The 90-KDa heat shock protein (Hsp90) is part of the molecular chaperone family, and as such it is involved in the regulation of protein homeostasis within cells. Specifically, Hsp90 aids in the folding of nascent proteins and re-folding of denatured proteins. It also plays an important role in the prevention of protein aggregation. Hsp90’s functionality is attributed to its several staged, multi-conformational ATPase cycle, in which associated client proteins are bound and released. Hsp90 is known to be associated with a wide array of client proteins, some of which are thought to be involved in multiple oncogenic processes. Indeed Hsp90 is known to be directly involved in perpetuating the stability and function of multiple mutated, chimeric and over-expressed signalling proteins that are known to promote the growth and survival of cancer cells. Hsp90 inhibitors are thus thought to be promising therapeutic agents for cancer treatment. A lack of a 3D structure of human Hsp90 however has restricted Hsp90 inhibitor development in large to in vivo investigations. This study, aims to investigate and calculate hypothetical homology models of the full human Hsp90 protein, and to probe these structural models for novel drug target sites using several in silico techniques. A multi-template homology modelling methodology was developed and in conjunction with protein-protein docking techniques, two functionally important human Hsp90 structural models were calculated; the nucleotide free “v-like” open and nucleotide bound closed conformations. Based on the conservation of ligand binding, virtual screening experiments conducted on both models using 316 natural compounds indigenous to South Africa, revealed three novel putative target sites. Two binding pockets in close association with important Hsp90-Hop interaction residues and a single binding pocket on the dimerization interface in the C-terminal domain. Targeted molecular docking experiments at these sites revealed two compounds (721395-11-5 and 264624-39-7) as putative inhibitors, both showing strong binding affinities for at least one of the three investigated target sites. Furthermore both compounds were found to only violate one Lipinski’s rules, suggesting their potential as candidates for further drug development. The combined work described here provides a putative platform for the development of next generation inhibitors of human Hsp90.

La leptine est une hormone peptidique ayant une action sur de nombreux tissus. Une dérégulation de la sécrétion de cette hormone est observée au cours de l’obésité. L’obésité est fréquemment associée à des troubles de santé dont les principaux sont le diabète de type II, l’hypertension artérielle et les maladies cardiovasculaires. Elle est également un facteur de risque du cancer du sein, particulièrement en post-ménopause favorisant la récidive et augmentant la mortalité. Ces perturbations, associées à un état de stress oxydant défini par un excès de production des espèces réactives de l’oxygène (ERO) par rapport aux systèmes de défense antioxydants, pourraient avoir un impact majeur dans le risque de carcinogenèse chez le sujet obèse. Il est clairement établi aujourd’hui que le statut oxydatif des cellules est directement corrélé aux capacités de prolifération mais aussi de survie des cellules dans leur environnement. A ce jour, très peu de données existent concernant le rôle de la leptine dans la modulation du statut oxydatif des cellules épithéliales mammaires saines et tumorales. L’objectif de cette thèse était d’étudier d'abord les mécanismes d’action et les effets de la leptine sur le statut oxydatif et inflammatoire des cellules épithéliales mammaires saines et néoplasiques ; puis dans un deuxième temps, une étude expérimentale a été conduite pour caractériser in vivo l’impact de l’obésité associée ou non à l’activité physique sur la croissance tumorale et le statut oxydatif et inflammatoire des tumeurs. Le projet avait également pour but de mettre en œuvre une nouvelle technique d’analyse basée sur la détection de fluorescence native induite par excitation laser à 224 nm afin d’évaluer la production de composés bio-actifs de la famille des éicosanoïdes, dont les isoprostanes, impliqués dans le processus inflammatoire. Nous avons exploré in vitro l’impact de la leptine sur le statut oxydatif des cellules épithéliales mammaires. Cette étude nous a permis d’établir que la réponse au signal leptinique varie en fonction du statut néoplasique de la lignée considérée, en fonction du temps de contact et non de la dose testée. Ensuite, nous avons étudié l’impact de l’obésité associée ou non à l’activité physique sur la croissance tumorale et sur le statut oxydatif et inflammatoire des tumeurs à l’aide d’un modèle de souris âgées C57BL/6 nourries avec un régime hyper-lipidique (HL) pendant 14 semaines, et hébergées soit dans un environnement enrichi (EE) pour favoriser l’activité physique et les interactions sociales, soit dans un environnement standard pendant 8 semaines, après quoi des cellules syngéniques de tumeur mammaire EO771 ont été implantées dans les quatrièmes coussinets adipeux mammaires. In vitro, la leptine a stimulé la production de ROS de façon indépendante de la dose et cette augmentation était dépendante de la production d'O2 cytosolique. Les résultats montrent une augmentation significative du poids dans les groupes recevant le régime HL à prise alimentaire journalière identique. La composition corporelle à 8 semaines montre une prise de masse grasse significative sous régime HL, majorée par l’ovariectomie et partiellement limitée par l’activité physique. Après implantation des tumeurs, le régime HL favorise la croissance tumorale et la perte de l’activité locomotrice. Par contre, l’EE prévient la perte d’activité physique des animaux. L’ensemble de ces travaux montre que la leptine contribue à l’apparition d’un stress oxydant en lien avec le statut tumoral des cellules épithéliales mammaires. Ceci peut expliquer en partie l’augmentation du risque de cancer mammaire associée à l’obésité en post-ménopause. Ces résultats permettront d'objectiver le bénéfice d'une intervention nutritionnelle ciblée afin de moduler la réponse des cellules aux stimulations des adipokines. A terme, cette étude doit contribuer à mieux comprendre l’intégration des signaux issus de l’environnement cellulaire. / Obesity is now considered, as a risk factor for developing breast cancer in postmenopausal women and for mortality in response to this pathology. Obesity, which is frequently associated with hyperleptinemia, induces cellular signalling pathways, some of which involving reactive oxygen species (ROS) as intracellular messengers. High levels of ROS contribute to oxidative stress, cellular damages and pathogenesis. Therefore, ROS production associated to obesity could be a major risk factor for mammary carcinogenesis. Furthermore, increased oxidative stress and inflammation characterised by infiltration of immune cells into adipocytes are described. This is associated with a lipid peroxidation and the production of bio-active compounds including isoprostanes.The aim of this study was to determine the impact of leptin in modulating the oxidative and inflammatory status of epithelial mammary cells and in tumor mammary tissue. Moreover, the purpose of this work was to develop a new analysis technique based on native fluorescence detection induced by laser excitation at 224 nm to evaluate the production of bio-active compounds from the family of eicosanoids, involved in the inflammatory process, including isoprostanes.Initially we identified in vitro the leptin effects on ROS production in 3 human epithelial mammary cell models which present different neoplastic status (healthy primary (HMEC) cells, MCF-7 and MDA-MB-231) in presence of two leptin concentrations (10 ng/ml close to physiological values, 100 ng/ml as obesity level). To better understand the potential involvement of adipocyte tumor microenvironment in mammary carcinogenesis, we secondly explored in vivo the impact of high fat diet (HFD) and of enriched environment (EE) on mammary tumor development. Female C57BL/6 mice were fed with a HFD versus a normo-caloric diet (NC) for 14 weeks. After 8 weeks mammary tumor syngeneic cells EO771 were implanted into the fourth mammary fat pads. Before injection, mice were housed in EE or in standard environment (ES) for 8 weeks. In vitro, leptin stimulated ROS production in dose-independent manner and this increase was dependent of cytosolic O2•- production. This ROS production contributed to a different antioxidative response depending of the neoplastic cell status. Leptin induced the antioxidative enzymes expression and activities such as heme-oxygenase or glutathione peroxidase only in HMEC cells. In neoplastic cells, these enzyme activities did not change whatever the leptin concentration used.Thus, high fat diet promoted mammary tumor development associated with a decrease in body fat and an increase in volume and weight of tumors that was not limited by physical activity. This diet induced a decrease of adiponectin and an increase of leptin plasma level compared to NC diet however, leptinemia was not influenced by EE.The native fluorescence isoprostanes determination method, turned out not to be quite sensitive. Therefore, the native fluorescence of these compounds is too low to allow their detection in biological media used. In contrast, the native fluorescence appears to be a potential cellular exploration tool.Through this work, we have shown that leptin contributes to the onset of oxidative stress linked to the status of mammary epithelial tumor cells. This may partly explained the increase of risk of breast cancer recurrence observed in situations of obesity. The results obtained in vivo eventually will support the benefit of a nutrition intervention to modulate cell response to adipokines stimulation. Ultimately, this study contributes to better understand the integration of signals from the cell environment.

Breast cancer is a disease associated with excess exposures to estrogens. While the mode of cancer causation is unknown, others have shown that oxidative stress induced by prolonged exposure to estrogens mediates renal, liver, endometrial and mammary tumorigenesis though the mechanism(s) underling this process is unknown. In this study, we show that 4-hydroxyl 17β-estradiol (4-OHE2), a catechol metabolite of estrogen, induces mammary tumorigenesis in a redox dependent manner. We found that the mechanism of tumorigenesis involves redox activations of nuclear respiratory factor-1 (NRF1); a transcriptions factor associated with regulation of mitochondria biogenesis and oxidative phosphorylation (OXPHOS), as well as mediation of cell survival and growth of cells during periods of oxidative stress. Key findings from our study are as follows: (i) Prolonged treatments of normal mammary epithelial cells with 4-OHE2, increased the formation of intracellular reactive oxygen species (ROS). (ii) Estrogen-induced ROS activates redox sensitive transcription factors NRF1. (iii) 4-OHE2 through activation of serine-threonine kinase and histone acetyl transferase, phosphorylates and acetylate NRF1 respectively. (iv) Redox mediated epigenetic modifications of NRF1 facilitates mammary tumorigenesis and invasive phenotypes of breast cancer cells via modulations of genes involved in proliferation, growth and metastasis of exposed cells. (v) Animal engraftment of transformed clones formed invasive tumors. (vi) Treatment of cells or tumors with biological or chemical antioxidants, as well as silencing of NRF1 expressions, prevented 4-OHE2 induced mammary tumorigenesis and invasive phenotypes of MCF-10A cells. Based on these observations, we hypothesize that 4-OHE2 induced ROS epigenetically activate NRF1 through its phosphorylation and acylation. This, in turn, through NRF1-mediated transcriptional activation of the cell cycle genes, controls 4-OHE2 induced cell transformation and tumorigenesis.

Le cancer représente la deuxième cause de mortalité dans les pays industrialisés. Il a été démontré que 20% des cancers sont d'origine infectieuse. Nous nous sommes intéressés à deux oncovirus HPV (virus du papillome humain) et EBV (Epstein-Barr Virus) responsable du cancer de l'utérus et de divers lymphome B réciproquement. Les événements clés pour le développement d'un cancer viro-induit sont la persistance du virus via la dérégulation des réponses immunitaires et l'induction d'une instabilité gé¬nomique via une dérégulation du cycle cellulaire. Nous avons donc cherché si EBV était capable d'altérer la réponse immunitaire innée. Nous avons montré que EBV était capable d'inhiber TLR9 un acteur clef de la réponse immunitaire innée. Comme TLR9 est inhibé dans un certain nombre de cancers, nous nous sommes demandé si ce récepteur pouvait également, avoir un rôle dans l'oncogenèse. Nous avons montré que la réexpression de TLR9 induisait un ralentissement transitoire de la prolifération cellulaire. Nous nous sommes par la suite intéressés aux mécanismes de dérégulation du cycle cellulaire induits par E6 une oncoprotéine de HPV16. Nous avons trouvé un nouveau mécanisme d'inhibition de l'inhibiteur du cycle cellulaire, p21. HPV16E6 se lie et inhibe les fonctions de du facteur de transcription p150Sal2, ce qui induit une inhibition de p21 dans un contexte p53 indépendant / Cancer represents the second most common cause of death in industrialized countries. Epidemiological and biological studies have now conclusively proved that a variety of infectious agents constitute one of the main causes of cancer worldwide. It has been pointed out that more than 20% of cancers are from infectious origin. HPV high-risk mucosal types are associated to 98% of all cervical cancer cases. Regarding EBV, over 90% of the world’s population is infected and can give rise to malignancies such as Burkitt lymphoma or Hodgkin disease.(Young and Rickinson 2004) Keys features for oncoviruses to induce cancer are firstly to per¬sist by dampening host immune responses and to induce genomic instability in the host by altering the regulation of the cell cycle leading the infected cells to an uncontrolled proliferation. The purpose of this thesis was to find new mechanisms by which EBV and HPV can promote carcinogenesis. We have shown that EBV can alter the regulation and expression of TLRs, the key effectors molecules of the innate immune response. EBV infection of human primary B cells resulted in the inhibition of TLR9 functionality. Our study described a mechanism used by EBV to suppress the host immune response by deregulating the TLR9 transcript through LMP1-mediated NF-κB activation. As TLR was found deregulated in many cancers, we hypothesized that TLR9 may also a direct role in the process of cell cycle control and that loss of its expression may lead to transformation of the cell. Our overall objective here was to study the role of TLR9 in suppressing the events that initiates transformation of epithelial cells in the setting of cervical cancer (virus-associated) and in head and neck cancer (non–virus-associated). A third project dealt with the mechanism cell cycle deregulation by the oncoprotein E6 which expressed during infection with HPV16. We reported that HPV16E6 targets the cellular factor p150Sal2, which positively regulates p21 transcription. HPV16E6 associates with p150Sal2, inducing its functional inhibition by preventing its binding to cis elements on the p21 promoter. These data described a novel mechanism by which HPV16E6 induces cell cycle deregulation with a p53-independent pathway preventing G1/S arrest and allowing cellular proliferation and efficient viral DNA replication

Le cancer du rein se situe au 7ème rang des tumeurs solides de l'adulte et son incidence est en forte augmentation. L'objet de nos recherches a été d'étudier la carcinogénèse rénale et d'identifier des marqueurs pronostiques.Nous avons utilisé le marquage isobarique iTRAQ® pour réaliser une quantification relative des protéines de tumeurs rénales. Nous avons identifié 928 protéines, dont 346 avaient des expressions modifiées en fonction du profil d'agressivité des tumeurs. L'analyse des voies métaboliques impliquées a mis en évidence une amplification du métabolisme préférentiel du glucose en lactate et une diminution du métabolisme oxydatif dans les carcinomes agressifs. Quatorze protéines ont été sélectionnées comme étant de possibles biomarqueurs. Parmi ces protéines, nous avons pu confirmer que l'expression des tumeurs en TGFBI était un marqueur de mauvais pronostique.Pour appréhender la carcinogénèse rénale, nous avons étudié le locus de prédisposition au cancer du rein 12p11.23. La première étape de ce travail a été de confirmer par une étude de réplication indépendante que cette région génétique prédisposait au cancer du rein. La seconde étape nous a permis de démontrer que ce locus agissait comme un activateur de l'expression du gène SHARP1 par l'intermédiaire du facteur de transcription c-Jun et du SNP rs7132434. Des études complémentaires seront nécessaires pour déterminer la fonction, précise de SHARP1 dans la carcinogénèse rénale. / Kidney cancer is the 7th largest solid tumors in adults and its incidence is rising. The purpose of our research was to study renal carcinogenesis and to identify prognostic biomarkers in clear cell renal cell carcinoma.We used the isobaric tagging iTRAQ® to perform a relative quantification of kidney tumor proteins. After proteomic analysis, 928 constitutive proteins were identified and 346 had a modified expression in tumor compared with that of normal tissue. Pathway and integrated analyses indicated the presence of an up-regulation of the pentose phosphate pathway in aggressive tumors. In total, 14 proteins were excreted and could potentially become biomarkers. Among them, we confirmed that TGFBI was significantly associated with oncologic outcomes.To understand renal carcinogenesis, we investigated the 12p11.23 renal cancer susceptibility locus. The first step was to confirm this locus by an independent study. Then we performed a functional analysis of the 12p11.23 region in relation to RCC risk. Our results suggest rs7132434 is a functional SNP at 12p11.23 responsible for the GWAS RCC signal, and that this locus acts as an enhancer of SHARP1 expression by binding c-Jun. Further investigations will be necessary to understand the role of SHARP1 in renal carcinogenesis.

<p><a>Prostate cancer is the second leading cause of cancer death among men in the United States. The androgen receptor (AR) antagonist enzalutamide is an FDA-approved drug for treatment of patients with late-stage prostate cancer and is currently under clinical study for early-stage prostate cancer treatment.</a> After a short positive response period to enzalutamide, tumors will develop drug resistance. In these studies, we uncovered that NOTCH signaling and DNA methylation are a deregulated in enzalutamide-resistant cells. <i>NOTCH2</i> and<i> c-MYC </i><a>gene expression<i> </i>positively correlated with <i>AR </i>expression in samples from patients with hormone refractory disease in which AR expression levels correspond to those typically observed in enzalutamide-resistance</a>. The expression of Notch signaling components was upregulated in enzalutamide-resistant cells suggesting the activation of the pathway. Inhibition of this pathway <i>in vitro</i> and <i>in vivo</i> promoted an increase in the sensitivity to enzalutamide with an impact on AR expression. On the other hand, DNMT activity and DNMT3B expression were upregulated in resistant lines. Enzalutamide induced the expression of DNMT3A and DNMT3B in prostate cancer cells with a potential role for p53 and pRB in this process. The overexpression of DNMT3B3, a DNMT3B variant, promoted an enzalutamide-resistant phenotype in C4-2 cells. DNA methylation inhibition, using low-concentration decitabine, and <i>DNMT3B</i> knockdown induced a re-sensitization of resistant prostate cancer cells and tumors to enzalutamide. Decitabine treatment in enzalutamide-resistant induced a decrease in the expression of AR-V7 and changes in genes from the apoptosis, DNA repair and mRNA splicing pathways. Decitabine plus enzalutamide treatment of 22RV1 xenografts induced a decrease in tumor weight, KI-67 and AR-V7 expression and an increase in Cleaved-Caspase3 levels. All the above suggest that Notch signaling and DNA methylation pathways are deregulated after enzalutamide resistance onset, and targeting these pathways restores the sensitivity to enzalutamide.<b><u></u></b></p>

The main aim of this study is to synthesize theranostic nanoparticles (NPs) that will drastically increase the diagnostics and therapeutic efficacy for cancer. In this research, we had prepared the NPs which constitute carbon dots (CDs), the imaging agent, Folic acid, the targeting agent, and Doxorubicin (DOX) or Gemcitabine (GEM) as the chemotherapy agents. The prepared NPs include noncovalent FA-CDs-DOX, covalent CDs-FA-DOX, and covalent FA-CDs-GEM. The spectroscopy, ultraviolet-visible spectroscopy (UV-vis), fluorescence spectroscopy, and Fourier transform-infrared spectroscopy (FT-IR), were used to confirm the successful fabrication of these complexes. Through UV-vis analysis, the drug loading capacity (DLC) and drug loading efficiency (DLE) of the complexes were determined. The noncovalent series had a higher DLE of about 83% while the covalent series showed higher DLC, 70% on average indicating high drug content. The in-vitro pH-dependent drug release shows that the noncovalent FA-CDs-DOX and the covalent FA-CDs-GEM series release more drugs into the cancer cells (pH of 5.0) than into healthy normal (pH of 7.4). The sizes of NPs were measure around 2-5 nm with Dynamic light Scattering (DLS). The toxicity of CDs, CDs-drug, and FA-CDs-drug on MDA-MB468 breast cancer cell was tested through the methylthiazolytetrazolium (MTT) assay and found that the FA bonded NPs exhibited strong therapeutic efficacy. More pharmaceutical data towards the cancer cells are investigated by our research collaborators – the pharmaceutical department at ETSU and Xavier University at Louisiana.

Introduction: Breast cancer is the most frequently diagnosed cancer found in women across the world, with an estimated 2.3 million new cases occurring in 2020. Additionally, over 684,000 deaths annually are attributed to breast cancer across the globe, making it the most common cause of cancer-related death in women. Further, treatment of breast cancer relies heavily on whether or not the cancer cells express estrogen, progesterone, and HER 2 receptors and this expression profile is often related to how quickly the cells grow and spread. In the United States, breast cancer cells that are hormone receptor positive and HER-2 negative make up about 73% of breast cancer cases, and cells that do not express any receptor and are known as triple negative, make up around 12% of cases (American Cancer Society, 2019). With that being said, CT1 and CT3 are novel compounds that have a cytotoxic effect on cell lines representing up to 85% of all breast cancer subtypes in the United States. Methods: The leaves of Chromolaena tacotana that contains the flavonoids CT1 and CT3 were dried and placed in a soxhlet extractor using dichloromethane (CH2Cl2) to extract the chlorophyll. The flavonoids were extracted using a column chromatography eluted with trichloromethane (CHCl3), a 1:1 dilution of CHCl3:methanol and methanol, followed by isolation and purification of the compounds. Human breast cancer cell lines MCF7, MDA-MB-231, and SKBr3 were treated with CT1 and CT3 at concentrations of 5, 10, 20, 40 and 80 µM, followed by incubation for 24 hours. To assess cell viability an MTT assay was conducted by adding a 5-diphenyl-tetrazolium bromide reagent. The purple-colored formazan crystals were solubilized with acidified isopropanol, then analyzed by spectrophotometry. Results: CT1 appeared to have the most cytotoxic effects compared to CT3 on MCF7. The opposite effect was observed for SKBr3 with CT3 showing the most effects as compared to CT1. No differential effect was observed on MDA-MB-231 since both CT1 and CT3 showed similar inhibition of cell viability. Conclusions: The results from the different breast cancer cell lines SKBr3, MCF7, and MDA-MB-231 vary based on how they responded to CT1 and CT3. CT3 was more effective on SKBr3 than CT1. CT1 was more effective on MCF7 than CT3. For MDA-MB-231, both CT1 and CT3 showed similar significant cytotoxic effects. The antiproliferative effects of CT1 and CT3 appear to be concentration dependent on all cells studied. In view of the results from MDA-MB-231 triple negative breast cancer cell line, the cytotoxic effect of the flavonoids is not dependent on the presence of estrogen, progesterone, or HER2 receptors on breast cancer cells. Further studies on the mechanism of action are necessary to elucidate the molecular targets of CT1 and CT3.

Docetaxel is a chemotherapeutic agent in the taxane group of drugs which is commonly used in the first line setting for metastatic hormone receptor negative breast cancer. We present a case of a 46 year old female who was diagnosed with de novo triple negative metastatic breast carcinoma, and has had an extended progression free survival (PFS) of almost 5 years on first line single agent treatment with Docetaxel. 46 year old female presented with a large left breast mass as well as axillary mass which revealed grade 3 invasive ductal carcinoma of breast on biopsy of both sites. Tumor was estrogen and progesterone receptor negative. Pathology showed discordance in HER2 testing between FISH and IHC, however on repeat testing, HER2 was confirmed to be negative. PET/CT scan for staging revealed large left sided pleural effusion and abnormal soft tissue in the lower anterior and posterior chest on the left concerning for pleural metastases. Patient underwent CT guided biopsy of left lower pleural space which was consistent with metastatic adenocarcinoma with breast primary. She was started on first line single agent chemotherapy with Docetaxel 100mg/m2 every 3 weeks. Tumor markers were non-contributory to assess disease response. Repeat systemic imaging in 3 months showed excellent partial response with decrease in size of breast mass, conglomerate axillary lymph nodes as well as pleural based metastatic foci. Patient had grade 1 neuropathy secondary to Docetaxel which was tolerable. Patient also had significant fatigue with warranted dose reduction by 20% after 6 months. She also demonstrated other adverse effects of Docetaxel such as nail dystrophy and mild blepharitis which were also tolerable. Patient showed good tolerance to chemotherapy, with intermittent treatment holidays. CT scans continued to demonstrate good response with stable size of breast and lung masses. After two years of stable disease and fair tolerance (after completing 34 cycles), chemo regimen was changed to every 4 weeks per patient’s wish. She was also started on Gabapentin for chemotherapy related neuropathy. At the end of 4 years, patient had completed 55 cycles of agent Docetaxel, maintaining ECOG of 1, with grade 2 neuropathy controlled with gabapentin. Patient is currently 56 months out from her initial diagnosis of metastatic triple negative breast cancer and follow-up scans continue to show stable disease. She has developed profound fatigue after several months of treatment. Patient has also faced challenges with fluid retention secondary to Docetaxel. Although her performance status remains fair, patient is contemplating changing frequency of chemotherapy to every 5 or every 6 weeks. Triple negative breast cancer is an aggressive disease with limited options of treatment with chemotherapy agents and no role for endocrine therapy or HER2 targeted treatment options. Docetaxel has shown to have median survival ranging between 10.1 to 14.7 months depending on the dose. Our patient has so far shown extended PFS of 56 months, with single agent Docetaxel in first line setting which surpasses current national averages.

Purpose: In the contemporary management of early-stage lung cancer with RadiationTherapy (RT), there is increased imaging utilization for the diagnosis and treatment and follow-up after completion of treatment. We evaluated whether this increased radiation exposure to patients with early-stage lung cancer that receive stereotactic body radiotherapy (SBRT) significantly increases the risk of radiation-induced carcinogenesis (RIC). Methods: Following IRB approval, one hundred and ninety-six consecutively treated lung cancer patients treated with SBRT were selected for analysis. Information collected included demographics and all ionizing imaging scans one year before SBRT treatment and one year following treatment. These included chest X-rays (CXR), computerized tomography scan (CT scan), positron emission tomography scan (PET-CT scan), bone scan, ventilation-perfusion scan (VQ scan), cone-beam CT scans. In addition to the lung cancer patients, comparative data on ten prostate and breast cancer patients each was collected to get an estimate of the radiation-induced risk (RIC) in other common malignancies. For each patient, the total effective dose (mSv) was calculated by the sum of all effective doses for all scans (1 year before SBRT to 1-year post-SBRT). After calculating the total effective dose, the summed dose was used to calculate the RIC using the RadRat tool. For the study, we decided that a 1% increase in the baseline risk of radiation-induced lung cancer will be considered a significant increase. Results: Among lung cancer patients, there were 87 males (44.4%) and 109 females (55.6%). The median number of Pre-SBRT CXRs (PA/lateral) was 2 (Range: 1-22), the median number of pre-SBRT CT scans was 2 (Range: 1-6), the median number of pre-SBRT PET-CT scans was 1 (Range: 1-4), the median number of Bone Scans or VQ scans pre-SBRT was 1. The median effective exposure dose from all scans was 72mSv (Range: 24-140.36mSv). The median excess lifetime risk (ELR) of developing lung cancer (a chance in 100,000) with a 90% uncertainty range was 57.15. The Excess Future risk (EFR), the risk from 2019 to the end of the expected lifetime of developing cancer (a chance in 100,000), showed a median of EFR mean of 73.75 (Range: 8.45- 416). The total future risk (TFR, a sum of baseline and excess risk) of developing cancer, from 2019 to end of an expected lifetime was 2732.5 (Range: 808-8290), the median of TFR upper bound was 2785.5 (Range: 856-8400) and median of TFR lower bound was 2679.5 (Range: 761- 8183). At 6 months, survival was 94.7% (144/152), at 1 year, 79% (94/119), at 3 years 32.5% (27/83). At five years, with survival data on 77 patients available, 9 (11.6%) were alive. Regarding the comparison of RIC from imaging before RT for patients with prostate cancer, the median total effective radiation dose from all pre-SBRT and post-SBRT scans was 20mSv (Range: 20-30mSv), and the median of mean ELR for development of RIC prostate cancer was 4.24 (per 100,000). Regarding early-stage breast cancer, the median total effective radiation dose from all pre-RT and post-RT scans was 16.56mSv (Range: 10.52-31.48mSv), and the median of mean ELR for development of RIC was 35.95 (per 100,000). Conclusion: The median excess cancer lifetime radiation-induced cancer risk for the lung cancer cohort was 0.05%, which is significantly less than the 1% risk that was determined to be clinically significant as per our study objective. The survival in this cohort of patients was poor. Enhanced imaging to enhance staging accuracy, safety during SBRT treatment, and adequate follow-up outweigh the RIC risk.