Neoplasm and Oncology Overview

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Questions and Answers

Which of the following suffixes indicates a benign neoplasm?

-carcinoma

-melanoma

-oma (correct)

-sarcoma

What term describes malignant neoplasms arising from mesenchymal tissues?

Carcinomas

Sarcomas (correct)

Fibromas

Adenomas

Which of the following is NOT a characteristic of malignant cells?

Abnormal mitotic figures

Regular size and shape of nuclei (correct)

Increased nucleo-cytoplasmic ratio

Anisokaryosis

What is the term used to describe a new growth that exceeds normal tissue growth?

Neoplasm Signup and view all the answers

Which of the following benign neoplasms is derived from glandular epithelium?

Adenoma Signup and view all the answers

Which of the following best describes oncogenes?

Mutated proto-oncogenes that promote uncontrolled cell division Signup and view all the answers

What primarily causes the persistence of tumors after the removal of inciting stimuli?

Genetic alterations in tumor cells Signup and view all the answers

What does anisocytosis refer to in the context of malignancy?

Variation in red blood cell sizes Signup and view all the answers

Which of the following malignant neoplasms originates from melanin-producing cells?

Melanoma Signup and view all the answers

Which of the following statements about proto-oncogenes is correct?

They can mutate into oncogenes responsible for cancer. Signup and view all the answers

What role do environmental agents play in carcinogenesis?

They may cause nonlethal genetic damage. Signup and view all the answers

What is an example of a benign neoplasm derived from connective tissue?

Chondroma Signup and view all the answers

Which abnormality is typical in the nuclei of malignant cells?

Irregular staining patterns Signup and view all the answers

What defines an abnormal mass of tissue in oncology?

It is categorized as a neoplasm. Signup and view all the answers

Which of the following best describes the relationship between host and tumors?

Tumors remain dependent on the host for nutrition and blood supply. Signup and view all the answers

Which of these mutations is most commonly associated with lung cancer?

RAS Signup and view all the answers

What is primarily responsible for the formation of tumors?

Clonal expansion of a single precursor cell Signup and view all the answers

Which class of normal regulatory genes is NOT a primary target of genetic damage in tumors?

Metabolic genes Signup and view all the answers

What characteristic best defines a benign tumor?

It typically remains localized and is amenable to surgical removal. Signup and view all the answers

Which of the following neoplasms is considered malignant?

Lung cancer Signup and view all the answers

What term describes the accumulation of multiple mutations leading to cancer?

Carcinogenesis Signup and view all the answers

What does the term 'malignant' imply in the context of neoplasms?

The tumor poses a threat to adjacent structures and can metastasize. Signup and view all the answers

Which of the following types of tumors can arise in the blood?

Leukemia Signup and view all the answers

Which regulatory gene class directly prevents uncontrolled cell death?

Apoptotic regulatory genes Signup and view all the answers

What primarily distinguishes malignant neoplasms from benign neoplasms?

Malignant neoplasms can metastasize to distant sites Signup and view all the answers

Which type of tumor is characterized by anaplastic cells?

Poorly differentiated tumors Signup and view all the answers

What is a common characteristic of benign tumors in terms of growth?

They remain localized to their site of origin Signup and view all the answers

Which process typically initiates the mechanism of tumor invasion?

Malignant cell surface receptor binding Signup and view all the answers

Which of the following tumors has a slow growth rate and does not metastasize?

Uterine leiomyoma Signup and view all the answers

What is typically the behavior of malignant neoplasms compared to benign neoplasms?

Malignant neoplasms infiltrate and invade surrounding tissues Signup and view all the answers

Which option describes the final step in the mechanism of tumor metastasis?

Embolization Signup and view all the answers

Which neoplasm is least likely to metastasize?

Basal cell carcinoma Signup and view all the answers

What is a primary characteristic of weight loss in cachexia compared to starvation?

It involves equal loss of fat and lean muscle. Signup and view all the answers

Which type of immunity involves the immediate response to pathogens?

Non-specific immunity. Signup and view all the answers

What role do T and B lymphocytes play in the immune system?

They are involved in the adaptive immune response. Signup and view all the answers

Which of the following components is NOT part of the innate immune system?

T lymphocytes. Signup and view all the answers

How does the adaptive immune system differ from the innate immune system?

The adaptive immune system has memory and specificity. Signup and view all the answers

What is one function of the immune system?

To recognize and dispose of foreign materials. Signup and view all the answers

Which statement best describes non-specific immunity?

It includes defenses that are always active. Signup and view all the answers

What is a key feature of immunity?

Immunity helps protect the body from pathogens. Signup and view all the answers

What is the primary function of T cells in the immune response?

They mediate cell-mediated immune responses. Signup and view all the answers

Which concept was formalized by Lewis Thomas and Macfarlane Burnet?

The immune system surveys the body for malignant cells. Signup and view all the answers

Which type of lymphocyte can destroy tumor cells without prior sensitization?

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

What is the role of interferon-γ in anti-tumor immunity?

Activates macrophages to enhance their cytotoxicity. Signup and view all the answers

Which factor is associated with the protective role of cytotoxic T lymphocytes?

Their involvement in eliminating virus-associated neoplasms. Signup and view all the answers

Why do most tumors develop mechanisms to evade the immune system?

Immune surveillance is ineffective in immunocompetent individuals. Signup and view all the answers

What is a key characteristic of monoclonal antibodies in tumor treatment?

They can be therapeutically effective against certain tumor types. Signup and view all the answers

What primarily distinguishes the immune response of B cells from T cells?

B cells produce a humoral response while T cells are responsible for cell-mediated immunity. 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. Now, the term is synonymous with neoplasm.
Oncology is the study of tumors or neoplasms (Greek oncos = tumor).
An eminent British oncologist, Rupert A. Willis, defined neoplasm as "an abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of the normal tissues and persists in the same excessive manner after cessation of the stimuli which evoked the change."
James Ewing defined neoplasm as a relatively autonomous growth of tissue.
The persistence of tumours, even after the initial stimulus is gone, results from genetic alterations passed down to the progeny of the tumor cells.
These genetic changes permit excessive and unregulated proliferation that becomes autonomous (independent of physiologic growth stimuli).
Tumours generally remain dependent on the host for nutrition and blood supply.

Oncogenes

Oncogenes are a group of genetic mutations that cause cancer.
These mutated genes are a mutated form of genes that manage cell growth.
Oncogenes cause uncontrolled cell growth and division when the genes change into oncogenes.
Genes promoting autonomous cell growth in cancer cells are called oncogenes, while their unmutated counterparts are called proto-oncogenes.
Oncogenes are created by mutations in proto-oncogenes and have the ability to promote cell growth even in the absence of normal growth-promoting signals.
Examples of genes that can mutate into oncogenes include RAS (lung), HER2 (breast), and Cyclin D.

Proto-oncogenes

Proto-oncogenes are genes that regulate normal cell growth and division.
They can mutate into oncogenes, which cause cancer.
Examples of proto-oncogenes include RAS, HER2, and Cyclin D.

Principles involved in the molecular basis of cancer

Nonlethal genetic damage is the core of carcinogenesis (the development of cancer).
Genetic damage (mutation) can be acquired through environmental factors (chemicals, radiation, viruses/bacteria) or inherited in the germ line.
Environmental factors, in this context, comprise any acquired defect caused by exogenous agents or endogenous products of cell metabolism.

Tumours

A tumour forms when a single precursor cell with genetic damage undergoes clonal expansion.
Tumours are often monoclonal, and sometimes multiclonal.
Tumours are abnormal tissue masses where cells proliferate excessively or do not die when they should.
Tumours can develop in any part of the body, including organs, joints, and bones.

Classes of normal regulatory genes

Five classes of normal regulatory genes are primary targets for genetic damage in cancer:
- Growth-promoting proto-oncogenes
- Growth-inhibiting tumor suppressor genes
- Genes that regulate cell death (apoptosis)
- Genes involved in DNA repair
- Metastatic genes

Carcinogenesis

Carcinogenesis is a multistep process that happens at both phenotypic and genetic levels.
The process results from the accumulation of multiple mutations.

Neoplasm types

Benign neoplasms: characterized by relatively innocent microscopic and macroscopic features.
Benign tumours remain localized.
Benign tumours are usually amenable to local surgical removal, and patients typically survive.
However, benign tumours can sometimes be responsible for serious diseases.
Examples of common benign neoplasms include fibroids, polyps, and sebaceous cysts.
Malignant neoplasms are collectively known as cancers.
Malignant tumours are characterized by a crab-like adherence to surrounding tissues.
Malignant neoplasms can invade and destroy adjacent structures and spread to distant sites (metastasis), often leading to death.
Examples of common malignant neoplasms include lung cancer, leukemia, and lymphoma.

Nomenclature

Neoplasms are named based on their two factors: histological types (mesenchymal and epithelial) and behavioural patterns (benign and malignant).
Benign mesenchymal neoplasms originating from muscle, bone, fat, blood vessels, nerves, and fibrous/cartilage tissues have names ending in -oma (e.g., Rhabdomyoma, osteoma, lipoma, hemangioma, neuroma, fibroma, chondroma).
Adenoma (benign neoplasm of glandular epithelium), fibroadenoma (benign neoplasm of the breast), and leiomyoma (benign neoplasm of smooth muscle)
Malignant Mesenchymal tumors are called Sarcomas (fleshy tumours), e.g., fibrosarcoma, liposarcoma, osteosarcoma, and hemangiosarcoma.
Malignant epithelial tumors derived from any of the three germ cell layers are called carcinomas.

Mechanisms of tumor invasion and metastasis

Carcinoma in situ is a group of abnormal cells confined to the original site of formation.
Malignant cells bind to basement membrane components (e.g., laminin).
Malignant cells break down the basement membrane by releasing collagenase type IV and other proteases.
Cells invade the extracellular matrix.
Cells detach from the primary tumour.
Cells undergo embolization and survival in the circulation.
Extravasation occurs in the secondary sites.
Cells can evade the host defense.
Progressive growth occurs.
Metastasis happens.

Pathways of spread

Seeding of body cavities and surfaces
Lymphatic spread
Hematogenous spread

Premalignant disorders

Hereditary premalignant disorders include familial cancers (breast, ovarian, colon, brain).
Some families have documented clustering of cancers.
Autosomal recessive syndromes with defective DNA repair can also be included.
Acquired preneoplastic disorders are also important causes of premalignant conditions.

Types of Carcinogenesis

Many factors induce neoplastic transformation in cells.
These include chemical, radiation, and viral carcinogens, including bacteria like H. pylori.

Effects of tumours on the host

Local and hormonal effects:
- Cancers in or metastatic to endocrine glands can lead to endocrine insufficiency by destroying the gland.
- Neoplasms, both benign and malignant, can cause obstruction in the gut as they enlarge.

Cancer cachexia

Cachexia is a common symptom of cancer, including progressive loss of body fat and lean body mass, weakness, anorexia, and anemia.
Unlike malnutrition, weight loss in cachexia equally affects fat and muscle tissue.
The level of cachexia is often correlated with the tumor burden.

Immunology

Immunology is the study of the cells, molecules, organs, and systems that recognize and eliminate foreign materials.
Immunity is the body's defense against pathogenic microorganisms.
Innate and adaptive immunity are the two main types of immunity.

Innate Immunity

Innate immunity provides a first line of defense against pathogens.
It is always on.
Physical barriers like skin, hair, mucous membranes (with acidic content in GIT, vagina) play a significant role.
White blood cells—basophils, mast cells, monocytes, neutrophils, and macrophages—are also involved in the process and act quickly.

Adaptive Immunity

Adaptive immunity steps in after innate defenses are compromised.
Adaptive immunity is specific to pathogens.
It develops over time, through encounter or vaccination with pathogens.
Adaptive immunity involves T and B cells.
T cells mediate cell-mediated immunity.
B cells mediate humoral immunity, producing antibodies.

Host Defense against Tumours - Immune Surveillance

Paul Ehrlich proposed that the immune system recognizes and eliminates tumor cells.
Lewis Thomas and Macfarlane Burnet further developed this concept, referring to it as immune surveillance.
The immune system monitors the body for emerging malignant cells.
The immune system aims to destroy these emerging cells.

Anti-tumour Effector Mechanisms

Cell-mediated immunity is the dominant anti-tumor mechanism in vivo.
Antibodies are not effective in controlling physiological tumor conditions.
Cytotoxic T lymphocytes (CD8+ CTLs) play a protective role against virus-associated tumors (like EBV and HPV tumors).
Natural killer (NK) cells can destroy tumor cells without prior sensitization—they provide the first line of defense against tumor cells.
Activated macrophages exhibit cytotoxicity against tumor cells in vitro (in test tubes); T cells and NK cells activate macrophages.
Antibodies against tumor cells may have therapeutic benefits but there is limited evidence in spontaneous tumors.

Immune Surveillance and Escape Mechanism

Most cancers arise in people without overt immunodeficiency.
This suggests that tumor cells develop mechanisms to evade the immune system.
The evasion involves strategies like:
- Failure to produce tumor antigens
- Antigen loss variants
- MHC deficiency

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Description

This quiz covers the fundamental concepts of neoplasia and the study of tumors in oncology. It explores definitions, characteristics, and the genetic changes that contribute to the formation of neoplasms. Test your knowledge on the terminology and implications of neoplastic growth!