Oncology and Neoplasia Overview

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Questions and Answers

What is the primary characteristic that distinguishes a neoplasm from normal tissue?

Neoplasm is dependent on external stimulants for growth.

Neoplasm is always benign in nature.

Neoplasm exhibits uncontrolled growth after the cessation of stimuli. (correct)

Neoplasm forms only in response to inflammation.

What defines the term oncogenes?

Mutated genes that normally promote controlled cell growth. (correct)

Normal genes that suppress tumor formation.

Proteins that stimulate apoptotic cell death in tumors.

Genes that repair DNA damage and prevent cancer.

Which statement accurately describes proto-oncogenes?

They are responsible for the death of tumor cells.

They are always mutated and cause cancer.

They are oncogenes that promote uncontrolled growth.

They regulate normal cell growth and can mutate into oncogenes. (correct)

What is the relationship between oncogenes and their proto-oncogene counterparts?

Oncogenes arise from mutations of proto-oncogenes. Signup and view all the answers

Which of the following accurately summarizes the impact of genetic alterations in neoplasms?

They cause autonomous growth independent of any host conditions. Signup and view all the answers

How does environmental damage contribute to carcinogenesis?

It may lead to non-lethal genetic damage that promotes tumor growth. Signup and view all the answers

Which option best describes the nutrients required for tumor sustenance?

Tumors are dependent on the host for blood supply and nutrients. Signup and view all the answers

What role do oncogenes play in the normal physiological context?

They modulate cell growth by responding to external signals. Signup and view all the answers

What do tumors primarily result from?

Clonal expansion of a precancerous cell with genetic damage Signup and view all the answers

Which of the following correctly differentiates benign and malignant tumors?

Malignant tumors can invade and destroy surrounding structures, unlike benign tumors. Signup and view all the answers

What is a common feature of malignant tumors?

They can spread to distant sites of the body. Signup and view all the answers

Which of the following is NOT considered a target for genetic damage in tumor formation?

Reproductive genes Signup and view all the answers

Which of the following neoplasms is considered benign?

Fibroids Signup and view all the answers

Why is carcinogenesis described as a multistep process?

It progresses through a series of genetic and phenotypic changes accumulating multiple mutations. Signup and view all the answers

Which of the following describes a characteristic of malignant tumors?

They adhere obstinately to tissues, akin to how crabs operate. Signup and view all the answers

Which genetic aspect is involved in determining whether a tumor will be benign or malignant?

The accumulation of mutations in regulatory genes Signup and view all the answers

Which of the following is correctly matched with its type of neoplasm?

Fibrosarcoma - malignant neoplasm of fibrous tissue Signup and view all the answers

Which characteristic is NOT typically associated with malignant cells?

Anisocytosis of red blood cells Signup and view all the answers

What suffix is used to denote benign neoplasms?

-oma Signup and view all the answers

Which of the following terms describes the loss of structural and functional differentiation in cancer cells?

Anaplasia Signup and view all the answers

Which of the following is a malignant neoplasm of glandular epithelium?

Adenocarcinoma Signup and view all the answers

What is the primary distinction between sarcomas and carcinomas?

Sarcomas originate from mesenchymal tissues, carcinomas from epithelial tissues Signup and view all the answers

What is anisokaryosis a key characteristic of?

Cancer cells Signup and view all the answers

Which of the following neoplasms is typically considered malignant?

Fibrosarcoma Signup and view all the answers

Which of the following statements about metastasis is true?

It is a reliable indicator of malignancy because of the potential for spread. Signup and view all the answers

What characterizes the growth pattern of malignant neoplasms compared to benign neoplasms?

Malignant neoplasms generally grow more rapidly. Signup and view all the answers

Which term describes tumor cells that do not resemble the mature cells of the tissue of origin?

Anaplastic cells Signup and view all the answers

What is the primary growth characteristic distinguishing benign neoplasms from malignant ones?

Benign neoplasms remain localized without invasion. Signup and view all the answers

Which step is NOT part of the mechanism of tumor invasion and metastasis?

Well-differentiation Signup and view all the answers

Which of the following is true regarding tumor types that rarely metastasize?

They may include gliomas and basal cell carcinoma. Signup and view all the answers

During which phase do malignant cells first appear to disrupt and invade the basement membrane?

Invasion of the extracellular matrix Signup and view all the answers

What primarily influences the growth rate of a neoplasm?

Tumor differentiation level Signup and view all the answers

What is the pathway of spread characterized by the leakage of fluid from its intended space into surrounding areas known as?

Extravasation Signup and view all the answers

Which type of spread is most commonly associated with the initial dissemination of carcinomas?

Lymphatic spread Signup and view all the answers

Which of the following organs are commonly involved in hematogenous spread of tumors?

Lung and liver Signup and view all the answers

Which category does NOT represent a type of carcinogenesis?

Biological carcinogenesis Signup and view all the answers

What characterizes cancer cachexia?

Progressive loss of body fat and lean body mass Signup and view all the answers

Which factor is most closely linked to familial cancers?

Familial clustering of cancer Signup and view all the answers

What type of spread occurs when a malignant neoplasm penetrates into natural open fields, affecting spaces such as the peritoneal cavity?

Transcoelomic spread Signup and view all the answers

Which of the following is NOT a consequence of neoplastic growth in the host?

Weight gain Signup and view all the answers

What type of immunity is primarily responsible for the anti-tumour response in vivo?

Cell-mediated immunity Signup and view all the answers

Which of the following cells is typically responsible for directly killing tumor cells?

Cytotoxic T lymphocytes (CD8+ CTLs) Signup and view all the answers

Who initially proposed the idea that tumors could be recognized and eliminated by the immune system?

Paul Ehrlich Signup and view all the answers

Which cytokine secreted by T cells and NK cells is known to activate macrophages?

Interferon-γ Signup and view all the answers

What is the term coined by Thomas and Burnet that describes the immune system's role in detecting and destroying emerging malignant cells?

Immune surveillance Signup and view all the answers

Which immune cells are responsible for lysis of tumors without prior sensitization?

Natural killer (NK) cells Signup and view all the answers

What has been shown regarding the protective role of antibodies in tumor immunity?

They are ineffective in protecting against tumors. Signup and view all the answers

In immunocompetent hosts, why do tumors develop mechanisms to avoid being attacked by the immune system?

To evade immune recognition and destruction Signup and view all the answers

Study Notes

Neoplasm

Neoplasia means new growth; a new growth is called a neoplasm.
Tumor originally referred to swelling caused by inflammation, but now is equated with neoplasm.
Oncology is the study of tumors or neoplasms, based on the Greek word for tumor (oncos).
A neoplasm is an abnormal mass of tissue, growing excessively and uncoordinated with normal tissue, persisting even after the initial stimulus ceases.
James Ewing defined a neoplasm as a relatively autonomous growth of tissue.

Normal and Cancer Cell Development

Normal cell development involves normal cell growth and division, resulting in healthy tissue.
Abnormal cell growth, due to genetic changes, leads to cancerous cells that divide uncontrollably, forming a malignant tumor.

Oncogenes

Oncogenes are genetic mutations that can cause cancer, arising from mutated genes that manage cell growth.
When genes change into oncogenes, cells grow and divide uncontrollably.
Genes promoting autonomous cancer cell growth are oncogenes; their normal counterparts are proto-oncogenes.
Oncogenes are created by mutations in proto-oncogenes, promoting cell growth without normal signals.

Proto-oncogenes

Genes that regulate normal cell growth and division.
Proto-oncogenes can mutate into oncogenes, causing cancer.

Molecular Basis of Cancer

Non-lethal genetic damage (mutations) underlies carcinogenesis.
Mutations can be acquired through environmental factors (chemicals, radiation, viruses/bacteria) or inherited in the germline.
The term "environmental" includes acquired defects from exogenous agents or endogenous products of cell metabolism.
Tumors form via the clonal expansion of a single precursor cell with genetic damage.
Normal regulatory genes—growth-promoting proto-oncogenes, growth-inhibiting tumor suppressor genes, cell death regulators (apoptosis), DNA repair genes, and metastatic genes—are primary targets for genetic damage.
Carcinogenesis is a multistep process affecting both phenotypic and genetic levels through the accumulation of multiple mutations.

Neoplasm Types

Neoplastic types include benign and malignant neoplasms.
Benign tumours are localized, non-invasive, and usually treatable surgically.
Malignant tumours are invasive, spread to distant sites, and are often fatal if not treated.
Malignant tumours are more commonly referred to as cancers.

Benign Neoplasms

Characterized by well-differentiated cells, slow growth rates, cohesive expansive growth patterns, and confinement to their site of origin, lacking the capability for metastasis.
Examples of common benign neoplasms include fibroids, polyps, and sebaceous cysts.

Malignant Neoplasms

Consist of undifferentiated cells (anaplastic), having erratic growth patterns, capable of local invasion and metastasis.
Types include sarcomas (mesenchymal origins), and carcinomas (epithelial origins).

Mechanisms of Tumor Invasion and Metastasis

Carcinoma in situ refers to a group of abnormal cells found only where they initially formed.
Malignant cells bind to basement membrane components.
Cancer cells disrupt and invade basement membranes via collagenase type IV and other proteases.
Tumor cells invade the extracellular matrix.
Cancer cells detach and enter the circulatory system (embolization).
Cancer cells survive in the circulation.
Cancer cells exit the circulatory system at secondary sites (extravasation).
Cancer cells evade the host immune system and grow progressively.
Metastatic colonization occurs at secondary sites.

Pathways of Spread

Seeding of body cavities and surfaces (transcoelomic spread) involves a malignant neoplasm penetrating a natural "open field" (e.g., peritoneal cavity, pleural, pericardial, subarachnoid, joint spaces).
Lymphatic spread is the primary pathway for carcinoma dissemination, with lymphatic node involvement proportional to tumor cell numbers reaching nodes.
Hematogenous spread is common to sarcomas and certain carcinomas, where tumor cells form emboli, aggregating in the circulatory system and adhering to leukocytes, mostly platelets.

Premalignant Disorders

Hereditary premalignant disorders include familial cancers. Examples include breast, ovarian, colon, and brain cancers.
Defective DNA repair is an autosomal recessive syndrome. Acquired preneoplastic disorders also exist.

Carcinogenesis

Genetic damage and neoplastic transformation of cells can result from exposure to a variety of harmful factors, classified into chemical, radiation, and viral/bacterial causes.

Effects of Tumors on the Host

Local and hormonal effects: Tumors in endocrine glands cause insufficiency through destruction, and in the gut, cause obstruction through expansion.
Cancer cachexia is a significant symptom, characterized by progressive loss of body fat and lean mass, weakness, anorexia, and anemia, with some correlation to tumor burden.

Immunology

Immunology is the study of molecules, cells, organs, and systems responsible for recognizing and eliminating foreign material in the body.
Immunity is the body's protective mechanism against pathogenic microorganisms, classified into non-specific (innate) and specific (adaptive) immunity.

Innate Immunity

The innate immune system is a body's rapid, non-specific first line of defense against pathogens.
It employs physical barriers (skin, hair, mucous membranes and acidic content of the GIT, Vagina).
Certain WBCs (basophils, mast cells, monocytes, neutrophils, macrophages) respond quickly to infections.

Adaptive Immunity

The adaptive immune system provides a specific defense to pathogens that have breached innate immunity.
It develops over time, via pathogen encounters or vaccinations.
It is more specific than innate immunity and has memory, relying on T and B lymphocytes to respond.

Host Defense Against Tumors (Immune Surveillance)

Tumors are not always entirely self. Paul Ehrlich proposed that the immune system can recognize and eliminate certain tumors.
Lewis Thomas and Macfarlane Burnet coined the term immune surveillance—a normal immune system function that monitors the body for emerging malignant cells and destroys them.

Anti-Tumor Effector Mechanisms

Cell-mediated immunity is the dominant anti-tumor mechanism, using T cells like cytotoxic T lymphocytes (CD8+ CTLs) to combat virus-associated neoplasms (e.g., EBV, HPV).
Natural killer (NK) cells directly destroy tumor cells without prior sensitization, a crucial first line of defense.
Macrophages exhibit cytotoxicity against tumor cells and collaborate with T and NK cells through cytokine interferon-γ activation.
Antibodies have limited protective effects against spontaneous tumors but can be therapeutic when targeting tumor cells. Monoclonal antibodies against CD20 (a B-cell surface antigen) are widely used for lymphoma treatment.

Immune Surveillance and Escape

Most cancers arise in individuals without overt immunodeficiencies, implying that tumor cells have mechanisms to escape or evade immunocompetent immune systems.
Tumor evasion mechanisms can include the failure to produce tumor antigens, antigen loss variants of tumor cells, mutations in MHC genes, production of immunosuppressive proteins such as TGF-β, etc.

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Description

This quiz explores the fundamental concepts of neoplasia, including neoplasms, tumor classifications, and the role of oncogenes in cancer development. Test your understanding of how normal and cancer cell development differs and the implications of genetic mutations. Perfect for students of oncology and related fields.