Chemotherapy: How does it work, Expectation, Duration, Blood tests, How is the dose given, Side effects, Types, Effectiveness and Outlook


Chemotherapy is the treatment of cancer using cancer destroying drugs.

July 13, 2018

Chemotherapy is a type of treatment that is widely used for cancer patients. The term chemotherapy refers to the drugs that prevent cancer cells from dividing and growing. This is done by killing the dividing cells.
A wide range of drugs is used to achieve these goals. The effectiveness of the treatment depends on the location of the tumor as well as the stage of the cancer being treated. As the adverse effects can be severe, the patients may need to discuss with their physician and oncologist about the eligibility and benefits of the treatment before starting it. The benefits of chemotherapy usually outweigh the risk of adverse effects.
Chemotherapy can prevent disease progression, eliminate cancer cells or bring about long term remission of symptoms. Chemotherapy is the treatment of cancer using cancer destroying drugs.
The cells of our body are constantly replaced through a process of dividing and growing naturally. These cells reproduce in an uncontrolled manner when cancer occurs. More and more cells are produced, and they start to occupy an increasing amount of space until they occupy the space previously inhabited by useful cells. Chemotherapy drugs interfere with the ability of a cancer cell to divide and reproduce.
A single drug or a combination of drugs is used. These can be delivered either directly through vein into the bloodstream, to attack cancer cells throughout the body, or they can be targeted to specific cancer sites.

How does chemotherapy drugs work?

Chemotherapy drugs works by either of the following way.

  • impairing mitosis, or preventing cell division, as in the case of cytotoxic drugs
  • targeting the food source of cancer cell, which consists of the enzymes and hormones they need to grow
  • triggering the suicide of cancer cells, known medically as apoptosis
  • stoping the growth of new blood vessels that supply a tumor in order to starve it

Stopping the blood flow may enhance the ability of a cell to resist treatment and cause metastasis instead of starving the cells. It could be effective in preventing the cancer cells from resisting treatment by targeting the proteins that are deployed by the cancer to increase resistance and drive metastasis.

Expectation from Chemotherapy:

As Chemotherapy drugs often target not only cancerous cells but also healthy cells, it can have severe adverse effects. Therefore it is important that patients should know what to expect before starting treatment and discuss the benefits with the oncologist. However, given early, chemotherapy can achieve a complete cure in some cases, making the side effects bearable for many patients

Duration of Chemotherapy:

The duration of treatment through chemotherapy will be specified by the oncologist, or cancer specialist and the patient will need regular chemotherapy over that period of time for best results.
There will be a specific plan for treatment sessions that will specify when will it occur and for how long. A course of treatment can range from a single dose on one day for few weeks, depending on the type and stage of the cancer. Patients who need more than one course of treatment will have a rest period to allow their body to recover. These rest period could be weeks. For example a week's rest if followed by initial day treatment and a three-week rest period is required after second session. A psychologist or counselor may be available to help the patient deal with the mental and emotional effect of chemotherapy.

Blood tests before and during chemotherapy:

Blood tests are needed to assess the overall health of a patient. This will help to ensure weather the patient will be able to cope with possible side effects. For example, if a blood test detects liver problems, further treatment may not be suitable unless the liver recovers. This is because chemotherapy chemicals and other drugs are metabolized, or broken down, in the liver and if the liver is overwhelmed, this could lead to a range of secondary effects. Also treatment may need to be delayed if blood testing before treatment shows a low count of red or white cells or platelets in the blood.
Regular blood tests will continue during the treatment period to ensure that blood and liver function are maintained. Blood tests are also done to monitor the effectiveness of the treatment.

How is the dose given?

The patient may take chemotherapy orally, or intravenously, injected into the vein or elsewhere depending on the type of cancer.

Orally:

Chemotherapy drugs can sometimes be taken at home if the health of patient permit. This is taken in tablets form. The drug may also be in capsule or liquid form.
However, the patient will have to make regular hospital visits to check their health and response to treatment. The dose must be taken exactly when specified. In case the patient forgets to take the dose at a specific time, they should call the medical team immediately.

Intravenous chemotherapy:

This may be injected directly into a vein with a needle or delivered through an intravenous infusion. The drugs can also be given:
as an injection into a muscle in the arm, thigh, or elsewhere

  • intrathecally, injected into the space between layers of tissue that cover the brain and spinal cord
  • as an intraperitoneal (IP) injection, delivered directly into the part of the body where the intestines, stomach, and liver are located
  • intra-arterially (IA), injected into the artery that leads to the cancer
  • The drug may be given through a drip or pushed through a pump, to ensure a constant rate of delivery.

The patient may have to wear the pump for several weeks or months if they need continuous infusion, protracted venous infusion, or ambulant infusion. They can walk about while receiving the medication. A catheter, a central line, and a portacath are used to deliver the solution. A portacath is an implantable port, a thin, soft, flexible plastic tube that goes into a vein. It has a port, or opening, just under the skin of the chest or arm. The port has a thin rubber disc which special needles can pass medicines into, or take blood from. Sometimes, the drugs can be applied topically, as a cream or ointment for rubbing into the skin.

Side effects of Chemotherapy:

Adverse effects of chemotherapy can range from mild to severe depending on the type and extent of the treatment and other individual factors. Some people will have no adverse effects. The impact of treatment on daily life of a person will depend on the extent of the symptoms.
Below listed are some of the adverse effects that may occur during chemotherapy.

Nausea and vomiting:

Most of the patients are affected by nausea and vomiting. Anti-emetic drugs may help in these cases. These should be taken even when symptoms have gone, to prevent recurrence of these symptoms.
Ginger or ginger supplements may help increase the effectiveness of anti-emetics.

Alopecia, or hair loss:

A a few weeks after treatment begins with some types of chemotherapy, hair may start to fall out or become thin or brittle. It can affect any part of the body. Although hair loss has no physical health consequences, it may cause distress or depression. Using a cold cap can keep the scalp cool while a dose is being administered which may prevent or reduce hair loss. However, patients who need the medication to reach their scalp cannot use a cold cap. Patients with leukemia also cannot use a cold cap. Normally hair grows back soon after treatment is finished.
Nails, too, can become flaky and brittle and skin may become dry and sore and oversensitive to sunlight. Using sun blocks, sunscreen lotion and covering the body with clothes can provide maximum protection during peak times.

Fatigue:

Fatigue is a common side effect of chemotherapy. It may be present most of the time or only after certain activities. Patients should get plenty of rest and avoid tasks that are overtiring. As a significant drop in red blood cells could lead to anemia, severe tiredness should be evaluated.

Hearing impairment:

The toxic effects of chemotherapy can lead to temporary or permanent hearing loss in some patients.

Low white blood cell count and susceptibility to infections:

The immune system will be weakened because the white blood cell count will go down while receiving chemotherapy. White blood cells are part of our immune system that help fight infection. When the count is low patients are more susceptible to infections resulting in a condition called neutropenia. Antibiotics may help reduce the risk of developing infections. Patients and their care taker should also be careful to follow precautions to avoid any kind of infection. These include:

  • Personal hygiene: At least once a day wash your hand with warm water and soap, take bath or shower. Regularly change clothes, bedclothes, and bathroom towels.
  • Preparing food: Follow food hygiene practices, including keeping meat and vegetable separate, thoroughly cooking animal produce, washing all vegetables and keeping surfaces, cutlery, and crockery clean.
  • Infected people: Stay away from anyone with signs of illness or infection.
  • Skin wounds: Carefully dress any cuts or grazes and cover them with a sterile dressing, to prevent bacteria from entering the skin.

If chemotherapy patients develop an infection, they need immediate treatment. This may require hospitalization and receiving intravenous antibiotics.

Low blood platelet count and bleeding problems:

Platelets are a type of blood cell that helps the blood to coagulate, or clot. A low platelet count can lead to bruises or bleeds such as nosebleeds and bleeding gums. The blood flow from a minor cut may be hard to stop. These blood clotting problems is called as thrombocytopenia. A person will need a blood transfusion if the platelet count falls too low. To reduce the risk of bleeding, patients should:

  • Use an electric razor, or avoid shaving
  • Use a soft toothbrush
  • Take care when using sharp objects, such as kitchen utensils or gardening tools.

Gloves can help prevent injuries when gardening.

Low red blood cell count and anemia:

Red blood cells in our blood carry oxygen to all the tissues in the body. A low level of red blood cells will lead to anemia. Tiredness, shortness of breath, and heart palpitations are the most common symptoms. A person with severe anemia may need an immediate blood transfusion.
Erythropoietin (EPO) can be used for anemia which helps the body produce more red blood cells. Good food sources of iron include dark green leafy vegetables, beans, meat, nuts, prunes, raisins, and apricots. These can be included in your diet to prevent anemia.

Mucositis:

Mucositis is the inflammation of the mucous membrane which can affect any part of the digestive system, including the mouth, esophagus, stomach, intestines, the rectum, and the anus.
Oral mucositis can lead to symptoms in your mouth. Often it starts 7 to 10 days after the treatment begins. There may be pain as if the mouth has been burned.
Ulcers can appear on the lining of the mouth, the tongue, and around the lips. Eating, drinking and talking can be painful if it occurs. There is a risk of infection if bleeding occurs.
The type and severity of symptoms is associated with the strength of the chemotherapy dose. These symptoms disappear a few weeks after finishing treatment. Caphosol is often prescribed for mucositis.

Loss of appetite:

Either chemotherapy or the cancer itself can affect the metabolism of your body, leading to a loss of appetite and weight loss until the cancer goes into remission or treatment is finished.
Severity depends on the type of cancer and chemotherapy treatment. Taking smaller and more frequent meals may help to keep up a supply of nourishment and prevent nutritional deficiency. Drinking liquids through a straw can help maintain fluid intake. Patients who are unable to consume food or liquid may need to be hospitalized and fed through the nose where a nasogastric tube is used so that the food goes directly to the stomach.

Pregnancy and fertility:

A temporarily loss of interest in sex during chemotherapy is very common. Libido usually returns after treatment is completed. Chemotherapy may also reduce fertility in men and women depending on the type of medication administered. Fertility often, returns after treatment is over. But there is also a chance of infertility even after the treatment get over.

Patients who may wish to have children in the future may consider freezing sperm or embryos for later use. It is important to avoid becoming pregnant during treatment as many chemotherapy drugs may cause congenital disabilities.
Oral birth control methods may interfere with chemotherapy. Therefore it is not recommended during the treatment. However, a barrier method of birth control can be used during treatment and for at least a year after.

It is essential to inform the doctor immediately if a woman is pregnant or becomes pregnant at the time of treatment.

Bowel problems:

Diarrhea can result when damaged cells are suddenly expelled from the body. Constipation may also occur. These symptoms often begin a few days after treatment starts.

Cognitive and mental health problems:

Problems with attention, thinking, and short-term memory during chemotherapy is very common during chemotherapy. This may persist for months or years after treatment in some cases. It can also affect the ability to reason, to organize, and to do multitask. Mood swings and depression can also develop. These symptoms can be related to the treatment itself or because of fears for the future.

Types of Chemotherapy:

There are different types of chemotherapy drug and different ways of receiving them.
Four major categories are:

Alkylating agents:

These work directly on the DNA and kill the cells at different stages of the cell life cycle. Examples include chlorambucil, cyclophosphamide, thiotepa, and busulfan.

Antimetabolites:

These drugs mimic proteins that the cells need to survive. They offer no benefit when consumed by the cells. Hence the cells starve. Examples include purine antagonists, pyrimidine antagonists, and folate antagonists.

Plant alkaloids:

These drugs block the ability of the cells to grow and divide. Examples include actinomycin D, doxorubicin, and mitomycin.

Antitumor antibiotics:

These drugs bind with DNA and stop RNA from synthesizing, so that the cells cannot reproduce. The are different from the antibiotics that are used for an infection. Examples include doxorubicin, mitoxantrone, and bleomycin.
The suitable option will be recommended to an individual by the oncologist depending on the below factors:

  • what type of cancer a person has
  • how advanced the cancer is
  • whether they have had chemotherapy before
  • whether they have any other health issues, such as diabetes

Effectiveness of Chemotherapy:

Chemotherapy can be effective in the treatment of cancer, sometimes leading to full remission in spite of its adverse effects.
Effectiveness depends on individual factors which include:

  • the location, type, and stage of the cancer
  • age, overall health, and existing medical conditions of the patient

In some cases, chemotherapy alone can achieve complete remission, where the patient is cured and the cancer does not return. Sometimes, chemotherapy is combined with other treatments, such as radiation therapy or surgery, for more effective results. Neo-adjuvant therapy can be used to shrink a tumor before surgery.
Chemotherapy is used to remove any remaining cancer cells followed by surgery or remission. Chemotherapy may slow disease progression and reduce symptoms if a cancer is in the advanced stages, even when a cure is not possible. This is called as palliative chemotherapy.

Outlook of Chemotherapy:

The patient will undergo blood tests and other examinations to assess the progress of the treatment during and after chemotherapy. Side effects of chemotherapy drugs tend to go away when the treatment is over. The earlier a cancer is treated, the more likely it is to go into remission with treatment.