Neoplasia: Characteristics, Growth, and Treatment

• Neoplasia is the study of tumors

Components of Tissue Renewal and Repair

• Cell proliferation involves cell division and an adaptive mechanism to replace body cells
• Cell differentiation is a specialization process where new cells gain the structure and function of the cells they replace
• Apoptosis is the programmed cell death that eliminates unwanted cells

Genes Controlling Cell Growth and Replication

• Protooncogenes are genes that promote cell growth
• Tumor suppressor genes control programmed cell death, also known as apoptosis
• Genes regulate the repair of damaged DNA
• Cancer development occurs when growth-promoting oncogenes are activated, tumor suppressor genes are inactivated, and genes controlling apoptosis are altered

Characteristics of Cancer

• Neoplasms exhibit autonomy and anaplasia
• Autonomy refers to the unregulated proliferation of the neoplasm
• Anaplasia refers to the loss of cell differentiation and, therefore, the loss of cell function; the greater the anaplasia, the more aggressive the tumor
• Neoplasms lack cell-to-cell communication that can lead to unrestricted growth
• Neoplasms can cause increased energy expenditure which deprives unaffected cells of nutrients
• Increased motility and loss of cohesion/adhesion promotes movement to other locations
• Rapid angiogenesis is the development of new blood vessels that provide extensive blood flow to tumor cells
• Substance secretion alters the metabolism and degrades neighboring unaffected cells
• The presence of foreign antigens on the cancer cell surface can trigger an immune response

Characteristics of Benign Neoplasms

• Benign neoplasms grow at a slow, progressive rate, potentially reaching a standstill or regressing.
• Benign neoplasms exhibit an expansive manner of growth.
• Benign neoplasms are unable to metastasize to distant sites.
• Benign neoplasms are composed of well-differentiated cells that resemble the cells of the tissue of origin.

Characteristics of Malignant Neoplasms

• Malignant neoplasms grow rapidly and spread widely
• Malignant neoplasms have the potential to kill, regardless of their original location
• Malignant neoplasms compress blood vessels and outgrow their blood supply, which can lead to ischemia and tissue necrosis
• Malignant neoplasms rob normal tissues of essential nutrients
• Malignant neoplasms liberate enzymes and toxins that destroy tumor tissue and normal tissue

Ways to Differentiate Between Benign and Malignant Neoplasms

• Cell characteristics differ
• Manner of growth changes
• Rate of growth can be indicative
• Metastasis potential is important
• Tendency to cause tissue damage varies
• Capacity to cause death

Mechanisms for Cancer Spread

• Local spread
• Direct extension and seeding
• Metastatic spread through the blood or lymph pathways

Factors Influencing Tumor Growth

• The growth of tumors is affected by the number of cells actively dividing or moving through the cell cycle
• The duration of the cell cycle is important
• The balance between the number of new cells and those being lost impacts growth
• Growth fraction, the ratio of dividing cells to resting cells in a tissue mass, is influential
• Doubling time, the duration for the total mass of tumor cells to double, affects tumor size

Host and Environmental Factors Leading to Cancer

• Heredity can predispose individuals to certain cancers
• Hormones can influence the development and progression of some cancers
• Carcinogens, including chemical and radiation exposure, are significant risk factors
• Oncogenic viruses are capable of inducing cancer
• Immunologic mechanisms play a role in cancer development and progression

Cancer Classifications

• The TNM (Tumor, Node, Metastasis) system is used for pathologic staging
• TX: Primary tumor cannot be evaluated
• T0: No evidence of primary tumor
• Tis: Carcinoma in situ (has not spread)
• T1-T4: Size and/or extent of the primary tumor
• NX: Regional lymph nodes cannot be evaluated
• N0: No regional lymph node involvement
• N1-N3: Involvement of regional lymph nodes
• MX: Distant metastasis cannot be evaluated
• M0: No distant metastasis
• M1: Distant metastasis to distant parts of the body
• Tumor staging ranges from I through IV with higher numeric stages indicating greater tumor size and spread
• Cytologic/histologic grading of tumors looks at the degree of differentiation and the number of proliferating cells
• Grade I neoplasms are well differentiated, while Grade IV are poorly differentiated and display marked anaplasia.

Stages of Invasive Breast Cancer

• Stage 0: Non-invasive cancer in ducts or lobules, not spread to surrounding tissue
• Stage I: Invasive cancer in normal breast tissue, has two substages
• Stage IA: Small tumor, not spread to the lymph node
• Stage IB: Tumor in lymph nodes and may be in breast tissue, less than 2 cm
• Stage II: Invasive cancer, with two substages
• Stage IIA: 2cm or smaller in the breast, but cancer cells spread to 1 to 3 lymph nodes
• Stage IIB: 2 to 5 cm and spread to 1 to 3 axillary lymph nodes
• Stage III: Invasive cancer is divided into three types
• Stage IIIA: Spread to 4 to 9 lymph nodes or larger than 5cm, spread to 1-3 lymph nodes
• Stage IIIB: Any size and the disease has spread to the chest wall
• Stage IIIC: Any size with spread to 10 or more lymph nodes, spread to other organs
• Stage IV (metastatic:) spread to other organs and tissues

Clinical Manifestations of Cancer

• Tissue integrity is compromised through compressed and eroded blood vessels, ulceration, necrosis, and bleeding
• Cancer cachexia leads to weight loss and wasting of body fat and muscle tissue, causing profound weakness, anorexia, and anemia
• Paraneoplastic syndromes involve inappropriate hormone release, circulating hematopoietic, neurological, and dermatological factors

Diagnostic Measures for Cancer Detection

• Lab tests, including Pap smears and tumor markers
• Biopsy and cytologic studies
• Endoscopic examinations
• Ultrasound, X-ray studies (MRI, CT, and PET scans)
• Screening for early detection
• Observation and palpation for physical signs
• Staging and grading of tumors

Goals of Cancer Treatment

• Curative
• Control
• Palliative

Cancer Treatment Modalities

• Surgery
• Radiation
• Hormonal therapy
• Targeted therapy
• Biotherapy (immunotherapy, biologic response)
• Chemotherapy (direct and indirect DNA-interacting, cell cycle-specific, cell cycle-nonspecific)

Stem Cells

• Stem cells are reserve cells that remain quiescent until the need for cell replenishment
• When a stem cell divides, one daughter cell retains the stem cell characteristics, and the other becomes a progenitor cell
• Stem cells can self-renew
• Stem cells have potency

Cancer Cell Differentiation

• Cancer cells: characterized by abnormal and rapid proliferation and loss of differentiation
• Anaplasia: describes this lack of differentiation
• Cytologic/histologic grading: is based on differentiation and proliferation rate
• The closer the tumor cells resemble normal tissue, functionally and morphologically, the lower the grade
• Grades range from I to IV, where I is well-differentiated, and grade IV is poorly differentiated with marked anaplasia

Oncologic Emergencies

• Syndrome of Inappropriate Antidiuretic Hormone (SIADH)
• Hypercalcemia
• Superior Vena Cava Syndrome
• Hematologic Disorders (anemia, DIC)
• Sepsis
• Tumor Lysis Syndrome

Stem Cell Transplant

• Stem Cell Mobilization: Stimulate the body to move more stem cells into the blood
• Collection of Stem Cells: Collect patient’s stem cells from blood
• Processing: Blood is processed through a machine to remove and freeze the stem cells
• Conditioning and Treatment: High-dose chemotherapy is performed to destroy the tumor cells
• Reinfusion Into Patient: The stem cells are thawed and infused back into the patient

Radiation Therapy

• Uses high-energy particles or waves to destroy or damage cancer cells
• Absorption of energy from radiation leads to ionization of molecules or creation of free radicals
• Free radicals damage cell structures.
• Interrupts cell cycle, kills cells, or damages DNA in cells
• Must produce double-stranded breaks in DNA to effectively kill cells
• Can negatively affect normal, fast growing tissue
• Tissues most affected include the skin, the gastrointestinal tract's mucosal lining, and bone marrow

Chemotherapy

• Direct DNA-interacting agents include alkylating agents, antitumor antibiotics, and topoisomerase inhibitors.
• Alkylating agents exert cytotoxic effects by transferring their alkyl group to many cellular constituents
• Indirect DNA-interacting agents include antimetabolites and mitotic spindle inhibitors.
• The antimetabolites (folic acid antagonists and purine and pyrimidine antagonists) interrupt biochemical pathways for nucleotide and nucleic acid synthesis
• Cell cycle specific impacts in a specific phase of the cell cycle
• Cell cycle non-specific is effective throughout all phases of the cell cycle

Biotherapy

• Biotherapy uses immunotherapy and biologic response modifiers as means of changing the person's own immune response to cancer
• The major mechanisms by which biotherapy exerts its effects are modifications of host responses or tumor cell biology

Targeted Therapy

• Uses drugs that selectively attack malignant cells without causing harm to normal cells
• Focuses on altered molecules and signaling pathways that allow cancer cells to grow and spread in an uncontrolled manner
• Targeted therapies block specific enzymes and growth factors involved in cancer cell growth

Explore neoplasia, including autonomy, anaplasia, and the characteristics of cancer. Differentiate between benign and malignant neoplasms, focusing on growth rate and metastasis. Also, learn cancer treatment options.