Os tumores malignos apresentam um aumento da expressão dos receptores de lipoproteínas, devido ao aceleramento da proliferação celular com consequente aumento da necessidade de lípides para a síntese das membranas celulares. Esse aumento da expressão dos receptores de LDL no câncer pode ser utilizado para concentrar fármacos de ação antineoplásica em tecido tumoral, utilizando lipoproteínas ou nanoemulsões semelhantes a lipoproteínas como veículo. No presente estudo, foram investigados os efeitos da quimioterapia convencional na expressão dos receptores de LDL e LRP-1 em 16 pacientes com carcinoma de mama estádios II ou III, não candidatas à cirurgia conservadora e com indicação de tratamento quimioterápico neoadjuvante. A expressão dos receptores LDLR e LRP-1 foi avaliada por imunoistoquimica em tecido mamário normal e em tecido neoplásico antes e depois da quimioterapia neoadjuvante. Quatro pacientes que apresentaram resposta completa à quimioterapia foram retiradas da análise da expressão de receptores por não existir tumor no fragmento cirúrgico. Em relação ao LDLR, a expressão desse receptor no tecido neoplásico foi maior em comparação ao tecido normal em 8 das 11 pacientes. Após a quimioterapia, a expressão do receptor de LDL diminuiu em 6, aumentou em 4 e não se alterou em 2 pacientes. Do mesmo modo, a expressão do receptor LRP-1 no tecido tumoral estava aumentada em relação ao tecido normal em 4 pacientes das 12 avaliadas. Em comparação com o tecido tumoral antes da quimioterapia, a expressão do receptor LRP-1 diminuiu em 6, aumentou em 4 e permaneceu inalterada em 2 pacientes após a quimioterapia. Esses dados mostram que o efeito da quimioterapia na expressão dos receptores de lipoproteínas foi heterogêneo. A redução da expressão dos receptores não foi o padrão observado, o que indica que o uso de sistemas de carreamento de fármacos via receptores de LDL para o tratamento do câncer pode ser de grande importância. Esses resultados podem contribuir para o desenho de futuros estudos clínicos / Proliferative tumor cells present a high expression of LDL receptors due to accelerated mitosis rates which takes to increased need of lipids internalization for building new membranes. Upregulation of LDL receptors may be used as a gate to deliver anticancer drugs to tumor tissues using lipoproteins or artificial nanoemulsions as vehicle. This study investigated the effects of conventional chemotherapy on the expression of LDL and LRP-1 receptors in 16 patients with breast cancer in stage II or III who were not candidates to conservative surgery and with indication of neo-adjuvant chemotherapy. Expression of LDL and LRP-1 receptor was evaluated by immunohistochemistry in normal and neoplastic breast tissue before and after chemotherapy. For absence of tumor in the surgical fragments, 4 patients who presented complete response to chemotherapy were excluded from this analysis. In relation of LDLR, the expression in neoplastic tissue was higher than in normal tissue in 8 of 11 patients. After chemotherapy, LDL receptor expression diminished in 6, increased in 4 and unchanged in 2 patients. Expression of LRP-1 in tumor tissue was higher in 4 of 12 patients when compared to normal tissue. After chemotherapy, the expression of LRP-1 diminished in 6, increased in 4 and showed no difference in 2 patients. These data show that the chemotherapy effects on the tumor expression of LDL receptors were very heterogeneous. The diminution of the receptor expression is not the post-chemotherapy pattern, allowing the use of drug carrier systems that target cancer cells via the LDL receptor pathway. These results may contribute for the design of future clinical assays

Pacientes com câncer de mama localmente avançado são submetidas à quimioterapia neoadjuvante na tentativa de reduzir a dimensão do tumor e aumentar a possibilidade da realização de uma cirurgia conservadora. Nosso grupo identificou previamente através da tecnologia de cDNA microarray, trios de genes, incluindo BZRP, CLPTM1, MTSS1, NOTCH1, NUP210, PRSS11, RPL37A, SMYD2 e XLHSRF-1, cuja expressão era capaz de predizer a resposta à quimioterapia neoadjuvante com doxorrubicina e ciclofosfamida em pacientes com câncer de mama. No presente estudo, avaliamos se a expressão destes genes é reprodutível na identificação de pacientes responsivas e não-responsivas através de RT-PCR em tempo real, que representa uma técnica mais acessível. Avaliamos inicialmente amostras de 28 pacientes anteriormente estudadas (grupo de validação técnica = 23 responsivas e cinco não-responsivas) e a seguir um grupo de 14 novas pacientes (grupo de validação biológica = 11 responsivas e três não-responsivas). Dentre os trios de genes inicialmente identificados, a expressão de RPL37A + XLHSRF-1 + NOTCH1 e RPL37A + XLHSRF-1 + NUP210 classificou corretamente 86% (24/28) das amostras do grupo de validação técnica e 71% (10/14) das amostras do grupo de validação biológica, através de análise de classificação discriminante. Desse modo, esses trios não demonstraram a mesma precisão em comparação com resultados de cDNA microarray. Uma nova análise combinatória foi realizada na procura do melhor modelo preditivo utilizando valores de expressão obtidos por RT-PCR em tempo real. Identificamos então um novo trio, composto pelos genes RPL37A, SMYD2 e MTSS1, cuja expressão classificou corretamente 93% das amostras do grupo de validação técnica (22/23 responsivas e 4/5 não-responsivas) e 79% do grupo de validação biológica (8/11 responsivas e 3/3 não-responsivas). Portanto, o teste apresentou 88% de sensibilidade e especificidade em detectar pacientes responsivas para o total de amostras analisadas. Ao verificarmos o poder de classificação do mesmo grupo de genes, utilizando os valores de expressão pela análise de cDNA microarray, observamos um resultado semelhante (91% de sensibilidade e especificidade em reconhecer as amostras responsivas). Dessa forma, demonstramos que o perfil de expressão gênica obtido com cDNA microarray é reprodutível através do uso de RT-PCR em tempo real. Um estudo integrando um maior número de pacientes e uma plataforma de cDNA microarray mais abrangente pode auxiliar na identificação de um modelo preditivo baseado em grupos de genes mais acurado para antever a resposta ao tratamento com quimioterapia baseada em doxorrubicina. / Patients with locally advanced breast cancer are submitted to primary chemotherapy as an attempt to reduce tumor dimension and increase breast conserving surgery rates. Our group has previously identified through cDNA microarray technology gene trios, including BZRP, CLPTM1, MTSS1, NOTCH1, NUP210, PRSS11, RPL37A, SMYD2 and XLHSRF-1, whose expression was capable of predicting response to neoadjuvant chemotherapy with doxorubicin and cyclophosphamide in breast cancer patients. In the current study, it was evaluated whether expression of these genes is reproducible in the identification of responsive and non-responsive patients by real time RT-PCR, which represents a more accessible technique. We initially evaluated samples from 28 patients earlier studied (technical validation group = 23 responsive and 5 non-responsive) and subsequent to a new 14 patients set (biological validation group = 11 responsive and three non-responsive). Among the initially identified gene trios, RPL37A + XLHSRF-1 + NOTCH1 and RPL37A + XLHSRF-1 + NUP210 expression correctly classify 86% (24/28) samples from the technical validation group and 71% (10/14) samples from the biological validation group, through discriminant classification analysis. Therefore, these trios didnt demonstrate the same precision as compared with cDNA microarray results. A new combinatorial analysis was also performed in search of the best predictive model using real time RT-PCR expression values. A new trio was identified, represented by RPL37A, SMYD2 and MTSS1 genes, whose expression correctly classified 93% samples from technical validation group (22/23 responsive and 4/5 non-responsive) and 79% samples from biological validation group (8/11 responsive samples and 3/3 non-responsive samples). Therefore, the test presented 88% sensibility and specificity in identifying responsive patients for all samples analyzed. By means of verifying the classification strength of the same gene group, using cDNA microarray expression values, we observed a similar result (91% sensibility and specificity in recognizing responsive samples). Thus, we demonstrated that gene expression profile obtained by cDNA microarray is reproducible through real time RT-PCR. A study integrating a larger number of patients and a more comprehensive cDNA microarray platform may help the identification of a more accurate predictive model based on gene groups to foresee response to doxorubicin-based chemotherapy treatment.

Os tumores malignos apresentam um aumento da expressão dos receptores de lipoproteínas, devido ao aceleramento da proliferação celular com consequente aumento da necessidade de lípides para a síntese das membranas celulares. Esse aumento da expressão dos receptores de LDL no câncer pode ser utilizado para concentrar fármacos de ação antineoplásica em tecido tumoral, utilizando lipoproteínas ou nanoemulsões semelhantes a lipoproteínas como veículo. No presente estudo, foram investigados os efeitos da quimioterapia convencional na expressão dos receptores de LDL e LRP-1 em 16 pacientes com carcinoma de mama estádios II ou III, não candidatas à cirurgia conservadora e com indicação de tratamento quimioterápico neoadjuvante. A expressão dos receptores LDLR e LRP-1 foi avaliada por imunoistoquimica em tecido mamário normal e em tecido neoplásico antes e depois da quimioterapia neoadjuvante. Quatro pacientes que apresentaram resposta completa à quimioterapia foram retiradas da análise da expressão de receptores por não existir tumor no fragmento cirúrgico. Em relação ao LDLR, a expressão desse receptor no tecido neoplásico foi maior em comparação ao tecido normal em 8 das 11 pacientes. Após a quimioterapia, a expressão do receptor de LDL diminuiu em 6, aumentou em 4 e não se alterou em 2 pacientes. Do mesmo modo, a expressão do receptor LRP-1 no tecido tumoral estava aumentada em relação ao tecido normal em 4 pacientes das 12 avaliadas. Em comparação com o tecido tumoral antes da quimioterapia, a expressão do receptor LRP-1 diminuiu em 6, aumentou em 4 e permaneceu inalterada em 2 pacientes após a quimioterapia. Esses dados mostram que o efeito da quimioterapia na expressão dos receptores de lipoproteínas foi heterogêneo. A redução da expressão dos receptores não foi o padrão observado, o que indica que o uso de sistemas de carreamento de fármacos via receptores de LDL para o tratamento do câncer pode ser de grande importância. Esses resultados podem contribuir para o desenho de futuros estudos clínicos / Proliferative tumor cells present a high expression of LDL receptors due to accelerated mitosis rates which takes to increased need of lipids internalization for building new membranes. Upregulation of LDL receptors may be used as a gate to deliver anticancer drugs to tumor tissues using lipoproteins or artificial nanoemulsions as vehicle. This study investigated the effects of conventional chemotherapy on the expression of LDL and LRP-1 receptors in 16 patients with breast cancer in stage II or III who were not candidates to conservative surgery and with indication of neo-adjuvant chemotherapy. Expression of LDL and LRP-1 receptor was evaluated by immunohistochemistry in normal and neoplastic breast tissue before and after chemotherapy. For absence of tumor in the surgical fragments, 4 patients who presented complete response to chemotherapy were excluded from this analysis. In relation of LDLR, the expression in neoplastic tissue was higher than in normal tissue in 8 of 11 patients. After chemotherapy, LDL receptor expression diminished in 6, increased in 4 and unchanged in 2 patients. Expression of LRP-1 in tumor tissue was higher in 4 of 12 patients when compared to normal tissue. After chemotherapy, the expression of LRP-1 diminished in 6, increased in 4 and showed no difference in 2 patients. These data show that the chemotherapy effects on the tumor expression of LDL receptors were very heterogeneous. The diminution of the receptor expression is not the post-chemotherapy pattern, allowing the use of drug carrier systems that target cancer cells via the LDL receptor pathway. These results may contribute for the design of future clinical assays

As imagens de ressonância magnética (RM) ponderadas em Difusão são conhecidas como uma técnica funcional capaz de refletir alterações estruturais e celulares de neoplasias. No câncer de mama, a difusão e sua quantificação através dos valores do coeficiente de difusão aparente (CDA) têm sido utilizados para avaliar resposta tumoral após quimioterapia neoadjuvante (QTN). Os variados desfechos clínicos do câncer de mama, incluindo as diferentes respostas ao tratamento quimioterápico podem estar relacionados à heterogeneidade da doença. A presença das células tronco tumorais (CTT) é uma das hipóteses aceitas para explicar os diferentes comportamentos biológicos dos tumores. Este estudo buscou avaliar uma possível associação entre os valores de CDA nas neoplasias invasivas da mama e a presença de marcadores de CTT e os principais marcadores prognósticos da doença em pacientes tratadas com QTN. Foram avaliadas prospectiva e consecutivamente as imagens de RM pré-tratamento de 27 pacientes com câncer da mama que realizaram QTN seguida de cirurgia. Os valores de CDA média, p10, p25 e p50 foram obtidos através de duas mensurações, uma com único ROI e outra com múltiplos ROIs envolvendo toda extensão tumoral. Esses valores de CDA foram correlacionados: à quantificação por citometria de fluxo de CTT com fenótipos ESA+/CD44+/CD24-, células ESA+ com alta atividade ALDH1 e células ESA+/ABCG2+, à capacidade de formação de mamoesferas, e aos principais fatores prognósticos do câncer de mama, incluindo estágio clínico, doença axilar linfonodal, grau tumoral, receptores de estrógeno (RE), receptores de progesterona (RP) e superexpressão do HER2. Também foi realizada correlação dos valores de CDA com a resposta patológica completa após QTN. A presença de CTT, a capacidade de formação de mamoesferas e a resposta patológica completa não se correlacionaram aos valores de CDA. Para ambas as medidas e todos os parâmetros avaliados de CDA (x10-3mm2/s), os valores foram significantemente menores nos tumores com estágio clínico III e IV vs II (0,90±0,16; 1,02±0,18); com doença linfonodal após QTN vs axila livre (0,89±0,16; 1,01±0,17); RE+ vs RE- (0,90±0,16; 1,00±0,18); RP+ vs RP- (0,91±0,16; 0,98±0,18) e HER2+ vs HER2- (0,92±0,17;0,97±0,18). Tumores grau 1 apresentaram CDA com valores significativamente maiores em relação aos tumores grau 2 (diferença 0,18; CI: 0,03-0,33, p=0,02). Os valores de CDA dos tumores de mama pré-QTN não predizem a presença de CTT, a capacidade de formação de mamoesferas ou a resposta patológica completa, porém se correlacionam com o estágio clínico da doença, doença linfonodal axilar após QTN, grau tumoral e expressão das proteínas RE, RP e HER2, sendo um promissor marcador de agressividade tumoral / The diffusion-weighted magnetic resonance imaging (DWMRI) is a functional technique able to reflect structural and cellular changes in the tumors. In the breast cancer, the diffusion-weighted images and its numeric value known as the apparent diffusion coefficient (ADC) has been applied to evaluate pathologic response in patients treated with neoadjuvant chemotherapy (NC). The difference in the clinical results after breast cancer treatment, including different rates of responses to the NC has been associated to the heterogeneity of the disease. The presence of the breast cancer stem cells (BCSC) is an accepted hypothesis to explain the different biologic breast cancers behaviors. The aim of this study was to correlate the ADC value of invasive breast cancer with the presence of cancer stem cells markers and the major prognostic factors in patients treated with neoadjuvant chemotherapy. Prospectively, the MRI pre-treatment of twenty-seven consecutive patients with invasive breast cancer posteriorly treated with NC followed by surgery were evaluated. The ADC values mean, 10th percentile, 25th percentile, 50th percentile were obtained from two measurements, one of them with a unique ROI and the other with multiple ROIs encompassing the entire lesion. The ADC values were correlated to: presence of BCSCs (cell surface markers CD44+/CD24-, ABCG2 and ALDH1) identified by flow cytometric analysis, tumor grade, breast cancer staging, lymph nodal involvement, expression of estrogen receptors (ER), expression of progesterone receptors (PR) and expression of HER2. The assay mammospheres (Mammocult ®) were analyzed in 18 samples. Additionally, the ADC values were correlated to the pathologic complete response after QN treatment. There were no correlations between ADC values and breast cancer stem cells markers or mammospheres formation efficiency. For all parameters calculated, the ADC values (x10- 3 mm 2 /s) were lower in: breast cancer stage III and IV than stage II (0,90±0,16; 1,02±0,18), tumors with lymph node metastasis than without lymph node metastasis (0,89±0,16; 1,01±0,17), ER expression than ER negative (0,90±0,16; 1,00±0,18), PR expression than PR 10 negative (0,91±0,16; 0,98±0,18) and HER2 expression than HER2 negative (0,92±0,17; 0,97±0,18). The ADC values were significantly higher in grade-1 tumors (difference 0,18; CI: 0,03-0,33) compared to grade-2 tumors (p=0,02). The tumors values of ADC pretreatment were not correlated to the pathologic complete response after NC. The ADC values in pre-treatment invasive breast cancers are not a predictor of BCSC presence, mammospheres formation efficiency or pathologic complete response to QN. However it is correlated to the tumor grade, breast cancer staging, lymph nodal involvement, expression of ER, PR and HER2 and may represent a promising marker of tumor aggressiveness

La chimiothérapie néoadjuvante (CNA) est une avancée majeure dans les traitements des cancers du sein. La CNA réduit nettement la tumeur primaire et permet une chirurgie conservatrice à tous les stades du cancer. Malheureusement, elle s’accompagne de dysfonctionnements neurologiques qui limitent le succès du traitement anti-tumoral. La prise en charge médicale de ces troubles neurologiques est problématique compte tenu de l’inefficacité des neuroprotecteurs disponibles. De plus, la recherche de nouvelles thérapeutiques est handicapée par l’absence de modèles expérimentaux reproduisant fidèlement les symptômes évoqués par la CNA séquentielle « épirubicine (EPI)/docétaxel (DO) » ou CNA-[EPI-DO] fréquemment utilisée. Ce travail de thèse a permis de caractériser pour la première fois un modèle animal pertinent de troubles neurologiques périphériques et centraux évoqués par la CNA-[EPI-DO]. Ce modèle préclinique a été utilisé pour révéler l’efficacité d’un traitement concomitant de duloxétine et d’alloprégnanolone contre la neuropathie périphérique douloureuse induite par la CNA-[EPI-DO]. Nos travaux montrent aussi que la duloxétine exerce une action bénéfique contre les déficits cognitifs évoqués par la CNA-[EPI-DO]. La thèse ouvre des perspectives prometteuses à explorer pour le développement de thérapies efficaces contre les altérations neurologiques CNA-induites. / Neoadjuvant chemotherapy (NAC) represents a major progress in breast cancer therapy. By shrinking significantly, the tumor volume, NAC allows conservative surgery at all stages of breast cancer. Unfortunately, NAC also induces neurological dysfunctions that jeopardize the chances of success of anti-tumor treatments. Therapeutic management of these neurological disorders remains a major concern because neuroprotective drugs currently available are not effective. Furthermore, investigations to characterize novel effective therapeutics are hampered by the lack of reliable experimental models mimicking the neurological symptoms evoked by the sequential epirubicin (EPI)/docetaxel (DO)-NAC or [EPI-DO]-NAC frequently used in humans. The present thesis work allowed the first characterization of a relevant animal model of [EPI-DO]-NAC-induced peripheral and central neurological disorders. This preclinical model has successfully been used to demonstrate the efficacy of duloxetine and allopregnanolone concomitant treatment against [EPI-DO]-NAC-evoked painful peripheral neuropathy. Our results also reveal a beneficial action of duloxetine against [EPI-DO]-NAC-induced cognitive deficits. The thesis opens promising perspectives to be explored for the development of effective therapies against [EPI-DO]-NAC-induced neurological alterations.

Gastric cancer (GC) is one of leading causes of death in the world, and peritoneal metastases (PM) are a major site of recurrence. PM from GC implies a poor prognosis, with median overall survival (mOS) approximately 3 months and no survival at five years. The aims of this thesis were to explore the incidence and evaluate prognostic factors for mOS of PM from GC in a defined population; to investigate the outcome of a new multimodal treatment; to analyse the treatment costs, and to investigate differences in drug sensitivity between individual patient samples and between various tumours. The incidence of loco-regional advanced GC was 3.8 per 100,000 person-years. Synchronous loco-regional GC in combination with synchronous distant metastasis was a negative prognostic factor while chemotherapy and good performance status, and radiotherapy plus chemotherapy were positive prognostic factors . There were no significant differences in mOS for the group of patients included during the period 2000-2004 versus 2005-2009, and this lack of improvement in mOS during the past decade justifies new treatment approaches. In a Phase II study of patients treated with neoadjuvant systemic chemotherapy followed by cytoreductive surgery + hyperthermic intraperitoneal chemotherapy, mOS was 14.3 months and for patients with macroscopically radical surgery mOS was 19.1 months. The mean overall cost of the loco-regional treatment was $145,700 compared to $59,300 with systemic chemotherapy treatment. In an ex vivo chemo-sensitivity test, it was determined that GC samples were equivalent to colorectal cancer in chemo-sensitivity to standard drugs and targeted drugs, whereas ovarian cancer samples were more sensitive. The individual GC samples varied considerably in sensitivity to increasing concentrations of the drugs, arguing for individualized drug selection. The incidence of loco-regional advanced GC was more common than previously reported and there were no improvements in mOS over the past decade. The mOS for patients with neoadjuvant systemic chemotherapy followed by macroscopically radical cytoreductive surgery + hyperthermic intraperitoneal chemotherapy was better than in recent reports on treatment with systemic chemotherapy. Treatment of advanced GC patients is costly irrespective of treatment modality. The GC samples varied considerably between individuals in terms of sensitivity to increasing concentrations of the drugs and were comparable to colorectal cancer in chemo-sensitivity.

No description available.

No description available.

Les tumeurs stromales gastrointestinales (GIST) sont les néoplasies mésenchymateuses les plus complexes du système gastrointestinal. Le traitement curatif standard de cette pathologie est la chirurgie avec l'obtention de marges microscopiques négatives. Les résultats impressionnants obtenus sur la prolongation de la survie avec l'administration d'imatinib (IM) chez les patients atteints de maladie métastatique et non-réséquable ont suggéré aux cliniciens que ce même médicament pourrait aussi collaborer à l'obtention de marges négatives plus aisément lors de cancer avancé. Jusqu'à présent, aucune étude prospective n'a caractérisée l'effet d'une thérapie néoadjuvante prolongée à l'IM sur la qualité de la résection chirurgicale subséquente. L'objectif de ce projet de maîtrise était d'évaluer l'efficacité de l'imatinib utilisé avant la chirurgie (néoadjuvant) jusqu'à l'obtention d'une réponse maximale, en vue d'augmenter le taux de résection microscopique complète (R0) dans le traitement chirurgical des GIST à haut risque de résection microscopique incomplète (R1) ou impossible (R2). Pour ce faire, une étude prospective multicentrique de phase II a été réalisée. Le traitement néoadjuvant à l'IM a été instauré chez des patients porteurs d'une GIST localement avancée ou métastatique. Au total, quatorze patients ont reçu une dose de 400-600 mg/d d'IM pour une durée de 6-12 mois avant la chirurgie. Quatorze patients ont été inclus dans l'étude. Onze ont eu une chirurgie à visée curative, un patient a démontré une maladie non-réséquable suite à une laparotomie exploratrice et deux patients ont refusé la chirurgie. Après un suivi moyen de 48 mois, tous les patients opérés étaient vivants et sept sans évidence de récidive. L'utilisation prolongée (12 mois) d'IM dans un contexte néoadjuvant est faisable, sécuritaire, efficace et comporte peu de toxicité. De plus, cette approche est associée à des hauts taux de résection complète (R0), tout en permettant une chirurgie moins extensive. Des études de phase III actuellement en cours sont nécessaires afin de confirmer nos résultats. / Gastrointestinal stromal tumor (GIST) is the most common mesenchymal malignancy of the GI tract. The current standard of care for GIST is surgical complete resection with negative margins. The agent response rate as well as survival advantages obtained with imatinib mesylate in patients with metastatic and/or non-resectable GIST has lead clinicians to evaluate this therapy as neoadjuvant treatment in patients with locally advanced or metastatic but potentially resectable GIST. This study was designed to evaluate the efficacy of neoadjuvant use of imatinib mesylate until maximal clinical response in potentially resectable GIST patients (locally advanced or metastatic), in order to provide preliminary data regarding the efficacy of this approach in the surgical treatment of GIST at high-risk of incomplete microscopic (R1) or macroscopic (R2) margins. A prospective multicenter phase II trial was designed. Fourteen consecutive patients diagnosed with advanced GIST received imatinib at dose of 400 mg/d to 600 mg/d, given from 6 to 12 months prior to surgery. Amoung the 14 patients included, 11 underwent surgery and had a complete microscopic resection (R0). After a median follow-up of 48 months, all operated patients were alive and 7 without evidence of recurrence. The prolonged use (12 months) of neoadjuvant imatinib is feasible, safe, eficient ans associated with low toxicity. Furthermore, it is associated with a high rate of microscopic resection (R0) and a less extensive surgical approach. Phase III study with higher cohorts are necessary to confirm our primary results.

Key words: adenocarcinoma of the esophagus and esophagogastric junction, neoadjuvant chemotherapy, PET/CT, histopathological response, technique of esophagogastric anastomosis, anastomotic leak, anastomotic stricture Previous studies have shown that preoperative chemotherapy of locally advanced AEG is beneficial only for patients with a good histopathological response, the so-called responders. The aim of the first part of the thesis was to prospectively verify whether positron emission tomography (PET/CT) could be used for early identification of histopathological non- responders, who could be spared ineffective neoadjuvant treatment. Our study did not prove that the early metabolic response, expressed as the percentage change of the consumption of glucosis on PET/CT performed before (PET1) and 12 to 22 days after the start of the first cycle of preoperative chemotherapy (PET2) correlated with the histopathological response in the resection specimen in the entire population of 90 patients. In a post hoc explorative analysis we found the correlation between metabolic and histopathological response in a subgroup of patients with PET2 performed ≤16 days after the start of the therapy, but this hypothesis needs to be prospectively validated. Our study suggests that PET/CT performed after the first...