Chapter 7: Neoplasia

Overview of Cancer

• Definition: Cancer is characterized by uncontrolled cell growth and proliferation due to mutations.
• Key Concepts:
  • Neoplasia: New, abnormal growth; can be benign or malignant.
  • Tumor: A mass that can be either benign or malignant.

Epidemiology of Cancer

• Leading Cause of Death: Second in the U.S. after cardiovascular disease.
• Age Factor: Most deaths occur in individuals over 55.
• Risk Rates:
  • Men: 1 in 2 risk of developing cancer.
  • Women: 1 in 3 risk.
• Survival Rate: 5-year survival rate is about 66%.
• Early Screening: Enhances prognosis.

Risk Factors for Cancer

• Lifestyle factors account for a third of cancer deaths:
  • Tobacco Use: Linked to lung cancer and others like pancreatic, kidney, bladder, etc.
  • Nutrition & Obesity: High fat, alcohol intake.
  • Sun Exposure: UV rays increase skin cancer risk.
  • Sexual Exposure: HPV linked to cervical cancer.
• Other risk factors:
  • Viruses, radiation, chemicals (e.g., asbestos).
  • Compromised immune system, genetic, and hormonal influences.

Classification of Cancer

• Based on tissue or cell origin.
  • Examples:
    • Brain/spinal cord: Gliomas.
    • Pigment cells: Melanomas.

Normal Cell Cycle

• Balance: Normal cells divide when told to and balance cell death with cell production.
• Growth Factors: Stimulate cell growth by binding to receptors, activating growth signals.

Genetic Mechanisms of Cancer

• Carcinogens: Potentially cancer-causing agents.
• Proto-Oncogenes: Normal genes coding for proteins necessary for cell division.
• Oncogenes: Mutated proto-oncogenes that may cause cancer.
• Tumor Suppressor Genes: Code for proteins that suppress tumor formation.

Development of Cancer

• Process: Initiation, Promotion, and Progression.
  • Initiation: Initial mutation in DNA.
  • Promotion: Stimulated division of mutated cells.
  • Progression: Tumor cells become aggressive and compete for resources.
• Mutation Timing: Early mutations lead to malignant tumors; late mutations lead to benign tumors.

Differences Between Benign and Malignant Tumors

• Benign Tumors:
  • Look like normal tissue cells, may overproduce hormones, encapsulated, non-invasive.
• Malignant Tumors:
  • Lack clear boundaries, invade tissues, mutate rapidly, can metastasize.
  • Produce telomerase, allowing endless division.

Metastasis

• Pathways: Circulatory, lymphatic systems, accidental transplantation, and local spread.
• Survival Needs: Compete for resources, attract blood supply.

Manifestations of Cancer

• Organ Function Changes: Damage, inflammation, failure.
• Paraneoplastic Syndrome: Consequences of hormone secretion by tumors.
• Bone Marrow Suppression: Reduced red/white blood cells, platelets.
• Local Effects: Compression, bleeding, pain.
• Cancer Cachexia: Weight loss, weakness.
• Immune System Suppression: Due to bone marrow impact.

Treatment Considerations

• Targeted Therapies: Based on tumor characteristics, like growth factor receptor blocking.
• Challenges: Tumor cells mutate and can become resistant to treatments.

Warning Signs of Cancer

• Adults: CAUTION acronym (Change in habits, A sore, Unusual bleeding, etc.).
• Children: CHILDREN acronym (Continued weight loss, Headaches, Swelling, etc.).

Treatment Case Studies

• Tamoxifen: Anti-estrogen, effective if estrogen receptor overproduction is the issue.
• Antibody Therapy: Targeted delivery of toxins to tumor cells.
• Surgical and Radiation: Removal of tumor followed by localized treatment.