What is personalised medicine?

When you are diagnosed with cancer, your cancer doctor and health professionals talk about the best treatment for your situation. They look at:

  • the type of cancer
  • its stage (the size of the cancer and if it has spread)
  • its grade (how the cells look under a microscope) – this can help tell how slowly or quickly the cancer may grow.

Pathologists (doctors who study cells and body tissues) can tell what type of cancer it is and its grade by how the cells look under a microscope. Depending on the cancer type, there may be other things doctors look for. For example, doctors can see if the cancer makes hormones or certain proteins that may encourage the cancer to grow.

Your cancer doctor and specialist nurse will talk to you about the most suitable treatment for the type of cancer you have. Cancers that start in the same organ in the body (primary site) are not always the same. Many cancers have sub-types. Treatment may be chosen based on the sub-types.

Personalised medicine tells us more about the cancer a person has. It does this by looking at the genetic make-up of the cancer cells. These are genetic changes that happen in the cancer cells, not in the genes that can be passed on in a family. Some cancers have changes to specific genes or proteins in the cancer cells that are not found in healthy cells.

Personalised medicine helps find if targeted therapy or immunotherapy drugs can target an individual's specific gene changes or proteins in the cancer cells. These drugs block the proteins or genes in cancer cells that help some cancers grow and spread.

You usually need tests on the cancer cells to find out if these drugs may be suitable.

Personalised medicine can sometimes be referred to as precision medicine.

What are genetic changes in a cancer?

Inside every cell in the body is a set of genes. Genes carry the instructions a cell needs to work properly. This includes how a cell grows and multiplies and when it dies.

Cancer may develop because of different genetic changes that happen during a person’s life. These are called acquired mutations. They can happen either by chance, or because of things that can damage cells, such as smoking or sun exposure.

Our cells can repair a lot of damage. But over time, the damage to the cells may build up. This can make the cells stop working normally and grow out of control. This is when a cancer starts to develop.

Every person’s cancer has a different genetic make-up. These are genetic changes that happen in cancer cells, not in the genes that can be passed on in your family.We have separate information about inherited cancer genes.

Finding out more about the genetic changes in a cancer helps doctors:

  • understand what causes a type of cancer to develop and grow
  • choose or develop new drugs that target these gene changes.

What are cell proteins?

Genes carry instructions to make proteins. Proteins work in different ways. They act as messengers for the cell, so the cell works properly. Changes to a gene can stop the cell giving the right instructions. For example, the cell may make much more of a protein than is needed. Or the cell might make an abnormal protein. This may make the cancer cells grow out of control. Or the cell may stop making a protein that usually repairs damage to cells.

Tests on the cancer cells (genomic or molecular testing)

New technology means doctors can sometimes find genetic changes in cancer cells. You might hear them called genomic or molecular tests. They can also be called biomarker tests.

There are also tests called cytogenetic tests. These look at the pattern of chromosomes in a cell. Chromosomes are made up of genes. Some cancers have one or more abnormal chromosomes.

Other tests look for particular proteins inside or outside the cancer cell. These tests look at:

  • certain gene changes in a cancer cell, or changes in the chromosomes
  • whether the cell is producing an abnormal protein or is making too much of a certain protein.

Information about gene changes that are unique to your individual cancer may help doctors find treatments that can target those gene changes.

You may only need a blood test. Or you might need further tests on cancer tissue from a biopsy or bone marrow test you have already had (see below). Your cancer doctor may ask for your consent (permission) before these tests are done.


You usually need a biopsy or bone marrow test to remove a sample of cancer cells for testing when you are first diagnosed. But if a cancer comes back, your cancer doctor may ask you to have another biopsy. This is because certain features of the cancer may have changed.

Liquid biopsies

This uses a blood sample. Doctors look at cancer cells and pieces of the tumour DNA in the blood. This helps them find out more about the genetics of the cancer. A liquid biopsy is not commonly done at present but may be used for lung cancer.

Getting test results

You may need to wait a few weeks to get the results of your tests. This can be a worrying time. You may worry you will not have the gene change needed for a certain targeted therapy or immunotherapy drug to work for you. Your cancer doctor will usually talk to you about other possible treatment options if a certain drug is not suitable for you.

Talking to a partner, family member or close friend can help. You can also talk about things with one of our cancer support specialists.

Personalised medicine using targeted and immunotherapy drugs

Targeted therapy and immunotherapy drugs block specific proteins or genes in cancer cells that help some cancers grow and spread.

This is different to chemotherapy. Chemotherapy works on all dividing cells, not just cancer cells. So it can affect healthy body tissue, where cells are constantly growing and dividing. This can cause side effects.

Targeted therapy and immunotherapy drugs cause some side effects that may be easier to manage than chemotherapy side effects. But they can also cause some serious side effects.

The drugs may also be given with other treatments, including chemotherapy.

Personalised medicine using targeted therapy and immunotherapy drugs is still in its early stages. The drugs that are available are not suitable for everyone. Even if tests show they are suitable, they may not work well for everyone. And some people may have to stop taking them because of the side effects they cause.

Some targeted drugs have been used successfully for some time. These include:

  • Imatinib for chronic myeloid leukaemia (CML). Most people with CML have a gene change called BCR-ABL1 in the leukaemia cell. It makes too much of a protein called tyrosine kinase, which imatinib blocks.
  • Trastuzumab for breast cancer. Some breast cancer cells have a lot of a protein called HER2, which makes cells grow and multiply. Trastuzumab attaches to HER2 and stops the cells growing.

These drugs have improved how long people with CML or breast cancer are expected to live for (prognosis).

Doctors are also using many other targeted therapy and immunotherapy drugs for different cancer types. We have more information about this below.

Clinical trials

There is a lot of research happening into developing new targeted therapy and immunotherapy drugs. Some drugs may only be available in clinical trials. Your cancer doctor can tell you more about clinical trials that may be suitable for you.

Gene expression profiling tests

These tests look at all the genes together in the cancer cell. They may help predict which cancers are most likely to come back. For example, different tumour profiling tests are used to find out which breast cancers are more likely to come back. The results can help women and their doctors make decisions about whether to have chemotherapy after surgery (adjuvant chemotherapy). This could help reduce the risk of the cancer coming back.

Sometimes a person is diagnosed with a secondary cancer, but doctors do not know where the cancer started. This is called cancer of unknown primary (CUP). Gene expression profiling can look at the genes in the secondary cancer, to try to find where the cancer started. This test for CUP is not available on the NHS. But it may be available in a clinical trial, or in some cases with private health insurance.

Personalised medicine and different cancers

Doctors already use many targeted therapy and immunotherapy drugs to treat different cancers. We have included some examples of this below. But because there are so many, we cannot include them all. You can find out more in the section about different types of cancer. Newer drugs that have been tested in clinical trials are also becoming available.

Breast cancer

Tests are done on the cancer cells to see if they produce the HER2 protein. If the cancer is HER2-positive, you will have a targeted therapy drug. For early-stage breast cancer, you usually have trastuzumab. Some people may also have pertuzumab (Perjeta®).

If breast cancer spreads to other parts of the body (secondary breast cancer), different targeted therapy drugs can be used.

Women with early-stage breast cancer may have tumour profiling tests to help them decide if they should have adjuvant chemotherapy.

Bowel cancer

If you have advanced bowel cancer, you may have a test to look for a RAS gene change. The results tell your doctors which treatments may work for you. They also show which treatments will not help.

If you do not have the RAS gene change, you can have targeted therapy drugs called cetuximab (Erbitux®) and panitumumab (Vectibix®). These are drugs that block signals that tell the cancer cells to grow. They do not work in people who have a RAS gene change.

Lung cancer

If you have non-small cell lung cancer that has spread you might have treatment with targeted therapy or immunotherapy drugs.

You usually need to have tests on the cancer cells to find out if a drug is suitable for you.

Your doctor may do tests on the cancer cells to check for a change in the epidermal growth factor receptor (EGFR) gene. They will check to see if there is too much EGFR protein. Too much of it can make the cancer cells grow.

If you have this gene change, your cancer doctor may give you some drugs to take. These drugs block signals from the EGFR protein. These signals tell the cancer cells to grow. Some of the drugs you might be prescribed are:

Some people have a test on the cancer cells to look for a gene change called T790M. If tests show this, your cancer doctor might give you a drug called osimertinib (Tagrisso®).

In a very small number of people with non-small cell lung cancer, there is a gene change called anaplastic lymphoma kinase (ALK). It makes an abnormal protein that makes the cancer cells grow. If tests show the ALK gene change, your cancer doctor may give you a drug called crizotinib (Xalkori®). Other ALK-blocking drugs are ceritinib (Zykadia®) and nintedanib (Vargatef®).

Pembrolizumab (Keytruda®) and nivolumab (Opdivo®) are immunotherapy drugs used to treat non-small cell lung cancer. They target a protein called PD‑1, which is found on certain T cells. T cells are part of our immune system. The immune system helps protect us from infection and disease. These drugs block PD-1. This allows the immune system to destroy the cancer cells. You might have tests on the cancer cells to find out if PD-1 is present.

See also


Chronic myeloid leukaemia (CML)

Most people with CML have the Philadelphia chromosome and an abnormal gene called BCR-ABL1. A test for this gene change can diagnose CML. It can also check how well treatment is working.

The BCR-ABL1 gene causes the leukaemia cell to make too much of a protein called tyrosine kinase. It makes the leukaemia cells grow and multiply. The main treatment for CML is a targeted therapy drug called imatinib that blocks this protein. Other drugs called dasatinib (Spyrcel®) and nilotinib (Tasigna®) are also used.

Acute lymphoblastic leukaemia (ALL)

Some people with ALL have the Philadelphia chromosome and an abnormal gene called BCR-ABL1.

Imatinib is used to treat Philadelphia chromosome-positive ALL. It can help improve the chances of getting ALL into remission.


Targeted or immunotherapy drugs are used to treat melanoma that has spread (advanced melanoma). These drugs have significantly improved how long people with advanced melanoma are expected to live for (prognosis).

Some of the drugs are being looked at in clinical trials for melanoma that has not spread. This is to see if they reduce the risk of the cancer coming back after surgery.

You usually have a test on the melanoma cells to check for a change on the BRAF gene. This change makes an abnormal protein that helps the melanoma cells grow and spread.

Targeted therapy drugs that block the abnormal protein are:

Immunotherapy drugs are also used to treat melanoma. These include:

They target certain proteins found on T cells. T cells are part of our immune system. Ipilumumab targets a protein called CTLA-4. Nivolumab and pembrolizumab target the PD-1 protein.

The drugs block these proteins and stimulate the immune system to destroy the melanoma cells.

The 100,000 Genomes Project

The 100,000 Genomes Project aims to improve cancer care by improving treatment and outcomes through personalised medicine.

Genomics is the study of the body’s genes. The 100,000 Genomes Project is run by NHS England. It works with genomic services in Scotland, Wales and Northern Ireland and different scientific groups. The project aims to decode 100,000 human genomes to create a new genomic medicine service in the UK. A genome is the code in our DNA that is made of genes. It looks at a person’s entire DNA, rather than specific genes or groups of genes.

A Genomic Medicine Service will provide genome sequencing to people with certain cancers and undiagnosed rare diseases. The aim is to discover the exact genetic changes that make cancers develop and grow, so doctors can choose more effective treatments.