BIOMED SCIE Lecture 24 cancer

• Cancer


  Diseases in which cells divide abnormally without control and are able to invade other tissues
• Types of Cancers


  • Carcinomas (85% of cancers, occur in epithelial cells)
  • Squamous cell carcinoma (affects squamous cells)
  • Adenocarcinoma (affects glandular cells)
  • Transitional cell carcinoma (affects transitional cells)
• Tumour


  A growth of tissue resulting from abnormal new cell growth (neoplasia)
• Benign tumour


  • Encapsulated
  • Non-invasive
  • Limited growth
  • Does not metastasize
  • Rarely lethal
• Malignant tumour


  • Non-encapsulated
  • Invasive
  • Uncontrolled growth
  • May metastasize
  • Often lethal
• Cancer Staging


  • Stage 0 (Carcinoma in situ)
  • Stage I (Localized to one part of the body)
  • Stage II (Locally advanced)
  • Stage III (Locally advanced with affected lymph nodes)
  • Stage IV (Metastasized or spread to other organs or throughout the body)
• Cellular Hallmarks of Cancer


  • Loss of contact inhibition of cell growth
  • Deregulation of cell cycle with absence of checkpoints
  • Low requirement for growth factors
  • Lack of apoptosis (cell death)
  • Chromosome abnormalities resembling embryonic cells
• Cell Cycle


  Interphase (G1, S, G2), followed by mitosis (nuclear division) and cytokinesis (cytoplasmic division)
• Mitosis


  The process of nuclear division including stages such as prophase, metaphase, anaphase, and telophase
• How Cells Become Cancerous


  1. DNA mutations caused by:

  2. DNA replication errors

  3. Radiation

  4. Chemical carcinogens or mutagens

  5. Virus infections (e.g., HPV and cervical cancer)
• Causes of Cancer Mutations


  • Environmental factors (29%)
  • Random mutations (66%)
  • Inherited mutations (5%)
• DNA Repair Mechanisms


  Cells have DNA repair mechanisms, but mutations in certain genes can lead to abnormal growth and cancer
• Ames Test


  Used to determine whether a substance acts as a carcinogen