Can positron emission tomography improve the quality of care for head-and-neck cancer patients?

Three-Dimensional Image Fusion of 18F-Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography and Contrast-Enhanced Computed Tomography for Computer-Assisted Planning of Maxillectomy of Recurrent Maxillary Squamous Cell Carcinoma and Defect Reconstruction

PURPOSE

The purpose of this study was to describe new technology assisted by 3-dimensional (3D) image fusion of ¹⁸F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) and contrast-enhanced CT (CECT) for computer planning of a maxillectomy of recurrent maxillary squamous cell carcinoma and defect reconstruction.

MATERIALS AND METHODS

Treatment of recurrent maxillary squamous cell carcinoma usually includes tumor resection and free flap reconstruction. FDG-PET/CT provided images of regions of abnormal glucose uptake and thus showed metabolic tumor volume to guide tumor resection. CECT data were used to create 3D reconstructed images of vessels to show the vascular diameters and locations, so that the most suitable vein and artery could be selected during anastomosis of the free flap. The data from preoperative maxillofacial CECT scans and FDG-PET/CT imaging were imported into the navigation system (iPlan 3.0; Brainlab, Feldkirchen, Germany). Three-dimensional image fusion between FDG-PET/CT and CECT was accomplished using Brainlab software according to the position of the 2 skulls simulated in the CECT image and PET/CT image, respectively. After verification of the image fusion accuracy, the 3D reconstruction images of the metabolic tumor, vessels, and other critical structures could be visualized within the same coordinate system. These sagittal, coronal, axial, and 3D reconstruction images were used to determine the virtual osteotomy sites and reconstruction plan, which was provided to the surgeon and used for surgical navigation.

RESULTS

The average shift of the 3D image fusion between FDG-PET/CT and CECT was less than 1 mm. This technique, by clearly showing the metabolic tumor volume and the most suitable vessels for anastomosis, facilitated resection and reconstruction of recurrent maxillary squamous cell carcinoma.

CONCLUSIONS

We used 3D image fusion of FDG-PET/CT and CECT to successfully accomplish resection and reconstruction of recurrent maxillary squamous cell carcinoma. This method has the potential to improve the clinical outcomes of these challenging procedures.

The utility of FDG-PET for assessing outcomes in oligometastatic cancer patients treated with stereotactic body radiotherapy: a cohort study

Background

Studies suggest that patients with metastases limited in number and destination organ benefit from metastasis-directed therapy. Stereotactic body radiotherapy (SBRT) is commonly used for metastasis directed therapy in this group. However, the characterization of PET response following SBRT is unknown in this population. We analyzed our cohort of patients to describe the PET response following SBRT.

Methods

Patients enrolled on a prospective dose escalation trial of SBRT to all known sites of metastatic disease were reviewed to select patients with pre- and post-therapy PET scans. Response to SBRT was characterized on PET imaging based on standard PET response criteria and compared to CT based RECIST criteria for each treated lesion.

Results

31 patients had PET and CT data available before and after treatment for analysis in this study. In total, 58 lesions were treated (19 lung, 11 osseous, 11 nodal, 9 liver, 6 adrenal and 2 soft tissue metastases). Median follow-up was 14 months (range: 3–41). Median time to first post-therapy PET was 1.2 months (range; 0.5-4.1). On initial post-therapy PET evaluation, 96% (56/58) of treated metastases responded to therapy. 60% (35/58) had a complete response (CR) on PET and 36% (21/58) had a partial response (PR). Of 22 patients with stable disease (SD) on initial CT scan, 13 had CR on PET, 8 had PR, and one had SD. Of 21 metastases with PET PR, 38% became CR, 52% remained PR, and 10% had progressive disease on follow-up PET. 10/35 lesions (29%) with an initial PET CR progressed on follow-up PET scan with median time to progression of 4.11 months (range: 2.75-9.56). Higher radiation dose correlated with long-term PET response.

Conclusions

PET response to SBRT enables characterization of metastatic response in tumors non-measurable by CT. Increasing radiation dose is associated with prolonged complete response on PET.

Diffusion-weighted imaging in head and neck cancers

This article reviews the utility of diffusion-weighted imaging (DWI) in the diagnosis, prognosis and monitoring of treatment response in tumors arising in the head and neck region. The apparent diffusion coefficient (ADC) value, determined from DWI, can help in cancer staging and detection of subcentimeter nodal metastasis. The ADC value also discriminates carcinomas from lymphomas, benign lesions from malignant tumors and tumor necrosis from abscesses. Low pretreatment ADC values typically predict a favorable response to chemoradiation therapy. These promising reports indicate the potential of DWI as a potential biomarker for diagnosis and monitoring of treatment response in head and neck cancers. In view of the overlapping ADC values between different salivary gland tumors, care should be taken when interpreting these results and other imaging parameters should be considered for a better diagnosis. Susceptibility and motion-induced artifacts may sometimes degrade DWI image quality; however, novel techniques are being developed to overcome these drawbacks.

18F-FDG PET/CT for image-guided and intensity-modulated radiotherapy

Advances in technology have allowed extremely precise control of radiation dose delivery and localization within a patient. The ability to confidently delineate target tumor boundaries, however, has lagged behind. (18)F-FDG PET/CT, with its ability to distinguish metabolically active disease from normal tissue, may provide a partial solution to this problem. Here we review the current applications of (18)F-FDG PET/CT in a variety of disease sites, including non-small cell lung cancer, head and neck cancer, and pancreatic adenocarcinoma. This review focuses on the use of (18)F-FDG PET/CT to aid in planning radiotherapy and the associated benefits and challenges. We also briefly consider novel radiopharmaceuticals that are beginning to be used in the context of radiotherapy planning.

[Neck dissection following chemoradiation for node positive head and neck carcinomas]

The optimal timing and extent of neck dissection in the context of chemoradiation for head and neck cancer remains controversial. For some institutions, it is uncertain whether neck dissection should still be performed upfront especially for cystic nodes. For others, neck dissection can be performed after chemoradiation and can be omitted for N1 disease as long as a complete response to chemoradiation is obtained. The question is debated for N2 and N3 disease even after a complete response as the correlation between radiological and clinical assessment and pathology may not be reliable. Response rates are greater than or equal to 60% and isolated neck failures are less than or equal to 10% with current chemoradiation protocols. Some therefore consider that systematic upfront or planned neck dissection would lead to greater than or equal to 50% unnecessary neck dissections for N2-N3 disease. Positron-emission tomography (PET) scanning to assess treatment response and have shown a very high negative predictive value of greater than or equal to 95% when using a standard uptake value of 3 for patients with a negative PET at four months after the completion of therapy. These data may support the practice of observing PET-negative necks. More evidence-based data are awaited to assess the need for neck dissection on PET. Selective neck dissection based on radiological assessment and peroperative findings and not exclusively on initial nodal stage may help to limit morbidity and to improve the quality of life without increasing the risk of neck failure. Adjuvant regional radiation boosts might be discussed on an individual basis for aggressive residual nodal disease with extracapsular spread and uncertain margins but evidence is missing. Medical treatments aiming at reducing the metastatic risk especially for N3 disease are to be evaluated.

Time benefit in the assessment of recurrences following fractionated radiotherapy in an experimental tumour system using positron‐emission tomography with18F‐fluorodeoxyglucose

PURPOSE

To determine the sensitivity and specificity of 18F-fluorodeoxyglucose-positron-emission tomography (FDG-PET) in the diagnosis of R1H tumours after fractionated radiotherapy, and the dependency of sensitivity and specificity on time after therapy. In addition, the time benefit of FDG-PET concerning early recognition of recurrences after fractionated radiotherapy was assessed.

MATERIAL AND METHODS

Subcutaneously growing rat rhabdomyosarcoma R1H tumours were irradiated by applying total doses of 80 or 85 Gy after reaching a start volume of 0.8 cm3. Twenty animals were treated. Tumour volume was determined twice a week. FDG-PET was performed weekly before, during and for 6 months after therapy using a conventional full-ring whole-body PET scanner. In total, 600 PET results were evaluated qualitatively using a six-scale score. PET results and actual tumour volumes were compared. The sensitivity and specificity of tumour detection by PET was calculated for different times after the onset of therapy. The optimal score for tumour detection and the influence of time after therapy on the quality of PET (time benefit) was evaluated using receiver-operating characteristics.

RESULTS

After irradiation, 8/20 tumours (40%) were locally controlled, while 12/20 recurred. In this tumour model, evidence of relapse is assured when a volume of 0.1 cm3 is reached. Sensitivity of tumour diagnosis by PET increases with time, i.e. with the volume of recurrent tumours after the onset of therapy, mounting to > 0.95 after 100 days. Specificities of 0.95-1.0 were determined after therapy, showing no increase with time. Tumour diagnosis by PET is highly accurate when performed 80 days after the start of treatment. On average, tumours were recognized by PET on 31, 62, 74 and 81 days (median) before approaching volumes of 0.2, 0.5, 0.8 or 1.0 cm3, respectively.

CONCLUSION

An experimental system was implemented that allows reproducible detection of recurrent R1H tumours after radiotherapy using FDG-PET. The usefulness of PET as a diagnostic test for R1H tumours is very good and a reliable resolution for PET is demonstrated for volumes < 1 cm3. The results indicate that FDG-PET enables early recognition of recurrences after fractionated radiotherapy.

PET-CT in radiation oncology: the impact on diagnosis, treatment planning, and assessment of treatment response

OBJECTIVE

To review the role of hybrid positron emission tomography (PET)-computed tomography (CT) systems in the design and management of cancer patients in the modern radiation oncology practice. PET is co-registered with CT and incorporated into a systematic approach to the staging, management, and assessment of response and surveillance of a variety of oncologic diagnoses.

METHODS

A review of the literature of functional imaging such as PET-CT in staging, treatment plan design, assessment of response and detection of recurrence for tumors involving the head and neck, lung, esophagus, rectum amongst others.

RESULTS

PET and PET-CT offer significant advantages which include more accurate staging which often results in management changes in roughly one-third of patients across a number of disease site. More accurate target definition may augment highly conformal radiation treatment plans using intensity-modulated radiation therapy and stereotactic radiosurgery and radiotherapy.

CONCLUSION

The emerging data appears to suggest the functional imaging may be a more useful tool to evaluate the therapeutic effect of treatment, detect early failures and prognosticate long-term outcome.

Definitive chemoirradiation for resectable head and neck cancer: treatment outcome and prognostic significance of MRI findings

The aim of this study was to evaluate the outcome and prognosticators for patients with resectable head and neck cancer (RHNC) undergoing definitive concurrent chemotherapy and radiotherapy (CCRT). In total, 110 RHNC patients receiving definitive CCRT to defer radical surgery were enrolled. Radiotherapy was given as either 2 Gy once daily with 70 Gy, or 1.2 Gy twice daily with 74.4 Gy. Chemotherapy involved the administration of 5-fluorouracil and cisplatin in two concomitant and two post-radiotherapy adjuvant cycles. 3 months after CCRT, MRI was performed to evaluate the response and determine further treatment plans. Survival outcome was calculated by the Kaplan-Meier method. Log-rank test and Cox regression analyses were used to estimate the significance of prognosticators. 4-year local-regional control, distant metastasis-free survival, disease-free survival and overall survival rates were 76.1%, 85.6%, 67.5% and 53.2%, respectively. Local recurrence (odds ratio = 4.09; p < 0.0001) and T3/T4 stage (odds ratio = 2.34; p = 0.01) were the independent factors associated with poor survival. T stage (odds ratio = 3.29; p = 0.03) and/or remission status on post-CCRT MRI (odds ratio = 7.22; p < 0.0001) were significantly associated with local control, distant metastasis-free survival and disease-free survival. 13 of 20 patients with imaging residuum had local recurrence, compared with 12 of 89 with complete remission (4-year local control rate of 27% vs 86%; p < 0.0001). Post-CCRT MRI may thus be used to predict the chance of a successful non-surgical approach.

FDG-PET/CT imaging for staging and radiotherapy treatment planning of head and neck carcinoma

Background

Positron emission tomography (PET) has a potential improvement for staging and radiation treatment planning of various tumor sites. We analyzed the use of ¹⁸F-fluorodeoxyglucose (FDG)-PET/computed tomography (CT) images for staging and target volume delineation of patients with head and neck carcinoma candidates for radiotherapy.

Methods

Twenty-two patients candidates for primary radiotherapy, who did not receive any curative surgery, underwent both CT and PET/CT simulation. Gross Tumor Volume (GTV) was contoured on CT (CT-GTV), PET (PET-GTV), and PET/CT images (PET/CT-GTV). The resulting volumes were analyzed and compared.

Results

Based on PET/CT, changes in TNM categories and clinical stage occurred in 5/22 cases (22%). The difference between CT-GTV and PET-GTV was not statistically significant (p = 0.2) whereas the difference between the composite volume (PET/CT-GTV) and CT-GTV was statistically significant (p < 0.0001).

Conclusion

PET/CT fusion images could have a potential impact on both tumor staging and treatment planning.

Head and neck squamous cell carcinoma: usefulness of diffusion-weighted MR imaging in the prediction of a neoadjuvant therapeutic effect

The purpose of our study was to evaluate the usefulness of diffusion-weighted imaging in predicting the responses to neoadjuvant therapy for head and neck squamous cell carcinomas. Diffusion-weighted, T2-weighted, and gadolinium-enhanced T1-weighted images were obtained from 28 patients with untreated head and neck squamous cell carcinomas with histological proof. A blinded radiologist evaluated the quantitative and qualitative signal intensities and apparent diffusion coefficients (ADCs) in the lesions on each sequence. All patients were treated by neoadjuvant therapies, and the post-therapeutic tumor regression rate was determined. Both the quantitative and qualitative signal intensities on diffusion-weighted images showed positive correlations (r = 0.367 and 0.412, p < .05), and the ADCs showed a weak, inversed correlation (r = -0.384, p < .05) with the tumor regression rates. Diffusion-weighted imaging including an assessment by ADCs may be able to predict tumor response to neoadjuvant therapy for head and neck squamous cell carcinomas.

[18FDG] PET-CT-based intensity-modulated radiotherapy treatment planning of head and neck cancer

PURPOSE

To define the best threshold for tumor volume delineation of the (18) fluoro-2-deoxy-glucose positron emission tomography ((18)FDG-PET) signal for radiotherapy treatment planning of intensity-modulated radiotherapy (IMRT) in head and neck cancer.

METHODS AND MATERIALS

In 25 patients with head-and-neck cancer, CT-based gross tumor volume (GTV(CT)) was delineated. After PET-CT image fusion, window level (L) was adapted to best fit the GTV(CT), and GTV(PET) was delineated. Tumor maximum (S) and background uptake (B) were measured, and the threshold of the background-subtracted tumor maximum uptake (THR) was used for PET signal segmentation. Gross tumor volumes were expanded to planning target volumes (PTVs) and analyzed.

RESULTS

The mean value of S was 40 kBq/mL, S/B ratio was 16, and THR was 26%. The THR correlated with S (r = -0.752), but no correlation between THR and the S/B ratio was seen (r = -0.382). In 77% of cases, S was >30 kBq/mL, and in 23% it was </=30 kBq/mL, with a mean THR of 21.4% and 41.6%, respectively (p < 0.001). Using PTV(PET) in radiotherapy treatment planning resulted in a reduced PTV in 72% of cases, while covering 88.2% of GTV(CT), comparable to the percentage of GTV(PET) covered by PTV(CT) (p = 0.15).

CONCLUSIONS

A case-specific PET signal threshold is optimal in PET-based radiotherapy treatment planning. Signal gating using a THR of 20% in tumors with S >30% +/- 1.6% kBq/mL and 40% in tumors with S </=30% +/- 1.6% kBq/mL is suitable.

Early assessment of clinical response to concurrent chemoradiotherapy in head and neck carcinoma using fluoro-2-deoxy-d-glucose positron emission tomography

OBJECTIVES

The aim of this study is to assess the utility of FDG-PET in the evaluation of therapeutic effects at 4 weeks after the completion of the concurrent chemoradiotherapy (CCR) in patients with head and neck squamous cell carcinoma (HNSCC).

METHODS

Thirty-one patients with previously untreated HNSCC were retrospectively investigated about FDG-PET, CT, MRI and biopsies of the carcinoma before and 4 weeks after the treatment.

RESULTS

The results of pathological examinations after CCR showed 6 residual cases and 25 ones with a pathologically complete response (pCR). The specificity of FDG-PET was 80%, although the sensitivity was limited to 67%.

CONCLUSIONS

FDG-PET has a high specificity but limited sensitivity to discriminate residual cancer from fibrosis or scar at 4 weeks after CCR. FDG-PET at 4 weeks after CCR was too early to perform because of limited sensitivity.

What Does PET Imaging Add to Conventional Staging of Head and Neck Cancer Patients?

PURPOSE

To determine the value of PET scans in the staging of patients with head and neck carcinoma.

METHODS AND MATERIALS

The charts of 25 patients who underwent neck dissection, computed tomography (CT) scan, and F-18-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging as part of their initial work-up for a head and neck squamous cell cancer between 2000-2003 were reviewed. All patients underwent clinical examination, triple endoscopy, and chest radiograph as part of their clinical staging, adhering to American Joint Commission for Cancer criteria. In addition to the clinical nodal (N) stage, PET findings were incorporated to determine a second type of N staging: clinical N + PET stage. The number of neck sides and nodal levels involved on CT or PET and on pathologic examination were recorded.

RESULTS

The sensitivity and specificity for detection of nodal disease were similar for CT and FDG-PET. Positive and negative likelihood ratios were similar for both diagnostic tests. None of our 25 patients had unsuspected distant disease detected by PET.

CONCLUSION

The addition of PET imaging did not improve diagnostic accuracy in our patients compared with CT. PET scanning did not alter clinical management in any of the patients.

[Contribution of 18-F-FDG PET for detection of head and neck carcinomas with an unknown primary tumor]

OBJECTIVES

To evaluate the usefulness of fusioning positron emission tomography with computed tomography (PET/CT) for the detection of head and neck carcinomas of unknown primary.

METHODS

This prospective study included 20 patients with cervical lymph node of squamous cell carcinoma of unknown primary after standard initial workup (nasofibroscopy and CT scan of the chest and head and neck). Patients underwent PET/CT and panendoscopy of the upper airways and upper digestive tract with PET/CT directed biopsies. The follow-up was 6 months minimum in all patients.

RESULTS

A potential primary tumor was found in 10 of the 20 cases and confirmed by histology in 7 cases (3 bases of tongue, 1 tonsillar pillar, 1 vallecula, 1 tonsillar fossa, 1 piriform sinus). Four of these seven patients presented a normal endoscopy (diagnosis was made with submucosal PET/CT directed biopsies). PET/CT was normal in 10 of 20 cases with 3 false negatives. The sensitivity of PET/CT was 70%, the specificity was 70% and the accuracy was 70%.

CONCLUSION

PET/CT seems to be of interest in the detection of head and neck carcinoma of unknown primary. PET/CT detected 15% of unknown primary tumors with treatment-related implications.

PET-CT vs contrast-enhanced CT: What is the role for each after chemoradiation for advanced oropharyngeal cancer?

PURPOSE

The aim of our study was to assess the utility of positron emission tomography (PET) and 2 fluoro-2-deoxy-D-glucose coupled with neck CT compared with contrast-enhanced CT in predicting persistent cancer either at the primary site or cervical lymphatics in patients with oropharyngeal cancer treated with concurrent chemoradiation

METHODS

Thirty consecutive patients underwent clinical examination, PET-CT, and contrast-enhanced CT to assess response after the completion of the treatment. The outcome variable was positive tissue diagnosis or negative disease at 6 months. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated for the primary site as well as cervical disease.

RESULTS

Contrast-enhanced CT alone showed the best accuracy in detecting disease at the primary site after treatment (85.7%). Accuracy in evaluating residual tumor in the cervical lymphatics for contrast-enhanced CT and PET-CT was 59.3% and 74.1%, respectively. For evaluating the neck, PET-CT and contrast-enhanced CT demonstrated 100% NPV, but the PPV was 36.3% and 26.6%, respectively.

CONCLUSIONS

In this preliminary study, PET-CT seems to be superior to contrast-enhanced CT in predicting persistent disease in the neck after chemoradiation for oropharyngeal or unknown primary cancer, but not at the primary site. However, the possibility of a false-positive result in the neck remains high, and thus overtreatment may result. Even more concerning are the false-negative results. Larger, prospective studies will be important in defining the role of PET-CT in obviating the need for salvage neck dissections after chemoradiation.

F-18 FDG PET-CT fusion in radiotherapy treatment planning for head and neck cancer

BACKGROUND

The fusion of fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) with CT scans has been shown to improve diagnostic accuracy and staging in non-small cell lung cancer. We report on the influence of PET-CT fusion on the management of patients with head and neck cancer.

METHODS

Thirty-six patients with intact primary head and neck cancers treated with radiation therapy (RT) received PET-CT as part of treatment planning. Workup before PET-CT included a contrast-enhanced CT scan of the head and neck and chest X-ray; patients with nasopharyngeal and paranasal sinus primary tumors also underwent MRI.

RESULTS

Changes in TNM score and American Joint Committee on Cancer stage occurred in 13 patients (36%) and five patients (14%), respectively, based on PET-CT. RT volume and dose were altered in five patients (14%) and four patients (11%), respectively. Five patients initially were seen with carcinoma of unknown primary, and PET-CT confirmed oropharyngeal primary tumors in two. PET-CT data also detected a synchronous lung cancer in one patient.

CONCLUSION

PET-CT fusion may have a significant impact on staging and determination of RT treatment volume and dose.

Sentinel Node Localization in Head and Neck Tumors

Sentinel lymph node biopsy (SLNB) is a minimally invasive method that was developed to stage the regional lymphatics of patients with cutaneous melanoma. Many studies performed worldwide have shown that SLNB is a feasible method to stage the cervical lymphatics in patients with head and neck squamous cell carcinoma (HNSCC). The accuracy of SLNB in patients with HNSCC is currently under investigation in a multicenter study sponsored by the American College of Surgeons Oncology Group that compares the results of SLNB with standard elective neck dissection. Research to date has also shown that multiple SLNs and individualized drainage patterns characterize head and neck mucosal sites. These findings suggest that lymphoscintigraphy alone may be useful to delineate the lymphatic basins that require treatment in patients with HNSCC and in patients whose head and neck lymphatics are disrupted because of prior surgery or irradiation.

Intensity-modulated radiation therapy in the treatment of head and neck cancer

Intensity-modulated radiation therapy (IMRT) is a new technical improvement of radiotherapy, in which computer-controlled treatment machines produce multiple beams of radiotherapy whose intensity is optimized to deliver a high dose of radiation to specified volumes, while reducing the dose to adjacent non-target organs. The potential benefits include the ability to deliver higher doses to the target with an improved safety than has previously been possible, and to reduce side effects and complications. Using IMRT to treat some head and neck cancers is especially attractive due to the close vicinity of the targets and many critical, dose-limiting and non-involved structures, and because of the lack of breathing-related motion. The main clinical uncertainties in the use of IMRT for head and neck cancer relate to uncertainties in the extent of radiation to the target areas. In addition, large volumes of adjacent, non-target tissue receive moderate to low radiation doses, raising concerns of increased risk of radiation-related carcinogenesis in young patients. Initial promising clinical data have emerged from IMRT treatment of several head and neck tumor sites.

Detección temprana con PET-FDG de tumores inesperados de colon en pacientes con otra patología tumoral conocida

Patients with known tumors can have other tumors in unexpected places, the so-called synchronic or second primary cancers. In these patients, whole-body fluorodeoxyglucose positron emission tomography (FDG-PET) to study known tumors can identify other tumors that would escape notice if only the sites of known tumors were investigated. We present 3 patients in whom whole-body FDG-PET was requested to study known tumors: 2 lung cancers and one melanoma. FDG-PET localized the known lesions and revealed hypermetabolic uptake in the abdomen in all 3 patients. Endoscopic polypectomy and pathologic analysis were performed, revealing 2 colon cancers and a tubular adenoma with a high degree of focal atypia. Whole body FDG-PET is a highly useful technique in the early diagnosis of colorectal cancer, which in turn allows complete cure of patients with this disease.

FDG-PET/CT imaging for preradiotherapy staging of head-and-neck squamous cell carcinoma

PURPOSE

Image localization of head-and-neck squamous cell carcinoma lags behind current techniques to deliver a precise radiation dose with intensity-modulated radiotherapy. This pilot study prospectively examined the use of registered 18-F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/CT for preradiotherapy staging of the neck.

METHODS AND MATERIALS

Sixty-three patients with squamous cell carcinoma of the oral cavity, oropharynx, larynx, or hypopharynx were enrolled into an institutional FDG-PET imaging protocol between September 2000 and June 2003. Of these patients, 20 went on to immediate neck dissection surgery and were studied further. Of these 20, 17 (85%) had American Joint Committee on Cancer Stage III or IV disease. All patients underwent preoperative FDG-PET and contrast-enhanced CT of the head and neck. FDG-PET/CT images were created using a nonrigid image registration algorithm developed at the University of Washington. Alternate primary and nodal gross tumor volumes were contoured with radiotherapy treatment planning software, blinded to each other and to the pathology results. One set of volumes was designed with CT guidance alone and the other with the corresponding FDG-PET/CT images. Neck dissection specimens were subdivided into surgical nodal levels intraoperatively, and the histopathologic findings were correlated with the CT and FDG-PET/CT nodal level findings.

RESULTS

FDG-PET/CT detected 17 of 17 heminecks and 26 of 27 nodal zones histologically positive by dissection (100% and 96% sensitivity, respectively). The nodal level staging sensitivity and specificity for FDG-PET/CT was 96% (26 of 27) and 98.5% (68 of 69), respectively. FDG-PET/CT correctly detected nodal disease in 2 patients considered to have node-negative disease by CT alone. Agreement between the imaging results and pathology findings was stronger for FDG-PET/CT (kappa 0.95, 95% confidence interval 0.82-0.99) than for CT alone (kappa 0.81, 95% confidence interval 0.63-0.91; p = 0.06 by two-sided McNemar's testing).

CONCLUSION

These early findings suggest that FDG-PET/CT is superior to CT alone for geographic localization of diseased neck node levels. Confirmatory trials to substantiate the accuracy of FDG-PET/CT neck staging should be prioritized.

The role of fluorodeoxyglucose positron emission tomography in cervical lymph node metastases from an unknown primary tumor

BACKGROUND

The authors performed a comprehensive review of the efficacy of fluorodeoxyglucose positron emission tomography (FDG-PET) in the detection of primary tumors in patients with cervical metastases from unknown primary tumors.

METHODS

Sixteen studies (involving a total of 302 patients) published between 1994 and 2003 were reviewed. These studies evaluated the role of FDG-PET in the detection of unknown primary tumors after conventional workup. In all studies, conventional workup included either panendoscopy or computed tomographic/magnetic resonance imaging, and in 10 of 16 studies, both of these diagnostic techniques were performed before diagnosis.

RESULTS

The overall sensitivity, specificity, and accuracy rates of FDG-PET in detecting unknown primary tumors were 88.3%, 74.9%, and 78.8%, respectively. Furthermore, FDG-PET detected 24.5% of tumors that were not apparent after conventional workup. FDG-PET imaging also led to the detection of previously unrecognized metastases in 27.1% of patients (regional, 15.9%; distant, 11.2%). FDG-PET had notably low specificity and a high false-positive rate (39.3%) in the tonsils. In contrast, the false-positive rates for FDG-PET of the base of tongue and hypopharynx were only 21.4% and 8.3%, respectively. FDG-PET exhibited decreased sensitivity to tumors in the base of tongue (81.5%). The sensitivity of this technique at other sites was 90.5%.

CONCLUSIONS

FDG-PET detected primary tumors that went undetected by other modalities in approximately 25% of cases and was sensitive in the detection of previously unrecognized regional or distant metastases in 27% of cases. FDG-PET had low specificity for tonsillar tumors and low sensitivity for base-of-tongue malignancies.

PET-CT in der Strahlentherapie

Combining positron emission tomography (PET) and X-ray computed tomography (CT) with simultaneous acquisition may improve diagnostic accuracy in oncology. Moreover this combination holds considerable promise in radiotherapy. Metabolic information may be used in decision making in radiotherapy and in planning target volumes. Furthermore early evaluation of treatment efficacy becomes possible. New tracers for the assessment of tumour hypoxia or apoptosis in clinical routine are currently being developed. These tracers may yield high relevance in radiotherapy. Hybrid scanners facilitate patient handling and shorten the duration of acquisition. Furthermore fusion accuracy is optimal. Prospective studies have to be conducted to show that the new technology improves patient care in terms of efficiency and quality.

The role of post-radiation therapy FDG PET in prediction of necessity for post-radiation therapy neck dissection in locally advanced head-and-neck squamous cell carcinoma

PURPOSE

The role of neck dissection after radiation therapy ([RT] with or without chemotherapy) for regionally advanced head and neck cancer is controversial. As much as 50% of residual lymphadenopathy after radiation has no viable tumor cells present on histopathologic analysis. [(18)F] fluorodeoxyglucose positron emission tomography (FDG PET) imaging can detect metabolically active cancer. This study examines the ability of post-RT FDG PET imaging to predict the tumor status of residual lymphadenopathy after nonsurgical management of regionally advanced neck disease.

METHODS AND MATERIAL

From February 2000 to October 2002, 41 patients were treated definitively by radiation (with or without chemotherapy) and underwent FDG PET and computed tomography (CT) imaging after treatment to assess response. Patients with negative CT and FDG PET scans were observed and did not undergo neck dissection. Patients with radiographically persistent lymphadenopathy underwent either neck dissection or fine-needle aspiration of the lymph nodes using ultrasound guidance. The results of the FDG PET scans were correlated with the pathologic findings.

RESULTS

Twelve patients with persistent lymphadenopathy underwent either neck dissection or fine-needle aspiration. Four of the 12 were found to have viable residual tumor in the cervical lymph nodes. The pathology did not correlate with the size of the lymph nodes in the pre-RT or post-RT CT studies. However, the pathology correlated strongly with the post-RT FDG PET studies. All patients with a negative post-RT FDG PET or those with a maximum standardized uptake value (SUV(max)) of less than 3.0 in the post-RT FDG PET were found to be free of residual viable tumor. Using an SUV(max) of less than 3.0 as the criterion for a negative FDG PET study, the negative predictive value was 100% and the positive predictive value was 80%.

CONCLUSIONS

A negative post-RT FDG PET scan is very predictive of negative pathology in neck dissection or fine-needle aspiration even with large residual lymphadenopathy. Therefore, if the post-RT FDG PET scan is negative, neck dissection might not be required for regional control. A prospective study with longer follow-up and greater patient numbers is needed to determine whether a policy of deferring neck dissection based on a negative FDG PET is supported.

Prognostic impact of tumor volumetry in patients with locally advanced head-and-neck carcinoma (non-nasopharyngeal) treated by radiotherapy alone or combined radiochemotherapy in a randomized trial

PURPOSE

Tumor volume (TV) is one of the main reported factors determining the outcome of treatment in head-and-neck carcinomas. In this study, the prognostic impact of TV was explored in the context of a randomized trial with the patients assigned to receive standard radiotherapy (RT) alone or RT plus platinum compounds (RT alone, RT plus cisplatin, or RT plus carboplatin).

METHODS AND MATERIALS

The tumor outlines were traced and digitized on each pretreatment CT slice for each of the 101 patients studied. Taking into account the magnification factor of the scan and CT slice thickness, a computer with specifically designed software calculated the TV in cubic centimeters.

RESULTS

The median overall survival for the whole group of patients was 21.6 months (95% confidence interval, 13.0-30.2) and the 3-year survival rate was 40%. The addition of platinum compounds to RT (Groups 2 and 3) significantly improved the survival rate (RT alone vs. RT plus cisplatin, hazard ratio 0.36, p = 0.002; RT alone vs. RT plus carboplatin, hazard ratio 0.53, p = 0.029). In univariate analysis, the most significant parameters for survival were treatment group, total gross tumor volume (TGTV), complete response, nodal GTV, primary GTV, and performance status. In multivariate analysis, treatment group, TGTV, gender, and primary site were independent prognostic factors for survival. A prognostic threshold of 22.8 cm(3) was detected for TGTV. Patients with a TGTV of <22.8 cm(3) were more likely to achieve a complete response and had a median survival of 45.3 months, and those with a TGTV >22.8 cm(3) had a median survival of 12.3 months (log-rank test, p = 0.0102).

CONCLUSION

The prognostic significance of the TGTV was confirmed and a cutoff value of 22.8 cm(3) derived. Our data indicated that locally advanced head-and-neck carcinomas should not be treated by standard (once-daily) RT alone. Tumor size and disease subsite should be taken into account in future randomized trials to increase their statistical power.

Cervical lymph node metastases of squamous cell carcinoma from an unknown primary

Cervical lymph node metastases of squamous cell carcinoma from occult primary constitute about 2-5% of all patients with carcinoma of unknown primary site (CUP). Metastases in the upper and middle neck are generally attributed to head and neck cancers, whereas the lower neck (supraclavicular area) involvement is often associated with primary malignancies below the clavicles. The diagnostic procedures include physical examination with thorough evaluation of the head and neck mucosa using fiber-optic endoscopy, biopsies from all suspicious sites or blindly from the sites of possible origin of the primary, computer tomography and/or magnetic resonance. A systematic tonsillectomy in the absence of suspicious lesions is often recommended since up to 25% of primary tumors can be detected in this site. The thoracic primary (tracheal, bronchial, lung, esophagus) has to be excluded, especially in the case of lower neck involvement. Positron emission tomography (PET) with fluoro-2-deoxy-D-glucose allows detection of primary tumor in about 25% of cases, but this procedure is still considered investigational. Therapeutic approaches include surgery (lymph node excision or neck dissection), with or without postoperative radiotherapy, radiotherapy alone and radiotherapy followed by surgery. In early stages (N1), neck dissection and radiotherapy seem to have similar efficacy, whereas more advanced cases (N2, N3) necessitate combined approaches. The extent of radiotherapy (irradiation of bilateral neck and mucosa versus ipsilateral neck radiotherapy) remains debatable. A potential benefit from extensive radiotherapy should be weighted against its acute and late morbidity and difficulties in re-irradiation in the case of subsequent primary emergence. The role of other methods, such as chemotherapy and hyperthermia, remains to be determined.

Radiation treatment planning with an integrated positron emission and computer tomography (PET/CT): a feasibility study

PURPOSE

To investigate the usefulness of hardware coregistered PET/CT images for target volume definition.

METHODS AND MATERIALS

Thirty-nine patients presenting with various solid tumors were investigated. CT and a FDG-PET were obtained in treatment position in an integrated PET/CT scanner, and coregistered images were used for treatment planning. First, volume delineation was performed on the CT data. In a second step, the corresponding PET data were used as an overlay to the CT data to define the target volume. Delineation was done independently by two investigators.

RESULTS

Coregistered PET/CT showed good fusion accuracy. The GTV increased by 25% or more because of PET in 17% of cases with head-and-neck (2/12) and lung cancer (1/6), and in 33% (7/21) in cancer of the pelvis. The GTV was reduced > or =25% in 33% of patients with head-and-neck cancer (4/12), in 67% with lung cancer (4/6), and 19% with cancer of the pelvis (4/21). Overall, in 56% (22/39) of cases, GTV delineation was changed significantly if information from metabolic imaging was used in the planning process. The modification of the GTV translated into altered PTV changes exceeding >20% in 46% (18/39) of cases. With PET, volume delineation variability between two independent oncologists decreased from a mean volume difference of 25.7 cm(3) to 9.2 cm(3) associated with a reduction of the standard deviation from 38.3 cm(3) to 13.3 cm(3) (p = 0.02). In 16% of cases, PET/CT revealed distant metastasies, changing the treatment strategy from curative to palliative.

CONCLUSION

Integrated PET/CT for treatment planning for three-dimensional conformal radiation therapy improves the standardization of volume delineation compared with that of CT alone. PET/CT has the potential for reducing the risk for geographic misses, to minimize the dose of ionizing radiation applied to non-target organs, and to change the current practice to three-dimensional conformal radiation therapy planning by taking into account the metabolic and biologic features of cancer. The impact on treatment outcome remains to be demonstrated.

Who merits a neck dissection after definitive chemoradiotherapy for N2-N3 squamous cell head and neck cancer?

BACKGROUND

The role of neck dissection (ND) after definitive chemoradiotherapy for squamous cell head and neck cancer is incompletely defined. We retrospectively reviewed 109 patients with N2-N3 disease treated with chemoradiotherapy to identify predictors of a clinical complete response in the neck (CCR-neck), pathologic complete response after ND (PCR-neck), and regional failure.

METHOD

All patients were given 4-day continuous infusions of 5-fluorouracil (1000 mg/m2/d) and cisplatin (20 mg/m2/d) during the first and fourth weeks of either once daily (n = 68) or twice daily (n = 41) radiation therapy. ND was considered for all patients after completion of chemoradiotherapy and was performed in 32 of the 65 patients achieving a CCR-neck after chemoradiotherapy and in all 44 patients with residual clinical evidence of neck disease. CCR-neck, PCR-neck, and regional failure were then correlated with potential predictors, including T, N, largest lymph node size (<3 cm, > or =3 cm), primary tumor site, and radiation fractionation schedule.

RESULTS

Achievement of a CCR-neck was predicted by N, N2 vs N3 (53 of 80 vs 12 of 29, p =.019) and by largest lymph node size, <3 cm vs > or =3 cm (19 of 25 vs 46 of 84, p =.06). Achievement of a PCR-neck could not be predicted by any clinical parameter. Regional failure occurred both in patients undergoing ND and those not dissected (5 of 76 vs 4 of 33, p =.33) and proved more likely only in the ND patients with residual positive pathology compared with those achieving a PCR-neck (5 of 25 vs 0 of 51, p <.001). Primary site was not a useful predictor of CCR-neck, PCR-neck, or regional failure. Most importantly, CCR-neck (vs <CCR-neck) did not predict either a PCR-neck (24 of 32 vs 27 of 44, p =.21) or regional failure (5 of 65 vs 4 of 44, p =.80).

CONCLUSIONS

After chemoradiotherapy, clinical parameters do not identify those patients with residual neck node disease or those at risk for regional failure, suggesting that ND be considered for all N2-N3 patients.

Cancer of the larynx

In Europe, laryngeal cancer accounts for only 2-5% of all cancers, the incidence being much higher among males than among females. Smoke and alcohol represent the major behavioural risk factors. Several carcinogens, occupations and vitamin deficiencies have been associated with laryngeal cancer. A genetic susceptibility to environmental risk factors and carcinogens is recognized. Hoarseness is the main symptom for which patients call for medical consultation. Mucosa is the most common histologic site of the primary lesions considered in the present chapter. Nodal involvement, the site and volume of the primary tumour, and some genes expression represent the major prognostic factors. A high death rate for not cancer-related events is to be pointed out. The loco-regional extent of the disease determines the success of cure. Surgery and radiotherapy represent the main therapeutic options. The choice between these two procedures is often controversial.

PET scan imaging in oncology

With the emergence of positron emission tomography (PET) from research laboratories into routine clinical use, it is important to redefine the most appropriate use of each imaging technique. The aim of this review article is to show the potential of PET in oncology. We discuss the most promising indications and the perspectives for the future. We will also point out the shortcomings and the important questions to be answered before fully considering PET as a necessary tool in the day-to-day practice of oncology. Although many studies have documented the high accuracy of 18F-FDG PET for the detection and staging of malignant tumours and for the monitoring of therapy results in these patients, it is very important to assess the impact of the technique on patient outcome and to show cost-effectiveness from the societal viewpoint.

Clinical aspects of IMRT for head-and-neck cancer

The tightly conformal doses produced by intensity-modulated radiotherapy (IMRT), the existence of many critical structures in close proximity to the target, and the lack of internal organ motion in the head and neck, provide the potential for organ sparing and improved tumor irradiation. Many studies of treatment planning for head-and-neck cancer have demonstrated the dosimetric superiority of IMRT over conventional techniques in these respects. The initial results of clinical studies demonstrate reduced xerostomia. They suggest an improvement in tumor control, which needs to be verified in larger studies and longer follow-up.

Image fusion between 18FDG-PET and MRI/CT for radiotherapy planning of oropharyngeal and nasopharyngeal carcinomas

PURPOSE

Accurate diagnosis of tumor extent is important in three-dimensional conformal radiotherapy. This study reports the use of image fusion between (18)F-fluoro-2-deoxy-D-glucose positron emission tomography (18FDG-PET) and magnetic resonance imaging/computed tomography (MRI/CT) for better targets delineation in radiotherapy planning of head-and-neck cancers.

METHODS AND MATERIALS

The subjects consisted of 12 patients with oropharyngeal carcinoma and 9 patients with nasopharyngeal carcinoma (NPC) who were treated with radical radiotherapy between July 1999 and February 2001. Image fusion between 18FDG-PET and MRI/CT was performed using an automatic multimodality image registration algorithm, which used the brain as an internal reference for registration. Gross tumor volume (GTV) was determined based on clinical examination and 18FDG uptake on the fusion images. Clinical target volume (CTV) was determined following the usual pattern of lymph node spread for each disease entity along with the clinical presentation of each patient.

RESULTS

Except for 3 cases with superficial tumors, all the other primary tumors were detected by 18FDG-PET. The GTV volumes for primary tumors were not changed by image fusion in 19 cases (89%), increased by 49% in one NPC, and decreased by 45% in another NPC. Normal tissue sparing was more easily performed based on clearer GTV and CTV determination on the fusion images. In particular, parotid sparing became possible in 15 patients (71%) whose upper neck areas near the parotid glands were tumor-free by 18FDG-PET. Within a mean follow-up period of 18 months, no recurrence occurred in the areas defined as CTV, which was treated prophylactically, except for 1 patient who experienced nodal recurrence in the CTV and simultaneous primary site recurrence.

CONCLUSION

This preliminary study showed that image fusion between 18FDG-PET and MRI/CT was useful in GTV and CTV determination in conformal RT, thus sparing normal tissues.

Intensity-modulated radiation therapy for head and neck cancer: emphasis on the selection and delineation of the targets

The head and neck contain many critical, noninvolved structures in close vicinity to the targets. The tightly conformal doses produced by intensity-modulated radiation therapy (IMRT), and the lack of internal organ motion in the head and neck, provide the potential for organ sparing and improved tumor irradiation. Many studies of treatment planning for head and neck cancer have demonstrated the dosimetric superiority of IMRT over conventional techniques in these respects. The initial results of clinical studies demonstrate reduced xerostomia. They suggest an improvement in tumor control, which needs to be verified in larger studies and longer follow-up. Critical issues for successful outcome of head and neck IMRT are accurate selection of the neck lymph nodes that require adjuvant treatment, and accurate delineation on the planning computed tomography (CT) of the lymph-node bearing areas and subclinical disease adjoining the gross tumor. This review emphasizes these topics and provides some guidelines.