FDG-PET Parameters as Prognostic Factor in Esophageal Cancer Patients: A Review

Background:18F-fluorodeoxyglucose positron emission tomography (FDG-PET) has been used extensively to explore whether FDG Uptake can be used to provide prognostic information for esophageal cancer patients. The aim of the present review is to evaluate the literature available to date concerning the potential prognostic value of FDG uptake in esophageal cancer patients, in terms of absolute pretreatment values and of decrease in FDG uptake during or after neoadjuvant therapy. Methods: A computer-aided search of the English language literature concerning esophageal cancer and standardized uptake values was performed. This search focused on clinical studies evaluating the prognostic value of FDG uptake as an absolute value or the decrease in FDG uptake and using overall mortality and/or disease-related mortality as an end point. Results: In total, 31 studies met the predefined criteria. Two main groups were identified based on the tested prognostic parameter: (1) FDG uptake and (2) decrease in FDG uptake. Most studies showed that pretreatment FDG uptake and postneoadjuvant treatment FDG uptake, as absolute values, are predictors for survival in univariate analysis. Moreover, early decrease in FDG uptake during neoadjuvant therapy is predictive for response and survival in most studies described. However, late decrease in FDG uptake after completion of neoadjuvant therapy was predictive for pathological response and survival in only 2 of 6 studies. Conclusions: Measuring decrease in FDG uptake early during neoadjuvant therapy is most appealing, moreover because the observed range of values expressed as relative decrease to discriminate responding from nonresponding patients is very small. At present inter-institutional comparison of results is difficult because several different normalization factors for FDG uptake are in use. Therefore, more research focusing on standardization of protocols and inter-institutional differences should be performed, before a PET-guided algorithm can be universally advocated

Mediastinal diseases: clinical and therapeutic aspects

Background: Mediastinal affections are common and encompass a great number of different diagnoses. Objective: To analyze the clinical aspects and the therapeutic response of 114 patients with mediastinal diseases treated at the Thoracic Surgery Department of Santa Casa de São Paulo Hospital, from 1979 and 1997. Method: The patients were grouped according to the benign or malignant nature of the disease, and the two groups were compared regarding gender, age bracket, symptomatology, topography of the lesion, mortality, and response to treatment. Results: Sixty-three patients had neoplasia: 31 benign and 32 malignant. Fifty-one cases were not neoplastic. No difference was found between the groups regarding gender or age bracket. Half of the patients were between 20 and 49 years of age. The anterior mediastinum was the most frequently affected compartment (66 patients), followed by the upper mediastinum (18 patients), the posterior mediastinum (16 patients), and the middle mediastinum (14 patients). The most frequent histological types were: benign thymus diseases (N = 40), mesenchymal tumors (N = 17), lymphomas (N = 15), neural tumors (N = 9), and germ cell tumors (N = 8). Malignant tumors were more frequently symptomatic (91%), and benign tumors were more frequent in asymptomatic patients (92%). The most frequent symptoms were related to myastenia gravis, followed by dyspnea and chest pain. Weight loss, anorexia and fever were significantly more frequent in patients with malignant neoplasias. Conclusions: Regarding the clinical aspects we can state that benign lesions were predominant, that mediastinal diseases were more prevalent in young adults, and that benign lesions were more frequent in asymptomatic patients. Treatment (clinical/surgical) was effective in most patients, benefiting approximately 90% of the patients with benign affections and 45% of the patients with malignant tumors. In 73% of the benign affections, surgical treatment was capable of achieving the cure. Mortality resulting from complications was 1.75%

18FDG uptake during induction chemoradiation for oesophageal cancer fails to predict histomorphological tumour response

To determine whether [18F]-fluorodeoxyglucose-positron emission tomography (FDG-PET) could predict the pathological response in oesophageal cancer after only the first week of neoadjuvant chemoradiation. Thirty-two patients with localised oesophageal cancer had a pretreatment PET scan and a repeat after the first week of chemoradiation. The change in mean maximum standardised uptake value (SUV) and volume of metabolically active tissue (MTV) was compared with the tumour regression grade (TRG) in the final histology. Those who achieved a TRG of 1 and 2 were deemed responders and 3-5 nonresponders. In the responders (28%), the SUV fell from 12.6 (±6.3) to 8.1 (±2.9) after 1 week of chemoradiation (P = 0.070). In nonresponders (72%), the results were 9.7 (±5.4) and 7.1 (±3.8), respectively (P = 0.003). The MTV in responders fell from 36.6 (±22.7) to 22.3 (±10.4) cm3 (P = 0.180), while in nonresponders, this fell from 35.9 (±36.7) to 31.9 (±52.7) cm3 (P = 0.405). There were no significant differences between responders and nonresponders. The hypothesis that early repeat FDG-PET scanning may predict histomorphologic response was not proven. This may reflect an inflammatory effect of radiation that obscures tumour-specific metabolic changes at this time. This assessment may have limited application in predicting response to multimodal regimens for oesophageal cancer. © 2006 Cancer Research UK