Tumor Biology and Antigens Quiz
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Questions and Answers

In which conditions are elevated levels of β-HCG particularly useful for evaluation?

  • Lymphoma
  • Chronic renal failure
  • Leukemia
  • Germ cell tumors (correct)

What is the normal range of prostate-specific antigen (PSA) for adult men?

  • < 20 ng/mL
  • < 4 ng/mL (correct)
  • < 15 ng/mL
  • < 10 ng/mL

Which of the following is NOT a condition associated with increased PSA levels?

  • Benign prostatic hypertrophy
  • Acute prostatitis
  • Prostate cancer
  • Kidney stones (correct)

What is the primary purpose of using tumor markers in clinical practice?

<p>To identify cancer in asymptomatic individuals (A)</p> Signup and view all the answers

Which characteristic is ideal for a tumor marker in terms of clinical use?

<p>High sensitivity and high specificity (B)</p> Signup and view all the answers

Which characteristic is NOT typically associated with cancer cells?

<p>Decreased metabolism (D)</p> Signup and view all the answers

What type of antigens must tumors express to be recognized by the immune system?

<p>Tumor-associated antigens (D)</p> Signup and view all the answers

Which of the following is a mechanism that cancer cells use to evade the immune system?

<p>Suppress immune recognition (B)</p> Signup and view all the answers

What is the role of MHC class I and II in relation to tumor-specific peptides?

<p>They present intracellular proteins on tumor cells. (A)</p> Signup and view all the answers

What type of tumors are caused by viral infections?

<p>Virus-induced tumors (D)</p> Signup and view all the answers

What happens when proto-oncogenes undergo alteration?

<p>They can lead to abnormal cell growth. (C)</p> Signup and view all the answers

Which characteristic facilitates the invasion and metastasis of cancer cells?

<p>Resistance to cell death (B)</p> Signup and view all the answers

What impact does inflammation have on cancer cell growth?

<p>It accelerates growth. (B)</p> Signup and view all the answers

What distinguishes malignant tumors from benign tumors?

<p>Malignant tumors consist of poorly differentiated cells that invade surrounding tissue. (D)</p> Signup and view all the answers

Which term describes a secondary tumor derived from a malignant primary tumor?

<p>Metastatic tumor (C)</p> Signup and view all the answers

What are proto-oncogenes primarily associated with?

<p>Promoting cell growth and division. (B)</p> Signup and view all the answers

Which statement best describes benign tumors?

<p>They remain localized and do not spread. (C)</p> Signup and view all the answers

What can cause malignant tumors to form?

<p>Genetic mutations in proto-oncogenes and tumor-suppressor genes. (D)</p> Signup and view all the answers

Which characteristic is NOT associated with malignant tumors?

<p>Well-defined borders (D)</p> Signup and view all the answers

Which of the following best describes neoplasms?

<p>They can be categorized as either benign or malignant. (D)</p> Signup and view all the answers

What is a key feature of poorly differentiated cells found in malignant tumors?

<p>They grow rapidly and lose structural organization. (A)</p> Signup and view all the answers

Which tumor marker is primarily used in the management of gastrointestinal tumors?

<p>Carcinoembryonic Antigen (CEA) (C)</p> Signup and view all the answers

What is the normal range for Carcinoembryonic Antigen (CEA) levels in healthy individuals?

<p>0-2.5 ng/ml (D)</p> Signup and view all the answers

Which condition is NOT associated with elevated levels of α-Fetoprotein (AFP)?

<p>Non-small cell lung cancer (D)</p> Signup and view all the answers

What is a significant value of CEA levels that may predict recurrence of colorectal tumors?

<p>4-5 times normal levels (D)</p> Signup and view all the answers

What role does Human Chorionic Gonadotropin (HCG) play in cancer detection?

<p>It is produced by neoplastic cells in testicular cancer. (B)</p> Signup and view all the answers

In terms of tumor burden determination, what is a primary function of tumor markers?

<p>To assess the size and spread of cancer. (C)</p> Signup and view all the answers

Which of the following conditions is associated with elevated CEA in patients?

<p>Inflammatory bowel disease (C)</p> Signup and view all the answers

What may cause a rise in α-Fetoprotein (AFP) levels aside from cancer?

<p>Cirrhosis (C)</p> Signup and view all the answers

Which common tumor marker is associated with ovarian cancer?

<p>CA 125 (B)</p> Signup and view all the answers

What is the primary function of active immunotherapy in cancer treatment?

<p>Stimulate the patient’s immune response to tumor antigens (A)</p> Signup and view all the answers

Which method is used to detect genetic mutations associated with cancer?

<p>Molecular methods (B)</p> Signup and view all the answers

Which tumor marker is commonly used for prostate cancer detection?

<p>PSA (D)</p> Signup and view all the answers

What type of therapy uses soluble components of the immune system to enhance response?

<p>Passive immunotherapy (B)</p> Signup and view all the answers

Which of the following is NOT a use of the tumor marker CEA?

<p>Preventative measures (B)</p> Signup and view all the answers

Which of the following statements is true regarding monoclonal antibodies in passive immunotherapy?

<p>They target specific tumor antigens and factors (B)</p> Signup and view all the answers

What type of cancer is associated with the tumor marker AFP?

<p>Liver cancer (D)</p> Signup and view all the answers

What are oncofetal antigens primarily characterized by?

<p>They are expressed later after malignant transformation. (B)</p> Signup and view all the answers

Which cytokine is known for destroying tumor cells?

<p>TNFα (A)</p> Signup and view all the answers

What is a role of NK cells in tumor immunity?

<p>They kill tumor cells with decreased MHC Class I expression. (A)</p> Signup and view all the answers

How do antibodies contribute to humoral-mediated immunity against tumors?

<p>They can lyse tumor cells through complement activation. (A)</p> Signup and view all the answers

Which of the following is a common characteristic of tumors evading the immune system?

<p>They may block CTL binding with anti-tumor antibodies. (A)</p> Signup and view all the answers

What is one function of macrophages in natural immunity against tumors?

<p>They mediate cytotoxicity against tumor cells. (D)</p> Signup and view all the answers

Which oncofetal antigen is typically associated with colorectal cancer?

<p>Carcinoembryonic antigen (CEA) (B)</p> Signup and view all the answers

Which of the following best describes the role of T cell-mediated immunity in tumor defense?

<p>Cytotoxic T lymphocytes directly lyse tumor cells. (D)</p> Signup and view all the answers

Flashcards

Neoplasm

An abnormal mass of tissue resulting from uncontrolled growth of normal cells, even after the growth stimulus is removed.

Benign Tumor

A mild and nonprogressive tumor that pushes aside normal tissue but doesn't invade it.

Malignant Tumor

A tumor consisting of poorly differentiated cells that grow quickly and invade surrounding tissue, depriving normal tissue of nutrients.

Metastatic Tumor

A secondary tumor derived from a primary malignant tumor.

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Proto-oncogenes

Genes that regulate normal cell growth and division. When mutated, they can become oncogenes.

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Tumor-suppressor Genes

Genes that suppress uncontrolled cell growth and division. Mutations in these genes can lead to uncontrolled growth.

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Oncogenes

Mutated proto-oncogenes that contribute to uncontrolled cell growth and tumor development.

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What is Cancer?

Cancer characterized by uncontrolled cell division and the ability to spread (metastasis).

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What are the hallmarks of cancer?

Cancer cells have features that allow them to grow uncontrollably, evade the immune system, and spread to other tissues.

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What are Tumor-Associated Antigens (TAAs)?

Tumor-associated antigens are molecules on tumor cells that are recognized as foreign by the immune system. These antigens can be proteins, enzymes, or other surface molecules.

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What are Tumor-Specific Peptides?

Intracellular proteins expressed on tumor cells with MHC Class I and II molecules. They can be chemically induced, meaning that certain substances can cause them to appear on tumor cells.

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How do viruses contribute to tumors?

Viruses can cause tumors by introducing viral antigens on tumor cell surfaces. These antigens are then recognized as non-self by the immune system, triggering an immune response.

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What is the difference between proto-oncogenes and oncogenes?

Proto-oncogenes are found in all nucleated cells and are involved in normal cell growth. Mutations in proto-oncogenes can make them oncogenes, leading to abnormal cell growth and tumor development.

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How do cancer cells evade immune defenses?

One hallmark of cancer cells is their ability to evade the immune system, allowing them to persist and grow unchecked.

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How do cancer cells alter their metabolism?

A hallmark of cancer cells is their ability to survive and grow even when they lack the necessary nutrients, which can happen when normal cells would die.

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How do cancer cells sustain their proliferation?

Cancer cells often grow very quickly, which is distinct from the slow growth of normal cells. They also continue to grow even when there is no external signal telling them to.

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What are Oncofetal Antigens?

Substances found on fetal cells that are normally present in low quantities after birth but become expressed in higher amounts during tumor formation.

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Macrophage-mediated Cytotoxicity

A type of immune response against tumors involving macrophages engulfing and destroying tumor cells.

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NK Cell-mediated Tumor Killing

A type of natural immunity against tumors where NK cells kill tumor cells that lack MHC class I expression.

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Humoral Immunity in Tumor Response

Antibodies produced against tumor cell antigens can cause lysis of tumor cells through complement activation or antibody-dependent cell-mediated cytotoxicity (ADCC).

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What is the Function of IL-1 in Tumor Immunity?

A cytokine that activates T, B, and NK cells, leading to an immune response against tumors.

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What is the Role of TNF-α in Tumor Immunity?

This cytokine is produced by activated T, B, and NK cells and can directly kill tumor cells.

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T Cell-mediated Immunity Against Tumors

A type of immune response against tumors involving CTLs (cytotoxic T lymphocytes) directly killing tumor cells.

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How Do Tumors Evade the Immune System?

Tumors can evade the immune system by expressing less MHC class I, blocking CTL binding sites, or providing weak co-stimulatory signals.

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What is PSA?

A glycoprotein that dissolves the gel-like substance in semen after ejaculation, helping sperm move freely.

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What is Beta-hCG?

A hormone produced during pregnancy. High levels can indicate conditions like gestational trophoblastic disease or certain tumors.

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What are tumor markers?

Substances found in increased amounts in the blood, fluids, or tissues of patients with a specific type of cancer. Helpful in diagnosing, monitoring, and treating cancer.

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What is population screening for cancer?

Used to identify cancer in individuals without symptoms. Can help detect cancer early, but may lead to false positive or false negative results.

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What is diagnosis using tumor markers?

Used to confirm a cancer diagnosis in a specific patient. For example, PSA levels can help confirm prostate cancer.

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Tumor Markers

Glycoproteins found in small amounts in normal serum, but elevated in certain types of cancer. They can be used to detect, monitor, and assess the extent of cancer.

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Carcinoembryonic Antigen (CEA)

A tumor marker used in the management of gastrointestinal tumors, particularly colon cancer, pancreatic cancer, liver cancer, and lung cancer. It can also be elevated in inflammatory bowel disease and other conditions.

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CEA Levels in Normal People

Normal CEA levels in the blood are up to 2.5 ng/ml. Levels that are 4-5 times normal can predict the recurrence of colorectal tumors.

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Alpha-Fetoprotein (AFP)

A tumor marker that is significantly elevated in patients with hepatocellular carcinoma, hepatoblastoma, testicular and ovarian cancer, viral hepatitis, and cirrhosis. It's crucial for monitoring cancer therapy.

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Normal Range of AFP

Normal AFP levels in humans are 0-20 ng/ml. A 5-fold or higher rise in AFP is used to monitor hepatocellular carcinoma and testicular cancers. It can also be elevated in non-malignant conditions such as cirrhosis and hepatitis.

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Human Chorionic Gonadotropin (HCG)

A tumor marker commonly used in pregnancy. It is composed of 2 subunits, alpha (α) and beta (β). The beta subunit (β-HCG) is particularly important for cancer diagnosis.

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β-HCG and Cancer

β-HCG, the beta subunit of HCG, is produced by cancerous cells in testicular cancer and other tumors.

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What is Immunohistochemistry?

Immunohistochemistry uses antibodies to detect tumor antigens in tissue biopsies. The antibodies are labeled with a marker that allows them to be visualized. This technique can be used to identify different types of cancer cells and to determine the extent of tumor spread.

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What are Immunoassays?

Immunoassays measure the levels of circulating tumor markers in the blood. This technique can be used to screen for cancer, to monitor the effectiveness of treatment, and to detect the recurrence of cancer.

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How does Active Immunotherapy work?

Active immunotherapy stimulates the patient's immune system to attack tumor cells. This can be done by using vaccines to introduce tumor antigens to the immune system. It can be used to prevent certain cancers.

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How does Passive Immunotherapy work?

Passive immunotherapy involves administering soluble components of the immune system to help fight cancer. This can include cytokines or monoclonal antibodies, which target specific tumor antigens.

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What are Monoclonal antibodies?

Monoclonal antibodies are antibodies that target a specific tumor antigen. They can be used to destroy tumor cells directly, to block the growth of tumor cells, or to deliver drugs or toxins to tumor cells.

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How are Cytokines used for immunotherapy?

Cytokines are proteins that help regulate the immune system. Certain cytokines can be used in immunotherapy to boost the immune response against cancer.

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What is Immunotherapy?

Immunotherapy involves using the body's own immune system to fight cancer. It can be active, where the patient's immune system is stimulated, or passive, where immune system components are administered.

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Study Notes

Tumor Biology

  • Tumor (neoplasm): An abnormal mass of tissue arising from uncontrolled growth of normal cells.
  • Benign tumor: Mild and non-progressive; does not invade surrounding tissue.
  • Malignant tumor: Consists of poorly differentiated cells growing rapidly and invading surrounding tissue.
  • Metastatic tumor: A secondary tumor resulting from a malignant primary tumor.

Tumor Antigens

  • Antigens: For the immune system to react, tumors must have antigens recognized as foreign.
  • Antigens can include: Enzymes, receptors, and membrane antigens.
  • Most relevant antigens are often surface membrane molecules, which may be antigenic, or involved in suppression of membrane proteins essential for immune recognition and activation.
  • Tumor-specific peptides: Intracellular proteins expressed on tumor cells with MHC class I and II.

Virus-Induced Tumors

  • Tumors can arise due to viral infections.
  • Tumor cells express viral antigens on their surfaces.
  • The immune system recognizes these cells as non-self.

Genome-Encoded Tumor Antigens

  • Oncogenes: If downregulated, the protein product can lead to a tumor.
  • Proto-oncogenes: Present in all nucleated cells. Involved in cell growth. Alterations in gene expression or protein structure may cause abnormal cell growth.

Oncofetal Antigens

  • Found on normal fetal cells.
  • Produced in minimal amounts after birth.
  • Expressed later during malignant transformation.
    • Examples:
      • Alpha-fetoprotein (AFP)
      • Carcinoembryonic antigen (CEA)

Immunity to Tumors

  • Natural immunity:
    • Macrophage-mediated cytotoxicity: When macrophages contact tumor cells.
    • NK cells: 50% of tumors have mutations decreasing MHC class I expression on their surfaces, facilitating killing by NK cells.
  • Humoral immunity:
    • Antibodies: Can target tumor cell surface antigens.
    • Lysis of tumor cells: Can occur through complement activation, or antibody-dependent cell cytotoxicity (ADCC) mediated by NK cells, neutrophils, and macrophages.
  • Cell-mediated immunity:
    • Cytokines involved in tumor immunity (e.g., IL-1, TNFα, IFNγ).
    • CTLs (cytotoxic T lymphocytes): Directly lyse tumor cells.

Immunoediting and Tumor Escape

  • Elimination: Robust innate and adaptive immune responses kill most tumor cells.
  • Equilibrium: Immune system controls a limited number of altered cells.
  • Escape: Immune system is suppressed; chronic inflammation promotes tumor growth.

Tumor Evasion of Immune System

  • Anti-tumor antibodies: Might block CTL binding sites.
  • Reduced MHC class I expression in tumor cells: Prevents CTL-mediated destruction.
  • Poor costimulatory signals from tumor cells: Reduces immune response activation.

Tumor Markers

  • Glycoproteins found at low levels in normal serum but elevated in certain cancers.
  • Used for cancer screening, monitoring treatment response, and determining tumor burden.
    • Examples include: AFP, CEA, CA 125, hCG, PSA.

Laboratory Tests for Tumors

  • Immunohistochemistry: Uses labeled antibodies to identify tumor antigens in tissue biopsies.
  • Immunoassays: Measures levels of circulating tumor markers.
  • Molecular methods: Detect genetic mutations associated with cancer (e.g., PCR, karyotyping, FISH, microarray, DNA sequencing).

Immunotherapy

  • Active Immunotherapy: Stimulates the patient's immune system (e.g., cancer vaccines).
  • Passive Immunotherapy: Administer soluble components of the immune system (e.g., cytokines, monoclonal antibodies).
  • Adoptive immunotherapy: Transfer immune cells to the patient. (e.g., TILs, CAR-T cells).

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Tumor Immunology PDF

Description

Test your knowledge on tumor biology, including the differences between benign, malignant, and metastatic tumors. Learn about tumor antigens and how viral infections can contribute to tumor formation. This quiz covers essential concepts for understanding cancer biology.

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