What is chemotherapy?
When one refers to chemotherapy, it is often linked to cancer. But, chemotherapy simply refers to the usage of chemicals to treat various diseases. Chemotherapy is widely used for the treatment of cancers among other diseases.
The main difference between chemotherapy and other modes of treatment is that chemotherapy is systemic. This means that the impact of the drugs has an effect on the entire body, through all the systems.
How does chemotherapy work?
The drugs have three main mechanisms of function:
- APOPTOSIS: Some of the drugs used in chemotherapy work by triggering a special cell function called apoptosis. Every cell has the innate ability to self-destruct once its function is over. When the chemo drugs trigger this action, the cancer cells undergo self-destruction and reduce greatly in number.
- STARVATION: some chemo drugs work by restricting or even completely cutting off the cells’ nutritional sources. Eventually, the cancer cells perish and die.
- IMPAIR MITOSIS: mitosis is a normal cell function which involves the cells splitting into two with duplicate DNA’s. This is different from the cell division that involves genetic traits as it is simply a form of duplication. The chemo drugs have a capacity to disrupt the process of mitosis and prevent the cancer cells from dividing. This interruption is at the DNA splitting stage.
Chemotherapy for blood cancers:
Blood, is present throughout the body, running from head to toe. It is also a transport medium for drugs and other substances. So, when the chemo drugs are introduced to the body, through the bloodstream, they directly affect the blood cells and spread rapidly through the body.
Also, since the chemo cells impair mitosis, they have an effect on blood cells. This is because the blood cells are rapidly undergoing mitosis even at a normal state.
What are some of the common cancers of the blood?
- Leukaemia: cancer of the white blood cells. They are of two types: myeloid and lymphoid.
- Non-Hodgkin’s lymphoma: cancer of the lymphocytic cells, which are a type of white blood cells.
- Hodgkin’s lymphoma: cancer of the lymphocytic cells, which contain a special type of cells called Reed Sternberg cells.
- Multiple myeloma: cancer of the blood plasma cells.
How are chemo drugs introduced into the bloodstream?
The common routes of administration of chemo drugs for blood cancers are:
- ORAL ROUTE: the drugs may be consumed as tablets or pills. This is only advised if the patient is deemed fit enough. They are also kept under regular check to ensure the proper functioning of the drug.
Coated capsules may be given for a slow releasing drug.
Sublingual tablets are small soluble tablets that can be placed under the tongue so that they get absorbed directly into the bloodstream.
Not all medications can be given this way. This is because sometimes the drug gets destroyed by the stomach acids and turn out to be ineffective. The released drug may also not be absorbable by the stomach and intestinal lining which ends up excreted without being metabolised. Sometimes, the drug may damage the intestinal walls if released in the stomach.
- INTRAVENOUS INJECTIONS: the chemo drugs are directly infused into the patient’s veins and is carried to the bloodstream. It is the quickest source of administration with modifiable dosage time and duration. Various methods of intravenous injections are given:
- Angio-catheter: a temporary catheter until the drug is administered.
- PICC lines: these are long plastic catheters that may be placed for a longer duration. It could be used for in-patient treatment or at-home infusions. Fluoroscopy X-rays are done to confirm if the catheter is placed in the right position.
- Tunnelled catheters: these are catheters placed subcutaneous, at the chest, and inserted into the superior vena cava. They have multiple lumens or entry points. They can be left in the patient’s body for months to years with the low risk of infection. Regular changing of dressings is necessary. It is used in extensive therapies like bone marrow transplants.
- Non-tunnelled catheters: these are directly entered into the jugular or subclavian vein to reach the superior vena cava. They are done for emergency or short-term treatments. Infections can spread faster and regular dressings are needed.
- Port-a-cath: this is a more permanent device. It can be left unchanged for 3-5 years. It is inserted directly into the superior vena cava in the right atrium of the heart.
- INTRATHECAL INJECTIONS: regular chemotherapy does not reach the brain and spinal cord. This acts as a hiding spot for cancer cells. To avoid this, we can inject the drugs into the cerebrospinal fluid, which will then circulate to these parts.
Possible side effects of chemotherapy:
- Hair loss: this is one of the first things noticed by the patient. Hair loss is not only on the scalp, it is throughout the body. Hair loss is a temporary side effect. Hair grows back normally once the treatment is completed. It can be reduced by wearing a cold cap (except in cases of leukaemia). This does not cause any physical health issues but has an adverse effect on the psychology of the patient.
Nails can become brittle and flaky as well.
- Nausea and vomiting: almost 65 to 70 %of patients face this problem. Anti-emetics (drugs which prevent vomiting) help to reduce and prevent its re-occurrence when the chemotherapy is completed.
- Low white blood cell count: due to chemotherapy drugs, the number of white blood cells is depleted. This condition is called neutropenia. This makes the patient more susceptible to infections. The patient must take utmost care to protect himself from infections by maintaining proper hygiene and cleanliness.
- Low platelet count: this condition is known as thrombocytopenia. It is a condition in which the patient has reduced platelets due to destruction by the chemotherapeutic agents. This leads to easy bleeding and bruising. This is especially seen when the patient has bleeding gums and small cuts even by razors. The patient needs to take care to not cause any open wounds that might bleed.
- Low red blood cell count: this is known as anaemia. Red blood cells carry oxygen to the body. They are rapidly destroyed in the presence of chemo drugs. This reduces the overall oxygen supply to the body and makes the patient dizzy, tired and breathless. The patient is usually advised to take foods rich in iron along with iron supplements and erythropoietin.
- Mucositis: this is the inflammation of mucous membranes. It could affect the mucous membrane of any part of the body. It usually manifests orally as a burning sensation with blisters, redness, and ulcerations. Drugs may be prescribed for the reduction of inflammation.
- Appetite loss: chemotherapy and cancer itself can reduce one’s appetite and metabolism. Patients are asked to eat smaller frequent meals and drink fluids through a straw. Patients who are incapable to physically feed on their own are fed through a nasogastric tube to maintain nutrition supply.
- Effect on pregnancy and fertility: the patient temporarily loses libido. Many chemotherapy drugs cause deformities in the foetus. Patients are advised to avoid pregnancy during chemotherapy. It can also reduce the fertility in both men and women.
- Cognitive and mental health problems: patients have previously reported short-term memory, reduced attention span, reduced capacity to multitask, depression and mood swings.
Chemotherapy as an adjuvant:
Chemotherapy is usually never used alone. It is almost always used as an adjunct to radiation therapy or/and surgery.
Prognosis of treatment:
Prognosis depends on many factors like age, the progression of the disease, the overall systemic health of the patient and patient compliance. The most important things for the success of the treatment is the clear understanding of what is to come and its management.