What is chemotherapy?

Chemotherapy has been around for decades and it is still one of the most commonly used cancer treatments today. In the UK, around 1 in 4 of all cancer cases are treated with some form of chemotherapy - either alone, or in combination with other standard treatments. But what is chemotherapy? How does it work, and how is it different to other cancer treatments? Most importantly, how is your support helping to push forward cancer chemotherapy research?

Chemotherapy is a type of cancer treatment that involves using very strong drugs to damage and kill cancer cells, and it is one of the three main, or standard, types of cancer treatment, along with surgery and radiotherapy. It is also increasingly used in combination with newer types of treatment, such as immunotherapies.

How does chemotherapy work?

Most chemotherapy drugs work inside the cancer cell, interfering with the various molecular mechanisms that cells use to divide, grow, and survive. Cancer cells undergo changes that give them the ability to divide and multiply very quickly, without control. This is how tumours form, and is what makes cancer cells so dangerous. Luckily, it also makes them very vulnerable to the effects of chemotherapy drugs.

Sometimes two or more different chemotherapy drugs are given together in what is called combination chemotherapy. The goal is to hit cancer cells in as many different ways as possible, which can make it more difficult for cancer cells to adapt and survive after treatment.

The main types of chemotherapy drug:

There are many different types and they each target the cell at slightly different stages of growth and division.

Alkylating agents

These work by ‘clogging up’ DNA molecules and stopping them from working properly. Fully functioning DNA is needed to keep the cell alive, growing, and dividing. By binding to DNA, alkylating agents disrupt the cell’s ability to survive and thrive.

Platinum drugs

These work in a similar way to alkylating agents.

Antimetabolite chemotherapy drugs

These drugs have a similar structure and shape to the smaller molecules which make up DNA and other types of genetic molecules inside our cells. This can cause problems for the cell when it is trying to make new copies of DNA. Without new DNA, the cell cannot divide.

Topoisomerase inhibitors

These drugs stop important cell molecules (called topoisomerase enzymes) from cutting and resealing long strands of DNA. This is particularly important when the cell is dividing, and new DNA needs to be made. Blocking these enzymes from working makes it harder for the cell to survive, especially when it is trying to divide.

Microtubule interacting agents

These drugs disrupt molecules called ‘microtubules’, which are part of our cell structure. Cells use microtubules to transport molecules, and to keep their shape. Microtubules are particularly important when cells are dividing.

When is chemotherapy used in cancer?

Chemotherapy can be an option if doctors think the cancer has spread, or if there is a high risk of it spreading. It can be used in the following main ways:

Induction therapy

When chemotherapy is given as the primary treatment for cancer. The aim is to reduce the size of the tumour, or even sometimes completely cure the cancer.

Adjuvant therapy

When chemotherapy is given in addition to another main treatment - after surgery or radiotherapy treatment for example. The aim is to destroy any cancer cells that have escaped initial treatment or spread away from the original area, and reduce the risk of cancer coming back.

Preoperative or neoadjuvant chemotherapy

Given before the main cancer treatment, which is usually surgery. The aim is to reduce the size of the tumour before the operation.

How is chemotherapy administered?

Many chemotherapy treatments are liquid drugs that are delivered by injection into the blood. It can sometimes take a several hours to infuse the chemotherapy drug into the body. Some chemotherapies are given by other routes, such as by mouth, or directly into the area to be treated.

It is usually administered as a course of several ‘cycles' made up of periods of treatment with periods of rest in between. The rest periods give healthy cells in your body time to recover - cancer cells tend to be less efficient at repairing themselves, and so will not be as fully recovered before the next cycle of treatment. Giving chemotherapy treatment over several rounds can also help to catch as many cancer cells as possible when they are dividing.

Doctors and scientists want to find better ways to administer chemotherapy, and research supported by our Curestarters is already helping to uncover new answers. Recent research suggests that a combination of chemotherapy and immunotherapy could be an effective treatment for some types of breast cancer.

What about the side-effects of chemotherapy?

Chemotherapy drugs will target any cells that are growing and dividing rapidly, and unfortunately, this can include healthy cells too.

Side-effects are often caused by inadvertent damage by chemotherapy drugs to healthy cells. For example, hair loss and nausea are linked to damage of the quickly dividing cells located in our hair roots and lining our gut.

Chemotherapy can also affect our bone marrow cells, which are responsible for producing other cells that make up our blood, including red and white blood cells. Chemotherapy-induced damage of these and other cells can increase the risk of side-effects such as infections, bruising or bleeding, and anaemia.

General tiredness and fatigue is also very common for people having chemotherapy (and other cancer treatments). It can be caused by a combination of reasons, including direct effects of treatment on the body, side-effects such as anaemia, and also the cancer itself.

Chemotherapy treatment must always involve finding a balance between effectively targeting cancer cells and minimizing damage to healthy cells. It has been around a long time and it is still one of the most effective treatments we have for many cancers, but it doesn’t always work well for everyone and these unwanted effects can also seriously impact a patient’s quality of life.

Our researchers are working hard, not only to improve the effectiveness of chemotherapy, but also to find kinder ways to deliver treatment, and reduce side-effects.

Professor Lorenza Penengo in Switzerland is working on finding out why some cancers treated with PARP inhibitor targeted therapies go on to develop resistance to chemotherapies.

Dr Renata Basto in France is hoping to help people with ovarian cancer by investigating how certain molecular changes can influence ovarian cancer progression and response to chemotherapy.

Dr Vincenzo Giambra and his team in Italy have been finding out how a critical gene in cancer stem cells may help the blood cancer leukaemia develop resistance to chemotherapy.

And Dr Andrew Beekman and his team at the University of East Anglia are aiming to find new ways to stop cancer cells from developing resistance to chemotherapy drugs, and ultimately help chemotherapy cure more people.