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Understanding Chemotherapy
Cancer treatment generally has three methods, namely chemotherapy, radiotherapy, and surgical operations. However, radiotherapy and surgical operations mainly focus on individual body parts, such as the breast, lungs, prostate, etc., and are considered local treatments. It is difficult for them to deal with cancer cells that have spread to other parts of the body. Chemotherapy, on the other hand, can make up for the shortcomings of the above two methods and attack cancer cells throughout the patient’s body.
Chemotherapy originally meant the use of chemical substances to treat various diseases. It has gradually evolved into a specific treatment method for cancer. The drugs are dissolved into the patient’s bloodstream and circulate throughout the body to kill cancer cells. Since chemotherapy takes advantage of the characteristic that cancer cells divide faster than normal cells to eliminate them, it may also affect nearby normal cells that are used to replenish the body, including bone marrow cells that produce blood, hair follicle cells that grow hair, and gastrointestinal tract cells, resulting in various side effects. Before choosing chemotherapy and deciding which drugs to use, a detailed consideration is necessary, including the type and distribution of cancer, as well as the patient’s age and physical condition.
Drugs and Chemotherapy Treatment
Pre-treatment Information
Some patients may need more than one drug to enhance the therapeutic effect. However, if multiple chemotherapy drugs need to be taken simultaneously, or if other medications need to be taken during chemotherapy, regardless of whether a doctor’s prescription is required, it is essential to ensure that the drugs do not interact with each other, so as not to weaken the therapeutic effect or exacerbate side effects. Patients should inform their doctors about the drugs they take regularly, including nutritional supplements and rheumatism medications. In addition, patients should be aware that specific vitamins may interact with chemotherapy drugs. For example, the antioxidant effects of vitamins A, E, and C can prevent the production of free radicals that damage cell DNA in the human body. However, some chemotherapy drugs may rely on these free radicals to destroy the DNA of cancer cells and prevent them from dividing.
Chemotherapy can be divided into systemic and local chemotherapy. The former has two main categories: injectable agents and oral drugs, with injectable agents being the most used. Some drugs are suitable for both injection and oral administration, but the distribution of the tumor and the patient’s physical condition should also be considered. Patients should follow their doctor’s instructions to choose the most appropriate method of drug administration.
Injection and oral treatment
Systemic Chemotherapy
There are three main types of injectable agents: intravenous injection, intramuscular injection, and subcutaneous injection. However, to avoid irritation of the skin and muscles by chemotherapy drugs, doctors usually choose the intravenous injection method. The principle of intravenous injection is to insert a needle with a rubber tube into a small vein in the patient’s arm or wrist and connect it to a transparent soft rubber tube for the infusion. Then, the drug is introduced into the body. This method allows the drug to circulate with the blood vessels and quickly travel throughout the body to attack cancer cells.
Another type of intravenous injection is called a “central venous catheter.” A needle is inserted into the subclavian or internal jugular vein in the patient’s chest cavity. The advantage is that it can be used multiple times. After the first treatment course, the needle does not need to be removed and can be left in place for daily use until the treatment course is completed. In addition, doctors and patients can choose the appropriate catheter and connector based on factors such as the treatment course duration, infusion time, personal preferences, and cost.
Generally, inserting a catheter or connector into the patient’s body does not require anesthesia. However, blood tests should be conducted beforehand to ensure that the platelet count is normal and that the insertion site can clot quickly. Nevertheless, there are still various risks associated with catheter insertion, such as puncturing the vein, causing bruising, bleeding, and even infection in the surrounding area.
There are four types of oral chemotherapy drugs: pills, tablets, capsules, and liquids, all of which can be taken at home by the patient. Although oral medications are less expensive than injectable agents, they are not as popular because stomach acid may dilute the drugs, or the gastrointestinal tract may not absorb the drugs. Moreover, some potent drugs may damage the gastric mucosa.
Multimodal Chemotherapy
Local Chemotherapy
Local chemotherapy refers to delivering a high dose of chemotherapy drugs directly to the tumour site, thereby killing cancer cells in the most concentrated manner and reducing the side effects caused by the treatment course. There are seven types of local chemotherapy methods:
- Intra-arterial Infusion
Doctors will identify the artery leading to the tumour site and insert a catheter into it. They will also maintain hydraulic pressure with a small pump outside the body. Different treatment courses for different parts have different academic names. For example, treating the liver is called “isolated liver perfusion,” and treating the limbs is called “isolated limb perfusion.”
- Intravesical Chemotherapy
This method is commonly used for early-stage bladder cancer. Patients must insert a catheter through the urethra into the bladder each time they take the medication. The drug will stay in the bladder for about two hours before being expelled from the body. The treatment course lasts from 4 to 12 weeks.
- Intrapleural Chemotherapy
This is usually used for pleural mesothelioma, lung cancer that has spread to the pleura, and breast cancer. Doctors insert a catheter into the patient’s chest to inject chemotherapy drugs and can also drain pleural effusion at the same time. If necessary, a hydraulic pump can be implanted.
- Intraperitoneal Chemotherapy
This is the standard treatment for ovarian cancer and is also applicable to recurrent colorectal cancer, cecal cancer that has spread in the abdominal cavity, and stomach cancer. After the chemotherapy drugs enter the patient’s abdominal cavity, they are absorbed by the tumour before entering the bloodstream, which increases the therapeutic effect. However, because the local treatment dose is higher, the body needs more time to absorb the drugs, and the side effects may be more than those of intravenous injection.
- Intrathecal Chemotherapy
The principle is to directly inject the drug into the cerebrospinal fluid in the patient’s brain and spinal cord[Note 1]. It is generally used when cancer cells have spread to the central nervous system and is most seen in leukemia. Some lymphomas and advanced breast and lung cancers are also applicable, but it is not suitable for tumors that originate directly in the brain or spinal cord. There are two detailed methods: one is to perform a lumbar puncture each time the medication is administered, inserting a needle between the vertebrae at the lower part of the spine to allow the drug to flow into the cerebrospinal fluid through the needle; the other is to place a small-drum-shaped connector under the scalp, with a connected catheter penetrating the skull and entering the brain ventricle. A special needle is then used to pierce the scalp and enter the connector to administer the drug.
- Intralesional Chemotherapy
This is a method of directly injecting chemotherapy drugs into the tumour. However, since the needle passes through the body surface and extends into the tumour without affecting other organs, this treatment is usually only used for skin and subcutaneous tissue tumours.
- Topical Chemotherapy
This mainly involves applying ointments to the skin and is commonly used to treat skin cancers such as basal and squamous cell carcinoma.
Psychological and Physiological reactions
Side Effects
Since chemotherapy drugs target the characteristic of rapid division of cancer cells and indirectly affect other normal cells, patients may experience various side effects after receiving chemotherapy, including fatigue, hair loss, loss of appetite, etc. Generally, these side effects may appear two to three weeks after the treatment or gradually emerge within a few hours after taking the medication.
- Fatigue
Due to the insufficient red blood cells in the patient’s body, the oxygen level is reduced, which can easily lead to feelings of weakness, confusion, and difficulty concentrating. Patients should ensure adequate rest, drink plenty of water, and engage in light exercise regularly.
- Nausea and Vomiting
These usually occur a few hours after the injection, and in severe cases, dehydration may occur. Before the injection, patients should eat a small amount of light food, such as soup or porridge. After the injection, they should drink plenty of fluids, eat small meals frequently, and choose easily digestible and light foods.
- Constipation and Diarrhea
Some chemotherapy drugs can affect the inner lining of the digestive system, leading to constipation or diarrhea. The former can be alleviated by consuming high-fiber foods such as fruits, vegetables, and whole-grain bread. At the same time, the latter can be managed by avoiding spicy foods and eating light or warm liquid foods to replenish the fluids lost during diarrhea. If the condition is mild, patients can take over-the-counter medications independently. However, if the condition is severe and leads to dehydration, they should notify their doctor immediately.
- Mucositis
Some chemotherapy drugs can cause oral mucositis, leading to redness, white patches, ulcers, and difficulty swallowing. Patients can clean their mouths by themselves, rinsing with warm salt water to prevent infection, taking medication to relieve pain, and consuming more liquid foods.
- Hair loss
Traditional chemotherapy drugs attack rapidly dividing cancer cells. Since hair follicle cells also renew quickly, they are affected by the drugs, leading to hair loss. Patients usually start to lose hair within two weeks after the first chemotherapy session. The extent of hair loss varies from person to person, but generally, hair regrows within one to two months after stopping the medication. Patients can use baby shampoo to protect the scalp during hair loss and use cotton, chemical fiber, or silk pillows.
- Skin itching and peeling
Chemotherapy may cause the skin to become dry, itchy, peel, or increase sensitivity to sunlight. Patients can apply cornstarch to the itchy areas or moisturizing cream to the dry spots.
- Neurological and muscular numbness
Some drugs can affect the patient’s nerves, causing tingling and numbness in the fingers or toes, weakness in the leg muscles, nystagmus, facial paralysis, hoarseness, blurred vision, tinnitus, etc. If any of these conditions occur, the doctor must be notified.
- Fertility issues
Chemotherapy may cause menstrual irregularities in women. Some women may resume normal menstruation after the treatment course, while others may experience permanent cessation of menstruation. After menopause, female patients may experience symptoms such as hot flashes, night sweats, and dry skin, for which doctors can prescribe medications to alleviate the discomfort. For men, chemotherapy may lead to a decrease in sperm count and motility, resulting in erectile dysfunction, but this condition is usually temporary.
Further Understanding
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Note 1: Cerebrospinal fluid is a transparent liquid that fills the space between the brain’s skull and cerebral cortex.
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