Two major dysfunctions present in the process of cancer are:
:(1) defective cellular proliferation (growth) and (2) defective cellular differentiation.
cancer cells divide indiscriminately and haphazardly and sometimes__
__produce more than two cells at the time of mitosis.
__normal cellular genes that are important regulators of normal cellular processes that keep them in their mature, functioning state.
o The first stage, initiation, is a __
__mutation in the cell's genetic structure resulting from an inherited mutation, an error that occurs during DNA replication, or following exposure to a chemical, radiation, or viral agent.
o Promotion, the second stage in the development of cancer, is characterized by __
__the reversible proliferation of the altered cells.
o Progression, the final stage, is characterized by __
__increased growth rate of the tumor, increased invasiveness, and spread of the cancer to a distant site (metastasis).
• Metastasis is __
__a multistep process in which tumor cells travel to distant sites via lymphatic and hematogenous routes.
• Since cancer cells arise from normal human cells__
__the immune response that is mounted against cancer cells may be inadequate to effectively eradicate them.
• Cancer cells may display altered cell surface antigens__
__called tumor-associated antigens, as a result of malignant transformation.
• Tumors can be classified according to__
__anatomic site, histologic grading, and extent of disease (staging).
• In the anatomic classification of tumors, the tumor is identified by__
__by the tissue of origin, the anatomic site, and the behavior of the tumor (i.e., benign or malignant).
• In histologic grading of tumors__
__, the appearance of cells and the degree of differentiation are evaluated pathologically.
• The staging classification system is based on __
__a description of the extent of the disease rather than on cell appearance.
o The TNM classification system uses three parameters__
__tumor size and invasiveness (T), presence or absence of regional spread to the lymph nodes (N), and metastasis to distant organ sites (M).
o When cure is the goal__
__ treatment is offered that is expected to have the greatest chance of disease eradication and may involve local therapy (i.e., surgery or radiation) alone or in combination with or without periods of adjunctive systemic therapy (i.e., chemotherapy).
o Control is the goal of the treatment plan for many cancers __
__that cannot be completely eradicated but are responsive to anticancer therapies and can be maintained for long periods with therapy.
o With palliation__
__relief or control of symptoms and the maintenance of a satisfactory quality of life are the primary goals rather than cure or control of the disease process.
• Modalities for cancer treatment with all three goals include __
__surgery, chemotherapy, radiation therapy, and biologic and targeted therapy.
• The two major categories of chemotherapeutic drugs are__
__cell cycle phase-nonspecific and cell cycle phase-specific drugs.
o Cell cycle phase-nonspecific drugs have their effect__
__on the cells during all phases of the cell cycle.
o Cell cycle phase-specific drugs exert their most significant effects __
__during specific phases of the cell cycle.
The most common delivery of chemotherapy is__
__intravenous, through central vascular access devices, peripherally inserted central venous catheters, or implanted infusion ports. The use of these means reduces the risk of extravasation.
• Regional treatment with chemotherapy involves the delivery of the drug __
__directly to the tumor site.
The most common methods of regional chemotherapy are__
__intraarterial, intraperitoneal, intravesical bladder, and intrathecal or intraventricular.
• Chemotherapy-induced side effects are the result of __
__the destruction of normal cells, especially those that are rapidly proliferating such as those in the bone marrow, lining of the gastrointestinal system, and the integumentary system (skin, hair, and nails).
• The general and drug-specific adverse effects of chemotherapy drugs are classified as__
__acute, delayed, or chronic
• Teletherapy or external beam radiation is __
__the most common form of radiation treatment delivery. With this technique, the patient is exposed to radiation from a megavoltage treatment machine.
• Brachytherapy, or internal radiation treatment, consists of __
__the implantation or insertion of radioactive materials directly into the tumor (interstitial) or in close proximity adjacent to the tumor (intracavitary or intraluminal).
o Myelosuppression is __
__one of the most common effects of chemotherapy and, to a lesser extent, with radiation. It can result in life-threatening effects, including infection and hemorrhage.
o The intestinal mucosa is one of__
__the most sensitive tissues to radiation and chemotherapy. These injuries result in diarrhea, mucositis, anorexia, nausea, and vomiting.
• Chemotherapy and radiation can produce __
__long-term sequelae months to years after the cessation of therapy that can affect every body system.
• The cancer survivor is at risk for developing __
__secondary malignancies, such as leukemia, angiosarcoma, and skin cancer.
• Biologic therapy consists of __
__agents that modify the relationship between the host and the tumor by altering the biologic response of the host to the tumor cells
• Targeted therapy__
__interferes with cancer growth by targeting specific cellular receptors and pathways that are important in tumor growth.