Unti 4 Oncology

Glossary Terms in Cancer Terminology

  • Neoplasm: Uncontrolled, unregulated cellular growth that serves no purpose.

Illustrations of Cancer Terminology

  • Normal Cells: Exhibit regular structure and function.

  • Atrophy: Cells shrivel up; normal cell count remains.

  • Dysplasia: Abnormal morphology of cells; some retain normal appearance, others appear red and begin to multiply faster, stacking on top of one another in an erratic formation.

  • Hypertrophy: Similar in cell arrangement to normal cells but has larger size; retains recognizable pattern.

  • Metaplasia: Presence of both normal and abnormal cells; abnormal ones do not align like normal cells, and they stack improperly.

  • Neoplasia: Full-blown malignancy with abnormal cells that spread uncontrollably into surrounding tissues.

Major Dysfunctions in Cancer

  1. Defective Cellular Proliferation

    • Normal cells divide, grow, and then rest in a balanced cycle – a process disrupted in cancerous cells.

    • Cancer cells constantly divide without resting or adhering to normal cellular division rules, resulting in rapid growth beyond normal rates.

    • Example of Contact Inhibition: Normal cells maintain spatial boundaries, while cancer cells overcrowd, defying spatial rules.

  2. Doubling Time and Exponential Growth

    • Cancer cells can divide resulting in exponential growth.

    • Example: If each cell divides into two, for 50 doublings, a tumor can become exceedingly large, changing dramatically in mass (up to nearly a ton).

Dedifferentiation and Mutation Risks

  • Cancer cells may appear less differentiated, resembling cells from different tissues leading to poorer prognosis and functionality.

  • Percentage of Causes of Cancer:

    • Cancer is associated with various environmental factors (e.g., tobacco, radiation) and inherited risks.

Risk Factors for Cancer Development

  1. Tobacco: The top carcinogen responsible for approximately 30% of cancer-related deaths.

    • Smokeless tobacco increases risks for oral, pancreatic, and esophageal cancer.

    • Example of immune suppression leading to secondary cancers post-organ transplant.

  2. Radiation: Includes sunlight and therapeutic radiation; risk management essential for radiologists.

  3. Viruses: Certain viruses lead to various cancers:

    • Epstein-Barr Virus (EBV): Linked to lymphoma or nasopharyngeal cancer.

    • HIV: Associated with Kaposi's sarcoma and other cancers.

    • Hepatitis B: Linked to liver cancer.

  4. Hormonal Factors:

    • Use of estrogen post-menopause decreases breast cancer risk but heightens endometrial cancer risk.

    • Contrasting therapies for breast cancer could raise ovarian cancer risks.

Carcinogenesis Phases

  1. Initiation: Abnormal genetic information expression begins; tends to be irreversible.

  2. Promotion: Steps are reversible if exposure to promoting agents declines; however, repeated exposure increases cancer risk.

  3. Progression: Tumors may grow larger, necessitating more blood supply, leading to invasive characteristics.

    • Involvement of proto-oncogenes (promote growth) and tumor suppressor genes (inhibit growth).

Mutation Sources for Cancer

  • Error rates during DNA replication contribute significantly (approximately two-thirds) to mutations resulting in cancer.

  • Environmental Influences: Harmful behaviors (e.g., smoking, sun exposure).

  • Inherited Factors: Genetic predispositions raise cancer likelihood.

Pancreatic Cancer Study Case

  • Approximately 75% of pancreatic cancer-related mutations from cellular division errors, 20% from environmental factors, and 5% from inherited mutations.

Metastasis Stages

  1. Stage 1: Cancer cells invade surrounding tissues and enter vessels.

  2. Stage 2: Movement occurs through blood or lymphatic vessels or local spreading into neighboring tissues.

  3. Stage 3: Establishment of secondary tumors at different body sites, forming metastases.

Cancer Classification

  1. Benign vs. Malignant Tumors

    • Benign: Slow growth, no metastasis.

    • Malignant: Faster growth, can metastasize.

  2. Anatomic Site: Identification of tumors based on origin (e.g., adenocarcinoma, osteosarcoma).

  3. Histologic Grading: Degree of differentiation of tumor cells; ranges from grade I (well-differentiated, favorable prognosis) to grade IV (poorly differentiated, severe).

Staging of Cancer (T.N.M. System)

  • T: Size or extent of the primary tumor.

  • N: Lymph node involvement.

  • M: Presence of distant metastasis.

Detection and Prevention of Cancer

  • Primary Prevention: Reducing risk through health behaviors (e.g., screenings).

  • Secondary Prevention: Early detection strategies for high-risk populations (e.g., screenings, blood tests).

Tumor Markers

  • Tumor markers provide insights into treatment responses:

    • CA-125 for ovarian cancer: Rising values indicate treatment ineffectiveness.

    • PSA for prostate cancer: Elevated levels suggest growing cancer.

Seven Warning Signs of Cancer (CAUTION)

  • C: Change in bowel or bladder habits

  • A: A sore that does not heal

  • U: Unusual bleeding or discharge

  • T: Thickening or lump in the breast or elsewhere

  • I: Indigestion or difficulty swallowing

  • O: Obvious changes in warts or moles

  • N: Nagging cough or hoarseness

  • Importance of recognizing these signs fosters early consultation with healthcare professionals, emphasizing patient education.