Tumor Markers in Cancer Management

Cancer & Tumor Markers

• Tumor markers are biochemical substances (hormones, enzymes, proteins) produced by cancer cells or the body's response to cancer.

• Symptoms of cancer vary depending on the type but general symptoms include fatigue, weight loss, pain, skin changes, unusual bleeding, persistent cough, and fever.

• Treatment options include chemotherapy, radiation, and surgery.

• Benign tumors are non-cancerous, while malignant tumors are cancerous and can spread to other tissues and organs.

Types of Cancer

• Common cancer types (according to the National Cancer Institute) include bladder, lung, breast, melanoma, endometrial, kidney cancer, leukemia, lymphoma, pancreatic, prostate, colon and rectal cancers.

• A diagram shows an example of primary cancers and areas they might metastasize (spread) to, including the brain, lungs, skin, and pancreas.

• The most common cancers in men include prostate, lung, and colorectal cancer.

  • For women: breast, lung, and colorectal cancer
  • For children: leukemia, brain tumors, and lymphoma

Types of Cancers - Classification

• Carcinoma: Starts in the skin or tissues lining internal organs (e.g., skin, lung, colon, pancreas). Subtypes include adenocarcinoma, basal cell carcinoma, squamous cell carcinoma, and transitional cell carcinoma.

• Sarcoma: Begins in bone, cartilage, or other connective tissue. This includes bone sarcomas and soft tissue sarcomas.

• Leukemia: Starts in blood-forming tissue, causing abnormal blood cells to enter the bloodstream. Ages of onset include 0-5, 14-18, 19-40, and 60+. Subtypes include lymphoblastic leukemia and T-cell leukemia.

• Lymphoma & Myeloma: Starts in white blood cells, affecting lymph nodes. The tissue sites it affects can include the stomach, brain, and intestines. Subtypes include B-cell lymphocytes and T-cell lymphocytes. -Myeloma develops in plasma cells, is a blood cancer, and can damage bones, kidneys, and the red blood cell count.

• Central Nervous System Cancers: Start in brain tissue and spinal cord. The brain controls the body by sending electrical signals along nerve fibers, and the brain and spinal cord form the central nervous system.

Normal vs. Cancerous Cells

• Normal cells divide and go through apoptosis (cell death) when damaged. Cancer cells multiply constantly, have an altered nucleus structure, irregular shapes, and lack defined boundaries in groups.

Role of Cell Division in Cancer

• Benign tumors do not spread
• Malignant tumors invade surrounding tissues.
• Cancer cells may break off and form new tumors (metastasis).

Spread of Cancer

• Primary cancer starts at a site in the body. It may spread (metastasize) to other parts of the body.
• Secondary cancers form from the spread of primary cancer.

Spread to Other Areas of Body

• Cancer cells can spread through blood vessels (capillaries) and the lymphatic system.
• Circulation tumor cells may get lodged in small blood vessels, move through capillary walls, and form new tumors in other organs.

###Properties of Cancer Cells

• Cancer cells display uncontrolled cell division leading to tumor formation.
• They have decreased cell adhesion.
• They show diverse genetic alterations.
• Cancer cells lack differentiation to normal cell characteristics.
• They lose the ability to communicate with other cells.
• They lose sensitivity, adhesion molecules.

Tumor Markers- Properties

• Tumor markers should be present in or produced by the tumor itself.

• Tumor markers should not be present in healthy tissues.

• Tumor marker levels need to be minimal in healthy subjects and benign conditions.

• Tumor markers should be specific to a tissue and have different immunological properties from those produced elsewhere in the body.

• Plasma marker levels are proportional to the tumor's size and activity.

• Tumor marker half-lives should not be excessively prolonged.

• Tumor markers should be detectable even in small tumors.

• Tumor markers are helpful in predicting recurrence.

Classification of Tumor Markers

• They are classified by molecular type. This includes enzymes/isoenzymes, hormones, oncofetal antigens, carbohydrate epitopes recognized by monoclonal antibodies, and receptors.

• Specific examples of tumor markers by type are provided for some common types of cancer.

Potential Uses of Tumor Markers

• Screening the general population.
• Diagnosing symptomatic patients.
• Clinically staging cancer.
• Estimating tumor volume.
• Prognostic indicator of disease progression.
• Evaluating the success of treatment. detecting recurrence of cancer.
• Monitoring response to therapy
• Radioimmunolocalization of tumor masses.

Tumor Marker Considerations

• Most tumor markers are not specific for singular tumors, but are found in multiple tumor types.
• Tumor markers are typically present in higher quantities in cancer patients' blood versus healthy subjects or those with benign diseases.
• Some tumor markers are proportionate to tumor size, while others reflect activity.
• The clinical staging of cancer can be assisted by tumor marker quantification.
• Serum levels reflect tumor burden and prognostic indicators of disease progression and survival.
• The response to therapies are often indicated by drops in tumor markers. Recurrence is often indicated by an increase in marker.

Specific Tumor Markers — Examples

• Enzymes: Alkaline phosphatase (ALP) and Prostatic acid phosphatase (PAP). Increased levels associated with liver cancer, bone/liver metastatic cancer or other malignancies like ovarian, lung cancers. PAP is used to stage prostate cancer & monitor treatment.

• PSA: Prostate-specific antigen. Used for prostate cancer—it's highly specific to it during early cancer.

• Hormones: Calcitonin. High levels are usually associated with medullary thyroid cancer and can correlate with tumor volume and metastasis.

• Oncofetal Antigens: a-fetoprotein (AFP) and carcinoembryonic antigen (CEA). AFP is useful for screening and diagnosing hepatocellular carcinoma, pregnancy and chronic liver disease. CEA is a marker for colorectal, lung, and breast cancers.

• Carbohydrate Markers: CA 15-3, CA 125, CA 19-9. CA 15-3 is correlated with breast cancer. CA 125 is linked to ovarian/endometrial cancers and detecting residual disease. CA 19-9 is a marker for pancreatic and colorectal cancers.

• Protein Markers: β2-microglobulin, ferritin, thyroglobulin, Immunoglobulins (including monoclonal paraproteins and Bence-Jones protein). β2-microglobulin links to multiple myeloma, Hodgkin lymphoma. Ferritin is a marker for Hodgkin lymphoma, leukemia, liver, lung, and breast cancers. Thyroglobulin helps detect differentiated thyroid cancer. Immunoglobulins/Bence-Jones are markers for multiple myeloma.

• Receptor Markers: Estrogen and progesterone receptors in breast cancer are used for hormonal therapies. Measuring cytoplasmic receptors are crucial.

Genetic Changes

• Proto-oncogenes, tumor suppressor genes, apoptosis-related genes, and DNA repair genes are related to cancer development.

• These genetic changes are linked to chronic myeloid leukemia, neuroblastoma, acute myeloid leukemia ,breast and ovarian cancers, and colorectal cancers, and other types.

• Genes are implicated in normal cell growth and differentiation, regulating apoptosis (programmed cell death), and DNA repair.

Chromosomal Translocations

• Translocations involve chromosomes exchanging segments. One example is the c-myc gene translocation in Burkitt's lymphoma. Also, translocations in chromosomes 9 and 22 are associated with chronic myeloid leukemia.

Conclusion

• Tumor markers assist in cancer diagnosis, staging, prognosis, and monitoring treatment success.
• However, because tumor markers are not always specific to a single tumor type, and some conditions other than cancer can produce these markers, additional testing is often necessary to clarify diagnostic and staging findings.

This quiz explores the essential characteristics and significance of tumor markers in cancer diagnostics and management. Questions cover their classification, uses, and limitations, providing a comprehensive understanding of their role in screening and treatment outcomes. Test your knowledge and see how well you understand tumor markers!