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Nathan Goodyear

Substantial contribution of extrinsic risk factors to cancer development - 0 views

  • Here we provide evidence that intrinsic risk factors contribute only modestly (<10~30%) to cancer development
  • we conclude that cancer risk is heavily influenced by extrinsic factors. These results carry immense consequences for strategizing cancer prevention
  • cancers are proposed to originate from the malignant transformation of normal tissue progenitor and stem cells
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  • “Intrinsic processes” include those that result in mutations due to random errors in DNA replication whereas “extrinsic factors” are environmental factors that affect mutagenesis rates (such as UV radiation, ionizing radiation, and carcinogens
  • intrinsic factors do not play a major causal role.
  • intrinsic cancer risk should be determined by the cancer incidence for those cancers with the least risk in the entire group controlling for total stem cell divisions
  • if one or more cancers would feature a much higher cancer incidence, for example, lung cancer among smokers vs. non-smokers, then this most likely reflects additional (and probably extrinsic) risk factors (smoking in this case)
  • Particularly, for breast and prostate cancers, it has long been observed that large international geographical variations exist in their incidences (5-fold for breast cancer, 25-fold for prostate cancer)14, and immigrants moving from countries with lower cancer incidence to countries with higher cancer rates soon acquire the higher risk of their new country
  • Colorectal cancer is another high-incidence cancer that is widely considered to be an environmental disease17, with an estimated 75% or more colorectal cancer risk attributable to diet
  • melanoma, its risk ascribed to sun exposure is around 65–86%
  • non-melanoma basal and squamous skin cancers, ~90% is attributable to UV
  • 75% of esophageal cancer, or head and neck cancer are caused by tobacco and alcohol
  • HPV may cause ~90% cases in cervical cancer23, ~90% cases in anal cancer24, and ~70% in oropharyngeal cancer
  • HBV and HCV may account for ~80% cases of hepatocellular carcinoma
  • H pylori may be responsible for 65–80% of gastric cancer
  • While a few cancers have relatively large proportions of intrinsic mutations (>50%), the majority of cancers have large proportions of extrinsic mutations, for example, ~100% for Myeloma, Lung and Thyroid cancers and ~80–90% for Bladder, Colorectal and Uterine cancers, indicating substantial contributions of carcinogen exposures in the development of most cancers
  • onsistent estimate of contribution of extrinsic factors of >70–90% in most common cancer types. This concordance lends significant credibility to the overall conclusion on the role of extrinsic factors in cancer development
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    Really great read.  Cancer is a majority lifestyle disease.
Nathan Goodyear

Postmenopausal circulating levels of 2- and 16α-hydroxyestrone and risk of en... - 0 views

  • our results do not support the hypothesis that greater metabolism of oestrogen via the 2-OH pathway, relative to the 16α-OH pathway, protects against endometrial cancer. Indeed our results are more suggestive of an increase in risk, rather than a decrease, with higher levels of 2-OHE1
  • women with a higher 2-OHE1 : 16α-OHE1 ratio did not have a decreased risk of endometrial cancer as compared with women with a lower ratio
  • The findings from this first prospective epidemiological study of oestrogen metabolites and endometrial cancer are in line with results from prospective studies on breast cancer, another oestrogen-related cancer. None of the seven studies on breast cancer reported significant associations overall
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  • On the whole, prospective epidemiological data do not support the hypothesis that the 2-hydroxyestrogen pathway is protective, and the 16α-hydroxyestrogen pathway harmful, in hormone-dependent cancers
  • Both 2- and 4-hydroxyestrogens are catecholestrogens, and it has been suggested that catecholestrogens increase risk of oestrogen-mediated cancers through direct genotoxic effects, rather than through stimulation of cell proliferation via binding to oestrogen receptors
  • the evidence is stronger for 4-hydroxyestrogens than for 2-hydroxyestrogens
  • a significant increase in risk of breast cancer with levels of 2-OHE1 has also been reported previously, although it was limited to hormone receptor-negative tumours
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    2:16 hydroxyestrone ratio not associated with uterine cancer risk.
Nathan Goodyear

Survival implications of time to surgical treatment of endometrial cancers - American J... - 0 views

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    Study finds that early (defined as 1-2 weeks after diagnosis) surgery after diagnosis of uterine cancer is associated with increased complications including death. This compared to lower postoperative death rates in delay out to 3-4 weeks.
Nathan Goodyear

How We Read Oncologic FDG PET/CT | Cancer Imaging | Full Text - 0 views

  • In early PET literature focusing on analysis of solitary pulmonary nodules, some researchers defined malignancy based on a SUVmax threshold of greater than 2.5
  • We contend that SUV analysis has virtually no role in this setting.
  • tumours grow as spheres, whereas inflammatory processes are typically linear
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  • Far more important than the SUVmax is the pattern rather than intensity of metabolic abnormality and the correlative CT findings
  • Descriptively, we define SUV < 5 as “low intensity”, 5–10 as “moderate”, 10–15 as “intense” and >15 as “very intense”
  • Evolving literature suggests that intensity of uptake is an independent prognostic factor and in some tumour subtypes superior to histopathologic characterisation.
  • aerobic glycolysis
  • Our practice of thresholding the grey and colour scale to liver as detailed above results in similar image intensity to a fixed upper SUV threshold of 8 to 10
  • The advantage of using the liver as a reference tissue is also aided by this organ having rather low variability in metabolic activity
  • When the liver is abnormal and cannot be used as a reference organ, we use the default SUV setting of an upper SUV threshold of 8
  • One of the most challenging aspects of oncologic FDG PET/CT review, however, is to recognise all the patterns of metabolic activity that are not malignant and which consequently confound interpretation
  • Many benign and inflammatory processes are also associated with high glycolytic activity
  • Future articles in the “How I Read” series will address the specific details of reading PET/CT in various cancers
  • The intensity of uptake in metastases usually parallels that in the primary site of disease
  • For example, discordant low-grade activity in an enlarged lymph node in the setting of intense uptake in the primary tumour suggests it is unlikely malignant and more likely inflammatory or reactive
  • By CT criteria the enlarged node is ‘pathologic’ but the discordantly low metabolic signature further characterises this is as non-malignant since such a node is not subject to partial volume effects and therefore the intensity of uptake should be similar to the primary site
  • The exception is when the lymph node is centrally necrotic as a small rim of viable tumour is subject to partial volume effects with expectant lower intensity of uptake; integrating the CT morphology is therefore critical to reaching an accurate interpretation
  • Small nodes that are visualised on PET are conversely much more likely to be metastatic as such nodes are subject to partial volume effects.
  • The exception to this rule is tumours with a propensity for tumour heterogeneity at different sites
  • The combination of FDG and a more specific tracer, which visualises the well-differentiated disease can be very useful to characterise this phenomenon
  • “metabolic signature”
  • For the majority of malignant processes, the intensity of metabolic abnormality correlates with degree of aggressiveness or proliferative rate.
  • a negative PET/CT study in a patient with biopsy proven malignancy would be considered false-negative
  • Warburg effect
  • There, however, are a significant minority of tumours that utilise substrates other glucose such as glutamine or fatty acids as a source of the carbon atoms required for growth and proliferation
  • This includes a subset of diffuse gastric adenocarcinomas, signet cell colonic adenocarcinomas and some sarcomas, particularly liposarcoma
  • There may be a role for other radiotracers such as fluorothymidine (FLT) or amino acid substrates in this setting.
  • Some tumours harbour mutations that result in defective aerobic mitochondrial energy metabolism, effectively simulating the Warburg effect
  • patients with hereditary paraganglioma and pheochromocytoma highlight this phenomenon
  • These have intense uptake on FDG PET/CT despite often having low proliferative rate.
  • Uterine fibroids, hepatic adenomas, fibroadenomas of the breast and desmoid tumours are benign or relatively benign lesions that can have quite high FDG-avidity.
  • Metabolic activity switches off rapidly following initiation of therapy
  • Common examples where patients have commenced active therapy but the referrer is requesting “staging” includes hormonal therapy (eg. tamoxifen) in breast cancer, oral capecitabine in colorectal cancer or high dose steroids in Hodgkin’s lymphoma
  • It is therefore critical to perform PET staging before commencement of anti-tumour therapy
  • The potential advantage of routine diagnostic CT is improved anatomic localisation and definition
  • Without intravenous contrast, additional identification of typical oncologic complications such as pulmonary embolism or venous thrombosis cannot be identified
  • If the study is performed as an “interim” restaging study after commencement of therapy but before completion, in order to reach a valid or clinically useful conclusion findings must be interpreted in the context of known changes that occur at a specific timing and type of therapy
  • The most well studied use of interim PET is in Hodgkin’s lymphoma where repeat PET after two cycles of ABVD-chemotherapy provides powerful prognostic information and may improve outcomes by enabling early change of management
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    good read on the PET/CT scan reading.  They mention that tumors are spheres and inflammation is linear, yet inflammation coexists with cancer; hard to simply delineate these on simple terms. I do agree aon the metabolic signature of the PET/CT scan
Nathan Goodyear

Communication between genomic and non-genomic signaling events coordinate steroid hormo... - 0 views

  • steroid hormones typically interact with their cognate receptor in the cytoplasm for AR, glucocorticoid receptor (GR) and PR, but may also bind receptor in the nucleus as appears to often be the case for ERα and ERβ
  • This ligand binding results in a conformational change in the cytoplasmic NRs that leads to the dissociation of HSPs, translocation of the ligand-bound receptor to the nucleus
  • In the nucleus, the ligand-bound receptor dimerizes and then binds to DNA at specific HREs to regulate gene transcription
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  • some steroid hormone-induced nuclear events can occur in minutes
  • the genomic effects of steroid hormones take longer, with changes in gene expression occurring on the timescale of hours
  • Classical steroid hormone signaling occurs when hormone binds nuclear receptors (NR) in the cytoplasm, setting off a chain of genomic events that results in, among other changes, dimerization and translocation to the nucleus where the ligand-bound receptor forms a complex with coregulators to modulate gene transcription through direct interactions with a hormone response element (HRE)
  • NRs have been found at the plasma membrane of cells, where they can propagate signal transduction often through kinase pathways
  • Membrane-localized ER, PR and AR have been reported to modulate the activity of MAPK/ERK, phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt), nitric oxide (NO), PKC, calcium flux and increase inositol triphosphate (IP3) levels to promote cell processes including autophagy, proliferation, apoptosis, survival, differentiation, and vasodilation
  • ERα36, a 36kDa truncated form of ERα that lacks the transcriptional activation domains of the full-length protein. Membrane-localized ERα36 can activate pathways including protein kinase C (PKC) and/or mitogen activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) to promote the progression of various cancers
  • G protein-coupled receptor 30 (GPR30), also referred to as G protein-coupled estrogen receptor (GPER), is a membrane-localized receptor that has been observed to respond to estrogen to activate rapid signaling
  • hormone-responsive G protein coupled receptor is Zip9, which androgens can activate
  • GPRC6A is another G protein-coupled membrane receptor that is responsive to androgen
  • androgen-mediated non-genomic signaling through this GPCR can modulate male fertility, hormone secretion and prostate cancer progression
  • non-NR proteins located at the cell surface can bind to steroid hormones and respond by eliciting rapid signaling events
  • Estrogens have been shown to induce rapid (i.e. seconds) calcium flux via membrane-localized ER (mER)
  • ER-calcium dynamics lead to activation of kinase pathways such as MAPK/ERK which can result in cellular effects like migration and proliferation
  • 17β-estradiol (E2) has been reported to promote angiogenesis through the activation of GPER
  • Membrane NRs may also mediate rapid signaling through crosstalk with growth factor receptors (GFR)
  • A similar crosstalk occurs between the receptor tyrosine kinase insulin-related growth factor-1 receptor (IGF-IR) and ERα. Not only does IGF-IR activate ERα, but inhibition of IGF-IR downregulates estrogen-mediated ERα activity, suggesting that IGF-IR is essential for maximal ERα signaling
    • Nathan Goodyear
       
      This is a bombshell that shatters the current right brain approach to ER. It completely shatters the concept of eat sugar, whatever you want, with cancer treatment in ER+ or hormonally responsive cancer!
  • Further, ER activates IGF-IR pathways including MAPK
  • GPER is involved in the transactivation of the EGFR independent of classical ER
  • tight interconnection between genomic and non-genomic effects of NRs.
  • non-genomic pathways can also lead to genomic effects
  • androgen-bound AR associates with the kinase Src at the plasma membrane, activating Src which then leads to a signaling cascade through MAPK/ERK
  • However, Src can also increase the expression of AR target genes by the ligand-independent transactivation of AR
  • extranuclear steroid hormone actions can potentially reprogram nuclear NR events
  • estrogen modulated the expression of several genes including endothelial nitric oxide synthase (eNOS) via rapid signaling pathways
  • epigenetic changes can then mediate genomic events in uterine tissue and breast cancer cells
Nathan Goodyear

New use of microsatellite instability analysis in endometrial cancer - 0 views

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    Nice look at MSI in endometrial cancer. Present in approximately 30%. MSI are the result of MMR defects.
Nathan Goodyear

Relative Expression of Progesterone Receptors A and B in Endometrioid Cancers of the En... - 0 views

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    Balance of progesterone receptors A and B in the development of endometrial cancer.
Nathan Goodyear

Sugar-Sweetened Beverage Intake and the Risk of Type I and Type II Endometrial Cancer a... - 0 views

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    intake of sugar drinks i.e. coke associated with increased risk of type I endometrial cancer in postmenopausal women.
Nathan Goodyear

Frontiers | Artesunate Suppresses the Proliferation and Development of Estrog... - 0 views

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    artesunate down regulates ER-alpha expression
Nathan Goodyear

Potential Mechanisms of Estrogen Quinone Carcinogenesis - 0 views

  • 4-hydroxyestrone/estradiol was found to be carcinogenic in the male Syrian golden hamster kidney tumor model, whereas, 2-hydroxylated metabolites were without activity
  • 4-hydroxyestradiol induced uterine tumors in 66% of CD-1 mice; whereas, mice treated with 2-hydroxyestradiol or 17β-estradiol had much lower uterine tumor incidence
  • DNA adducts of catechol estrogen quinones have been detected in the mammary glands of ACI rats treated with 4-hydroxyestradiol or it’s quinone
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    great read on the proposed mechanisms of how estrogen metabolites produce quinone intermediates that are carcinogenic.
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