Herceptin can help control the growth of cancer cells that contain high amounts of human epidermal growth factor receptor 2 (HER2).
HER2 is found in all human cells. It controls cell growth and repair.
High levels of HER2 are found in some types of breast, oesophageal and stomach cancer, which helps the cancer cells grow and survive.
These are known as HER2 positive cancers. About 1 in 5 breast and stomach cancers are HER2 positive.
Herceptin works by blocking the effects of HER2 and encouraging the immune system (the body's natural defences) to attack and kill the cancer cells.
Herceptin can be used to treat:
If you have breast, oesophageal or stomach cancer, you will have tests to check if the cancer is HER2 positive before herceptin is offered.
Herceptin is given during visits to a hospital or clinic.
It can be given in 2 ways:
The first time you have herceptin you will need to stay in hospital for around 6 hours so you can be monitored for any side effects. For further treatment sessions you'll usually only need up to 2 hours in hospital.
If you have breast cancer, you'll have treatment every 1 or 3 weeks. Stomach and oesophageal cancer are usually treated once every 3 weeks.
Early-stage breast cancer will need treatment for 1 year. For breast, oesophageal or stomach cancer that's spread, treatment is used for as long as it is helpful.
Herceptin often causes side effects, although many of these will become less severe over time.
The following side effects are experienced by around 1 in 10 people:
Find out more about the complete list of known side effects of herceptin from EMC.
Cancer Research UK also has more information about the common side effects of herceptin.
Tell your doctor if you have particularly troublesome side effects, as there may be medicines available to treat them.
Heart problems can sometimes develop while you're taking herceptin and they can be serious.
Your heart will also be regularly checked during treatment.
It's important to tell your doctor if you're being treated with herceptin and you get:
If you develop a problem with your heart during treatment, it will usually improve if you have a short break from taking herceptin.
Herceptin should not be used to treat people with breast, oesophageal or stomach cancer that is not HER2 positive.
It may also not be suitable if:
Avoid becoming pregnant while taking herceptin and for at least 7 months after treatment stops, as it could harm your developing baby.
Also avoid breastfeeding until at least 7 months after treatment stops, as the medicine can enter breast milk and may be harmful for babies.
You can report any suspected side effects from a medicine you are taking to the UK Safety Scheme (Yellow Card Scheme).
The scheme is run by the Medicines and Healthcare products Regulatory Agency (MHRA).