- Results from a process of altered cell differentiation and growth
- Lacks normal regulatory control over cell growth and division
Oncology – study of tumor and their treatment
Cancer in situ – localized pre-invasive lesion depending on location
Tissue renewal and repair
- Cell proliferation
- Or the process of cell division
- Inherent adoptive mechanism for replacing body cells when old cells die or additional cells are needed
- 2 Major Categories of Cells
- Gametes (Ovum/Sperm)
- Somatic cells
- Cell differentiation
- Process of specialization whereby new cells acquire the structure and function of the cells they replace
- Fertilized ovum
- Where all of the different cell types of the body originate
Tumor / Neoplasm
- Swelling caused by inflammation or trauma
- Benign
- Contains well-differentiated cells that are clustered together in a single mass which resembles cells of tissue origin
- Presence of well-defined fibrous capsule (facilitates easy surgical removal, no metastasis)
- Malignant
- Anaplasia
- Lack of cell differentiation and characteristic (mutation occurs early in the process of differentiation)
- Ability to break loose, enters circulatory and lymphatic system and form secondary malignant tumors on other sites (metastasis)
- Usually causes suffering and death
- Rapid growth and spread (outnumber normal cells), non-functional, long lived
- Compresses blood vessels and decreases blood supply resulting to ischemia and tissue necrosis
- Rob normal cells of essential nutrients and liberate enzymes and toxins that destroy tumor and normal cells
- Lots of cohesiveness and adhesion, impaired cell to cell communication
- Crablike projections in surrounding tissues making removal difficult
- 2 categories of cancer
- Solid tumors – confined to specific tissue or organ
- Hematologic cancer – involves blood forming cells
- Number of cells that are actively dividing or moving thru cell cycle
- Duration of cell cycle
- Number of cells lost and number of cells produced
- Growth fraction – ratio of dividing cells to resting cells in a tissue mass
- Doubling time – length of time it takes for fatal mass of cells in a tumor to double, continues until there is a decreased blood supply and nutrients
- Detection – doubled 30 times, contains 1 billion cells
Oncogenesis – genetic mechanism wherein normal cells are
transformed into cancer cells
2 Kinds of Genes
- Proto-oncogenes – growth promoting regulatory gene
- Anti – oncogenes – growth inhibiting regulatory genes; inhibits proliferation of cancer cells
Contributing Factors
- Hereditary – family history of cancer
- Carcinogen – agents capable of causing cancer
- Radiation – cancer of skin and blood (leukemia)
- Atomic bomb survivors, diagnostically exposed patients
- Industrial workers, scientists
- Ultra Violet Rays (UVR) – skin cancer
- Radon – radioactive gas formed from uranium decay (uranium miners)
- Oncogenic viruses
- Papillomavirus, human t-cell leukemia virus, Epstein-barr virus, hepa-B virus, herpes simplex 2
- Immunologic defects
- Play a central role against development of tumor
Antineoplastic Agents
- Alkylating agents
- Non-cell cycle specific (affect cell even in resting phase)
- Action: binds with cellular DNA, disrupting cellular mechanism
- Indication: slow-growing Cancer
- Drugs that protect cells from side effects of cisplastin
- Amifestine (Ethyol)
- Preserves healthy cells from toxic effects
- Scavenger of free radicals
- Given within 30 minutes after starting cisplastin therapy (timing is important)
- Side Effects: nausea and vomiting
- Mesna (mesnex)
- Reduces incidence of haemorrhagic cystitis
- Side effects: nausea and vomiting
- Antimetabolites
- Replace needed metabolites and prevent normal cell function
- Used as a combination therapy to prevent development of resistance
- Action: inhibits DNA production in cells that depend on certain natural metabolites
- Indication: rapidly dividing cells
- Drugs that protect cells against metabolites
- Leocovorin (Welleovorin)
- Active form of folic acid used to “rescue” normal cells from adverse effects of methotrexate
- Antineoplastic antibiotics
- Cell cycle specific
- Action: interferes, disrupts cellular DNA synthesis
- Cardioprotective antineoplastic drug:
- Dexrazoxane (Zinecard)
- Powerful intracellular chelating agent, interferes with cardiotoxic effects of doxorubicin
- Given 30 minutes before doxorubicin
- Mitotic inhibitors
- Cell cycle specific
- Action: kill cells as process of mitosis begins, inhibit DNA synthesis
- Contraindications: allergy, pregnancy, lactation
- Caution: bone suppression, renal/hepatic dysfunction, GI ulcerations
- Adverse Effects: bone marrow suppression, leukopenia, thrombocytopenia, anemia, pancytopenia, nausea and vomiting, anorexia, diarrhea, hepatic/renal toxicity
- Hormones and hormone modulators
- Receptor-site specific / hormone specific
- Action: block stimulation of growing cells that are sensitive to the presence of that hormone
- Indications: breast cancer in post-menopausal women or without ovarian function
- Contraindications: allergy, preganancy, lactation, hypercalcemia if used with toremifene
- Adverse effects: menopausal effects (estrogen is blocked or inhibited), hot flashes, vaginal spotting and dryness, moodiness, depression, GI toxicity, hepatic dysfunction, hypercalcemia
- Interactions: anticoagulants: increased risk of bleeding
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