32 Neoplasms – Chemotherapy

Chemotherapy

Chemotherapy is a type of treatment using anti-cancer drugs (i.e. anti-neoplastic drugs) that are designed to stop cell cycling and cell growth.  Chemotherapy is often used in combination with surgery and radiation. Chemotherapy typically involves two to four drugs given at intervals.

Chemotherapy drugs work by blocking mitosis, or metabolism, or by directly destroying cells.  Chemotherapy drugs interfere with protein synthesis, DNA replication, and cell mitosis.  Chemotherapy drugs include: anti-mitotics, anti-metabolites, antibiotics, and alkylating agents.

Delivery Methods of Chemotherapy

Delivery methods include oral, subcutaneous, intravenous, muscle, tumor injection which can include injections into subarachnoid space, peritoneal cavity, and brain ventricles.

Benefits and Potential Adverse Side-Effects of Chemotherapy

Potential benefits of chemotherapy include eliminating tumors as well as metastases from the body which can not only potentially cure cancer, but also eliminate any problems the tumor and migrating cancerous cells were creating.  The tumor may have been causing pain, obstruction, damage to surrounding tissues, and loss of function of surrounding tissues.  Chemotherapy is better at eliminating metastases than both radiation therapy and surgery.

Adverse side-effects of chemotherapy can be both local and systemic and can be very similar to the effects of radiation therapy, as rapidly dividing cells are the most negatively affected by the treatment.  The death of these healthy mitotic cells of the body (e.g., bone marrow, skin, GI tract, and gonads) cause adverse side effects until the body is able to replace them.

Chemotherapy causes temporary irritation and losses of GI mucosal cells, resulting in nausea, vomiting, diarrhea, loss of appetite, taste changes, dry mouth (xerostomia), and trouble swallowing.   The negative effects on the GI mucosa can lead to malnutrition, fatigue, dehydration, ulceration, and bleeding which can result in hematemesis (blood in vomit) and melena (blood in feces).  As the irritation and loss of cells causes inflammation, the effects on the respiratory mucosa may lead to a swelling in the throat causing difficulty breathing.

Within the bone marrow, the levels of red blood cells (RBCs), white blood cells (WBCs), and platelets being produced is negatively affected which contributes to fatigue, pallor, dizziness, increased heart rate, and susceptibility to infections and bleeding (slower clotting times).  The reduced numbers of blood cell numbers is called bone marrow depression or myelosuppression.  Often, chemotherapy treatments are timed to allow for blood cell numbers to recover, before the next round of chemotherapy drugs are delivered.  Neutropenia, leukopenia and thrombocytopenia can occur during chemotherapy treatments.  The term nadir is used which is defined as the lowest WBC count after each treatment.  Chemotherapy increases the risk of developing infections by opportunistic pathogens potentially resulting in oral Candida fungal infections, pneumonia or septicemia.

Chemotherapy affects naturally rapidly dividing epithelial cells through the body which results in hair loss (alopecia), vasculitis (damage and inflammation to blood vessels), and slow healing rates.  The effect on gonads can cause infertility.  The effect of chemotherapy on the bladder can cause cystitis (bladder irritation and inflammation).  Patients may also experience stress, headaches, depression, and anxiety.  Antiemetic drugs may be given to prevent nausea.

Chemotherapy drugs can cause fibrosis in the lungs, as well as damage to nephrons and myocardial cells.