Human Diseases: A Systemic Approach - Cancer Study Notes
Copyright Information
Source: Human Diseases: A Systemic Approach, 8/e by Zelman | Raymond | Holdaway | Dafnis | Mulvihill
Copyright: © 2015, 2011 by Pearson Education, Inc. All Rights Reserved
Chapter Overview
Chapter Theme: Cancer
Objectives of the Chapter
Define basic cancer terminology
Compare benign and malignant tumors
Explain how benign and malignant tumors are named
Identify known risk factors for cancer
Describe the etiology of cancer
Describe how cancer is diagnosed
Describe how cancer is treated
Describe how cancer can be prevented
Introduction to Cancer
Description: Cancer is characterized by uncontrolled growth of abnormal cells.
Metastasis: The process by which cancer spreads from one part of the body to another.
Epidemiology: The study of how diseases affect the health and illness of populations.
Statistical Data on Cancer (2013/2012)
Leading Sites of New Cases of Cancer in the United States (Refer to Table 4-1).
Leading Sites of Cancer Deaths in the United States (Refer to Table 4-2).
Leading Sites of New Cases of Cancer Worldwide (Refer to Table 4-3).
Types of Tumors
Benign Tumor
Organized growth of cells: Cells grow in a controlled manner.
Growth by expansion: Benign tumors grow locally without invading neighboring tissues.
Retained cellular characteristics: Cells in benign tumors look similar to normal cells of their origin.
Non-invasive: They do not invade other tissues or organs.
Encapsulated: Encased by fibrous connective tissue, making them easier to remove surgically.
Malignant Tumor
Uncontrolled growth of cells: Unlike benign tumors, malignant tumors proliferate uncontrollably.
Growth by invasion: Malignant tumors invade surrounding tissues and organs.
Loss of cellular characteristics: Cancer cells may look significantly different from normal cells.
Metastatic potential: Malignant cells can spread to different parts of the body through blood and lymphatic systems.
Tumor Formation
Tumor (Neoplasm): An abnormal growth of tissue. Can be benign or malignant.
Tumor Nomenclature
Naming: Tumors are classified based on the type of tissue from which they arise.
Benign tumors: Usually have the suffix “-oma” with the organ name as the root.
Carcinomas: Cancers derived from epithelial cells (e.g., breast, prostate, lung, colon cancers).
Sarcomas: Cancers derived from connective tissues such as bone, cartilage, nerves, and fat.
Leukemias: Cancers that arise from blood-forming tissues, affecting blood cells.
Lymphomas: Cancers of the lymphatic system.
Blastomas: Cancers from immature precursor cells or embryonic tissue.
Known Risk Factors for Cancer
Age: Older age increases the risk of developing cancer.
Tobacco Use: Leading cause of various cancer types and cancer deaths.
Infections: Certain infections can increase cancer risk (e.g., HPV, HIV).
Radiation: Exposure to high-energy radiation can damage DNA and contribute to cancer development.
Immunosuppressive Medications: Lowered immune function can hinder the body's ability to fight cancer.
Alcohol: Consumption linked to cancers of the mouth, throat, esophagus, liver, and breast.
Carcinogens: Environmental exposures leading to DNA damage may cause cancers.
Chronic Inflammation: Conditions such as inflammatory bowel diseases are associated with higher cancer risk.
Diet: Certain dietary components have been linked to changes in cancer risk.
Hormones: Estrogens are considered carcinogenic and associated with increased risk of breast and endometrial cancers.
Obesity: Associated with increased risks for breast, colon, rectum, and endometrial cancers.
Sunlight: UV radiation exposure can lead to skin cancer.
Signs and Symptoms of Cancer
Signs and Symptoms depend on:
Location: Where the cancer is situated in the body.
Size: Size of the tumor impact on surrounding tissues.
Extent of tissue involvement: How much tissue is affected.
Metastasis: Symptoms may appear in various parts of the body if the cancer has spread.
General Signs
Unexplained weight loss
Fever
Fatigue
Pain
Skin changes
Change in bowel or bladder function
Sores that do not heal
Unusual bleeding or discharge
Thickening or lump in the breast or other body parts
Indigestion or trouble swallowing
Recent changes in a wart or mole
Nagging cough or hoarseness
Leukoplakia
Etiology of Cancer
Cancer etiology is complex and puzzles researchers. It’s partially explained by:
Genetics:
Mutations in specific genes lead to abnormal cell behavior.
Oncogenes promote cell growth; mutations cause uncontrolled growth.
Tumor Suppressor Genes prevent cancer; mutations can lead to loss of protective functions.
DNA Repair Genes correct DNA mistakes; their mutations can lead to cancer.
Lifestyle: Lifestyle choices can influence cancer risk.
Environmental Factors: Environmental exposure can lead to gene mutations and increased cancer risk.
Mutations: Genetic changes that occur either inherited or acquired can lead to cancer development.
Carcinogens: Substances causing cancer by altering DNA.
Diagnosis of Cancer
Blood Tests: Identifying tumor markers or abnormalities in blood composition.
Diagnostic Imaging: Techniques used to visualize inside the body.
Radiography: Standard X-ray imaging.
CT (Computed Tomography): Cross-sectional imaging for detailed view.
MRI (Magnetic Resonance Imaging): Imaging using magnetic fields.
Ultrasonography: Using sound waves for imaging.
Biopsy: Taking a tissue sample for histological examination.
Cancer diagnosis process involves:
Detailed personal history.
Family medical history.
Physical examination.
Imaging tests as outlined above.
Cancer Grading and Staging
Grading
Definition: Assess the degree of abnormality of cancerous tissues, predicting behavior and prognosis.
Scale: Ranges from 1 to 4, with 4 being the most abnormal.
Staging
Definition: Determine the extent of cancer progression and formulating treatment plans.
TNM Classification System:
T: Size of the primary tumor and invasion extent.
N: Regional lymph node involvement.
M: Presence of distant metastasis.
Cancer Treatment Modalities
Surgery
Purpose: Diagnosis, staging, treatment, preventive measure.
Types:
Staging Surgery: Assess cancer amount and spread.
Curative Surgery: Targeted to localized cancer.
Debulking Surgery: Reduces tumor mass, not complete removal.
Palliative Surgery: Alleviates symptoms caused by cancer.
Reconstructive Surgery: Restores functionality and appearance after major surgery.
Preventive Surgery: Removal of tissues at risk of cancer.
Radiotherapy (Radiation Therapy)
Approach: Destroys cancer cells via DNA damage.
Application: Specific to tumors, often combined with surgery or chemotherapy.
Common Side Effects: Include fatigue, nausea, hair loss, changes in blood cell counts.
Chemotherapy
Mechanism: Targets and disrupts cancer cell division across the body.
Drugs: Utilizes single or combination drugs optimizing treatment to spare normal cells.
Side Effects: Include fatigue, infection risk, gastrointestinal issues, hair loss, and potential neurological impact.
Targeted Therapy
Description: Focuses on specific cancer cell characteristics aiming to spare normal cells.
Mechanism: Blocks growth signals, targets cellular mutations, or enhances immune response.
Immunotherapy
Approach: Engages the patient’s immune system against cancer cells.
Mechanism: Enhance immune response through proteins or specialized antibodies.
Types: Includes monoclonal antibodies (both naked and conjugated), cancer vaccines.
Cancer Prevention Strategies
Avoid tobacco use.
Maintain a healthy weight.
Engage in regular physical activity.
Adopt a healthy diet.
Limit alcohol consumption.
Protect skin from excessive sun exposure.
Stay up to date with immunizations.
Avoid risky behaviors that could lead to infections.
Seek regular cancer screenings for early detection.