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?

To identify cancer in asymptomatic individuals Signup and view all the answers

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

High sensitivity and high specificity Signup and view all the answers

Which characteristic is NOT typically associated with cancer cells?

Decreased metabolism Signup and view all the answers

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

Tumor-associated antigens Signup and view all the answers

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

Suppress immune recognition Signup and view all the answers

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

They present intracellular proteins on tumor cells. Signup and view all the answers

What type of tumors are caused by viral infections?

Virus-induced tumors Signup and view all the answers

What happens when proto-oncogenes undergo alteration?

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

Which characteristic facilitates the invasion and metastasis of cancer cells?

Resistance to cell death Signup and view all the answers

What impact does inflammation have on cancer cell growth?

It accelerates growth. Signup and view all the answers

What distinguishes malignant tumors from benign tumors?

Malignant tumors consist of poorly differentiated cells that invade surrounding tissue. Signup and view all the answers

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

Metastatic tumor Signup and view all the answers

What are proto-oncogenes primarily associated with?

Promoting cell growth and division. Signup and view all the answers

Which statement best describes benign tumors?

They remain localized and do not spread. Signup and view all the answers

What can cause malignant tumors to form?

Genetic mutations in proto-oncogenes and tumor-suppressor genes. Signup and view all the answers

Which characteristic is NOT associated with malignant tumors?

Well-defined borders Signup and view all the answers

Which of the following best describes neoplasms?

They can be categorized as either benign or malignant. Signup and view all the answers

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

They grow rapidly and lose structural organization. Signup and view all the answers

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

Carcinoembryonic Antigen (CEA) Signup and view all the answers

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

0-2.5 ng/ml Signup and view all the answers

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

Non-small cell lung cancer Signup and view all the answers

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

4-5 times normal levels Signup and view all the answers

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

It is produced by neoplastic cells in testicular cancer. Signup and view all the answers

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

To assess the size and spread of cancer. Signup and view all the answers

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

Inflammatory bowel disease Signup and view all the answers

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

Cirrhosis Signup and view all the answers

Which common tumor marker is associated with ovarian cancer?

CA 125 Signup and view all the answers

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

Stimulate the patient’s immune response to tumor antigens Signup and view all the answers

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

Molecular methods Signup and view all the answers

Which tumor marker is commonly used for prostate cancer detection?

PSA Signup and view all the answers

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

Passive immunotherapy Signup and view all the answers

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

Preventative measures Signup and view all the answers

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

They target specific tumor antigens and factors Signup and view all the answers

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

Liver cancer Signup and view all the answers

What are oncofetal antigens primarily characterized by?

They are expressed later after malignant transformation. Signup and view all the answers

Which cytokine is known for destroying tumor cells?

TNFα Signup and view all the answers

What is a role of NK cells in tumor immunity?

They kill tumor cells with decreased MHC Class I expression. Signup and view all the answers

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

They can lyse tumor cells through complement activation. Signup and view all the answers

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

They may block CTL binding with anti-tumor antibodies. Signup and view all the answers

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

They mediate cytotoxicity against tumor cells. Signup and view all the answers

Which oncofetal antigen is typically associated with colorectal cancer?

Carcinoembryonic antigen (CEA) Signup and view all the answers

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

Cytotoxic T lymphocytes directly lyse tumor cells. Signup and view all the answers

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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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.