On the normativity of evidence - Lessons from philosophy of science and the "VALIDATE" project.

"Evidence" is a key term in medicine and health services research, including Health Technology Assessment (HTA). Randomized clinical trials (RCTs) have undoubtedly dominated the scene of generating evidence for a long period of time, becoming the hallmark of evidence-based medicine (EBM). However, due to a number of misunderstandings, the lay audience and some researchers have sometimes placed too much trust in RCTs compared to other methods of investigation. One of the principal misunderstandings is to consider RCTs findings as isolated and self-apparent pieces of information. In other words, what has been essentially lacking was the awareness of the value-context of the evidence and, in particular, the value- and theory-ladenness (normativity) of scientific knowledge. This paper aims to emphasize the normativity that exists in the production of scientific knowledge, and in particular in the conduct of RCTs as well as in the performance of HTA. The work is based on some lessons learned from Philosophy of Science and the European project "VALIDATE" (VALues In Doing Assessments of healthcare TEchnologies"). VALIDATE was a three-year EU Erasmus+ strategic partnerships project (2018-2021), in which training in the field of HTA was further optimized by using insights from political science and ethics (in accordance with the recent definition of HTA). Our analysis may reveal useful insights for addressing some challenges that HTA is going to face in the future.

Natural mutations of human XDH promote the nitrite (NO2-)-reductase capacity of xanthine oxidoreductase: A novel mechanism to promote redox health?

Several rare genetic variations of human XDH have been shown to alter xanthine oxidoreductase (XOR) activity leading to impaired purine catabolism. However, XOR is a multi-functional enzyme that depending upon the environmental conditions also expresses oxidase activity leading to both O2·- and H2O2 and nitrite (NO2-) reductase activity leading to nitric oxide (·NO). Since these products express important, and often diametrically opposite, biological activity, consideration of the impact of XOR mutations in the context of each aspect of the biochemical activity of the enzyme is needed to determine the potential full impact of these variants. Herein, we show that known naturally occurring hXDH mutations do not have a uniform impact upon the biochemical activity of the enzyme in terms of uric acid (UA), reactive oxygen species (ROS) and nitric oxide ·NO formation. We show that the His1221Arg mutant, in the presence of xanthine, increases UA, O2·- and NO generation compared to the WT, whilst the Ile703Val increases UA and ·NO formation, but not O2·-. We speculate that this change in the balance of activity of the enzyme is likely to endow those carrying these mutations with a harmful or protective influence over health that may explain the current equipoise underlying the perceived importance of XDH mutations. We also show that, in presence of inorganic NO2-, XOR-driven O2·- production is substantially reduced. We suggest that targeting enzyme activity to enhance the NO2--reductase profile in those carrying such mutations may provide novel therapeutic options, particularly in cardiovascular disease.

Optical and Mechanical Properties of New Ceramic CAD/CAM Materials.

OBJECTIVE: The purpose of this study was to compare the optical and mechanical properties of newer ceramic CAD/CAM materials to more established materials on the market. METHODS AND MATERIALS: The following ceramic materials were tested: lithium disilicate/lithium-aluminum silicate (Tessera, Dentsply/Sirona), lithium disilicate (Initial LiSi Block, GC), IPS e.max CAD, Ivoclar Vivadent), and 4Y polycrystalline stabilized zirconia (IPS e.max ZirCAD MT, Ivoclar Vivadent; Katana STML, Kuraray; YZ ST, VITA). Optical properties (translucency, opalescence) were determined using a dental spectrophotometer on 0.5-, 1.0-, 1.5-, or 2.0-mm specimens. Mechanical properties (flexural strength, flexural modulus, flexural fatigue strength, Weibull modulus, and characteristic strength) were determined with beams undergoing 3-point bend testing. The data were analyzed with multiple analyses of variance and Tukey's post hoc tests (α=0.05). RESULTS: Significant differences were found between groups based on type of ceramic or property (p<0.05). CONCLUSIONS: In general, the lithium disilicate based-ceramic materials had greater optical properties and lower mechanical properties than the zirconia-based ceramic materials.

Ethics of digital therapeutics (DTx).

Digital therapeutics (DTx) are a subset of digital health which are often coupled with artificial intelligence (A.I.) techniques and machine learning systems. DTx differ from common wellness apps or medication reminder tools in that they require "rigorous" clinical evidence. They are emerging as a new treatment option and are being applied in a variety of areas, including type II diabetes, hypertension, chronic respiratory problems, obesity, insomnia, Alzheimer's disease, various types of dementia or addiction (smoking, alcohol, drugs), anxiety, depression, autism, learning disabilities, and attention deficits. Today, there are roughly 35 to 40 products on the market, 8 of which approved by regulatory agencies. The value of the global DTx market was estimated at USD 1.8 billion in 2018, and it is expected to reach USD 8.9 billion by 2027. Implementing DTx across healthcare systems raises a number of ethical concerns. The present article aims to provide an overview of the main ethical issues pertaining the assessment, implementation, and use of this emerging technology. The final purpose is to support and facilitate an open and transparent deliberation with regard to DTx.

The transcription factor ERG regulates a low shear stress-induced anti-thrombotic pathway in the microvasculature.

Endothelial cells actively maintain an anti-thrombotic environment; loss of this protective function may lead to thrombosis and systemic coagulopathy. The transcription factor ERG is essential to maintain endothelial homeostasis. Here, we show that inducible endothelial ERG deletion (ErgiEC-KO) in mice is associated with spontaneous thrombosis, hemorrhages and systemic coagulopathy. We find that ERG drives transcription of the anticoagulant thrombomodulin (TM), as shown by reporter assays and chromatin immunoprecipitation. TM expression is regulated by shear stress (SS) via Krüppel-like factor 2 (KLF2). In vitro, ERG regulates TM expression under low SS conditions, by facilitating KLF2 binding to the TM promoter. However, ERG is dispensable for TM expression in high SS conditions. In ErgiEC-KO mice, TM expression is decreased in liver and lung microvasculature exposed to low SS but not in blood vessels exposed to high SS. Our study identifies an endogenous, vascular bed-specific anticoagulant pathway in microvasculature exposed to low SS.

Epidemiologic Study and Genotyping of BK Virus in Renal Transplant Recipients.

BK virus (BKV) infection occurs during childhood and remains latent in the urinary tract. The virus is reactivated in immunosuppressed patients, particularly in those with cellular immunity deficiency, allowing its detection in urine and blood. Nephropathy caused by the virus in renal transplantation recipients may lead to graft failure. The purpose of this study is to know the prevalence of BKV variables in renal transplantation recipients and to evaluate their clinical evolution through molecular methods of "in house" development. Urine and peripheral blood samples from 66 renal transplantation recipients from the province of Buenos Aires, Argentina, were systematically analyzed every 3 months as well as when there was graft dysfunction. Renal biopsies, which were included in the BKV detection study, were performed on those patients with graft dysfunction. Genotyping of 24 BKVs was performed, and the following distribution was found: 21 (87.5%) belonged to subtype I, 3 (12.5%) to subtype II. BKV belonging to subtypes III or IV were not found. As regards subtype I subgroups, the following were identified: 1 (4.76%) from Ia, 10 (47.61%) from Ib1 and 10 (47.61%) from Ib2. Presence of subgroup Ic was not shown. Viremia presented in 33.33% of cases, whereas 75% corresponded to subgroup Ib 1. Genotype Ib1 is prevailing in Southeast Asia, while Ib2 is prominent in Europe. Although an important proportion of the inhabitants of the province of Buenos Aires are European descendants, the prevailing genotype is Ib1, the Asian type. Genotyping might be related to the evolution of the disease in the recipient.

Circulating tumor cells in metastatic colorectal cancer: do we need an alternative cutoff?

PURPOSE: To assess the prognostic and predictive value of circulating tumor cells (CTCs) in metastatic colorectal cancer (mCRC) irrespective of detection level. MATERIALS AND METHODS: We evaluated the prognostic and predictive significance of CTC count at baseline and under treatment in 119 mCRC subjects and compared the standard cutoff (≥3 CTCs/7.5 mL to ≥1 CTCs/7.5 mL). RESULTS: An overall comparison was made between patients with 0, 1-2 and ≥3 CTC (median PFS 8, 4 and 5 months, respectively). Two poor prognostic groups were found, including patients with ≥1 CTCs before and during treatment and patients with 0 CTC at baseline who converted to ≥1 CTCs (p = 0.014). CONCLUSIONS: The presence of at least 1 CTC at baseline count is predictive for poor prognosis in mCRC patients. Patients with 1-2 CTC should be switched from the favorable prognostic group--conventionally defined by the presence of <3 CTC--to the unfavorable, deserving a more careful monitoring.

Amelioration of renal damage by administration of anti-thymocyte globulin to potential donors in a brain death rat model.

Brain death (BD), a non-immunological factor of renal injury, triggers an inflammatory process causing pathological signs of cell death in the kidney, such as necrosis and apoptosis. Kidneys from brain dead donors show lower success rates than kidneys from living donors and one strategy to improve transplantation outcome is to precondition the donors. For the first time, anti-rat thymoglobulin (rATG) was administered in an experimental brain death animal model to evaluate if it could ameliorate histopathological damage and improve organ function. Animals were divided into three groups: V (n=5) ventilated for 2h; BD (n=5) brain death and ventilated for 2h; and BD+rATG (n=5) brain death, ventilated for 2h, rATG was administered during brain death (10mg/kg). We observed lower creatinine levels in treatment groups (means): V, 0·88±0·22 mg/dl; BD, 1·37±0·07 mg/dl; and BD+rATG, 0·64±0·02 mg/dl (BD versus BD+rATG, P<0·001). In the BD group there appeared to be a marked increase of ATN, whereas ATN was decreased significantly in the rATG group (V, 2·25±0·5 versus BD, 4·75±0·5, P<0·01; BD+rATG, 2·75±0·5 versus BD 4·75±0·5 P<0·01). Gene expression was evaluated with reverse transcription-polymerase chain reaction; tumour necrosis factor (TNF)-α, interleukin (IL)-6, C3, CD86 showed no significant difference between groups. Increased IL-10 and decreased CCL2 in BD+rATG compared to BD (both cases P<0·01). Myeloperoxidase was increased significantly after the brain death setting (V: 32±7·5 versus BD: 129±18). Findings suggest that rATG administered to potential donors may ameliorate renal damage caused by BD. These findings could contribute in the search for specific cytoprotective interventions to improve the quality and viability of transplanted organs.

Prognostic value of circulating tumor cells in nonmuscle invasive bladder cancer: a CellSearch analysis.

BACKGROUND: Circulating tumor cells (CTCs) provide prognostic information in patients with metastatic tumors. Recent studies have shown that CTCs are released in circulation in an early phase of cancer disease so that their presence is under investigation in the adjuvant setting. Few studies investigated the prognostic significance of CTCs enumeration in patients with metastatic and advanced bladder cancer. The current study has analyzed the presence of CTC in patients with nonmuscle-invasive bladder cancer (NMIBC). PATIENTS AND METHODS: Forty-four NMIBC patients were enrolled and included in a 24-month follow-up program. Blood drawings were carried out in all patients at the first diagnosis. CellSearch system (Veridex; LLC, Raritan, NJ) was used for CTCs enumeration. RESULTS: CTC were detectable in 8/44 patients (18%). Presence of CTC was found significantly associated to shorter time to first recurrence (6.5 versus 21.7 months, P < 0.001). Median time to progression was not reached, due to the short follow-up period. CTC presence was found associated to concomitant carcinoma in situ and higher T category. CONCLUSION: The detection of CTC in this setting of disease may allow to distinguish patients with high risk of recurrence from those with high risk of progression, as well as to early identify patients candidate for adjuvant treatment.

Preconditioning donor with a combination of tacrolimus and rapamacyn to decrease ischaemia-reperfusion injury in a rat syngenic kidney transplantation model.

Reperfusion injury remains one of the major problems in transplantation. Repair from ischaemic acute renal failure (ARF) involves stimulation of tubular epithelial cell proliferation. The aim of this exploratory study was to evaluate the effects of preconditioning donor animals with rapamycin and tacrolimus to prevent ischaemia-reperfusion (I/R) injury. Twelve hours before nephrectomy, the donor animals received immunosuppressive drugs. The animals were divided into four groups, as follows: group 1 control: no treatment; group 2: rapamycin (2 mg/kg); group 3 FK506 (0, 3 mg/kg); and group 4: FK506 (0, 3 mg/kg) plus rapamycin (2 mg/kg). The left kidney was removed and after 3 h of cold ischaemia, the graft was transplanted. Twenty-four hours after transplant, the kidney was recovered for histological analysis and cytokine expression. Preconditioning treatment with rapamycin or tacrolimus significantly reduced blood urea nitrogen and creatinine compared with control [blood urea nitrogen (BUN): P < 0·001 versus control and creatinine: P < 0·001 versus control]. A further decrease was observed when rapamycin was combined with tacrolimus. Acute tubular necrosis was decreased significantly in donors treated with immunosuppressants compared with the control group (P < 0·001 versus control). Moreover, the number of apoptotic nuclei in the control group was higher compared with the treated groups (P < 0·001 versus control). Surprisingly, only rapamycin preconditioning treatment increased anti-apoptotic Bcl2 levels (P < 0·001). Finally, inflammatory cytokines, such as tumour necrosis factor (TNF)-α and interleukin (IL)-6, showed lower levels in the graft of those animals that had been pretreated with rapamycin or tacrolimus. This exploratory study demonstrates that preconditioning donor animals with rapamycin or tacrolimus improves clinical outcomes and reduce necrosis and apoptosis in kidney I/R injury.

Validación de la versión en español del Addenbrooke's Cognitive Examination-Revisado (ACE-R) / Validation of the Spanish Version of the Addenbrooke's Cognitive Examination-Revised (ACE-R)

Introducción: El Addenbrooke's Cognitive Examination-Revisado (ACE-R) es una actualización del test de cribado ACE, cuya versión en inglés ha demostrado una alta sensibilidad y especificidad para detectar disfunción cognitiva en pacientes con demencia. La versión original del ACE ya ha sido adaptada y validada en castellano. El objetivo del presente estudio fue adaptar y validar en una población argentina la versión revisada del mismo. Métodos: Un grupo de pacientes con enfermedad de Alzheimer (EA) y pacientes con la variante conductual de la demencia frontotemporal (vcDFT) apareados por edad, sexo y años de educación y un grupo control fueron evaluados con la versión en español del ACE-R. La severidad de la demencia fue medida con el Clinical Dementia Rating Scale (CDR), incluyéndose únicamente pacientes en los estadios tempranos de ambas afecciones. La versión en inglés del ACE-R fue traducida al español y luego retraducida al inglés por dos expertos independientes ciegos a la versión original. Resultados: La fiabilidad interna fue alta (alfa de Cronbach=0,89). La validez concurrente, determinada por la correlación entre el ACE-R y el CDR, fue estadísticamente significativa (p<0,001) y la concordancia entre evaluadores fue excelente (kappa de Cohen=0,98). Los sujetos control obtuvieron puntajes estadísticamente superiores a los pacientes con EA y vcDFT en la mayoría de los subdominios del ACE-R, encontrándose diferencias significativas entre ambos grupos de demencia. Con un puntaje de corte de 85 puntos, la sensibilidad fue del 97,5% y la especificidad del 88,5%, con un cociente de probabilidades de 99,3:1 para la detección de demencia. El ACE-R presentó una sensibilidad más elevada que el MMSE para la detección de demencia. Conclusiones: La versión en español del ACE-R es una herramienta breve y válida para la detección temprana del déficit cognitivo asociados a demencia y ha demostrado ser de utilidad para la diferenciación entre AD y vcDFT (AU)

Background: The Addenbrooke's Cognitive Examination Revised (ACE-R) is an improved version of the earlier brief screening test which has been validated in English with high sensitivity and specificity to detect cognitive dysfunction. The aim of this study was to validate the Spanish version of the ACE-R in an Argentine population. Methods: A group of patients with Alzheimer Disease (AD) and patients with behavioural variant Frontotemporal Dementia (bvFTD) paired by age, sex, and years of education with healthy controls were assessed using the ACE-R. Stage of dementia was measured with the Clinical Dementia Rating Scale (CDR). The English version of the ACE-R was first translated into Spanish and then back-translated into English by two blind independent experts. Results: Internal reliability was very good (Cronbach's alpha=0.89). Concurrent validity, determined by the correlation between total ACE-R and CDR was significant (P<.001) and inter-rater reliability was excellent (Cohen's kappa=0.98). Controls significantly outperformed AD and bvFTD patients on most subdomains of the ACE-R, with significant differences between the dementia groups. With a cut-off score of 85 points, sensitivity was 97.5% and specificity was 88.5%, with a likelihood ratio of 99.3 for the detection of dementia. The ACE-R showed higher sensitivity than the MMSE for the detection of dementia. Conclusions: The Spanish version of the ACE-R is a brief yet reliable screening tool for the detection of early cognitive impairment and has shown to discriminate between bvFTD and AD (AU)

Incidence of cancer in kidney transplantation waiting list patients: a single center experience.

INTRODUCTION: It is widely accepted that the risk of malignancies is significantly increased among patients with end-stage kidney disease (ESKD) and after kidney transplantation compared with the general population. Only a few data are available on kidney transplantation waiting list patients. The aim of this study was to investigate solid organ cancer incidence among subjects on the waiting list at a single center. MATERIALS AND METHODS: We retrospectively reviewed the records of all patients enrolled on our kidney transplantation waiting list between August 1, 2008 and July 31, 2010, seeking to evaluate the causes of withdrawal from the list, incidence of cancer, type of neoplasm, and its correlation with clinical features. We estimated the ratio of observed to expected numbers of cancers, the standardized incidence ratio (SIR). RESULTS: Among 1184 patients, we excluded 569 patients from the waiting list including 26 (4.56%) who displayed malignancies. The overall incidence of cancer was 0.11 events/person-months and the overall prevalence of cancer was 2.2%. In 97% of patients, the malignant disease was confined to the primitive organ of origin without secondary dissemination. We observed a prevalence of cancers related to ESKD (17; 65.38%). The SIR for all cancer types in our population compared with the general population was 2.22. The SIR for native kidney and thyroid cancers among our population compared with the general population was >10. CONCLUSION: The incidence of cancer was significantly increased among kidney transplantation waiting list patients compared with the general population. Our study highlighted the importance of a careful, targeted neoplastic screening. It could be particularly important for ESKD-related malignancies like native kidney tumors or thyroid cancers.

Targeting PDK1 in cancer.

Abnormal activation of phosphoinositide 3-kinase (PI3K) signalling is very common in cancer, leading to deregulation of several intracellular processes normally controlled by this enzyme, including cell survival, growth, proliferation and migration. Mutations in the gene encoding the tumour suppressor phosphatase and tensin homologue deleted on chromosome 10 (PTEN), which leads to uncontrolled activation of the PI3K pathway, are reported in different cancers. Among the downstream effectors of PI3Ks, 3- phosphoinositide-dependent protein kinase 1 (PDK1) and protein kinase B (PKB)/Akt have a key role in several cancer types. More recent data indicate that alteration of PDK1 is a critical component of oncogenic PI3K signalling in breast cancer, suggesting that inhibition of PDK1 can inhibit breast cancer progression. PDK1 has an essential role in regulating cell migration especially in the context of PTEN deficiency. Downregulation of PDK1 levels inhibits migration and experimental metastasis of human breast cancer cells. PDK1 activates a large number of proteins, including Akt, some PKC isoforms, S6K and SGK. Data also reveal that PDK1 is oncogenic and this is dependent on PI3K pathway. Therefore, accumulating evidence demonstrates that PDK1 is a valid therapeutic target and suggests that PDK1 inhibitors may be useful to prevent cancer progression and abnormal tissue dissemination. This review will focus on published data on the role of PDK1 in cancer and approaches used to inhibit PDK1.

Validation of the Spanish Version of the Addenbrooke's Cognitive Examination-Revised (ACE-R).

BACKGROUND: The Addenbrooke's Cognitive Examination Revised (ACE-R) is an improved version of the earlier brief screening test which has been validated in English with high sensitivity and specificity to detect cognitive dysfunction. The aim of this study was to validate the Spanish version of the ACE-R in an Argentine population. METHODS: A group of patients with Alzheimer Disease (AD) and patients with behavioural variant Frontotemporal Dementia (bvFTD) paired by age, sex, and years of education with healthy controls were assessed using the ACE-R. Stage of dementia was measured with the Clinical Dementia Rating Scale (CDR). The English version of the ACE-R was first translated into Spanish and then back-translated into English by two blind independent experts. RESULTS: Internal reliability was very good (Cronbach's alpha=0.89). Concurrent validity, determined by the correlation between total ACE-R and CDR was significant (P<.001) and inter-rater reliability was excellent (Cohen's kappa=0.98). Controls significantly outperformed AD and bvFTD patients on most subdomains of the ACE-R, with significant differences between the dementia groups. With a cut-off score of 85 points, sensitivity was 97.5% and specificity was 88.5%, with a likelihood ratio of 99.3 for the detection of dementia. The ACE-R showed higher sensitivity than the MMSE for the detection of dementia. CONCLUSIONS: The Spanish version of the ACE-R is a brief yet reliable screening tool for the detection of early cognitive impairment and has shown to discriminate between bvFTD and AD.

Weekly combination of non-pegylated liposomal doxorubicin and taxane in first-line breast cancer: wALT trial (phase I-II).

BACKGROUND: Through different pharmacodynamic-kinetic interactions, weekly administration of proved efficacy agents can overcome resistance with lower toxicity and greater benefit. Based on this assumption, we designed a phase I-II trial with weekly non-pegylated liposomal anthracycline and taxane in first-line breast cancer patients. PATIENTS AND METHODS: We enrolled 56 previously untreated metastatic breast cancer patients; they were randomly assigned to receive paclitaxel (Taxol) (50 mg/mq) or docetaxel (Taxotere) (30 mg/mq) combined with non-pegylated liposomal anthracycline (25 mg/mq) on days 1, 8 and 15 every 4 weeks. The primary end points were the clinical benefit and treatment-related toxic effects assessment. Secondary end points were time-to-disease progression (TTP) and overall survival (OS). RESULTS: The overall clinical benefit was 87.04%. World Health Organization G3-4 toxic effects included neutropenia (45%), anemia (44%), complete alopecia (83%), severe onycholysis and neuropathy. The 24% of patients developed left ventricular ejection fraction reduction but none >10% with recover after treatment completion. The median absolute decrease from baseline was 1%. Median TTP was 11 months and median OS was 23 months. CONCLUSIONS: Combined weekly administration of taxane and non-pegylated liposomal anthracycline is well tolerated and clinical benefit data encourage phase III study design.

Circulating tumor cells (CTCs) in metastatic breast cancer (MBC): prognosis, drug resistance and phenotypic characterization.

BACKGROUND: the expression of ATP-binding cassette transporters on circulating tumor cells (CTCs) is predictive of response to chemotherapy in cancer patients. We tested the hypothesis that drug-resistant CTCs might have predictive value in metastatic breast cancer (MBC) and possibly retain stem-like properties. PATIENTS AND METHODS: CTCs obtained from 42 MBC patients were evaluated for multidrug-resistance-related proteins (MRPs), aldehyde dehydrogenase 1 (ALDH1), estrogen receptor α (ERα) and human epidermal growth factor receptor 2 (HER2/neu). Primary objective was to evaluate the prognostic and predictive value of CTCs profile. Secondary end points were the level of concordance in ERα and HER2/neu status between primary tumors and CTCs and the correlation in CTCs between ALDH1, drug resistance profile and number of MRPs. RESULTS: A difference in progression-free survival (PFS) was found between CTCs-positive and CTCs-negative patients. PFS was shorter in patients with a 'drug resistance' CTCs profile and in patients whose CTCs expressed two or more MRPs. No correlation was found between tumor characteristics and ALDH1. ALDH1 correlated to negative ERα and positive HER2/neu status in CTCs. The correlation between the number of MRPs expressed in CTCs and ALDH1 was statistically significant. CONCLUSION: in MBC, the presence of CTCs expressing MRPs and ALDH1 is predictive of response to chemotherapy.

Circulating tumor cells in cancer therapy: are we off target?

What clinical oncologists learned about metastatic process, is that it is the main cause of cancer-related deaths. What scientists learned about metastatic disease, is that it is due to a highly selective process, which involves a minority of tumor cells that are able to survive within the bloodstream, and to initiate a new growth in distant sites. These cells "in transit" are known as circulating tumor cells (CTCs). Although their nature is not fully understood, what is widely accepted, is that they are drug resistant, and that their presence may represent the main reason for treatment failure. Despite this body of evidence, the pharmacological approach against cancer, with both chemotherapic and biological drugs, is still targeted on the primary tumor, raising the question as to whether we are missing the target. Targeting circulating tumor cells, may represent a new promising approach to indivisualize anticancer therapy.

Cancer stem cells and epithelial-mesenchymal transition: revisiting minimal residual disease.

The cancer stem cell (CSC) hypothesis provides an attractive model of tumour development and progression, holding that solid tumours are hierarchically organized and sustained by a minority of the tumour cell population with stem cell properties, such as self-renewal, tumorigenicity and multilineage differentiation capacity. Therapeutic resistance, underlying tumour recurrence and the lack of curative treatments in metastatic disease, raise the question if conventional anticancer therapies target the right cells. Indeed, these treatments might miss CSCs, which represent a more chemoresistant and radioresistant subpopulation within cancer. Recently, a direct link between the epithelial-mesenchymal transition process and the gain of stem cell competence were demonstrated in cultured breast cells. In particular, it was shown that the induction of EMT program not only allow cancer cells to disseminate from the primary tumor, but also promotes their self-renewal capability. Furthermore, the expression of stemness and EMT markers in CTCs were associated with resistance to conventional anti-cancer therapies and treatment failure, highlighting the urgency of improving tools for detecting and eliminating minimal residual disease.