Chemotherapy, a treatment given for the purpose of killing cancer cells, can be given in various ways. Of note, chemotherapy regimens can be given through various parts of the body. In addition, there are several different chemotherapy regimens such as adjuvant chemotherapy, primary chemotherapy, and combination chemotherapy.
The chemotherapy regimens can be given through different places in the body depending on the type of cancer and depending on the patient and what would be most effective. For example, chemotherapy regimens can be given by injection into muscles, skin, veins, arteries, or a tumor. Chemotherapy regimens can also be given by mouth, injected into the spinal fluid, applied onto the skin, or can be given in the peritoneal cavity.
Adjuvant chemotherapy is a type of therapy where patients are given anti-cancer treatment after the main tumor is removed. This type of chemotherapy is given to attack cancer cells that remain after the main tumor is removed. Adjuvant chemotherapy has been used in osteogenic sarcoma, colorectal cancer, Wilms' tumor, and breast cancer. The effectiveness of adjuvant chemotherapy depends on the particular dosage given and issues such as drug resistance and side effects.
Primary chemotherapy, which is sometimes referred to as induction chemotherapy or neoadjuvant chemotherapy, refers to the process of using chemotherapy as a main or primary treatment for a patient. For example, individuals who have lymphomas, Hodgkin's disease, embryonal rhabdomyosarcoma, lung cancer, anal cancer, breast cancer, laryngeal cancer, soft tissue sarcoma, head and neck cancers, bladder cancer, and some childhood cancers tend to have chemotherapy as the primary treatment given before radiation or surgery. Primary chemotherapy tends to reduce the size of tumors to makes it easier for surgeons to remove them. Also, primary chemotherapy facilitates radiation treatment because it improves the blood flow to the tumor, which makes it more likely that radiation will have impact on the cancer.
Granted, some cancers are drug-resistant. Thus, if the cancer cells are drug-resistant, it makes it less likely the primary chemotherapy will be effective. Also, there is the danger of toxicity in the body if too much chemotherapy is given.
Combination chemotherapy regimens include cases where there is more than one drug given to treat the cancer. Using combinations can be useful because there is a better likelihood of destroying cancer cells. Drug toxicity is a potential danger when using more than one drug, though. Another potential danger might be that in research done with mice, chemotherapy drugs cause longer term damage in the brain through the killing of neural cells and oligoendrocytes that make myelin insulation, which is necessary for normal functioning of neurons. Thus, the oncologist must keep these things in mind in determining treatment.