8.3 Treatments and Nutrition

Cancer is a complex disease characterized by uncontrolled cell growth and division. It develops through genetic mutations, which can be inherited or acquired through environmental factors. Understanding the process of cancer development is crucial for effective diagnosis and treatment.

Cancer therapy involves multiple phases, from diagnosis and staging to various treatment modalities. These include surgery, radiation therapy, chemotherapy, targeted therapy, and immunotherapy. Each approach plays a unique role in combating cancer, often used in combination for optimal results.

Introduction to Cancer

Process of cancer development

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• Cancer develops from genetic mutations in normal cells causing uncontrolled growth and division
  • Mutations can be inherited (passed down from parents) or acquired through environmental factors (exposure to carcinogens)
  • Accumulation of multiple mutations over time leads to the transformation of normal cells into cancerous cells
• Key characteristics of cancer cells enable them to grow and spread uncontrollably
  • Sustained proliferative signaling allows cancer cells to continuously divide and multiply
  • Evasion of growth suppressors enables cancer cells to bypass normal cellular control mechanisms that limit cell division
  • Resistance to cell death (apoptosis) allows cancer cells to survive and accumulate despite damage or stress
  • Induction of angiogenesis involves the formation of new blood vessels to supply oxygen and nutrients to the growing tumor
  • Activation of invasion and metastasis enables cancer cells to spread from the primary tumor site to other parts of the body
  • Replicative immortality allows cancer cells to divide indefinitely without undergoing senescence or cell death

Genetic vs environmental cancer factors

• Genetic factors contribute to cancer development through inherited mutations
  • Inherited mutations in tumor suppressor genes (BRCA1, BRCA2) increase the risk of developing certain cancers (breast, ovarian)
  • Inherited mutations in proto-oncogenes (RET, PTEN) can lead to the activation of oncogenes and promote cancer growth
  • Family history of specific cancers may indicate the presence of inherited genetic mutations that increase cancer risk
• Environmental factors play a significant role in cancer formation
  • Exposure to carcinogens such as tobacco smoke, UV radiation, and asbestos can cause DNA damage and mutations
  • Chronic inflammation resulting from infections (hepatitis B and C, H. pylori) can create a tumor-promoting environment
  • Dietary factors like high-fat diets and low fiber intake may increase the risk of certain cancers (colon, breast)
  • Lifestyle factors such as lack of physical activity and obesity can contribute to the development of various cancers

Types of cancer and features

• Carcinomas originate from epithelial cells and are the most common type of cancer
  • Examples include lung, breast, colon, prostate, and skin cancers
  • Carcinomas can be further classified based on the specific type of epithelial cell (squamous cell carcinoma, adenocarcinoma)
• Sarcomas arise from connective tissues such as bone, cartilage, muscle, and fat
  • Examples include osteosarcoma (bone), liposarcoma (fat), and leiomyosarcoma (smooth muscle)
  • Sarcomas are relatively rare compared to carcinomas
• Leukemias originate in blood-forming tissues (bone marrow) and are characterized by the abnormal production of white blood cells
  • Examples include acute myeloid leukemia (AML) and chronic lymphocytic leukemia (CLL)
  • Leukemias can be classified based on the type of white blood cell affected (myeloid or lymphoid) and the rate of progression (acute or chronic)
• Lymphomas develop from cells of the lymphatic system, such as lymph nodes and the spleen
  • Examples include Hodgkin's lymphoma and non-Hodgkin's lymphoma
  • Lymphomas are characterized by the abnormal growth and accumulation of lymphocytes
• Central nervous system (CNS) tumors arise from brain and spinal cord tissues
  • Examples include gliomas (arise from glial cells), meningiomas (arise from the meninges), and medulloblastomas (arise from the cerebellum)
  • CNS tumors can be benign (non-cancerous) or malignant (cancerous) and are classified based on the specific cell type and location

Tumor Classification and Cell Cycle

• Tumors can be classified as benign or malignant based on their growth characteristics and potential to spread
  • Benign tumors are typically slow-growing, well-differentiated, and remain localized
  • Malignant tumors are characterized by rapid, uncontrolled growth and the ability to invade surrounding tissues and metastasize
• The cell cycle plays a crucial role in cancer development and progression
  • Dysregulation of the cell cycle can lead to uncontrolled cell division and tumor formation
  • DNA repair mechanisms are essential for maintaining genomic stability and preventing cancer-causing mutations
  • Defects in DNA repair pathways can contribute to the accumulation of genetic alterations and cancer development

Phases of Cancer Therapy

Phases of cancer therapy

1. Diagnosis and staging involve identifying the type and extent of cancer to determine the appropriate treatment plan
   • Diagnostic tests may include imaging (CT, MRI, PET scans), biopsy, and blood tests
   • Staging assesses the size and spread of the tumor using the TNM system (Tumor size, lymph Node involvement, Metastasis)
2. Surgery aims to remove the primary tumor and/or affected lymph nodes
   • Surgery can be used for diagnosis (biopsy), staging (assessing the extent of cancer), and treatment (removing the tumor)
   • Types of surgery include lumpectomy (breast cancer), prostatectomy (prostate cancer), and colectomy (colon cancer)
3. Radiation therapy uses high-energy radiation to kill cancer cells and shrink tumors
   • Radiation can be delivered externally (external beam radiation) or internally (brachytherapy)
   • Radiation therapy can be used before, during, or after surgery to improve treatment outcomes
4. Chemotherapy is a systemic treatment that uses drugs to kill rapidly dividing cancer cells throughout the body
   • Chemotherapy drugs can be administered orally, intravenously, or through other routes (intrathecal, intraperitoneal)
   • Chemotherapy can be used as a primary treatment or in combination with other therapies (surgery, radiation)
5. Targeted therapy involves drugs designed to target specific molecules involved in cancer growth and progression
   • Examples include small molecule inhibitors (tyrosine kinase inhibitors) and monoclonal antibodies (trastuzumab for HER2-positive breast cancer)
   • Targeted therapies are more specific than chemotherapy and may have fewer side effects
6. Immunotherapy stimulates the body's immune system to fight cancer cells
   • Examples include immune checkpoint inhibitors (pembrolizumab, nivolumab) and CAR T-cell therapy
   • Immunotherapy can be used alone or in combination with other treatments
7. Hormone therapy is used for cancers that are sensitive to hormones, such as breast and prostate cancers
   • Hormone therapy blocks the production or action of hormones to slow cancer growth
   • Examples include tamoxifen (breast cancer) and leuprolide (prostate cancer)
8. Palliative care focuses on relieving symptoms and improving quality of life for patients with advanced cancer
   • Palliative care can be provided at any stage of cancer treatment and may include pain management, nutritional support, and emotional support
   • Hospice care is a type of palliative care provided to patients with a limited life expectancy (usually less than 6 months)

Additional Treatment Approaches

• Adjuvant therapy is given after primary treatment (such as surgery) to reduce the risk of cancer recurrence
• Neoadjuvant therapy is administered before the primary treatment to shrink tumors and improve surgical outcomes
• The goal of cancer treatment is to achieve remission, where there are no detectable signs of cancer and symptoms are reduced or eliminated