Cancer Biology Overview

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Questions and Answers

What role do pro-angiogenic factors play in tumor growth?

They act as a barrier preventing tumor invasion.

They induce apoptosis in surrounding stroma.

They inhibit tumor cell proliferation.

They promote tumor growth by increasing blood supply. (correct)

Which enzyme is primarily involved in the invasion of organ stroma by tumor cells?

Protease-activated receptor (PAR)

Matrix metalloproteinase-9 (MMP9) (correct)

Matrix metalloproteinase-2 (MMP2)

Tissue plasminogen activator (tPA)

What does the 'seed and soil' hypothesis suggest about metastasis?

Certain tumor cells have an affinity for specific organ microenvironments. (correct)

Metastasis occurs randomly without any preference.

All metastases are driven by genetic mutations.

Tumor cells have an inherent ability to survive any environment.

What must tumor cells do to successfully enter circulation?

They must survive the turbulent flow and immune responses. Signup and view all the answers

What two main factors influence the mechanics of metastasis?

Anatomical structure and hemodynamic conditions Signup and view all the answers

Which hallmark of cancer allows tumors to grow independently of external growth signals?

Self-sufficiency in growth signals Signup and view all the answers

What role do mutations in oncogenes generally play in cancer development?

They lead to uncontrolled cell growth. Signup and view all the answers

Which of the following is NOT one of the newly proposed hallmarks of cancer in the update published in 2011?

Sustaining proliferative signaling Signup and view all the answers

What is the effect of RAS mutations in human cancers?

They block hydrolysis of GTP to GDP, leading to unchecked signaling. Signup and view all the answers

What underlying factor contributes to the acquisition of hallmark traits in tumors?

Genome instability and inflammation Signup and view all the answers

Which component of the tumor microenvironment contributes to the development of hallmark traits?

Stromal cells Signup and view all the answers

In the context of cancer, what is the significance of genome instability?

It generates genetic diversity that helps in acquiring hallmark functions. Signup and view all the answers

Which of the following processes is most likely disrupted in cancer cells leading to uncontrolled growth?

Cell cycle checkpoint mechanisms Signup and view all the answers

What characterizes benign tumors compared to malignant tumors?

Benign tumors are easily manageable with surgical removal. Signup and view all the answers

What is the primary distinction between invasion and metastasis in cancer?

Invasion directly affects neighboring tissues. Signup and view all the answers

Which of the following best describes the term 'carcinogenesis'?

The gradual progression from normal cells to malignant cancer. Signup and view all the answers

During which phase of multistep carcinogenesis does a permanent change in DNA occur?

Initiation. Signup and view all the answers

Which of the following is NOT considered a promoter in the promotion phase of carcinogenesis?

Radiation exposure. Signup and view all the answers

What is the correct sequence of steps in multistep carcinogenesis?

Initiation, promotion, progression. Signup and view all the answers

What is the main risk associated with malignant tumors?

They can metastasize and invade distant organs. Signup and view all the answers

Which characteristic is true for malignant tumors?

Can adhere to other tissues in an aggressive manner. Signup and view all the answers

Which tumor marker is specifically associated with prostate cancer?

Prostate-specific antigen (PSA) Signup and view all the answers

What is the primary purpose of Polymerase Chain Reaction (PCR) in cancer diagnosis?

To amplify specific DNA sequences Signup and view all the answers

Which of the following best describes the function of Carcinoembryonic antigen (CEA)?

Indicates presence of lung and breast cancers Signup and view all the answers

Which technique would be most appropriate for detecting genetic changes in cancer cells?

Fluorescence in situ hybridization (FISH) Signup and view all the answers

What is a main application of Next-generation sequencing (NGS) in cancer therapy?

Identify genetic mutations swiftly Signup and view all the answers

Which option correctly identifies an application of molecular techniques in cancer treatment?

Diagnosis of hereditary predisposition to cancer Signup and view all the answers

Which of the following is NOT a product of tumors that can be used as a tumor marker?

Albumin Signup and view all the answers

Which carcinogen is known to cause adenocarcinoma of the lung?

Asbestos Signup and view all the answers

Which dietary factors are linked to an increased risk of certain cancers?

High intake of red and processed meats Signup and view all the answers

How does regular physical activity impact cancer risk?

It helps reduce excess body fat, lowering cancer risks. Signup and view all the answers

What is one of the key components of tobacco smoke that contributes to cancer risk?

Over 80 carcinogenic agents Signup and view all the answers

Which type of radiation is NOT considered a manmade source of cancer risk?

Radon gas from geological formations Signup and view all the answers

Which occupational exposure is primarily associated with bladder cancer?

Chemical dye industry exposure Signup and view all the answers

What is the main reason infectious agents can lead to cancer?

They cause mutations in normal cells. Signup and view all the answers

Which group of individuals is at higher risk for melanoma due to ultraviolet exposure?

Fair-skinned people with many moles Signup and view all the answers

What percentage of cancer deaths is attributed to tobacco use?

22% Signup and view all the answers

Study Notes

Benign Tumors

Relatively harmless in terms of microscopic and macroscopic characteristics
Remain localized and do not spread
Easily managed with surgical removal
Patients generally survive
Can still cause significant morbidity and even death

Malignant Tumors

Also known as cancers
Can invade and destroy surrounding tissues
Can spread to distant sites (metastasize)
Often lead to death

Invasion & Metastasis

Abnormal cancer cells proliferate and spread
Invasion: Direct migration and penetration into surrounding tissues
Metastasis: Cancer cells spread through the lymphatic system and blood vessels

Multistep Carcinogenesis

Initiation: A carcinogen causes permanent DNA change
Promotion: The initiated cell is stimulated to grow by a promoter. Examples include alcohol, high estrogen, dietary fat, etc.
Progression & Malignancy: A pre-neoplastic cell acquires additional mutations leading to invasive cancer.

Metastasis

Seed and soil hypothesis: Certain tumor cells have an affinity for specific organs based on the organ's environment. This explains why metastases occur in specific locations.

Metastasis Factors

Vascularization: Primary tumors grow through the synthesis and secretion of pro-angiogenic factors.
Invasion of the organ stroma: Cells enhance expression of enzymes like MMP9 to invade.
Invasion of lymphatic or vascular channels: Cancer cells enter the circulatory system.
Survival in circulation: Cells must survive the turbulence of blood flow and evade immune and non-immune mechanisms.
Arrest in capillary beds: Cells stop in the capillaries of distant organs.
Extravasation: Cells move out of the blood vessels into the distant organ.
Survival and proliferation: Tumor cells need a compatible environment to survive and multiply.

Cancer Risk Factors

Diet: High intake of red and processed meats, salted foods, and low consumption of fruits and vegetables increase cancer risks.
Physical activity: Regular physical activity can reduce the risks of developing colon, breast, and endometrial cancers.
Tobacco: Contains carcinogens that cause various types of cancer.
Ionizing radiation: Man-made sources of radiation like radon, x-rays, and gamma rays can cause cancer. Exposure to UV radiation from the sun or tanning beds can lead to skin cancer.
Workplace hazards: Exposure to certain chemicals or substances like asbestos can increase cancer risks.
Infection: Infectious agents like viruses can cause changes in cells that increase the risk of cancer.

Hallmarks of Cancer

Sustaining proliferative signaling: Tumors can proliferate without external stimuli.
Evading growth suppressors: Cancer cells bypass normal growth-regulating mechanisms.
Resisting cell death: Cancer cells avoid programmed cell death (apoptosis).
Enabling replicative immortality: Cancer cells evade mechanisms that limit cell division.
Inducing angiogenesis: Tumors create new blood vessels to supply nutrients and oxygen.
Activating invasion and metastasis: Cancer cells spread to other parts of the body.
Genome instability: Mutations accumulate rapidly, driving the development of cancer.
Inflammation: Inflammation can promote cancer development.

Self-Sufficiency in Growth Signals

Oncogenes: Mutations in proto-oncogenes convert them to oncogenes, which encode oncoproteins that promote cell growth.
Growth factors: Cancer cells may secrete their own growth factors or induce other cells to produce them.

Tumor Markers

Prostate-specific antigen (PSA): Prostate cancer
Cancer antigen 125 (CA125): Ovarian cancer
Alpha-fetoprotein (AFP): Liver and testicular cancer
Carcinoembryonic antigen (CEA): Lung, stomach, colon, ovarian and breast
Carbohydrate antigen 19-9 (CA19-9): Pancreatic, gallbladder, and stomach cancers

Molecular Diagnosis

Polymerase Chain Reaction (PCR): Detects and amplifies specific DNA sequences associated with cancer.
Fluorescence in situ hybridization (FISH): Detects genetic changes and chromosomal abnormalities.
Gene sequencing: Identifies mutations and other genetic changes.
Next-generation sequencing (NGS): Advanced method of reading DNA for rapid analysis of genetic changes.

Molecular Diagnosis Applications

Diagnosis of malignancy
Prognosis and behavior prediction
Detection of minimal residual disease
Diagnosis of hereditary predisposition to cancer
Therapeutic decision-making

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Description

This quiz covers the fundamental distinctions between benign and malignant tumors, including characteristics of invasion and metastasis. Additionally, it explores multistep carcinogenesis and the progression of cancer from initiation to malignancy. Test your knowledge on these critical concepts in cancer biology.