PET changes management and improves prognostic stratification in patients with head and neck cancer: results of a multicenter prospective study

Growth in the use of PET for six cancer types after coverage by medicare: additive or replacement?

BACKGROUND

In July 2001, PET became a covered service for Medicare beneficiaries when used for the diagnosis, staging, and restaging of non-small-cell lung, esophageal, colorectal, and head and neck cancers as well as lymphoma and melanoma. Whether physicians use PET as a replacement for or in addition to CT, MRI, or bone scintigraphy (BS) is uncertain.

METHODS

A 20% sample of Medicare fee-for-service beneficiaries aged > 64 years from 2004 through 2008 was used. Annually for each cancer type, a cohort of patients was created defined as having at least one admission with a primary cancer diagnosis or two nonhospital claims with a cancer diagnosis ≥7 days apart per calendar year. Each year, imaging claims and claim-days were counted by modality and cancer type. The sequence of PET use was examined as before, after, or instead of other imaging.

RESULTS

About 125,000 beneficiaries (2.5% of the cohort) met the cancer definition each year. In 2008, the combined annual imaging days per person-year were 2.3 for CT, 0.49 for MRI, 0.70 for PET, and 0.13 for BS. The annual rates of imaging from 2004 to 2008 increased by 0.5% for CT, 3.2% for MRI, and 18.0% for PET (range, 14.6%-19.9% by cancer type) and decreased by 12.7% for BS. The growth in PET use was not associated with meaningful changes in body CT. In 2007 and 2008, body CT preceded PET within 30 days in about half of patients, whereas PET preceded CT in only 22%.

CONCLUSIONS

Several years after its introduction, PET continued to grow rapidly, with evidence that it is replacing BS. Growth of PET occurred without evidence of a decline in body CT. About half of PET use occurred shortly after body CT, suggesting an additive or final arbiter role.

Imaging in cervical nodal metastases of unknown primary

In patients presenting with a neck adenopathy from a clinically unknown primary, efforts should be made to localize the primary tumour, as this allows a more focused therapy. Imaging is helpful in identifying suspicious mucosal sites that should be further investigated endoscopically, including biopsy. In case no primary tumour is detected in the head and neck, a positron emission tomography (PET) study can be considered to search for an infraclavicular primary tumour. This article reviews the diagnostic value of computed tomography (CT), magnetic resonance imaging, PET and PET/CT in this clinical context.

PET imaging of brain cancer with positron emitter-labeled liposomes

Since nanocarriers such as liposomes are known to accumulate in tumors of tumor-bearing animals, and those that have entrapped a positron emitter can be used to image a tumor by PET, we applied (18)F-labeled 100-nm-sized liposomes for the imaging of brain tumors. Polyethylene glycol (PEG)-modified liposomes, which are known to accumulate in tumors by passive targeting and those modified with Ala-Pro-Arg-Pro-Gly, which are known to home into angiogenic sites were used. Those liposomes labeled with DiI fluorescence accumulated in a glioma implanted in a rat brain 1h after the injection, although they did not accumulate in the normal brain tissues due to the protection afforded by the blood-brain barrier. Preformed liposomes were easily labeled with 1-[(18)F]fluoro-3,6-dioxatetracosane, and enabled the imaging of gliomas by PET with higher contrast than that obtained with [(18)F]deoxyfluoroglucose. In addition, the smallest tumor among those tested, having a diameter of 1mm was successfully imaged by the liposomal (18)F. Therefore, nanocarrier-based imaging of brain tumors is promising for the diagnosis of brain cancer and possible drug delivery-based therapy.

Cancer Response Criteria and Bone Metastases: RECIST 1.1, MDA and PERCIST

Response criteria represent the standard by which the efficacy of therapeutic agents is determined in cancer trials. The most widely used criteria are based on the anatomic measurement of solid tumors. Because bone metastases are typically located in irregularly shaped bones and are difficult to measure with rulers, they have been previously considered unmeasurable disease. New developments in cancer response criteria have increased awareness of the importance of the response of bone metastases to therapy. The recently updated Response Evaluation Criteria in Solid Tumors (RECIST 1.1) now consider bone metastases with soft tissue masses > 10 mm to be measurable disease. Response criteria specific to bone metastases have been developed at The University of Texas MD Anderson Cancer Center (MDA criteria) and can be used to assess therapeutic response in numerous types of bone metastases. Functional imaging criteria, such as the recently developed Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST) allow response to be measured in the absence of anatomic change through assessment of metabolic activity. As monitoring tumor response of bone metastases becomes more important in the management of cancer, so does the demand on radiologists and nuclear medicine physicians for accurate interpretation of the behavior of these lesions. This article reviews anatomic, bone, and metabolic response criteria, providing illustrations for the interpretation of therapy-induced change in bone metastases.

Positron emission tomography with [18F]fluorodeoxyglucose improves staging and patient management in patients with head and neck squamous cell carcinoma: a multicenter prospective study

PURPOSE To address the impact of positron emission tomography with [(18)F]fluorodeoxyglucose (PET-FDG) on the initial staging and management of patients with head and neck squamous cell carcinoma (HNSCC). PATIENTS AND METHODS This multicenter, prospective study included 233 patients with newly diagnosed and untreated HNSCC. TNM stage and therapeutic decision were first determined based on the conventional work-up (including physical examination, computed tomography [CT]/magnetic resonance imaging of the head and neck region, and thoracic CT) and sealed in envelope 1. Whole-body PET-FDG was then performed, and subsequent TNM stage and therapeutic decision were written in envelope 2. Changes in TNM stages and in patient management as a result of PET-FDG imaging were recorded. Clinical outcome and histopathology were used as gold standards to validate the TNM stage. Conventional and PET stages were compared using the McNemar test. Results Conventional and PET stage were discordant in 100 (43%) of 233 patients. PET proved to be accurate in 47 patients and inaccurate in 13 patients. TNM status was left unconfirmed in 40 patients because no therapeutic change was expected from the stage difference. Conventional + PET TNM classification (envelope 2) was significantly more accurate than conventional classification (envelope 1; P < .0001, McNemar test). PET-FDG altered the therapeutic plan in 32 (13.7%) of 233 patients. CONCLUSION Adding whole-body PET-FDG to the pretherapeutic conventional staging of HNSCC improved the TNM classification of the disease and altered the management of 13.7% of patients. These findings support the implementation of PET-FDG in the routine imaging work-up of HNSCC.

Clinical impact of (11)C-methionine PET on expected management of patients with brain neoplasm

PURPOSE

We retrospectively examined the clinical efficacy of (11)C-methionine positron emission tomography ((11)C-MET PET) in patients with brain neoplasm, especially whether the (11)C-MET PET changed the clinical management and whether the change was beneficial or detrimental.

METHODS

This study reviewed 89 (11)C-MET PET scans for 80 patients (20 scans for initial diagnosis of brain tumor and 69 scans for differentiating tumor recurrence from radiation necrosis). Final diagnosis and the effect on the intended management were obtained from the questionnaire to the referring physicians or directly from the medical records. The diagnostic sensitivity, specificity, and accuracy for the (11)C-MET PET were evaluated. Regarding the management impact, the rate of scans that caused changes in intended management was also evaluated. Moreover, the occurrence of scans having detrimental diagnostic impact (DDI) and beneficial diagnostic impact (BDI) were evaluated.

RESULTS

Sensitivity, specificity, and accuracy of (11)C-MET PET was 87.8, 80.0, and 85.9%. The intended management was changed in 50.0% of the scans. DDI and BDI were observed in 4.3 and 36.2% of the total relevant scans, respectively.

CONCLUSION

(11)C-MET PET can provide useful information in initial diagnosis and differentiating tumor recurrence from radiation necrosis. The intended management was changed in half of the scans. Since a few cases did not receive the requisite treatment due to false-negative results of (11)C-MET PET, management decision should be made carefully, especially in the case of a negative scan.