Understanding Cancer: Etiology and Pathophysiology

• Cancer is a group of diseases characterized by uncontrolled and unregulated growth of cells.

Etiology and Pathophysiology

• Defects in cellular proliferation and differentiation can lead to cancer development.
• Protooncogenes are normal cell genes that regulate cell growth and differentiation; mutations can change them into oncogenes, which promote uncontrolled cell growth.
• Tumor suppressor genes regulate cell growth and prevent cells from going through the cell cycle; mutations can make them inactive, resulting in loss of tumor suppression.
• Cancer development is a multistep process involving initiation, promotion, and progression.
• Initiation involves a mutation in the cell’s genetic structure.
• Promotion is characterized by the reversible proliferation of altered cells.
• Progression is the final stage characterized by increased growth rate, invasiveness, and metastasis.
• The immune system can reject or destroy cancer cells through a process called immunological surveillance.
• Cancer cells can evade the immune system by suppressing factors that stimulate T cells, altering surface antigens, or secreting immunosuppressant cytokines.

Classification of Cancer

• Cancers are classified by the tissue of origin (anatomical site), behavior (benign or malignant), and histologic grade (degree of differentiation).
• Carcinomas originate from epithelial tissue.
• Sarcomas originate from connective tissue and muscle.
• Lymphomas and leukemias originate from the hematopoietic system.
• The TNM classification system is used to determine the extent of the disease: T (tumor size and invasion), N (spread to regional lymph nodes), and M (metastasis).
• Cancer stage is based on TNM classifications.
• Grade I tumors differ slightly from normal cells (well differentiated) and Grade IV tumors are immature and undifferentiated.

Metastasis

• Metastasis is the spread of cancer to a distant site.
• Cancer cells can spread through direct extension, lymphatic system, or hematogenous route.
• The most frequent sites of metastasis are lungs, liver, bone, brain, and adrenal glands.

Cancer Prevention and Detection

• Lifestyle habits such as avoiding smoking, excessive sun exposure, maintaining a healthy weight, eating a balanced diet, and regular exercise can reduce the risk of cancer.
• Practice self-examination of the breast or testes.
• Have regular physical examinations.
• Diagnostic tests include:
  • Radiologic studies like x-rays, CT scans, MRI, ultrasound
  • Biopsy
  • Endoscopy
  • Laboratory tests

Cancer Treatment Goals

• Cure: eradicating the cancer
• Control: preventing progression
• Palliation: relief of symptoms

Cancer Treatment Modalities

• Surgery can be used for diagnosis, staging, cure, control, palliation, and rehabilitation.
• Chemotherapy uses drugs to kill cancer cells.
  • Chemotherapy drugs can be administered via various routes, including oral, IV, and regional.
  • Side effects of chemotherapy include myelosuppression, fatigue, nausea and vomiting, mucositis, alopecia, and peripheral neuropathy.
• Radiation therapy uses high-energy radiation to damage or destroy cancer cells.
  • Radiation can be delivered externally (teletherapy) or internally (brachytherapy).
  • Side effects of radiation depend on the treatment site, but common side effects include fatigue, skin reactions, and gastrointestinal disturbances.
• Targeted therapy targets specific cancer cells without harming normal cells.
  • Common targeted therapies include monoclonal antibodies and tyrosine kinase inhibitors.
  • Side effects vary depending on the specific drug but can include skin reactions, diarrhea, and hypertension.
• Immunotherapy boosts the body’s immune system to fight cancer.
  • Immunotherapy includes drugs such as checkpoint inhibitors, cytokines, and cell therapies.
  • Side effects vary but can include fatigue, skin reactions, and autoimmune reactions.
• Hematopoietic stem cell transplantation (HSCT) involves replacing diseased or damaged bone marrow with healthy stem cells.
  • Stem cells can be obtained from the patient (autologous), a donor (allogeneic), or umbilical cord blood.
  • HSCT is used to treat hematologic malignancies.
  • High risk for infection and graft-versus-host disease (GVHD).

Nursing Management

• Assessment: comprehensive history, physical examination, and psychosocial assessment.
• Common nursing diagnoses include risk for infection, fatigue, imbalanced nutrition, pain, and disturbed body image.

Managing Specific Problems

• Superior vena cava syndrome: obstruction of the superior vena cava by a tumor or thrombosis.
• Spinal cord compression: tumor in the epidural space of the spinal cord.
• Third space syndrome: shifting of fluid from the vascular space to the interstitial space.
• Syndrome of inappropriate antidiuretic hormone secretion (SIADH): abnormal production of antidiuretic hormone.
• Hypercalcemia: elevated serum calcium levels.
• Tumor lysis syndrome (TLS): metabolic abnormalities caused by the breakdown of cancer cells.
• Cardiac tamponade: fluid accumulation in the pericardial sac.
• Carotid artery rupture: invasion of the arterial wall by tumor.

Pain Management

• Undertreated cancer pain is a significant problem.
• Pain can be caused by the cancer itself, treatment, or unrelated factors.
• Pain management strategies include pharmacologic and nonpharmacologic interventions.
• Opioid analgesics are commonly used to manage cancer pain.

Nutritional Therapy

• Malnutrition can occur due to cancer or cancer treatment.
• Interventions to improve nutrition include appetite stimulants, antiemetics, and nutritional supplements.
• Patients may need enteral or parenteral nutrition.

Psychologic Support

• Cancer can cause significant emotional distress.
• Interventions include providing information, active listening, and support groups.
• Referrals to mental health professionals.
• Maintaining quality of life is an important goal.

Geriatric Considerations

• Cancer is more common in older adults.
• Treatment decisions should consider the older adult’s overall health status, functional abilities, and preferences.

Explore the etiology and pathophysiology of cancer, including cellular proliferation, oncogenes, and tumor suppressor genes. Learn about the multistep process of cancer development: initiation, promotion, and progression. Understand the role of the immune system.