Chemotherapy by ZUNDA WONGANI - Oncology-unza

Chemotherapy ZUNDA WONGANI DATE: 21st JULY 2021 Introduction • Chemotherapy is the use of antineoplastic drugs to promote tumor cell destruction by interfering with cellular function and reproduction • It includes the use of various chemotherapeutic agents and hormones • The intent of chemotherapy is to destroy as many tumor cells as possible with minimal effect on healthy cells • Cancer cells depend on the same mechanisms for cell division that are found in normal cells • Damage to those mechanisms leads to cell death. Chemotherapy is utilized in different clinical settings: • As induction chemotherapy for advanced disease 1. Primary treatment for patients who present with advanced cancer for which no alternative treatment exists 2. As an adjunct to local methods of treatment -Adjuvant chemotherapy is the use of systemic treatment after the primary tumor has been controlled by surgery and/or radiation therapy • To palliate symptoms of metastatic disease and/or prolong survival Chemotherapeutic agents can be effective on one of the four phases of the cell cycle or during any phase of the cell cycle • G1 (gap one) phase: ribonucleic acid (RNA) and protein synthesis (enzymes for DNA synthesis are manufactured) • S (synthesis) phase: During a long time period, the DNA component doubles for the chromosomes in preparation for cell division. • G2 (gap two) phase: This is a short time period; protein and RNA synthesis occurs, and the mitotic spindle apparatus is formed • M (mitosis) phase: In an extremely short time period, the cell actually divides into two identical daughter cells • Cells not active in the cell cycle are designated as ―resting (G0). Cells in this phase are, for the most part, refractory to chemotherapy. Therapeutic strategies 1. Adjuvant therapy: • Given to patients who have no evidence of residual disease but who are at high risk for relapse • The justification for adjuvant chemotherapy is the high recurrence rate after surgery for apparently localized tumors 2. Neoadjuvant therapy (Preoperative chemotherapy): • Administered prior to surgery in an attempt to downstage the primary tumor so that less invasive surgery can be performed • For example, patients with large breast tumors can preserve the breast and undergo lumpectomy instead of mastectomy • The goal of therapy is to decrease the amount of tissue that needs to be removed as well as to attempt to maximize cure potential 3. High dose/intensive therapy • Administration of high doses of chemotherapy, usually in association with growth factor support or before bone marrow transplant/stem cell rescue • Dose intensification has received increasing emphasis in recent years as a strategy for overcoming resistance to chemotherapy • Malignant cells may be resistant to certain drugs from the start of therapy (natural resistance) or become resistant after therapy has begun (acquired resistance) • Dose intensification suggests that chemotherapy should be given in the highest tolerated dose over the briefest interval, with the growth factor support –This has been tested in breast cancer, and results show that it is more effective than standard treatment schedules and is equally tolerated 4. Single agent chemotherapy: use of one cytotoxic drug and is rarely curative as genetically resistant cells are selected out. 5. Combination chemotherapy: use of drug combinations with different mechanisms of actions and side effect profiles which together reduce likelihood of resistance and toxicity. The drugs used should have; • Cytotoxic activity for that tumour, preferentially able to induce remission • Different MOAs, ideally additive or synergistic • Non overlapping toxicity to maximise benefit of full therapeutic doses • Different mechanisms of resistance. Routes of administration • Oral—capsule, tablet, or liquid • I.V.—push (bolus) or infusion over a specified time period. • Intramuscular • Intrathecal/intraventricular—given by injection via an Ommaya reservoir or by lumbar puncture • Intra-arterial • Intracavitary—such as peritoneal cavity • Intravesical—into uterus or bladder • Topical • Dosage is based on surface area (mg/m2) in both adults and children • Most chemotherapeutic agents have dose-limiting toxicities that require nursing interventions • Chemotherapy predictably affects normal, rapidly growing cells (bone marrow, GI tract lining, hair follicles) • It is imperative that these toxicities be recognized early on by the nurse Systemic Anti-cancer therapies (SACT) • Cancer is a "systemic" disease - …