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Objectives : A French multicenter study was promoted by the national French cancer federation (Unicancer R&D) to assess the potential of [18F]FLT (positron emission tomography (PET) biomarker of proliferation)to manage breast cancer neoadjuvant chemotherapy (NAC). The main objective was to compare changes in tumor [18F]FLT uptake to histopathological changes induced by NAC, assuming an arrest of tumor growth related to the effectiveness of NAC. Methods : 97 patients (age 48.6 +/- 10.2 y.) were included in 13 nuclear medicine centers. All patients were eligible to anthracycline-based NAC for a de novo unifocal breast cancer (ductal n = 84, lobular = 11, other type = 2; stage II n = 75, stage III n = 21 et stage IV n = 1). 90 patients underwent a baseline PET before the onset of NAC (PET1) and a final PET after the end of NAC and before surgery (PET3). PET acquisitions were performed 60±7min after FLT injection. SUVmax (maximum standardized uptake value), SUVpeak (1 cm3 ROI including pixel max) and SUV41 (isocontour 41% of pixel max) were computed. Changes in SUV on PET3 vs PET1 were analyzed in relation to histopathological findings at the end of NAC (Sataloff criteria). Results : Tumor FLT uptake decreased markedly between TEP1 and TEP3 (SUVmax = 6.2±4.8 vs 1.3±1.2 respectively; SUVpeak = 4.6±3.2 vs 0.9±0.9; SUV41 = 3.6±2.8 vs 0.8±0.7). Total or near-total therapeutic effect (grade A) were obtained in 20 patients, more than 50% therapeutic effect but less than total or near-total effect (grade B) in 37 patients, less than 50% therapeutic effect but visible effect (grade C) in 22 patients, or no therapeutic effect (grade D) in 11 patients. SUVmax decreased dramatically (87.5%) to background levels in all patients with a complete response (grade A). Overall, changes in SUV differed depending on the type of histological response (p<0.01) i.e. SUVmax changes were more pronounced as pathological responses were good: 61% for grade D; 65.7% grade C and 69.8% grade B. The same results were obtained with the two other SUV types. Conclusions : Pathologic response to NAC in breast cancer can be assessed accurately by FLT. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-01-05.

Radiations accidents involving high exposures require accurate assessment of radiation dose for correct surgical or medical management. Techniques involving computed tomography and antimyosin-antibody scintigraphy were evaluated in an experimental model of acute localized irradiation overexposure to 192Ir. Ten rabbits were exposed to a single dose of 192Ir gamma irradiation (120 Gy) on the back (right iliospinal muscle). Computed tomography and antimyosin-antibody scintigraphy results were compared with those in four control animals. Planar scintiscans (posterior views) were performed 48 h post-injection of antimyosin-antibody each week for 2 mo after exposure. An antimyosin uptake was observed in irradiated muscle five weeks after exposure and correlated with computed tomography and histopathology results, showing muscle necrosis. Biodistribution assessed at 7 and 9 wk post exposure confirmed antimyosin-antibody accumulation in damaged muscle. A semi-quantitative analysis of a region of interest over the uptake area in the irradiated muscle (on the right side) and a contralateral non-irradiated region of interest used as control showed that uptake was significantly higher in irradiated animals than in control animals (p < 0.02). Antimyosin-antibody scintiscans used in nuclear cardiology to explore ischemic heart disease, myocarditis or heart transplant rejection could be realized to assess the extent of muscle necrosis after trauma or radiation induced injury.

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