Neoplasms and Cancer

Chapter 20: Neoplasms and Cancer

I. Overview of Normal Cells

• Components of a cell include:
  • Plasma (cell) membrane
  • Nucleus and nucleolus
  • Structures within the cytoplasm:
  • Rough endoplasmic reticulum
  • Free ribosomes
  • Mitochondria
  • Golgi complexes
  • Lysosomes

II. Oncology

• Definition: The study of cancer.
• Includes:
  • Diagnosis
  • Treatment
  • Prevention

III. Neoplasms

• Definition of Neoplasm/Tumor:
  • A cellular growth that no longer responds to normal genetic controls, continuing to reproduce without the typical need for such processes.
  • Deprives neighboring cells of nutrition.
  • May consist of atypical or immature cells.
  • Tumor characteristics are dependent on:
  • The type of cell from which the tumor arises
  • The unique structure and growth pattern.

IV. Nomenclature of Tumors

• Benign tumors:
  • Named using the tissue name + the suffix -oma (e.g., adenoma).
• Malignant tumors (cancers):
  • Named using the tissue name + the suffix -carcinoma (e.g., adenocarcinoma).
• Connective tissue tumors are typically called sarcomas, which are often malignant.
• Notable unique names for malignant tumors:
  • Hodgkin’s disease
  • Wilms’ tumor
  • Leukemia

V. Tumor Characteristics

A. Benign Tumors

• Features:
  • Typically differentiated cells that reproduce at a higher rate than normal.
  • Encapsulated by fibrous tissue.
• Tissue damage occurs primarily due to compression of adjacent structures, which can be life-threatening (e.g., in the brain).

B. Malignant Tumors

• Features:
  • Composed of undifferentiated, nonfunctional cells.
  • Undergo rapid and abnormal reproduction (increased mitosis with atypical figures).
  • Infiltrate or spread into surrounding tissues.
  • May metastasize to distant sites.

VI. Comparison Table: Characteristics of Benign vs. Malignant Tumors

TABLE 20-2

VII. Characteristics of Malignant Tumors

• Lack control of mitosis; do not undergo apoptosis.
• Exhibit no normal organization or differentiation.
• Show no contact inhibition.
• Possess abnormal cell membranes and altered surface antigens.
• Cells do not adhere to one another, leading to invasion of other tissues and potential spread to distant sites.

VIII. Warning Signs of Cancer

1. Unusual bleeding or discharge from any body part.
2. Change in bowel or bladder habits (prolonged diarrhea or discomfort).
3. Change in a wart or mole (color, size, or shape).
4. A sore that does not heal (on skin or in mouth).
5. Unexplained weight loss.
6. Anemia or low hemoglobin, leading to persistent fatigue.
7. Persistent cough or hoarseness without apparent reason.
8. A solid lump, often painless, found somewhere in the body (breast or testes).

IX. Local Effects of Tumors

• Pain:
  • Often absent until advanced stages; severity varies based on tumor type.
• Obstruction:
  • Can obstruct ducts or passageways, restricting blood supply or lymphatic flow (e.g., digestive tract, airflow in bronchi).
• Tissue necrosis and ulceration:
  • May lead to bleeding or infection around the tumor.

X. Systemic Effects of Malignant Tumors

A. Weight Loss and Cachexia

• Symptoms include anorexia, fatigue, and increased stress on the body.

B. Anemia

• Resulting from blood loss at the tumor site or reduced hemoglobin synthesis due to nutritional deficits.

C. Severe Fatigue

• Caused by inflammatory changes, cachexia, and anemia, along with treatment stress and psychological factors.

D. Effusions

• Inflammation may lead to fluid buildup in body cavities.

E. Infections

• Common as body resistance declines.

F. Bleeding

• Erosion of blood vessels by tumor cells may cause excessive bleeding.

G. Paraneoplastic Syndrome

• Certain tumors release substances affecting neurological function or have hormonal impacts.

XI. Diagnostic Tests

A. Routine Screening

• Essential for early detection and post-treatment monitoring for recurrent tumors.

B. Self-Examination

• Important for early detection (e.g., breast, testicular, and skin checks).

C. Blood Tests

• Monitor blood cell levels; can detect tumor markers (e.g. PSA test).

D. Imaging Techniques

• Radiographic methods, ultrasound, MRI, and CT scans visualize tissue changes.

E. Cytological Tests

• Histological and cytological examinations determine differentiation degree and tumor type; may assess growth promoter sensitivities.

F. Tumor Markers

• Substances produced by some neoplastic cells used for screening high-risk individuals.

G. Genomic Tumor Assessment

• Identifies genetic mutations occurring only with the disease, independent of heredity.

XII. Spread of Malignant Tumors

A. Invasion

• Local spread of tumor cells into adjacent tissues (e.g., uterine carcinoma invading the vagina).

B. Metastasis

• Spread via blood, lymph, or other body fluids to distant sites (e.g., colon carcinoma spreading to the liver).

XIII. Staging Cancer

• Essential for standardizing treatment studies and estimating prognosis.
• TMN system is most common:
  • T: Size of primary tumor
  • N: Involvement of regional lymph nodes
  • M: Spread (metastasis) of tumor

XIV. Carcinogenesis

• The process by which normal cells are transformed into cancer cells, characterized as:
  • Multifactorial disease influenced by environmental effects, hereditary gene expression changes, and infections (e.g., cervical and hepatic cancers).
  • Some cancers have well-established risk factors.

XV. Stages in Carcinogenesis

• Initiating factors: Procarcinogens cause irreversible changes in cellular DNA but do not create active neoplasms.
• Exposure to promoters (hormones, environmental chemicals) leads to DNA changes, less differentiation, higher mitosis rates, and potential tumor development.

XVI. Risk Factors for Cancer

A. Genetic Factors

• Oncogenes regulate cell growth.

B. Viruses

• Oncoviruses can alter the host cell's DNA.

C. Radiation

• Ultraviolet rays, X-rays, gamma rays, and radioactive isotopes increase risk with higher cumulative exposure.

D. Chemicals

• Organic solvents, asbestos, heavy metals, formaldehyde, and chemotherapy agents.

E. Biological Factors

• Chronic irritation and inflammation, age, diet, and hormones.

XVII. Risk Reduction Measures

• Limit UV exposure from the sun/tanning booths.
• Engage in regular medical and dental check-ups.
• Emphasize self-examination routines.
• Maintain a healthy diet (increase fiber, reduce fats, consume 5-10 servings of fresh fruits and vegetables for antioxidants).

XVIII. Immunity and Cancer Risk

• Cell-mediated immunity can recognize and destroy some tumor cells.
• Vaccination for cervical cancer and hepatitis recommended to reduce infection-related cancer risk.

XIX. Treatment of Cancer

• Treatment methods depend on the specific type of cancer and may include:
  • Surgery
  • Chemotherapy
  • Immunotherapy
  • Radiation
  • Combination of therapies

XX. Surgery

• Removal of tumor and surrounding tissue, which may be done laparoscopically for reduced tissue damage and improved recovery.
• Adequate surrounding tissue removal may influence function.
  • Radiofrequency ablation (RFA) as an alternative for small tumors.

XXI. Radiation Therapy

A. Overview

• Can be used alone or with other therapies, inducing mutations or alterations to target DNA, particularly effective against rapidly dividing cells.

B. Administration Methods

1. External sources (e.g., cobalt machine).
2. Internal insertion of radioactive material at the tumor site.
3. Injection of radioisotope solutions into a body cavity, with close monitoring for leakage.

XXII. Adverse Effects of Radiation

• Bone marrow depression (risk of infection, fatigue, bleeding).
• Epithelial cell damage (affecting blood vessels and skin; hair loss).
• Infertility (due to abdominal radiation).
• General fatigue and lethargy.

XXIII. Chemotherapy

• Usage of antineoplastic drugs alone or combined with other treatments.
• Typical regimens involve 2-4 drugs administered at regular intervals.
• Classifications:
  • Antimitotics
  • Antimetabolites
  • Alkylating agents
  • Antibiotics
• Acts by hindering protein synthesis and/or DNA replication.

XXIV. Cell Cycle and Chemotherapy

• Interventions targeting specific cell cycle phases illustrated:
  • G₁, S, G₂, M phases represented in the context of various drugs (e.g., doxorubicin, vinblastine).

XXV. Adverse Effects of Chemotherapy

A. Blood and Bone Marrow Effects

• Blood tests before treatments due to potential bone marrow depression.
• The nadir point refers to the lowest blood cell count following treatment.

B. Other Effects

• Nausea, easily damaged epithelial cells (resulting in hair loss and skin breakdown), and potential damage to specific organs (lungs, heart, kidneys).

XXVI. Other Drugs

• Hormonal blocking agents target growth promoter receptors on cancer cells.
• Biological response modifiers (BRMs) enhance the immune response.
• Angiogenesis inhibitors hinder blood vessel growth.
• Analgesics utilized for pain management.

XXVII. Emerging Therapies

• New drugs like nivolumab emerge, extending survival but not curing cancer; ongoing studies to determine effectiveness.

XXVIII. Gene Therapy

• Experimental treatment designed to:
  • Replace mutated genes.
  • Inactivate mutated genes.
  • Introduce healthy genes into cells.

XXIX. Nutrition

• Patients with advanced cancer often face malnutrition due to:
  • Changes in taste, anorexia, treatment-induced vomiting/diarrhea, and malabsorption from inflammation.

XXX. Complementary Therapies

• Include massage, meditation, counseling, exercise, and therapeutic touch.
• Lack of research on raw food diets and insulin/glucose use with chemotherapy suggests moderation in recommendations.

XXXI. Prognosis

• Cancer-free state typically defined as 5-year survival without recurrence; some cancers may be considered cured after 10 years of cancer-free status.
• Remission indicates no clinical signs of cancer.
• Life expectancy and death rates vary by cancer type.

XXXII. Examples of Malignant Tumors

• Skin cancer: Generally visible, easy to diagnose and treat; excellent prognosis except for malignant melanoma.
• Ovarian cancer: Hidden nature leads to poor prognosis and high mortality.
• Brain tumors: Both benign and malignant can be life-threatening due to brain compression; primary tumors are often fatal with no metastasis.

XXXIII. Cancer Incidence

• Most common cancers:
  • Men: Prostate, lung, colorectal.
  • Women: Breast, lung, colorectal.