Cell Cycle and Cancer Biology

Normal Cell Cycle

• Cells have different division rates depending on their type.
  • Permanent cells, such as neurons and cardiac muscle cells, are out of the cell cycle.
  • Stable cells, such as liver and kidney cells, are dormant or resting in the G0 phase.
  • Labile cells, including GIT cells, skin, endometrium, and blood cells, are continuously dividing.
• The cell cycle consists of four phases:
  • G0: Dormant or resting phase.
  • G1: Normal cell activities.
  • S: DNA synthesis.
  • G2: Pre-mitotic phase, synthesizes protein and prepares for cellular division.
  • M: Mitotic phase (IPMAT: Interphase, Prophase, Metaphase, Anaphase, Telophase)

Proposed Molecular Cause of Cancer

• Cancer may be caused by changes in DNA structure, altered DNA function, cellular aberration, cellular death, and neoplastic change.
• Proto-oncogenes and anti-oncogenes play a critical role in regulating cell growth and division.

Etiology of Cancer

• Physical agents like radiation, exposure to irritants, sunlight, altitude, and humidity can cause cancer.
• Chemical agents: smoking, dietary ingredients, drugs, and industrial compounds are associated with cancer development.
• Genetics and Family History: Colon cancer and premenopausal breast cancer have a familial predisposition.
• Dietary Habits: Low-fiber, high-fat, processed foods, and alcohol consumption are risk factors for certain cancers.
• Viruses and Bacteria: DNA viruses (Hepatitis B, Herpes, EBV, CMV, Papilloma Virus), RNA viruses (HIV, HTCLV) and bacteria (H. pylori) can contribute to cancer.
• Hormonal Agents: DES (Diethylstillbestrol) is associated with certain cancers.
• Immune Disease: AIDS is a risk factor for various cancers.

Carcinogenesis/Oncogenesis

• Malignant transformation is a process that encompasses initiation, promotion, and progression.
• Initiation: Carcinogens alter the DNA of cells, leading to either cell death or repair.
• Promotion: Repeated exposure to carcinogens leads to abnormal gene expression and a latent period.
• Progression: This irreversible stage involves neoplastic transformation and the development of malignancy.

Pathogenesis of Cancer

• Cellular transformation and derangement theory: Cancer arises from changes in cell behavior and structure.
• Failure of the immune response theory: The immune system's inability to recognize and destroy cancerous cells allows cancer to develop.

Spread of Cancer

• Lymphatic spread: The most common way cancer spreads, involving lymphatic vessels.
• Hematogenous spread: Cancer cells travel through the bloodstream, commonly affecting the liver and lungs.
• Direct spread: Cancer cells spread directly to adjacent tissues through seeding.

Body Defenses Against Tumor

• The Cytotoxic T cells are lymphocytes that directly kill tumor cells
• B cells can produce antibody molecules to target cancer cells
• The T-N-M system is used to stage cancer.

TNM Staging System

• T - Tumor Size:
  • T0: No evidence of primary tumor.
  • T1, T2, T3, T4: Increasing size of the primary tumor.
  • Tis: Carcinoma in situ (cancer cells are confined to the original location).
• N - Lymph Node Involvement:
  • N0: No regional lymph node involvement.
  • N1, N2, N3: Increasing involvement of regional lymph nodes.
• M - Distant Metastasis:
  • M0: No distant metastasis.
  • M1, M2, M3: Presence of distant metastasis.

Cancer Grading

• Grade 1: Well-differentiated cells (resemble normal cells).
• Grade 2: Moderately well-differentiated cells.
• Grade 3: Poorly differentiated cells.
• Grade 4: Very poorly differentiated cells (hard to distinguish from normal cells).

Laboratory Tests for Cancer

• Circulating Tumor Cell (CTC) Test: Used to monitor metastatic breast, colorectal, and prostate cancers.
• Complete Blood Count (CBC) Test: Measures the number of blood cells in the bloodstream.
• Flow Cytometry: Diagnoses and classifies certain cancers, such as leukemia and lymphoma, and evaluates the risk of recurrence.
• MammaPrint Test: Determines the risk of breast cancer recurrence.
• BluePrint Test: Identifies the specific mutations driving cancer behavior and aids in treatment decisions.

Imaging Tests Used to Detect Cancer

• Ultrasonography: Uses high-frequency sound waves to create images of internal tissues and organs.
• Magnetic Resonance Imaging (MRI): Provides detailed images of anatomy and physiological processes by using strong magnetic fields and radio waves.
• Computerized Tomography Scan (CT Scan): Uses X-rays and computer technology to create cross-sectional images of the body.
• Esophagogastroduodenoscopy (EGD): An invasive procedure to visualize the upper gastrointestinal (GI) tract, obtain a biopsy, or treat gastrointestinal conditions.
• Positron Emission Tomography (PET): A functional imaging technique that uses radioactive substances to visualize and measure metabolic changes in the body.

Treatment for Cancer

• Surgery:
  • Curative surgery: Aims to completely remove the cancer.
  • Radical surgery: Wider tissue removal than curative surgery.
  • Palliative surgery: To relieve complications of cancer and improve quality of life.
  • Reconstructive surgery: May follow curative or radical surgery to improve function or cosmetic appearance.
• Radiation Therapy:
  • External RT (Teletherapy, DXT): Radiation delivered from a machine outside the body.
  • Internal RT (Brachytherapy): Radioactive sources placed inside the body.
• Biotherapy: Utilizes biological response modifiers (BRMs) to stimulate the immune system to fight cancer.
  • Hematopoietic Growth Factors (Ex. Erythropoietin, Neupogen, Neumega): Stimulate the production of blood cells.
  • Monoclonal Antibodies (MoAbs): Targeted therapy that binds to specific antigens on cancer cells.
  • Bone Marrow Transplantation: Used to replace damaged bone marrow with healthy cells..

Nursing Management in Cancer Care

• Pre-Surgical Nursing:
  • Provide education and emotional support to the patient and family.
  • Assess patient and family needs for coping mechanisms.
  • Encourage active participation in decision-making, if possible.
  • Answer questions regarding diagnostic tests and surgical procedures.
• Post-Surgical Nursing:
  • Monitor for complications, such as infection, bleeding, wound dehiscence, fluid and electrolyte imbalance, and organ dysfunction.
  • Provide comfort measures.
  • Educate the patient on wound care, activity restrictions, nutrition, and medication information.

Radiation Therapy Nursing Considerations

• Sealed Source IRI:
  • Client's back should be turned towards the door.
  • Encourage the client to turn to sides at regular intervals.
  • Complete bed rest is necessary during the procedure.
  • Enema and low-fiber diet are recommended before the procedure.
  • Foley catheter should be in place.
  • Long forceps and a lead container must be readily accessible.
• External Radiation Therapy:
  • Inform patients that radiation therapy is painless.
  • Address grieving related to loss of health, income, sexuality, and body image.
  • Answer questions about cancer and treatment options.
  • Identify and refer to support groups.

Management of Complications (Radiation Therapy)

• Infection:
  • Fever (above 38.3°C) is a significant indicator.
  • Administer prescribed antibiotics for two weeks.
  • Maintain aseptic technique.
  • Avoid exposure to crowds.
  • Avoid fresh fruits and vegetables.
  • Practice frequent handwashing.
  • Limit invasive procedures.
• Septic Shock:
  • Monitor vital signs closely.
  • Administer fluids and medications as prescribed.
  • Prepare for possible vasopressors and antibiotics.
• Bleeding:
  • Monitor for signs and symptoms of bleeding.
  • Apply pressure to the bleeding site.
  • Elevate the affected area.
  • Administer blood transfusions, if necessary.
  • Limit invasive procedures as much as possible.

Psychosocial Aspects of Cancer Care

• Provide support to both the patient and their family.
• Promote positive self-concept.
• Facilitate coping with the cancer experience.