Neoplasia.

Characteristics of Cancer
Disorder of altered cell differentiation and growth
Results in neoplasia (“new growth”)
Growth is uncoordinated and relatively autonomous
Lacks normal regulatory controls over cell growth and division
Tends to increase in size and grow after stimulus ceases or needs of organism are met
Components of Tissue Renewal and Repair
Cell proliferation
Process of cell division
Inherent adaptive mechanism for replacing body cells
Cell differentiation
Process of specialization
New cells acquire the structure and function of cells they replace
Apoptosis
Form of programmed cell death to eliminate unwanted cells
The Cell Cycle
Definition: The interval between each cell division
Genetic information is duplicated
Duplicated chromosomes are appropriately aligned for distribution between two genetically identical daughter cells
Checkpoints in cycle provide opportunities for monitoring the accuracy of deoxyribonucleic acid (DNA) replication
Edited and repaired defects ensure full complement of genetic information to each daughter cell
Phase of the Cell Cycle
G1 (gap 1): the post mitotic phase
DNA synthesis ceases while ribonucleic acid (RNA) and protein synthesis and cell growth take place
S phase: DNA synthesis occurs, giving rise to two separate sets of chromosomes, one for each daughter cell
G2 (gap 2): the premitotic phase
DNA synthesis ceases; RNA and protein synthesis continues
M phase: the phase of cellular division or mitosis
Cell Proliferation
Definition
The process by which cells divide and reproduce
Regulation
Regulated in normal tissue, so the number of cells actively dividing equal the number of cells dying or being shed
Two Major Categories of Cells Existing in Humans
Gametes (ovum and sperm)
Haploid (containing one set of chromosomes from one parent)
Designed for sexual fusion forming a diploid cell (containing both sets of chromosomes)
Somatic cell
The diploid cell that forms the rest of the body

Categories of Cell Types of the Body
Well-differentiated neurons and cells of skeletal and cardiac muscle unable to divide and reproduce
Parent or progenitor cells that continue to divide and reproduce
Blood cells, skin cells, liver cells
Undifferentiated stem cells that can be triggered to enter cell cycle and produce large numbers of progenitor cells when needed
Types of Stem Cells
Unipotent: give rise to one type of differentiated cell
Muscle satellite cell
Epidermal stem cell
Spermatogonium
Basal cell of the olfactory epithelium
Olgipotent: produce small number of cells
Pluripotent: give rise to numerous cell types
Types of Tumors
Adenoma: benign tumor of glandular epithelial tissue
Adenocarcinoma: malignant tumor of glandular epithelial tissue
Carcinoma: malignant tumor of epithelial tissue
Osteoma: benign tumor of bone tissue
Sarcoma: malignant tumors of mesenchymal origin
Papillomas: benign microscopic or macroscopic fingerlike projections growing on a surface

Factors differentiating Benign and Malignant Neoplasms
Cell characteristics
Manner of growth
Rate of growth
Potential for metastasizing or spreading
Ability to produce generalized effects
Tendency to cause tissue destruction
Capacity to cause death
Characteristics of Benign Neoplasms
A slow, progressive rate of growth that may come to a standstill or regress
An expansive manner of growth
Inability to metastasize to distant sites
Composed of well-differentiated cells that resemble the cells of the tissue of origin
Characteristics of Malignant Neoplasms
Tend to grow rapidly and spread widely
Have the potential to kill regardless of their original location
Tend to compress blood vessels and outgrow their blood supply, causing ischemia and tissue necrosis
Rob normal tissues of essential nutrients
Liberate enzymes and toxins that destroy tumor tissue and normal tissue
Methods by which Cancer Spreads
Direct invasion and extension
Seeding of cancer cells in body cavities
Metastatic spread through the blood or lymph pathways
Factors Affecting Tumor Growth
The number of cells that are actively dividing or moving through the cell cycle
The duration of the cell cycle
The number of cells that are being lost compared with the number of new cells being produced
Genes that Control Cell Growth and Replication
Proto-oncogenes
Tumor suppressor genes
Genes that control programmed cell death or apoptosis
Genes that regulate repair of damaged DNA
Steps Involving the Transformation of Normal Cells into Cancer Cells
Initiation
Cells exposed to doses of carcinogenic agents making them susceptible to malignant transformation
Promotion
Unregulated accelerated growth in already initiated cells caused by various chemicals and growth factors
Steps Involving the Transformation of Normal Cells into Cancer Cells (cont.)
Progression
Tumor cells acquire malignant phenotypic changes that promote invasiveness, metastatic competence, autonomous growth tendencies, and increased karyotypic instability


Host and Environmental Factors Leading to Cancer
Heredity
Hormones
Carcinogens
Chemical
Radiation
Oncogenic viruses
Immunologic mechanisms
Clinical Manifestations of Cancer
Tissue Integrity
Compressed and eroded blood vessels, ulceration and necrosis, frank bleeding, and hemorrhage
Cancer Cachexia
Weight loss and wasting of body fat and muscle tissue; profound weakness, anorexia, and anemia
Paraneoplastic Syndromes
Manifestations in sites not directly affected by the disease
Diagnostic Measures for Cancer Detection
Pap smear
Biopsy
Tumor markers
Staging and grading of tumors

Goals of Cancer Treatment
Curative
Control
Palliative
Cancer Treatment Modalities
Surgery
Radiation
Chemotherapy
Hormonal therapy
Biotherapy
Types of Surgery for Cancer
Cryosurgery: instilling liquid nitrogen into the tumor through a probe
Chemosurgery: using corrosive paste with multiple frozen sections to ensure complete removal of tumor
Laser surgery: using a laser beam to resect tumor
Laparoscopic surgery: performing surgery through two small incisions
Stem Cell Transplantation
Bone marrow transplantation (BMT)
Peripheral blood stem cell transplantation (PBSCT)
Two treatment approaches for individuals with leukemias, certain solid tumors, and other cancers previously thought to be incurable
Common Solid Tumors of Childhood
Brain and nervous system tumors
Neuroblastoma
Wilms’ tumor
Rhabdomyosarcoma and embryonal sarcoma
Retinoblastoma
Osteosarcoma
Ewing’s sarcoma
Characteristics of Childhood Cancers
Most involve the hematopoietic system, nervous system, or connective tissue
Heritable forms of cancer tend to have:
an earlier age of onset
a higher frequency of multifocal lesions in a single organ
bilateral involvement of paired organs or multiple primary tumors