PET Imaging-Based Phenotyping as a Predictive Biomarker of Response to Tyrosine Kinase Inhibitor Therapy in Non-small Cell Lung Cancer: Are We There Yet? / 대한핵의학회잡지

The increased understanding of the molecular pathology of different malignancies, especially lung cancer, has directed investigational efforts to center on the identification of different molecular targets and on the development of targeted therapies against these targets. A good representative is the epidermal growth factor receptor (EGFR); a major driver of non-small cell lung cancer tumorigenesis. Today, tumor growth inhibition is possible after treating lung tumors expressing somatic mutations of the EGFR gene with tyrosine kinase inhibitors (TKI). This opened the doors to biomarker-directed precision or personalized treatments for lung cancer patients. The success of these targeted anticancer therapies depends in part on being able to identify biomarkers and their patho-molecular make-up in order to select patients that could respond to specific therapeutic agents. While the identification of reliable biomarkers is crucial to predict response to treatment before it begins, it is also essential to be able to monitor treatment early during therapy to avoid the toxicity and morbidity of futile treatment in non-responding patients. In this context, we share our perspective on the role of PET imagingbased phenotyping in the personalized care of lung cancer patients to non-invasively direct and monitor the treatment efficacy of TKIs in clinical practice.

Thallium-201 SPECT in Differential Diagnosis of Malignancy from Benign Pathology in Patients with a Solitary Pulmonary Lesion / 대한핵의학회잡지

PURPOSE: T1-201 SPECT has been used in differentiating benign and malignant pulmonary lesions. While its sensitivity may be high, the specificity and predictive values are reported to be variable depending on the type of benign lung lesion. The purpose of this study was to prospectively assess the efficacy of T1-201 SPECT for differentiating benign and malignant single pulmonary lesions in a population with a high prevalence of begin pulmonary lesions, especially, tuberculosis. MATERIALS AND METHODS: One-hundred thirty-three patients, having 89 malignant and 44 benign lesions(23 active tuberculosis, 5 inactive tuberculosis, 3 aspergilloma, 3 focal pneumonia, 2 thymoma, and 8 others), were imaged using a dual-headed system at 15 minute(early) and 3 hour (delayed) following administration of 111MBq T1-201. The images were read visually and lesion-to-background ratios(L/B) were obtained from transverse tomographic slices. Retention index was expressed as [(delayed L/B-early L/B) / early L/B]. RESULTS: 82/89(92%) and 83/89(93%) of the malignant lesions were visually positive on the early and delayed images, and 27/44(61%) and 26/44(59%) of the benign lesions wefe also between the mean L/B's of the malignant and benign lesions, L/B was not useful for differentiating the two due to a large overlap. There was no difference in retention indices. CONCLUSION: Despite of its high sensitivity, the specificity of T1-201 SPECT was unacceptably low in patients with active benign lesions. The positive and negative predictive values for lung cancer in a population with a high prevalence of the benign single pulmonary lesion was only marginal.