2. Characteristics of Benign and Malignant Neoplasms (Ch7) Flashcards
Neoplasia means new growth and a new growth is called a?
neoplasm
Tumor originally applied to the swelling caused by inflammation but the noneoplastic usage of tumor has vanished = neoplasm. What is the study of tumors or neoplasms?
Oncology
All tumors have two basic components 1) neoplastic cells that constitute the parenchyma (how they’re classified) and 2) reactive stroma made up of (growth and spread dependent on stroma)?
connective tissue, BVs, and cells of the adaptive and innate immune system
In some tumors, the parenchymal cells stimulate the formation of an abundant collagenous stroma referred to as?
desmoplasia
Scirrhous = stony hard tumor
What type of tumor is it when its gross and microscopic appearances are considered relatively innocent, implying that it will remain localized, will not spread to other sites and is amenable to local surgical removal?
Benign tumor
benign tumors are designated using -oma- mesenchymal tumors follow this rule. What are some examples?
Fibroma
Chrondroma
-mesenchymal derivatives
Benign epithelial tumors are more complex- classified on different aspects of the tumor. What is applied to benign epithelial neoplasms derived from glands- although may not have a glandular structure?
Adenoma
benign epithelial neoplasms producing small visible fingerlike or warty projections are referred to as?
papillomas
projection on mucosal surface=polyp
Cystademonas are those that form large cystic masses such as in the ovaries. When you combine papillary projects with cysts what do you get?
papillary cystadenoma
What tumors can invade and destroy adjacent structures and spread to distinct sites to cause death?
malignant tumors
Malignant tumors arising from solid mesenchymal tissues are usually called? What about when they arise from blood forming cells?
sarcomas
leukemias/lymphomas
**Malignant neoplasms of epithelial cell origin, derived from any of the three germ layers are called?
carcinomas
Squamous cell carcinomas denotes cancer in which the tumor cells resemble stratified squamous epithelium and ______ denotes a lesion in which the neoplastic epithelial cells grow in a granular pattern.
adenocarcinoma
*sometimes tissue or organ is used in the name
Divergent differentiation of a single neoplastic clone creastes a mixed tumor. These tumors contain epithelial components scattered within a ?
myxoid stroma that may contain islands of cartilage or bone
What neoplasm has the ability to arise from a single clone capable of producing both epithelial and myoepithelial cells?
pleomorphic adenoma
most neoplasms are derived from a single germ layer except ______ which contain recognizable mature or immature cells or tissues belonging to more than one germ cell layer.
teratoma
Teratomas have cells that can differentiate into any cell in the body (totipotent), so it is common to see bone, epithelium, muscle, fat, nerve and other tissues. What differentiates principally along ectodermal lines to create a cystic tumor lined by skin replete with hair, sebaceous glands, and tooth structures?
Ovarian cystic teratoma
Hamartomas are benign masses composed of cells indigenous to the involved site. What term is applied to a heterotrophic rest of cells?
Choristoma (pancreatic tissue nodule in stomach)
What is the extent to which the neoplastic parenchymal cells resemble the normal parenchymal cells, both morphologically and functionally , with lack of differentiation called anaplasia-irreversible?
Differentiation
In general, benign tumors are well differentiated (looks same as normal cells), in which mitoses are usually?
rare and are of normal configuration
Malignant neoplasms exhibit a wide range of parenchymal cell differentiation, most exhibit morphologic alterations that?
show their malignant nature
Malignant neoplasms are composed of poorly differentiated cells are said to be anaplastic, which?
lack differentiation and is a hallmark of malignancy- Anaplasia is associated with many morpholigic changes
Cancer cells display pleomorphism which is variation in size and shape, thus cells in the same tumor are not uniform, but rangle from small cells with undifferentiated appearance to?
Giant cells many times larger than their neighbors
Abnormal nuclear morphology is seen with anaplasia- characteristically, the nuclei are disproportionately large for the cell, with a nuclear to cytoplasm ratio that may approach?
1:1 instead of the normal 1:4
shape is irregular, chromatin clumped and distributed along membrane-darkly stained
Unlike benign tumors, in undifferentiated tumors- many cells are in mitosis reglecting high proliferative activity of parenchymal cells. What is important for malignancy?
atypical, bizarre mitotic figures with tri/quad/multipolar spindles
In addition to cytoogic abnormalilites, the orientation of anaplastic cells is markedly disturbed- tumors grow in unorganized fasion. Often, rapidly growing malignant tumors develop?
centers of ischemic necrosis d/t lack of blood supply
well differentiated benign tumors and carcinomas reflect the tissue theyre in so they secrete hormones characteristic of their origin. Anaplastic, undifferentiated lose their?
resemblance to the normal cells in which they arose- sometimes they form random things not associated with the tissue normally
Metaplasia is defined as replacement of one type of cell with another due to damage/repair /regeneration (barretts esophagus). What is dysplasia (reversible)?
Disordered growth encountered in epithlia and is characterized by a loss of uniformity of the individual cells as well as a loss in their architectural orientation
Dysplastic cells often contain larger hyperchromatic nuclei with a high nuclear to cytoplasm ratio. The architecture is usally?
disorderly
What is the grading scale for differentiation?
- Well differentiated: looks a lot like the parent tissue. ** best
- Moderately differentiated: can identify features of the original tissue, but it is not the dominant pattern and there is additional atypia present.
- Poorly differentiated: a small number of cells have features of the parent tissue and is associated with cellular anaplasia.
- Undifferentiated: tissue of origin cannot be discerned and is always associated with anaplasia **worst
An example is in dysplastic squamous epithelium, the normal progessive matuartion of tall cells in the basal layer to flattened squames on the surface may fail in part or entirely leading to replacement of the epithelium with?
basal-appearing cells with hyperchromatic nuclei with mitotic figures in all cells
When dysplatic changes are marked and involve full thickness of the epithelium, but the lesion does not penetrate the basement membrane, it is considered to be?
a pre-invasive neoplasm and is referred to as carinoma in situ
(dysplasia to in situ to invasive)
**Although dyplasia may be a precursor to malignant transformation, it does not?
always progress to cancer
*if the basement membrane is not involved, dysplasia is reversible)
What is accompanied by progressive infilitration, invasion, and destruction of the surrounding tissue, whereas nearly all benign tumors grow as cohesive expansile masses that remain localized to their site of origin and lack the capacity to infiltrate, invade or metastasize to distant sites?
Growth of CANCERs
Benign tumors usually grow slowly and form a fibrous tissue around them called a capsule which consists of ECM deposited by fibroblasts. What does this capsule allow?
creates tissue that is discrete, palpable and moveable (non-fixed)
In contrast, malignant tumors are poorly demarcated from the surround normal tissue and are without a welldefined tissue border. What kind of image is common among cancers that penetrate adjacent structures?
Crablike picture (pattern of growth)
What is the most reliable feature that differentiates between cancers and benign tumors?
Metastasis
-invasiveness is the second best characterization of a malignant cancer vs. benign growth
What is defined by the spread of a tumor to sites that are physically discontinuous with the primary tumor, and unequivocally marks a tumor as malignant as by definition benign neoplasms do NOT metastasize?
Metastasis
Most malignant tumors metastisize but some hardly ever do including gliomas (malignant glial cells of CNS) and what of the skin?
Basal cell or squamous cell carcinomas
Approximately 30% of solid tumors present with metastasis, strongly reduced the chance of cure. What is in the blood and usually disseminated at diagnosis?
leukemias and lymphomas - derived from blood forming cells that travel to distant sites
Pathways of speed: dissemination of cancers may occur through on of the 3 pathways 1) direct seeding of body cavities or surfaces 2) lymphatic spread 3) ?
Hematogenous spread
Seeding of body cavities and surface occurs when malignant neoplasm penetrates into an open field- commonly the peritoneal cavity. This seeding is characteristic of?
carcinomas of the ovaries
*tumor is only on surface and does not penetrate inside- fills cavity with pseudomyxoma peritonei (gelatinous mass)
Transport through the lymphatics is the most common pathway for the initial spread/dissemination of?
carcinomas
Sometimes used by sarcomas, carcinomas use near by lympathics to spread. This usually leads to metastasis at ?
the regional lymph nodes
Breast cancers in the upper outer quadrants go to axillary LN while inner quadrants drain to LN in the?
internal mammary arteries
What is often used to asses the presence or absence of metastatic lesions in the lymph nodes, which is defined as the first node in a regional lymphatic basin that receives lymph flow from the primary tumor?
Sentinel nodes (biopsy of)
Sentinel node mapping is done by injecting radiolabeled tracers or colored dyes and examination of frozen section of the sentinel LN performed during surgery can guide the surgeon to the appropriate therapy- what is this commonly used for?
metastasis of melanoma, colon and other cancers
Hematogenous spread is typical of ____ but is also seen with carcinomas.
sarcomas
Arteries with thicker walls are less commonly penetrated than veins are. When the cells spread via veins, where do they end up?
in the first capillary bed they find which is generally the liver and lungs
Nodal enlargement can be one of two things, including?
dissemination of the cancer to the LN OR reactive hyperplasia of the T cells fighting off the cancer inside
Arterial spread occurs when tumor cells pass through pass through the pulmonary capillary beds, pulmonary arteriovenous (AV) shunts, or ?
when the pulmonary tumor give rise to additional tumor emboli in the blood
Thryroid and prostate commonly mestatsize to vertebral column via paravertebral plexus. There are certain carcinomas that have a propensity for invasion of veins including? 2
Renal cell carcinoma (renal vein to IVC in heart) Hepatocellular carcinoma (portal/hepatic veins)
Anatomical location and path of veins does not always explain the distributions of metastasis, for example breast carcinoma spread to bone, etc. What two areas are rare sites of secondary deposits?
skeletal muscles and spleen event though they receive alot of blood
In 2008, it was estimated that there were about 12.7 million new cancer cases worldwide, leading to 7.6 million deaths (21,000 deaths per day). Due to increasing population size and age, by 2030 it is projected that the number of cancer cases and cancer related deaths world wide will?
increase to 21.4million cases and 13.2 million deaths
The most common tumors in men are prostate, lung and colorectal and in female are breast, lung and colorectal. What cancers have the highest mortality?
LUNG cancer (no screening for this :/)
breast/prostate (have screen for these)
colorectal
Although genetic and environmental factors contribute to the development of cancer, environmental influences appear to be?
the dominant risk for most cancers
Environmental risk factors for cancer include infectious agents like HPV, smoking, alcohol consumption, diet, obesity, and what other two things?
reproductive history (estrogen - breast/ endometrial ca) environmental carcinogens
Age has an important influence on the likelihood of being afflicted with cancer. Most carcinomas occur in the latera years of life as in?
> 55 years
Cancer is the main cause of death among women 40-79 and men 60-79, the decline in deaths after age 80 is due to?
low number of individuals who reach this age
What is the explanation of increased age with increased cancer?
accumulation of somatic mutations associated with the emergence of malignant neoplasms
(decline in immune competence may contribute as well)
10% of all deaths in children younger than 15 is due to cancer, however, the type of cancer affecting children is different than adults. How so?
Carcinomas are most prev. in adults
In children, leukemia, CNS neoplasms are most common. Along with small rough blue cell tumors (neuroblastomas), wilms tumors Rb, and rhabdomyosarcomas
Acquired condition that predispose to cancer can be divided into chronic inflammations, precursor lesions and?
Immunodeficiency states.
What can be defined as localized morphologic changes that are associated with a high risk of cancer, all arising in epithelial surfaces/ associated with increased risk of various forms of carcinoma?
Precursor lesions
Chronic inflammation increases the pool of tissue stem cells which may be susceptible to transformation. Aditionally, activated immune cells produce ?
ROS that are genotoxic as well as inflammatory mediators that promote cell survival (bad)
Chronic epithelial damage causes metaplasia, change of one cell to another for better adaption. However this can lead to potential?
oncogenic mutations to survive leading to cancer
Many precursor lesions arise in chronic inflammation and can be recognized by metaplasia, examples? 4
- Barrett Esophagus: gastric and colonic metaplasia of the esophageal mucosa in the setting of gastric reflux
- Squamous Metaplasia of the Bronchial Mucosa in response to smoking
- Squamous Metaplasia of the bladder in response to schistosomiasis infection
- Colonic metaplasia of the stomach in the setting of pernicious anemia and chronic atrophic gastritis
Other precursor lesions are noninflammatory hyperplasia with one of the most common being endometrial hyperplasia which is caused by?
sustained estrogenic stimulation of the endometrium
(another is leukoplakia - thickening of squamous epithelium that may occur in oral cavity or on penis/vulva giving rise to squamous carcinoma)
the final group of precursor lesions is benign neoplasms that are at risk for malignant transformations. The classic example is clonoic villous adenoma which if left untreated?
progresses to cancer 50% of the time
**Note: MOST benign tumors transform RARELY such as uterine leiomyomas and pleomorphic adenomas
Immunodeficient (especially T cell immunodeficient) patients are at increased risk for cancers espcially those caused by oncogenic viruses such as lymphomas. Why?
CD8Tcells recognize tumor antigen in the context of MHC class I and kill tumor cells (if you’re deficient you cant do that)
Sporadic malignant neoplasms = 95% of cancers in the US. 5% of cancers can be ascribed to germline mutations in a tumor suppressor gene. Cancer is the most common in?
adults over the age of 60 and the variation that occurs geographically is likely due to environmental reasons
There are many genomic themes in carcinogenesis such as nonlethal genetic damage which allows the cell to proliferate and survive, which is then able to undergo?
colonal expansion of the single cell
**needs genetic damage
There are four classes of normal regulatory genes- the growth promoting proto-oncogenes, growth inhibiting tumor suppressor genes, and what other two?
genes that regulate programmed cell death (apoptosis) and genes inolved in DNA repair
*all these are principle targets of cancer causing mutations
Carcinogenesis results from the accumulation of complementary mutations in a stepwise fashion over time. Malignant neoplasms have several phenotypic attributes referred to as cancer hallmarks such as? 3
excessive growth, local invasivness, and the ability to form distant metastases which stem from the genomic alterations that change the expression and function of key genes.
What are the mutations that contribute to the development of the malignant phenotype?
driver mutations
the first driver mutation that starts a cell on the path to malignancy is the initiating mutation, however it is required that the initiated cell aqcuires?
many driver mutations, each helping to develop cancer
*cancers arise from ‘cancer stem cells’
Loss of function mutations in genes that maintain genomic integrity appear to be a common early step on the road to malignancy, particularly in?
solid tumors
Mutations that lead to genomic instability increase the likelihood of acquiring driver mutations, and also greatly increase the frequency of mutations that have no phenotypic consequences, called?
passenger mutations - more common than driver
Tumors evolve under the pressure of selection - survival of the fittest. Early on all the tumor cells are the same- coming from one parent cell. By the time the tumor comes to clinical attention (1gm mass) it has gone through a minimum of?
30 cell divisions*** for clinical presentation
During tumor evolution, there is competition among tumor cells for nutrients, and subclones with the capacity to overgrow their predecessors tend to win the dawinian contest and dominate the tumor mass. This tendancy of tumors to becomes more agressive is known as?
tumor progression
*at clinical presentation, tumor cells are extremely heterogenous
One of the most profound selective pressures that cancer cells face is effective chemotherapy or radiotherapy. Tumors that recur after therapy are almost always found to be?
resistant if the same treatment is used again
Epigenetic modifications also contribute to the malignant properties of cells. These modifications include DNA methylation which silences gene expression and what other modification?
histone modification - enhances or suppresses gene expression
Together, both DNA methylation and histone modification are expressed together, which determines which genes are expressed and in turn determines?
the lingeage comittment and differentiation state of both normal and neoplastic cells
Epigenetics has made a new path for cancer treatments because unlike DNA mutations, epigenetic alterations are ?
reversible by drugs that inhibit DNA or histone modification
All cancers display 8 fundemental changes in cell physiology which are considered hallmarks of cancer. What hallmark is that tumors have the capacity to proliferate without external stimuli, usually as a consequence of oncogene activation?
self-sufficiency in growth signals
Tumors may not respond to molecules that inhibit proliferation of normal cells, usually because of inactivation of tumor suppressory genes that encode components of these growth inhibitory pathways… Which cancer hallmark?
insensitivity to growth inhibitory signals
What are the other 6 hallmarks of cancer?
- altered cellular metabolism (warburg effect)
- evasion of apoptosis
- limitless replicative potential (immortality)
- sustained angiogenesis
- Ability to envade and metastasize
- Ability to evade the host immune repsonse
The aqcuisition of the genetic and epigenetic alterations that confer the 8 hallmarks of cancer may be accelerated by what two things?
genomic instability and cancer promoting inflammation
What are created by mutations in protooncogenes and encode proteins called oncoproteins that have the ability to promote cell growth in the absence of normal growth promoting signals?
Oncogenes- freed from normal checkpoints so can proliferate excessively
What is the most frequently mutated oncogenic pathway in human neoplasms?
receptor tyrosine kinase pathway
Pro-growth oncoproteins endow cells with self-sufficiency in growth. The factors that have the greatest impact on malignant phenotype is RAS and its two signaling arms downstream…?
mitogen activated protein kinase (MAPK) and phosphoinositidyl-3kinase (PI3K/AKT) pathway are important in promoting cell growth
Cancer cells acquire the ability to release GFs for their receptors, creating an autocrine cell signaling loop. What are three situations in which GF are over expressed, creating this loop of activation?
PDGF-B-overexpression = astrocytoma
TGFA- overexpression = astrocytoma
*normally signal transducer is activated compared to GF production
Most oncogenes encode GFreceptors which are mainly receptor tyrosine kinases. They are activated without GF binding to the receptor, hence delivering?
continuous mitogenic signals to the cell (even without a signal)
What protooncogene encodes the epidermal growth factor receptor (EGFR) which is involved in point mutations in certain cancers?
ERBB1 (EGF receptor fam)
Of greatest clinical significance are several different ERBB1 point mutations that are found in a subset of? These mutations result in activation of EGFR tyrosine kinase.
lung adenocarcinomas
What protooncogene encodes a RTK family- HER2, and instead of mutation, the gene is amplified in _______ carcinomas, leading to overexpression?
ERBB2 gene
(EGF receptor fam)
amplified in breast carcinomas
**Note treatment by blocking HER2 is proven
Gene rearrangements occur to activate RTKs as well, such as tyrosine kinase ALK. For example a deletion on chr 5 fuses ALK with another gene _____ in which carcinomas? Leading to?
ALK fuses with EML4 in lung adenocarcinomas resulting in a chimeric protein that is constituitively active
RTKs stimulate RAS, MAPK and PI3K/AKT downstream. In what cancer is it seen where there can be a RAS mutation that does NOT need the RTK to be activated in order for signaling and growth to occur?
lung adenocarcinomas
What is the most common type of abnormality involving proto-oncogenes in human tumors?
Point mutations of RAS family genes (HRAS, KRAS, NRAS)
The RAS family genes were discovered in transforming retroviruses. 15-20% of all cancers contain RAS mutations. 50% of colon,endometrial, and tyroid cancers, 30% of lung adenocarcinomas and myeloid leukemias and 90% of?
pancreatic adenocarcinomas and cholangiocarcinomas
RAS is a G protein that binds GDP to make GTP which stimulates MAPK and PI3K/AKT. These phosphorylate and activate a number of cytoplasmic effectors as well as several?
transcription factors for rapid cell growth
*note GAPs (GTPase activating proteins) terminal RAS signaling, preventing uncontrolled signaling- some RAS mutations get around this
Disabling mutations of neurofribromin 1, a GAP encoded by NF1 gene are associated with inherited cancer syndrome ?
familial neurofibromatosis type 1
NF1 is an example of a tumor suppressor gene that acts through negative regulation of RAS signaling
BRAF mutations, a RAF family, have been detected in 100% of what cancer? As well as 60% of melanomas, and 80% of benign nevi.
hairy cell leukemias
BRAF is a serine protein kinase that sits at the top of the cascade of MAPK. Mutations in BRAF stimulate downstream activation and transcription factors, however downstream from BRAF mutations uncommonly cause cancer.. what does this suggest?
mutations affecting factors near the top of the RAS/MAPK cascade produce significant pro-grow signals
PI3K and its antagonist PTEN are commonly mutation. PI3K activations a cascade of serine/threonine kinases including AKT. What are the main things AKT activates? 2
mTOR (stims protein and lipid syn)
BAD (pro-apoptotic)
30% of breast carcinomas have a GOF mutation in the alpha-isoform of _______. when the function of PTEN is lost
PI3K
Alteration in nonreceptor tyrosine kinases normally localize in the cytoplasm- not on the membrane and usually take form as chromosomal translocation sor rearrangments, forming?
fusion genes encoding active tyrosine kinases
In chronic myelogenous leukemia** CML and acute lymphoblastic leukemias, the ABL gene is translocated from its normal chromosome 9 to?
chromosome 22 (translocation)
On Chr 22 ABL fuses with BCR gene, making an active BCR-ABL tyrosine kinase. The most important contribution of the BCR moiety is that ?
it promotes self association of BCR-ABL = activation
What occurs in which tumor cells are highly dependent on the activity of one or more oncogenes?
oncogene addiction (best example is CML inhibition of BCR-ABL)
What protooncogene is expressed in all eukaryotic cells (organisms with nucleus inclosed in a membrane) and belongs to the immediate early response genes which are induced by RAS/MAPK?
MYC (transcription factor)
MYC activates expression of genes that are involved in cell growth, like D cyclins involved in cell cycle progression. It is a TF that can act together to reprogram somatic cells into pluripotent stem cells and in some contexts MYC can upregulate?
expression of telomerase
In what type of B/T cell lymphoma is the MYC oncogene on chromosome 8 translocated to chr 14, causing increased MYC protein and expression of pro-growth genes?
Burkitt Lymphoma
NMYC and LMYC are genes that are amplified in neuroblastomas and small cell cancers of the lung, respectively. IN many other instances, oncogenic mutations involving components of upstream signaling pathways elevated MYC protein levels by?
increasing MYC transcription, enhancing MYC mRNA translation or stbailizing MYC protein
GFs tranduce signals that induce progression of cells through the cell cycle mainly via what, which are activated by binding to cyclins?
Cyclin dependent kinases CDKs
*CDKInhibitors regulate cell cycle when CDKs are active
What are the main two cell cycle checkpoints, each of which is tightly regulated by a balance of growth promoting and growth supressing factors?
G1/S and G2/M transitions
G1/S defects are more important in cancer. gain of function mutations in what are oncogenes that promote G1/S progression?
GOF mutations in cyclin D and CDK4
*CDK4 is seen in melanomas, sarcomas, glioblastomas
The other group that affects the G1/S checkpoint is loss of function mutations in?
tumor suppressor genes that inhibit G1/S progression such as CDKIs (CDK4/Dcyclin inhibitor)
Activation of JAK 2 tyrosine kinase by a point mutation can cause what kind of cancer?
myeloproliferative disorders
Tummor suppressor genes apply the breaks to cell proliferation and abnormalities in these genes leads to?
failure of growth inhibition - hallmark or carcinogenesis
Retinoblastoma gene what the first tumor suppressor gene discovered. 40% of retinoblastomas are familial with the predisposition to develop the tumor being transmitted?
autosomal dominantly
10,000 fold increase in developing Retinoblastoma
What hypothesis is used to explaint the retinblastoma mutations?
a two-hit hypothesis of oncogenesis in which in familial inheritance there is one Rb gene defective and the chance of a sporadic mutation is high = bilateral Rb
in sporadic cases you need 2 mutations on the same gene= very less likely = unliateral Rb
What is known as the governor of proliferation, which is a key negative regulator of the G1/S cell cycle transition and is directly or indirectly inactivated in most human cancers?
RB
- active HYPOphosphorylated state in quiescent cells
- inactive HYPERphosphorylated state in cells passing thru cell cycle
High levels of CDK4/cyclin D,etc lead to hyperphosphorylation=inhibition of RB, releasing E2F transcription factors that drive progression of cell cycle. Germline and somatic LOF mutation of the RB gene is assocaited with what two cancers?
Retinoblastoma and osteosarcoma