In oncology, PET has already been found useful in assessing the viability of tumours and the efficacy of anti-cancer drugs. Although 18FDG provides information on tumour metabolism, it has limited utility in certain tumours with lower grades of metabolism. In addition it has been shown that glucose metabolic changes occur much later than changes in nucleic acid metabolism. Thus nucleoside analogues represent a structural class regarded as potential markers of DNA proliferation, and thymidine derivatives are also under evaluation.
Currently, the clinical application of PET is used in the initial staging and detection of recurrent disease in the following tumour types:
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Non-small cell lung carcinoma
The evaluation of non-small cell lung carcinoma (NSCLC) with 18F-FDG PET in the Centre for PET has focused on three clinical scenarios:
1) staging of newly diagnosed NSCLC
2) assist in radiation treatment planning of NSCLC
3) monitoring response to therapy
Evidence has been obtained showing that 18F-FDG PET is more accurate than conventional staging techniques in evaluating patients with NSCLC, which is in agreement with overseas literature. This has changed the standard of care for NSCLC patients, such that thoracic surgeons in Melbourne will not perform surgery in this patient group until patients undergo 18F-FDG PET scans. 18F-FDG PET has also been shown to be more accurate at identifying distant metastatic disease.
18F-FDG PET has been evaluated in radiation treatment planning, and is currently used at the Austin Hospital as an integral part of routine radiation treatment planning in patients with NSCLC. A prospective protocol examining 18F-FDG PET in evaluating tumour response to therapy is ongoing, but preliminary data has shown that 18F-FDG PET is more accurate than computed tomography (CT) scan at predicting response following initial chemotherapy cycles.
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Colorectal carcinoma
In colorectal cancer, a prospective study with surgical and/or conventional imaging followup of PET in patients with suspected recurrent disease has been undertaken. The Austin Hospital Centre for PET has also participated in a multinational study of PET in colorectal cancer in conjunction with the US based Institute for Clinical PET.
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Head and neck carcinoma
We have undertaken two prospective studies in head and neck carcinoma, to establish the accuracy of 18F-FDG PET compared to conventional imaging (eg CT scan) in detecting primary and metastatic disease in the following clinical scenarios:
1) staging of head and neck carcinoma at initial diagnosis
2) staging of head and neck carcinoma following initial treatment (eg radiotherapy)
In both scenarios, surgery is the appropriate standard of care for next stage of treatment. Surgery usually involves extensive neck dissection, with associated morbidity and costs. Current standard methods for evaluation (including clinical examination and conventional imaging modalities eg CT scan) are inadequate in staging disease in regional nodes, hence surgery cannot be planned based on available techniques of evaluation.
Evaluation of patients with head and neck carcinoma who have undergone treatment for extensive or recurrent disease has also been performed with 18F-FDG PET, in order to establish the presence or extent of disease. The data generated is being evaluated with respect to management change in these patients. In collaboration with Peter MacCallum Cancer Institute, a prospective study of 18F-FMISO PET is also being performed in patients with head and neck carcinoma undergoing chemotherapy or radiotherapy.
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Metastic melanoma
The Austin Hospital has a melanoma unit as part of its Comprehensive Cancer Centre, and as part of this unit new treatment protocols are evaluated in melanoma patients. While 18F-FDG PET scans may be used for the staging of patients with melanoma prior to surgery, the principle use of 18F-FDG PET at the Austin Hospital has been in the staging of melanoma patients prior to, or subsequent to, therapy protocols. The potential utility of 18F-FDG PET scans in this setting is to enable more accurate decisions regarding treatment (eg surgery, chemotherapy, biologic therapy or observation alone) to be made, and avoiding unnecessary therapy that may have associated morbidity and high cost.
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Glioma
18F-FDG PET has been established as an accurate method of non-invasively determining the grade and prognosis of primary cerebral tumours. It is also able to evaluate treatment response, and is more accurate than CT or MRI at distinguishing radiation necrosis from recurrent tumour.
We have performed 18F-FDG PET studies in 250 pts with brain tumours since 1992. As part of our PET evaluation, the accuracy of 18F-FDG PET is being assessed in patients who are referred for evaluation prior to surgery, and as part of therapy management. A comparison of 18F-FDG PET to 201Tl-Chloride SPECT and CT/MRI is also being performed.
As part of the evaluation of patients with glioma adjacent to sensorimotor areas of the brain, H215O water activation studies are also performed to aid in surgical planning. This provides invaluable information prior to neurosurgery that cannot be routinely provided by functional MRI. The evaluation of hypoxia in gliomas is also being evaluated.
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Renal cell carcinoma
An ongoing prospective analysis of 18F-FDG PET in patients with renal cell carcinoma has been performed.
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Lymphona
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Germ cell tumours
An ongoing analysis of 18F-FDG PET in patients with germ cell tumours has been performed.
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Breast carcinoma
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