Masato Asakura

Detection of colorectal cancer using 18F-FLT PET: comparison with 18F-FDG PET

ObjectiveWe investigated the feasibility of 3′-deoxy-3′-18F-fluorothymidine (FLT) positron emission tomography (PET) for the detection of colorectal cancer, in comparison with 2-deoxy-2-18F-fluoro-D-glucose (FDG) PET, and investigated correlation of the two radiotracers used with proliferative activity as indicated by Ki-67 index. MethodsA total of 26 patients with newly diagnosed colorectal cancer were examined with FLT PET and FDG PET. Tumor lesions were identified as areas of focally increased uptake, exceeding that of surrounding normal tissue. For semiquantitative analysis, the maximal standardized uptake value (SUV) was calculated. ResultsIn all 26 patients, colorectal cancers were detected by both FLT PET and FDG PET. The mean (±SD) values of FLT SUV in colon cancer (5.4±2.4) and in rectal cancer (5.6±1.3) were significantly lower than the corresponding values of FDG SUV (12.4±6.3 and 12.5±4.7, respectively) (P<0.003). There was no significant correlation between Ki-67 index and either FLT SUV or FDG SUV. ConclusionAlthough uptake of FLT was found to be significantly lower than that of FDG, both FLT PET and FDG PET were able to detect colorectal cancers in all 26 patients. Neither of the two radiotracers used was correlated with proliferative activity.

3'-Deoxy-3'-18F-Fluorothymidine as a Proliferation Imaging Tracer for Diagnosis of Lung Tumors : Comparison With 2-Deoxy-2-18F-Fluoro-D-Glucose

Objective: The purpose of this study was to evaluate the accuracy of 3′-deoxy-3′-18F-fluorothymidine (FLT) positron emission tomography (PET) for detection of lung tumor in comparison with 2-deoxy-2-18F-fluoro-D-glucose (FDG) PET. Methods: Fifty-four patients with newly diagnosed pulmonary nodules on chest computed tomographic (CT) scan suggestive of a malignant tumor were examined with both FLT and FDG PET. The intensity of uptake in lung tumors was scored. For visualized lesions, the maximum standardized uptake value (SUV) was calculated. Results: Thirty-six patients were found to have lung cancer; and 18, benign lesions. Using visual analysis, the sensitivity of FLT PET for detection of lung cancer was 83%; the specificity, 83%; and the accuracy, 83%. The corresponding values for FDG PET were 97%, 50%, and 81%, respectively. The specificity of FLT PET was significantly higher than that of FDG PET. The uptake of FLT in lung cancer was significantly lower than that of FDG. Using semiquantitative analysis, the sensitivity of FLT was 86%; the specificity, 72%; and the accuracy, 81%. The corresponding values for FDG were 89%, 67%, and 81%, respectively. Conclusions: These preliminary results indicate that FLT PET may be specific for malignant tumors although uptake of FLT in lung cancer was significantly lower than that of FDG.

Hypertension and Proteinuria as Predictive Factors of Effects of Bevacizumab on Advanced Breast Cancer in Japan

Bevacizumab (BV), an inhibitor of vascular endothelial growth factor, is used in combination with paclitaxel (PTX) to treat advanced breast cancer. Hypertension and proteinuria are characteristic adverse events of BV therapy. We assessed the potential of these adverse events as predictors of BV treatment responses. Our results revealed that groups that developed hypertension and proteinuria early (by day 56) had a stronger antitumor response (Fishers exact test p<0.05). However, no significant difference was observed in progression-free survival (the Kaplan-Meier method and Log-rank test). As a reference, age, the treatment line, subtypes, liver and renal function, diabetes mellitus and hyperlipidemia history, body mass index, influencing concomitant medicine, average relative dose intensity and hematotoxicity did not significantly differ between groups with or without hypertension and with or without proteinuria. These results indicate the potential of the development of hypertension and proteinuria as predictors of improved outcomes with PTX plus BV therapy in patients with breast cancer. However, since both adverse events may preclude the continuation of treatment, their earlier management may be required.

Association of Bevacizumab-induced Hypertension and Progression Free Survival in Patients with Breast Cancer

Background: Bevacizumab(Bev), an inhibitor of vascular endothelial growth factor (VEGF), is used in combination with paclitaxel (Pac)for the treatment of inoperable, advanced, or recurrent breast cancer (Pac on days 1, 8, and 15, Bev on days 1 and 15, of a 28 daycycle). Hypertension is a known side effect associated with Bev, with its incidence being 17.9% in Japan. Objective: We investigated an association between Bev-induced hypertension andprogression free survival. Method: We retrospectively studied 13 patients who received Bev for the treatment of advanced breast cancer. Weused a multiple regression analysis, in which the number of cycles were used as dependent variables and age and use or no use of antihypertensive agents were used as explanatory variables. A Mann–Whitney test was used to compare the number of cycles among antihypertensive therapy group and non-antihypertensive therapy group. Result and discussion: Multiple regression analysis showed no significant association between the number of cycles of Bev therapy and age, while a significant association between the number of cycles of Bev therapy and the use of antihypertensive agents was detected (p < 0.01). The results also show a weak correlation between age and use of antihypertensive agents(r = 0.14). In the comparison of the number of cycles of Bev between patients in the antihypertensivetherapygroup and those in the non-antihypertensive therapy group, a significant between-group difference was found (p < 0.01). Therefore a side effect hypertension can be a positive predictive factor for the effect of Bev therapy.