-18 FDG PET/CT accurately detected the primary carcinoma in 115 of 449 patients whose primaries could not be detected by conventional examination (25.6%), with additional 27 false-positive patients. The most common primary site was the lung (34.8%). In addition, except for in metastatic melanoma (1/19, 5.3%) and axillary metastasis patients (2/49, 4.1%), F-18 FDG PET/CT had a comparative performance in detecting primary carcinoma in other pathological types and anatomical locations. The scan is able to guide treatment strategy modifications to some extent (130/449, 29.0%). We strongly recommend the use of F-18 FDG PET/CT in the early phase of examination. It is also recommended as a supplementary radiological method, and certain patients may benefit from its application in cases where regular examination is inconclusive. However, in metastatic melanoma or axillary metastasis patients where the primary site cannot be identified by routine examination, regular application of F-18 FDG PET/CT for the sole purpose of detecting the primary carcinoma should not be encouraged.

Positron-emission tomography/computed tomography imaging in head and neck oncology: An update

Cancers of the head and neck account for more than half a million cases worldwide annually, with a significant majority diagnosed as squamous cell carcinoma (HNSCC). Imaging studies such as contrast-enhanced computed tomography (CT), magnetic resonance imaging (MRI) and ¹⁸F-2-fluoro-2-deoxy-D-glucose positron-emission tomography/computed tomography (¹⁸F-FDG PET/CT) are widely used to determine the presence and extent of tumors and metastatic disease, both before and after treatment. Advances in PET/CT imaging have allowed it to emerge as a superior imaging modality compared to both CT and MRI, especially in detection of carcinoma of unknown primary, cervical lymph node metastasis, distant metastasis, residual/recurrent cancer and second primary tumors, often leading to alteration in management. PET/CT biomarker may further provide an overall assessment of tumor aggressiveness with prognostic implications. As new developments emerged leading to better understanding and use of PET/CT in head and neck oncology, the aim of this article is to review the roles of PET/CT in both pre- and post-treatment management of HNSCC and PET-derived parameters as prognostic indicators.

Positron Emission Tomography in Head and Neck Squamous Cell Carcinoma of Unknown Primary

This article summarizes selected published studies on the use of FDG-PET and PET/CT in the workup of head and neck carcinoma of unknown primary (HNCUP). It shows that PET is a useful imaging modality in identification of the occult primary tumor and discovery of distant metastases. The results of PET often lead to a change in management in these patients. The limitations of PET in HNCUP are also discussed.

Role of 18-Fludeoxyglucose positron emission tomography-computed tomography and subsequent panendoscopy in head and neck squamous cell carcinoma of unknown primary

OBJECTIVES/HYPOTHESIS

Head and neck squamous cell carcinomas of unknown primary (HNSCCUP) accounts for up to 10% of presenting head and neck squamous cell carcinomas. Identification of the primary site allows for directed therapy. Where initial investigations have failed to locate the primary site, 18-fludeoxyglucose positron emission tomography-computed tomography (PET/CT) has emerged as a useful tool with improved sensitivity over positron emission tomography alone. Following PET/CT scan, the role of subsequent panendoscopy ± biopsy has not been fully assessed. We aim to evaluate and quantify the role of PET/CT and subsequent panendoscopy in HNSCCUP.

STUDY DESIGN

Retrospective cohort study.

METHODS

Patients with HNSCCUP presenting between January 2005 and December 2010 at a regional oncology referral center were studied. All patients who presented with a metastatic neck node and unknown primary who had undergone PET/CT prior to panendoscopy were included. The accuracy of PET/CT was calculated and compared with panendoscopy and histopathological findings.

RESULTS

Fifty-two patients were included. Twenty-seven PET/CT scans suggested a primary site. Calculated diagnostic parameters were 83% sensitivity, 87% specificity, positive predictive value 89%, and negative predictive value 80%. Three false-positive PET/CT scans were noted after panendoscopy and normal histology. Importantly, three confirmed tongue base tumors were found on panendoscopy, which were undetected on PET/CT.

CONCLUSIONS

PET/CT is a valuable resource for locating tumors in HNSCCUP. It helps direct biopsy and aids in the detection of local and distant metastases along with synchronous primary tumors. Importantly, due to both false-positive and false-negative PET/CT rates, panendoscopy and biopsy remains an essential adjunct investigation irrespective of PET/CT results.

LEVEL OF EVIDENCE

4 Laryngoscope, 126:1354-1358, 2016.

Utility of PET for Radiotherapy Treatment Planning

PET imaging has contributed substantially in oncology by allowing improved clinical staging and guiding appropriate cancer management. Integration with radiotherapy planning via PET/computed tomography (CT) simulation enables improved target delineation, which is paramount for conformal radiotherapy techniques. This article reviews the present literature regarding implications of PET/CT for radiotherapy planning and management.

Role of 18F-FDG PET/CT in pre and post treatment evaluation in head and neck carcinoma

Head and neck cancer (HNC) ranks as the 6^th most common cancer worldwide, with the vast majority being head and neck squamous cell carcinoma (HNSCC). The majority of patients present with complicated locally advanced disease (typically stage III and IV) requiring multidisciplinary treatment plans with combinations of surgery, radiation therapy and chemotherapy. Tumor staging is critical to decide therapeutic planning. Multiple challenges include accurate tumor localization with precise delineation of tumor volume, cervical lymph node staging, detection of distant metastasis as well as ruling out synchronous second primary tumors. Some patients present with cervical lymph node metastasis without obvious primary tumors on clinical examination or conventional cross sectional imaging. Treatment planning includes surgery, radiation, chemotherapy or combinations that could significantly alter the anatomy and physiology of this complex head and neck region, making assessment of treatment response and detection of residual/ recurrent tumor very difficult by clinical evaluation and computed tomography (CT) or magnetic resonance imaging (MRI). ¹⁸F-2-fluoro-2-deoxy-D-glucose positron emission tomography/CT (¹⁸F-FDG PET/CT) has been widely used to assess HNC for more than a decade with high diagnostic accuracy especially in detection of initial distant metastasis and evaluation of treatment response. There are some limitations that are unique to PET/CT including artifacts, lower soft tissue contrast and resolution as compared to MRI, false positivity in post-treatment phase due to inflammation and granulation tissues, etc. The aim of this article is to review the roles of PET/CT in both pre and post treatment management of HNSCC including its limitations that radiologists must know. Accurate PET/CT interpretation is the crucial initial step that leads to appropriate tumor staging and treatment planning.

PET/CT in head and neck oncology: State-of-the-art 2013

OBJECTIVES/HYPOTHESIS

Combined positron emission tomography with simultaneous computed tomography (PET/CT performed using 18F-fluorodeoxyglucose [FDG] as a radiopharmaceutical) results in improvement in anatomic localization of tumor. This review explores the contemporary application of PET/CT to pretreatment assessment, posttreatment monitoring, and subsequent treatment planning for patients with squamous carcinoma of the head and neck.

DATA SOURCES

Contemporary publications on the use of PET/CT in head and neck oncology are reviewed and synthesized.

REVIEW METHOD

This review presents selected literature interpreted by expert opinion.

RESULTS

PET/CT is highly sensitive in staging of patients with squamous cancer of the head and neck. The sensitivity is limited by tumor size, and PET/CT cannot currently replace the information obtained from elective neck dissection in the assessment of cervical metastases. In the setting of posttreatment monitoring, PET/CT allows for identification of persistent carcinoma prior to clinical observation in approximately two-thirds of cases. However, contemporary reports do not allow assessment of cost effectiveness, and they do not allow determination if the application of PET/CT in this setting results in improved treatment outcomes. PET/CT is insensitive to evaluation of patients with glandular tumors, and those with low volume tumors and cystic metastases.

CONCLUSIONS

PET/CT requires further evaluation before recommendations can be made regarding comparative effectiveness when compared to CT or MRI for posttreatment monitoring. The improved sensitivity and specificity of PET/CT during treatment planning justifies its use in this setting for patients with advanced stage squamous cancer of the head and neck.

Utility of quantitative 18 F-fluorodeoxyglucose uptake measurement to identify occult tonsillar carcinoma in patients with cervical metastasis of unknown primary tumours: a retrospective case-control study

OBJECTIVES

Due to relatively high (18) F-fluorodeoxyglucose accumulation in the tonsillar region, the detection of occult tonsillar cancers by (18) F-fluorodeoxyglucose positron emission tomography/computerised tomography remains controversial. Therefore, we assessed the usefulness of quantitative tonsil (18) F-fluorodeoxyglucose uptake in identifying occult tonsillar squamous cell carcinoma.

DESIGN

A case-control study of retrospective cohorts.

SETTING

University Teaching Hospital.

MAIN OUTCOME MEASURES

We assessed all patients diagnosed with tonsillar cancers or cervical lymph node metastasis of unknown primary tumours between 2005 and 2010 who underwent (18) F-fluorodeoxyglucose positron emission tomography/computerised tomography. The subjects were grouped into A (apparent early pT-stage tonsillar squamous cell carcinoma; n = 27), B (occult tonsillar squamous cell carcinoma, primary tumours were found by surgery; n = 21), C (cervical metastasis of unknown primary tumour, primary tumours were not found by surgery and for follow-up; n = 16) and D (33 healthy controls). Tonsillar maximum standardised uptake values were bilaterally measured and compared between groups.

RESULTS

The sensitivity and specificity of qualitative assessment of (18) F-fluorodeoxyglucose positron emission tomography/computerised tomography for detection of occult tonsillar cancers were 67% and 69%, respectively. Mean maximum standardised uptake values of tonsils with cancer were 11.19 ± 5.46 in group A and 8.12 ± 4.52 in group B, which were significantly higher than that of group C (4.62 ± 1.76) or group D (4.57 ± 1.62) (P < 0.01). The mean maximum standardised uptake value differences of groups A (6.35) and B (3.11) were significantly greater than those of groups C (0.32) and D (0.59) (P < 0.01). Similarly, the mean maximum standardised uptake value ratios of groups A (2.47) and B (1.73) were significantly greater than those of groups C (1.06) and D (1.16) (P < 0.01).

CONCLUSION

(18) F-fluorodeoxyglucose positron emission tomography/computerised tomography with tonsil SUVmax measurement is useful to identify occult tonsillar squamous cell carcinoma.

p16 expression in carcinoma of unknown primary: diagnostic indicator and prognostic marker

BACKGROUND

Carcinoma of unknown primary (CUP) of the neck are heterogeneous tumors in their clinical and biological characteristics, and a preoperative prognostic marker is desirable to optimize staging and therapy and to improve outcome and survival. For CUP syndrome, no optimized diagnostic and treatment strategy or biomarker have yet been determined.

METHODS

Forty-seven patients presenting with CUP syndrome were analyzed after thorough standard diagnostic staging procedures. All patients were surgically treated with tonsillectomy, neck dissection of the diseased neck, as well as adjuvant chemoradiation. The tissue of lymph node metastases (and, if found, of the primary tumor) was analyzed regarding expression of p16, epidermal growth factor receptor (EGFR), and presence of human papillomavirus (HPV) DNA.

RESULTS

In 39% of all cases (20 of 47), the primary cancer was found during diagnostic workup. If HPV DNA was detected in the neck lymph node metastasis, the primary cancer was significantly more frequently found in the oropharynx (p = .002). Patients with a p16-positive tumor had a significantly higher 5-year overall survival (OS; 33% vs 69%; p = .045, disease-free survival [DSF] 77% vs 89%; p = not significant [NS]). Patients with p16-positive neck metastasis and no detectable primary cancer had a better prognosis. Expression of EGFR in this series did not have a significant effect on prognosis.

CONCLUSION

In patients presenting with CUP syndrome, p16 immunohistochemistry can serve to locate the primary cancer in the oropharynx. It is a positive prognostic indicator in patients with those heterogeneous cancers.

[Usefulness of (18)F-fluorodeoxyglucose-positron emission tomography-computerized tomography in the identification of the primary tumor in patients with cancer of unknown origin]

BACKGROUND AND OBJECTIVE

We determined the utility of the (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET)-computerized tomography (CT) in the localization of the primary tumor in patients with tumor of unknown origin (TUO).

PATIENTS AND METHOD

(18)F-FDG PET-CT scans, performed between November 2006 and November 2010, in search for the primary tumor in patients with TUO, were retrospectively evaluated. Patients underwent a standard PET-CT, 50-60minutes after intravenous injection of 296-370MBq (18)F-FDG. PET-CT studies were assessed as pathological, with/without identification of the primary tumour and no pathological. Final diagnosis was established by histological confirmation and/or clinical/radiologic follow-up longer than 6 months.

RESULTS

We studied 74 patients (59 males, 15 females), with ages ranging from 41-89 years. In 38 (51%) patients the PET-CT assessed the correct origin of the primary tumour. In 8 cases, a histological confirmation in the primary lesion was obtained. In 4 patients the PET-CT showed a false positive result.

CONCLUSION

PET-CT scanning identified 51% of the primary sites in our sample of patients.

Cancers of unknown primary origin: current perspectives and future therapeutic strategies

It is widely accepted that systemic neoplastic spread is a late event in tumour progression. However, sometimes, rapidly invasive cancers are diagnosed because of appearance of metastatic lesions in absence of a clearly detectable primary mass. This kind of disease is referred to as cancer of unknown primary (CUP) origin and accounts for 3-5% of all cancer diagnosis. There is poor consensus on the extent of diagnostic and pathologic evaluations required for these enigmatic cases which still lack effective treatment. Although technology to predict the primary tumour site of origin is improving rapidly, the key issue is concerning the biology which drives early occult metastatic spreading. This review provides the state of the art about clinical and therapeutic management of this malignant syndrome; main interest is addressed to the most recent improvements in CUP molecular biology and pathology, which will lead to successful tailored therapeutic options.

Contemporary management of lymph node metastases from an unknown primary to the neck: I. A review of diagnostic approaches

In an era of advanced diagnostics, metastasis to cervical lymph nodes from an occult primary tumor is a rare clinical entity and accounts for approximately 3% of head and neck malignancies. Histologically, two thirds of cases are squamous cell carcinomas (SCCs), with other tissue types less common in the neck. With modern imaging and tissue examinations, a primary tumor initially undetected on physical examination is revealed in >50% of patients and the site of the index primary can be predicted with a high level of probability. In the present review, the range and limitations of diagnostic procedures are summarized and the optimal diagnostic workup is proposed. Initial preferred diagnostic procedures are a fine-needle aspiration biopsy (FNAB) and imaging. This allows directed surgical biopsy (such as tonsillectomy), based on the preliminary findings, and prevents misinterpretation of postsurgical images. When no primary lesion is suggested after imaging and panendoscopy, and for patients without a history of smoking and alcohol abuse, molecular profiling of an FNAB sample for human papillomavirus (HPV) and/or Epstein-Barr virus (EBV) is important.