Lack of correlation of hypoxic cell fraction and angiogenesis with glucose metabolic rate in non-small cell lung cancer assessed by 18F-Fluoromisonidazole and 18F-FDG PET.

UNLABELLED: PET offers a noninvasive means to assess neoplasms, in view of its sensitivity and accuracy in staging tumors and potentially in monitoring treatment response. The aim of this study was to evaluate newly diagnosed non-small cell lung cancer (NSCLC) for the presence of hypoxia, as indicated by the uptake of (18)F-Fluoromisonidazole ((18)F-FMISO), and to examine the relationship of hypoxia to the uptake of (18)F-FDG, microvessel density, and other molecular markers of hypoxia. METHODS: Twenty-one patients with suspected or biopsy-proven NSCLC were enrolled prospectively in this study. All patients had PET studies with (18)F-FMISO and (18)F-FDG. Seventeen patients subsequently underwent surgery, with analysis performed for tumor markers of angiogenesis and hypoxia. RESULTS: In the 17 patients with resectable NSCLC (13 men, 4 women; age range, 51-77 y), the mean (18)F-FMISO uptake in tumor was significantly lower than that of (18)F-FDG uptake (P < 0.0001) and showed no correlation with (18)F-FDG uptake (r = 0.26). The mean (95% confidence interval [CI]) (18)F-FMISO SUV(max) (maximum standardized uptake value) was 1.20 [0.95-1.45] compared with the mean [95% CI] (18)F-FDG SUV(max) of 5.99 [4.62-7.35]. The correlation between (18)F-FMISO uptake, (18)F-FDG uptake, and tumor markers of hypoxia and angiogenesis was poor. A weakly positive correlation between (18)F-FMISO and (18)F-FDG uptake and Ki67 was found. CONCLUSION: The hypoxic cell fraction of primary NSCLC is consistently low, and there is no significant correlation in NSCLC between hypoxia and glucose metabolism in NSCLC assessed by (18)F-FDG. These findings have direct implications in understanding the role of angiogenesis and hypoxia in NSCLC biology.

Functional imaging of intratumoral hypoxia.

PURPOSE: Tumor hypoxia plays a fundamental role in tumor progression and treatment resistance. Recent evidence that hypoxia also influences the regulation and transcription of various genes involved in malignant growth and metastases, and promotes a more aggressive tumor phenotype makes its diagnosis even more important. PROCEDURES: The evidence for the biology of hypoxia in tumors, and imaging of hypoxia with different technologies was reviewed through literature review and Medline searches, and clinical studies with 18F-fluoromisonidazole (FMISO) Positron Emission Tomography (PET). RESULTS: Until recently, determination of the level of tumor oxygenation was only possible using invasive methods that limited its clinical application. Imaging techniques that have shown promise in assessing hypoxia include magnetic resonance imaging and spectroscopy, single photon emission computed tomography (SPECT) and PET. Quantitative hypoxia measurement with 18F-FMISO PET in patients with malignant gliomas and lung cancer have demonstrated intratumoural hypoxia and dissociation of glucose metabolism from hypoxia in some cases, indicating the complex nature of cellular metabolic response to stress. CONCLUSION: The emerging role of therapies that have improved efficacy in hypoxic conditions, and recent advances in the ability to noninvasively measure in vivo intratumoral hypoxia with functional imaging has renewed interest in the clinical measurement of tumor hypoxia and its impact on cancer treatment.

Assessing regional hypoxia in human renal tumours using 18F-fluoromisonidazole positron emission tomography.

OBJECTIVE: To assess renal tumours for hypoxic regions using 18F-fluoromisonidazole (18F-FMISO) positron emission tomography (PET), a recognized noninvasive method for detecting hypoxia in tumours, as renal cell carcinoma (RCC) can be potentially cured with nephrectomy but recurrence develops in most patients, who then respond poorly to treatments such as chemotherapy, and hypoxia is known to confer resistance to radiotherapy and chemotherapy in many solid tumours. PATIENTS AND METHODS: In all, 17 patients had 18F-FMISO PET scans before nephrectomy for presumed RCC. Specimens were examined histologically, and immunohistochemistry was used to compare the microvessel density (MVD) as an indicator of angiogenesis in the tumour and normal parenchyma, in 15 patients. Tumour oxygenation was measured invasively in three patients using a polarographic oxygen sensor probe. RESULTS: Of the 15 patients with histological results, 11 had RCC and four had other tumours. Although there was a trend there was no statistically significant (P = 0.14) difference in the maximum standardized uptake value (SUV(max)) when comparing the region of the kidney involved with RCC; the mean (95% confidence interval) SUV(max) in the tumours was 1.3 (0.15), whilst that in the normal contralateral kidney was 1.1 (0.22). The MVD was greater in RCC, at 13.7 (3.1) mean vessels per high-power field than in normal tissue, at 6.9 (1.9). Hypoxia as measured polarographically was detected in three RCCs (median pO2 9.6 mmHg) compared to normal parenchyma at 37.6 mmHg. CONCLUSIONS: Although 18F-FMISO scans showed significant uptake in other solid tumours, there was only mild 18F-FMISO uptake in the present RCCs. The invasive measurements indicated that there was hypoxia in RCC, but the median pO2 did not fall below 9.5 mmHg. Further direct studies of renal tumour oxygenation combined with therapies directed towards hypoxia may allow a better understanding of the relationship between 18F-FMISO results and the biological significance of hypoxia in RCC.

Detection of occult bone metastases of lung cancer with fluorine-18 fluorodeoxyglucose positron emission tomography.

Accurate staging of cancer has a critical role in optimal patient management. Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) is superior to CT in the detection of local and distant metastases in patients with non-small cell lung cancer. Although Tc-99 m methylene diphosphonate (MDP) bone scanning is well established in the evaluation of bone metastases, there are conflicting reports on the use of FDG PET in the evaluation of skeletal metastases. We report on a patient with locally advanced lung carcinoma in whom FDG PET accurately identified previously unsuspected widespread asymptomatic bone metastases (bone scan and X-rays negative, confirmed on MRI). Assessment of glucose metabolism with FDG PET might represent a more powerful tool to detect bone metastases in lung cancer compared with conventional bone scans.