18F-fluorodeoxyglucose positron emission tomography/computed tomography in the assessment of occult primary head and neck cancers--an audit and review of published studies

Multifocal and Recurrent Tonsillar Squamous Cell Carcinoma

The following study describes a complex clinical course of recurrent and multifocal squamous cell carcinoma (SCC) of the tonsil, involving both initial and subsequent malignancies over several years. The patient, a 54-year-old male with a history of tobacco use, first presented with SCC of the left tonsil, treated with tonsillectomy and neck dissection. Despite clear margins post-surgery, the patient developed SCC in the right tonsil two years later, requiring further surgical intervention and a comprehensive treatment approach. The disease then progressed to the base of the tongue and right larynx, necessitating a total laryngectomy and subtotal glossectomy. The report emphasizes the critical role of advanced imaging and surgical techniques, including robotic-assisted surgery, in managing such complex cases. Additionally, the case highlights the challenges of treating advanced oropharyngeal SCC, the importance of multidisciplinary management, and the need for consistent follow-up to monitor treatment efficacy and manage complications. The case underscores the complexity of SCC in the head and neck region and the necessity for tailored therapeutic strategies to improve patient outcomes.

[Value of PET imaging in head and neck cancer]

The combination of positron-emission tomography (PET) with cross-sectional imaging in particular is becoming increasingly important in the diagnosis of head and neck tumors because, in addition to pure anatomy, the metabolic activity of tissue can be visualized and assessed. The combination of PET and computed tomography (CT) is already an established procedure in head and neck tumor patients in some indications, e.g., for primary tumor detection in cancer of unknown primary (CUP) syndrome or also after completed primary radio(chemo)therapy for evaluation of response, especially also with regard to nodal status. In some cases, salvage neck dissection can thus be avoided in the case of PET-negative findings. In the context of primary diagnosis, PET/CT imaging can be used primarily to evaluate distant metastasis. According to current guidelines, PET-based imaging is not (yet) of value in determining the local extent at initial diagnosis. A challenge is the still limited reimbursement by health insurance companies, which currently allow only certain indications, and the still lack of nationwide coverage.

[Value of PET imaging in head and neck cancer]

The combination of positron-emission tomography (PET) with cross-sectional imaging in particular is becoming increasingly important in the diagnosis of head and neck tumors because, in addition to pure anatomy, the metabolic activity of tissue can be visualized and assessed. The combination of PET and computed tomography (CT) is already an established procedure in head and neck tumor patients in some indications, e.g., for primary tumor detection in cancer of unknown primary (CUP) syndrome or also after completed primary radio(chemo)therapy for evaluation of response, especially also with regard to nodal status. In some cases, salvage neck dissection can thus be avoided in the case of PET-negative findings. In the context of primary diagnosis, PET/CT imaging can be used primarily to evaluate distant metastasis. According to current guidelines, PET-based imaging is not (yet) of value in determining the local extent at initial diagnosis. A challenge is the still limited reimbursement by health insurance companies, which currently allow only certain indications, and the still lack of nationwide coverage.

Transoral Laser Resection of the Tongue Base in the Workup of Unknown Primary Head and Neck Squamous Cell Carcinoma

Objective Failure to localize the primary tumor site in head and neck carcinoma of unknown origin after imaging and endoscopic evaluation leads to increased treatment-related morbidity. The use of transoral laser microsurgery to improve the detection of unknown primary carcinoma site identification is described in this article. Methods A retrospective cohort of 71 consecutive cases of cervical carcinoma of an unknown primary source from 2006 until 2012 from a single academic institution was analyzed. Of these, 10 patients were excluded based on our exclusion criteria. All patients underwent endoscopy with biopsies performed by fellowship-trained head and neck cancer surgeons.  Results The primary detection rate was 76% for patients who underwent laser tongue base resection versus 34% for traditional operative examination. There were no complications or prolonged recovery times in either group. Operative time was increased by the addition of the transoral base of tongue resection by 30 minutes. Conclusions Laser tongue base excision offers improved sensitivity in primary site detection without a significant increase in morbidity and only a modest increase in operative time.

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.

PET Imaging for Head and Neck Cancers

Head and neck cancers are commonly encountered cancers in clinical practice in the United States. Fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) PET/CT has been clinically applied in staging, occult primary tumor detection, treatment planning, response assessment, follow-up, recurrent disease detection, and prognosis prediction in these patients. Alternative PET tracers remain investigational and can provide additional valuable information such as radioresistant tumor hypoxia. The recent introduction of ¹⁸F-FDG PET/MR imaging has provided the advantage of combining the superior soft tissue resolution of MR imaging with the functional information provided by ¹⁸F-FDG PET. This article is a concise review of recent advances in PET imaging in head and neck cancer.

Tonsillar Metastasis From Colon Cancer Detected on 18F-FDG PET/CT Imaging

A 54-year-old woman with smoking history who was diagnosed with invasive adenocarcinoma of the rectosigmoid colon with subsequent surgical resection and chemotherapy was presented. The patient developed local recurrence and pulmonary metastases that required further chemotherapy and surgical resection. During follow-up, the patient had F-FDG PET/CT scan showing asymmetric hypermetabolic tonsils with activity greater on the right compared with the left. The patient underwent bilateral tonsillectomy, and pathology revealed moderately to poorly differentiated adenocarcinoma in the right tonsil, consistent with metastasis from known colonic primary.

PET-CT for Staging and Detection of Recurrence of Head and Neck Cancer

FDG PET-CT is one the main investigations for squamous cell (Sq) head and neck (H&N) cancer patients. FDG PET-CT has a key role for the staging of patients with T4 cancer of the hypopharynx and nasopharynx and patients with N3 nodal disease. It is effective in detecting recurrent disease accurately. In addition, it has an emerging role in the surveillance of Sq H&N cancer survivors. In patients with advanced neck nodal disease treated with chemoradiotherapy, there is compelling evidence that patients with no FDG uptake in the neck 12 weeks following completion of treatment do not require neck dissection. There is considerable interest in using FDG PET-CT for develop more effective clinical pathways for the surveillance of Sq H&N cancer. Currently, the detection rate of recurrence in patients who attend regular clinical follow-up is poor, less than 1% in asymptomatic patients. FDG PET-CT may enable survivors to be stratified into groups based on the likelihood of having recurrent disease. Optimal surveillance pathways can be developed, reserving most intense imaging regimes and most frequent follow-up for survivors at high risk of recurrence. FDG PET CT is sometimes considered for patients with non Sq H&N cancer. If used in this context, a baseline FDG PET-CT should be done to ensure that the tumour is avid. Most H&N malignant tumours are avid. However, salivary gland cancers, and tumours with muco-epidermoid, adenoid cystic and clear cell histology show paucity of FDG avidity, especially when they recur. In addition, peri-neural invasion cannot be detected reliably with FDG PET-CT.

Comparison Between PET-CT-Guided Neck Dissection and Elective Neck Dissection in cT1-2N0 Tongue Squamous Cell Carcinoma

Objective: Neck management in cT1-2N0 tongue squamous cell carcinoma (SCC) remains controversial. Our goal was to compare the survival difference between PET-CT–guided neck dissection and elective neck dissection (END) for the treatment of cT1-2 tongue SCC.

Methods: Patients with surgically treated cT1-2N0 tongue SCC were retrospectively enrolled. These patients were divided into two groups. Group A: The decision of whether to perform neck dissection was mainly based on the results of preoperative PET-CT examinations. Group B: Patients received END treatment without preoperative PET-CT examinations. The study endpoints were regional control (RC) and disease-specific survival (DSS). The Kaplan–Meier method was used to calculate the survival rates.

Results: Group A consisted of 66 patients, and 16 patients underwent neck dissection owing to positive PET-CT results. Group B consisted of 169 patients. The 5-year RC rates in group A and group B were 86 and 87%, respectively, and the difference was not significant (p = 0.731). The 5-year DSS rates in group A and group B were 93 and 90%, respectively, and the difference was not significant (p = 0.583).

Conclusions: Neck dissection can be safely avoided when the PET-CT scan reveals no neck lymph node involvement.

A systematic review on Transoral robotic surgery (TORS) for carcinoma of unknown primary origin: Has tongue base mucosectomy become indispensable?

Background

Transoral robotic surgery (TORS) is increasingly used in head and neck surgery and in carcinoma of unknown primary (CUP) origin specifically. Due to the rising incidence of human papillomavirus (HPV)‐related oropharyngeal squamous cell carcinoma (OPSCC), there is a rationale for finding ways to de‐escalate treatment strategies. This review aims to test the hypothesis that TORS is a meaningful adjunct in the diagnostic (and therapeutic) pathway in CUP in head and neck.

Methods

A structured search of the literature was performed with the search terms ‘TORS’ and ‘Carcinoma of Unknown Primary’.

Results

Two hundred and seventy four cases of CUP in which TORS was used were identified for further analysis. Workup for CUP was comparable in all series with regard to physical examination, fine and/or gross needle examination of cervical nodes, fibre optic endoscopy, imaging and robot assisted mucosectomy of the base of tongue (BOT). Identification rate of the primary tumour was 72% on average (range 17%‐ 90%), and 55%‐ 96% were HPV positive. Clear margins were achieved in 60% (range 0%‐85%) of resected occult tumours. Complication rate of TORS BOT mucosectomy was low with mainly grade I‐III sequelae according to Clavien–Dindo.

Conclusions

Transoral robotic surgery seems to be a useful and safe adjunct in the diagnostic and therapeutic pathway in case of CUP in an era of increasing incidence of HPV‐positive OPSCC.

Fibroblast activation protein inhibitor (FAPI) PET for diagnostics and advanced targeted radiotherapy in head and neck cancers

Purpose

Cancer-associated fibroblasts (CAFs) expressing fibroblast activation protein (FAP) have been associated with the aggressive nature of head and neck cancers (HNCs). These tumours grow diffusely, leading to extremely challenging differentiation between tumour and healthy tissue. This analysis aims to introduce a novel approach of tumour detection, contouring and targeted radiotherapy of HNCs using visualisation of CAFs: PET-CT with ⁶⁸Ga-radiolabeled inhibitors of FAP (FAPI).

Methods

FAPI PET-CT was performed without complications prior to radiotherapy in addition to contrast enhanced CT (CE-CT) and MRI on 14 patients with HNC. First, for tissue biodistribution analysis, volumes of interest were defined to quantify SUV_mean and SUV_max in tumour and healthy parenchyma. Secondly, using four thresholds of three-, five-, seven- and tenfold increase of FAPI enhancement in the tumour as compared with normal tissue, four different gross tumour volumes (FAPI-GTV) were created automatically. These were compared with GTVs created conventionally with CE-CT and MRI (CT-GTV).

Results

The biodistribution analysis revealed high FAPI avidity within tumorous lesions (e.g. primary tumours, SUV_max 14.62 ± 4.44; SUV_mean 7.41 ± 2.39). In contrast, low background uptake was measured in healthy tissues of the head and neck region (e.g. salivary glands: SUV_max 1.76 ± 0.31; SUV_mean 1.23 ± 0.28). Considering radiation planning, CT-GTV was of 27.3 ml, whereas contouring with FAPI resulted in significantly different GTVs of 67.7 ml (FAPI × 3, p = 0.0134), 22.1 ml (FAPI × 5, p = 0.0419), 7.6 ml (FAPI × 7, p = 0.0001) and 2.3 ml (FAPI × 10, p = 0.0001). Taking these significant disparities between the GTVs into consideration, we merged FAPI-GTVs with CT-GTVs. This resulted in median volumes, that were, as compared to CT-GTVs, significantly larger with FAPI × 3 (54.7 ml, + 200.5% relative increase, p = 0.0005) and FAPI × 5 (15.0 ml, + 54.9%, p = 0.0122). Furthermore, FAPI-GTVs were not covered by CE-CT-based planning target volumes (CT-PTVs) in several cases.

Conclusion

We present first evidence of diagnostic and therapeutic potential of FAPI ligands in head and neck cancer. Larger studies with histopathological correlation are required to validate our findings.

Electronic supplementary material

The online version of this article (10.1007/s00259-020-04859-y) contains supplementary material, which is available to authorized users.

The effectiveness of the follow-up of patients after surgery due to cancer of the head and neck

Aim: The aim of this study was to assess the effectiveness of the follow-up (FU) of patients after head and neck cancer treatment. Materials & methods: This is a retrospective cross-sectional study and concerns the analysis of outpatient records of 85 women and 355 men who reported at FU visits between 2011 and 2016 in ENT Department in the University Of Medical Sciences in Poznan, Poland. Results: The value of the FU scheme was confirmed by a high rate of recurrence detected in a medical examination (60%) and routine imaging studies (27%), as opposed to only 13% in spontaneous reports. Conclusion: The FU therapeutic profit in the form of high percentages of preclinical relapse at a reasonable cost is justified medically and socially.

GEORCC recommendations on target volumes in radiotherapy for Head Neck Cancer of Unkown Primary

Head Neck Cancer of Unknown Primary (HNCUP) is a rare condition, representing approximately 5-10% of all head neck cancers. Radiotherapy, adjuvant or radical, is usually employed in the treatment of those patients. To date, no specific guidelines for the optimal definition of the target volume to be irradiated have been published. In recent years, there have been advances in the knowledge of the molecular biology of HNCUP, its diagnostic imaging and the implementation of sophisticated radiotherapy techniques with enhanced precision in target localization and treatment delivery. These progresses have provided valuable information about the natural history of HNCUP that will allow for establishment of the best treatment for each patient, including standardized, consistent and reproducible target volumes definitions. Several recommendations regarding how to choose volumes when contouring HNCUP in clinical practice are reported, in order to achieve a high rate of loco-regional control while avoiding unnecessary toxicity.

The preclinical study of predicting radiosensitivity in human nasopharyngeal carcinoma xenografts by 18F-ML-10 animal- PET/CT imaging

Previous studies have reported that the radiosensitivity is associated with apoptosis. Hereby, we aimed to investigate the value of ¹⁸F-ML-10 PET/CT, which selectively targeted cells undergoing apoptosis, in predicting radiosensitivity of human nasopharyngeal carcinoma (NPC) xenografts. We used CNE1 (highly differentiated) and CNE2 (poorly differentiated) NPC cell lines to construct tumor models, which had very different radiosensitivities. After irradiation, the volumes of CNE2 tumors decreased significantly while those of CNE1 tumors increased. In ¹⁸F-ML-10 imaging, the values of tumor/muscle (T/M) between CNE1 and CNE2 mice were statistically different at both 24 h and 48 h after irradiation. Besides, ΔT/M_1-0 and ΔT/M_2-0 of CNE2 mice were higher than those of CNE1 mice, demonstrating obvious discrepancy. Furthermore, we observed obvious changes of radioactive distribution in CNE2 group. On the contrary, T/M of ¹⁸F-FDG in irradiation group revealed no obvious change in both CNE1 and CNE2 groups. In conclusion, ¹⁸F-ML-10 animal PET/CT showed its potential to predict radiosensitivity in NPC.

PET/CT and PET/MRI in head and neck malignancy

Combined 2-[18F]-fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography (PET)/computed tomography (CT) has an established role in the staging of difficult cases of head and neck (HN) squamous cell carcinoma (SCC), looking for an unknown primary, assessing response post-chemotherapy at 3-6 months, and differentiating relapse from treatment effects in patients suspected to have tumour recurrence. The PET NECK trial, comparing PET/CT surveillance versus neck dissection in advanced head and neck cancer showed survival was similar among patients who underwent PET/CT-guided surveillance and those who underwent planned neck dissection, but surveillance was more cost-effective. There is growing interest in the use of hypoxia PET tracers, especially in targeting radiotherapy, where the radiotherapy dose can be boosted in regions of hypoxia; the use of 68Ga peptide tracers in neuroendocrine malignancy and also in the growing field of combined PET/magnetic resonance imaging (MRI). PET/MRI has the advantage of increased anatomical detail and radiation dose reduction combined with the molecular and metabolic data from PET, although PET/CT has the advantage in better sensitivity for imaging lung metastases. Thus far, there is good agreement between PET/CT and PET/MRI with high correlation between semi-quantitative measurements in primary, nodal, osseous, and soft-tissue lesions imaging. PET/MRI may indeed provide greater accuracy than the currently available imaging procedures in the staging and later treatment response evaluation in HNSCC.

Efficacy of 18F-FDG PET/CT in investigation of elevated CEA without known primary malignancy

Aim:

To evaluate the efficacy of ¹⁸flurodeoxyglucose positron emission tomography/computer tomography (¹⁸F-FDG PET/CT) in investigating patients with elevated carcinoembryonic antigen (CEA) and without known primary malignancy, and the impact of PET/CT findings on patient management.

Setting and Design:

PET/CT scans done in a tertiary hospital between December 2007 and February 2012 for elevated CEA in patients without known primary malignancy were retrospectively reviewed.

Materials and Methods:

The PET/CT findings, patients' clinical information, level of CEA, histological diagnosis, and subsequent management were retrieved by the electronic patient record for analysis.

Statistical Analysis:

Data were analyzed using SPSS version 19.

Results:

One hundred and one PET/CT scans were performed for patients with elevated CEA. Fifty-eight of these were performed for patients with known primary malignancy and were excluded; 43 PET/CT scans were performed for patients without known primary malignancy and were included. Thirty-three (77%) had a positive PET/CT. Among the 32 patients with malignancy, 15 (47%) suffered from lung cancer and 8 (25%) suffered from colorectal cancer. The sensitivity (97%), specificity (82%), positive predictive value (94%), negative predictive value (90%), and accuracy (93%) were calculated. Thirty (91%) patients had resultant change in management. The mean CEA level for patients with malignancy (46.1 ng/ml) was significantly higher than those without malignancy (3.82 ng/ml) (P < 0.05). In predicting the presence of malignancy, a CEA cutoff at 7.55 ng/ml will achieve a sensitivity of 91% and a specificity of 73%.

Conclusion:

PET/CT, in our study population, appears to be sensitive, specific, and accurate in investigating patients with elevated CEA and without known primary malignancy. In addition to diagnosis of underlying primary malignancy, PET/CT also reveals occult metastases which would affect patient treatment options. Its role in investigating patients with elevated CEA and without known primary, compared with other investigation modalities, remains to be studied.

Overview of the predictive value of quantitative 18 FDG PET in head and neck cancer treated with chemoradiotherapy

18 F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) allows to quantify the metabolic activity of a tumor (glycolysis) and has become a reference tool in oncology for the staging, restaging, radiotherapy planning and monitoring response in many cancers. Quantitative analyses have been introduced in order to overcome some of the limits of the visual methods, allowing an easier and more objective comparison of the inter- and intra-patients variations. The aims of this review were to report available evidences on the clinical value of quantitative PET/CT parameters in HNC. Forty-five studies, for a total of 2928 patients, were analyzed. Most of the data available dealt with the intensity of the metabolism, calculated from the Standard Uptake Value (SUV). Metabolic Tumor Volume (MTV) was well correlated with overall survival and disease free survival, with a higher predictive value than the maximum SUV. Spatial distribution of metabolism and textural analyses seems promising.

Role of fluorine-18 fluorodeoxyglucose PET/CT in head and neck oncology: the point of view of the radiation oncologist

Squamous cell carcinoma is the most common malignant tumour of the head and neck. The initial TNM staging, the evaluation of the tumour response during treatment, and the long-term surveillance are crucial moments in the approach to head and neck squamous cell carcinoma (HNSCC). Thus, at each of these moments, the choice of the best diagnostic tool providing the more precise and larger information is crucial. Positron emission tomography with fluorine-18 fludeoxyglucose integrated with CT (¹⁸F-FDG-PET/CT) rapidly gained clinical acceptance, and it has become an important imaging tool in routine clinical oncology. However, controversial data are currently available, for example, on the role of ¹⁸F-FDG-PET/CT imaging during radiotherapy planning, the prognostic value or its real clinical impact on treatment decisions. In this article, the role of ¹⁸F-FDG-PET/CT imaging in HNSCC during pre-treatment staging, radiotherapy planning, treatment response assessment, prognosis and follow-up is reviewed focusing on current evidence and controversial issues. A proposal on how to integrate ¹⁸F-FDG-PET/CT in daily clinical practice is also described.

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.

Modern Radiology in the Management of Head and Neck Cancer

The accurate staging of head and neck cancer is vital to direct appropriate management strategies and to deliver the best radiation therapy and surgery. Initial challenges in head and neck cancer imaging include determination of T- and N-stage, stage migration with detection of metastatic disease and identification of primary disease in the patient presenting with nodal metastases. In follow-up, imaging has an important role in assessing patients who may require salvage surgery after radiotherapy and assessing clinical change that may represent either residual/recurrent disease or radiation effects. This overview gathers recent evidence on the optimal use of currently readily available imaging modalities (ultrasound, computed tomography, magnetic resonance imaging and positron emission tomography-computed tomography) in the context of head and neck squamous cell cancers.

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.

PET/MR in cancers of the head and neck

One early application of PET/MRI in clinical practice may be the imaging of head and neck cancers. This is because the morphologic imaging modalities, CT and MR, are recognized as similarly effective tools in cross-sectional oncological imaging of the head and neck. The addition of PET with FDG is believed to enhance the accuracy of both modalities to a similar degree. However, there are a few specific scenarios in head and neck cancer imaging where MR is thought to provide an edge over CT, including perineural spread of tumors and the infiltration of important anatomical landmarks, such as the prevertebral fascia and great vessel walls. Here, hybrid PET/MR might provide higher diagnostic certainty than PET/CT or a separate acquisition of PET/CT and MR. Another advantage of MR is the availability of several functional techniques. Although some of them might enhance the imaging of head and neck cancer with PET/MR, other functional techniques actually might prove dispensable in the presence of PET. In this overview, we discuss current trends and potential clinical applications of PET/MR in the imaging of head and neck cancers, including clinical protocols. We also discuss potential benefits of implementing functional MR techniques into hybrid PET/MRI of head and neck cancers.

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.

Advances in the management of squamous cell carcinoma of the head and neck

Squamous cell carcinoma of the head and neck (SCCHN) is the sixth most common cancer worldwide. The main risk factors for cancers of the oral cavity, larynx, oropharynx, and hypopharynx are alcohol and tobacco use. In addition, the human papillomavirus (HPV) is an established cause of oropharyngeal cancer. An experienced multidisciplinary team is necessary for adequate management and optimal outcome. The treatment of locally advanced disease generally requires various combinations of radiotherapy, surgery, and systemic therapy, but despite this aggressive multimodal treatment, 40% to 60% of the patients will relapse. In this report, we will discuss recent advances in the management of SCCHN, including new developments in molecular biology, imaging, and treatment.

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.

Clinicopathological characteristics of carcinoma from unknown primary in cervical lymph nodes

Carcinoma in cervical lymph nodes of unknown origin represents a rare clinical entity where optimal diagnostic and therapeutic management is still a widely debated issue. Molecular classification of these metastases is thus of utmost importance. We analyzed the expression of eight basic molecular markers in 26 metastases from unknown primaries, 31 metastases from overt primaries and their associated primaries. Medical records of the respective patients were reviewed for main clinicopathological parameters. The expression rates showed no significant differences between the two tumor entities, neither in absolute terms nor in comparison among the parameters. Surprisingly, patients with metastases from unknown primary demonstrated improved progression-free survival (p = 0.046) despite advanced age (p = 0.029), advanced nodal stage (p = 0.006) and higher incidence of extracapsular spread (p = 0.045) compared to patients with metastases from overt primaries. Presence of extracapsular spread was associated with increased expression of epidermal growth factor receptor in metastases from overt primaries (p = 0.035) and reduced expression of matrix metalloproteinase-2 in metastases from unknown primary (p = 0.031). We thus conclude that cervical metastases from unknown and overt primaries show similarities in their molecular profile, but fundamental differences in clinical parameter.

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.

FDG PET/CT diagnosis of clinically occult gastric cancer

AIM: To investigate the use of fluorodeoxyglucose (FDG) positron emission tomography ( PET)/CT imaging in diagnosis of clinically occult gastric cancer.

METHODS: The imaging data for 26 patients with clinically occult gastric cancer who underwent FDG PET/CT imaging were reviewed retrospectively. They were hospitalized for metastatic tumors and therefore underwent FDG PET/CT for detecting carcinoma of unknown primary origin. They were finally diagnosed with gastric cancer by endoscopy (n = 24) or laparoscopy (n = 2). Based on imaging manifestations, the patients were divided into three groups: easily diagnosed, suspected, and hardly diagnosed.

RESULTS: PET imaging showed 57.7% (15/26) of intensively positive cases, 23.1% (6/26) of positive cases, and 19.2% (5/26) of negative cases. CT imaging showed 76.9% (20/26) of intensively positive cases, 11.5% (3/26) of positive cases, and 11.5% (3/26) of negative cases. The percentages of easily diagnosed, suspected, and hardly diagnosed patients were 53.8% (14/26), 34.6% (9/26) and 11.5% (3/26), respectively.

CONCLUSION: FDG PET/CT imaging can help diagnose clinically occult gastric cancer in about 88.4% of patients.

Radiographic imaging of human papillomavirus related carcinomas of the oropharynx

Imaging, especially contrast-enhanced computed tomography (CECT) for anatomy and positron emission tomography (PET) with labeled (18)F fluorodeoxyglucose for physiologic detail, is critical for staging carcinomas of the oropharynx. As the incidence of human papillomavirus (HPV) infection and related carcinomas of the tonsil and base of tongue (BOT) increases, experience with CECT and PET for staging HPV+ tumors is growing. No imaging modality, however, can determine whether the tumor is HPV+. There are some unique challenges posed by HPV+ oropharyngeal squamous cell carcinoma (SCC). In most locations of the head and neck, a malignancy enhances more than surrounding normal structures, which facilitates tumor mapping. Unfortunately, normal lymphoid tissue of the oropharynx, in the BOT and palatine tonsillar fossa, enhances on CECT and gadolinium enhanced magnetic resonance imaging in a manner similar to SCC. The primary tumor may be small or even occult at presentation, and easily over-looked on CECT. PET coupled with CECT has made a true "unknown primary" very rare, as the metabolically active tumor is almost always detectable on PET. The nodal metastases, so common with HPV+ SCC, can be truly cystic; and as such, can be misdiagnosed as a second branchial cleft cyst, a congenital benign lesion. These pitfalls, coupled with the complex anatomy of the upper aerodigestive tract, make staging these tumors difficult. In this monograph we describe the anatomy of the oropharynx and review the imaging modalities available for staging. Figures highlight the points raised in the text.