Cancer Overview and Cell Characteristics

Cancer

• A group of disorders with distinct causes, manifestations, treatments, and prognoses.
• In 2019, the USA diagnosed over 1.7 million new cancer cases.
• Cancer is the 2nd leading cause of death in America.
• The majority of cases (80%) are diagnosed in individuals over 55 years old.
• Lung, breast, and colorectal cancers are the most common in women.
• Men are more likely to develop lung, prostate, and colorectal cancers.

Characteristics of Benign and Malignant Cells

• Benign cells:
  • Resemble normal cells of origin.
  • Grow by expansion and are usually encapsulated.
  • Grow slowly.
  • Do not metastasize.
  • Localized effects.
• Malignant Cells:
  • Undifferentiated and may not resemble normal cells of origin.
  • Invade and infiltrate surrounding tissues.
  • Variable growth rate, with faster growth in anaplastic tumors.
  • Metastasize through the blood and lymphatic systems.
  • Cause generalized effects.

Predisposing Factors

• Age: Older individuals are at higher risk due to longer exposure to carcinogens and altered immune systems.
• Sex: Breast cancer is common in females, while prostate cancer is common in males.
• Urban vs. Rural: Urban dwellers have higher cancer rates due to increased exposure to carcinogens, stressful lifestyles, and preservative consumption.
• Geographic Distribution: Gastric cancer is prevalent in Japan, while breast cancer is dominant in the USA. This may be related to environmental factors like diet and pollution.
• Occupation: Workers in chemical factories, farmers, and radiology personnel have higher risks due to carcinogen exposure.
• Heredity: A positive family history increases cancer risk, with familial basis in approximately 34% of cancers.
• Stress: Depression, grief, and life stresses decrease immunodeficiency, potentially promoting tumor growth.
• Precancerous Lesions: Pigmented moles, burn scars, senile keratosis, and benign polyps increase cancer risk.

Staging and Grading of Neoplasia

• Nomenclature of Neoplasia:
  • Parenchyma: Naming based on tissue of origin (e.g., Hepatoma- liver).
  • Pattern and Structure: Based on gross or microscopic patterns (e.g., Cyst, Adeno, Papillo, Polyp).
  • Embryonic Origin: Based on originating germ layer (e.g., Ectoderm, Endoderm, Mesoderm).
• Benign Tumors: Suffixed with "-OMA" (e.g., LipOMA, osteOMA).
• Malignant Tumors:
  • Ectodermal, endodermal, glandular, epithelial: Suffixed with "-CARCINOMA" (e.g., Pancreatic AdenoCARCINOMA).
  • Mesodermal, connective tissue: Suffixed with "-SARCOMA" (e.g., FibroSARCOMA, MyoSARCOMA).
• Exceptions:
  • Some "-OMA" suffixes denote malignancy (e.g., HepatOMA, LymphOMA, GliOMA, MelanOMA).
  • Tumors from all three germ layers are called "TERATOMA".

Cancer Cell Proliferation

• Effusion: Fluid buildup in serous cavities (e.g., pleural effusion, ascites) due to lymphatic obstruction.
• Ulceration and Necrosis: Tumor erosion of blood vessels and pressure on tissue lead to ischemia, tissue damage, bleeding, and infection.
• Vascular Thrombosis, Embolism, Thrombophlebitis: Abnormal clotting factors produced by tumors can cause pulmonary embolism.

Predisposing Factors/Etiologic Factors

• Cellular Aberrations:
  • Cancer Cell Proliferation: Disrupts normal cell growth and function, leading to:
    • Pressure
    • Obstruction
    • Pain
    • Effusion
    • Ulceration
    • Vascular thrombosis, thrombophlebitis.
  • Paraneoplastic Syndrome: Malignant cells produce enzymes, hormones, and substances that cause:
    • Anemia
    • Hypercalcemia
    • Edema
    • Disseminate Intravascular Coagulation (DIC)
• Anorexia and Cachexia Syndrome: A consequence of unrestrained cancer cell growth, resulting in:
  • Tissue wasting
  • Severe weight loss
  • Severe debilitation

Treatment Modalities

• Surgical Interventions:
  • Diagnostic Surgery: Used for cytologic specimen collection and biopsy.
  • Preventive Surgery: Removal of precancerous lesions or benign tumors (e.g., subtotal colectomies for familial polyposis or ulcerative colitis).
  • Curative Surgery: Removal of the entire tumor and surrounding lymph nodes for localized cancers.
  • Reconstructive Surgery: Improving the appearance and function of affected organs.
  • Palliative Surgery: Relieving distressing signs and symptoms and retarding metastasis to improve quality of life, involving:
    • Pain reduction.
    • Relief of airway obstruction.
    • Relief of obstruction in the GI and GU tracts.
    • Pressure relief in the brain and spinal cord.
    • Prevention of hemorrhage.
    • Removal of infected and ulcerating tumors.
    • Abscess drainage.
• Radiation Therapy:
  • Uses high-energy ionizing radiation to damage DNA and prevent cell reproduction.
  • Primary Therapy: Used as the sole treatment for early-stage cancers (e.g., skin cancer, Hodgkin's disease, cervical carcinoma).
  • Adjuvant Therapy: Pre or postoperative treatment to enhance cancer cell destruction, often used with chemotherapy.
  • Palliative Therapy: Relief of pain, obstruction, fractures, spinal cord compression, and metastases.
  • Rapidly dividing cells (like cancer cells) are more sensitive to radiation.
  • Types of Radiation Therapy:
    • External Radiation Therapy (Teletherapy or DXT): Administered through an X-ray machine.