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Herceptin can help control the growth of cancer cells that contain high amounts of HER2 (human epidermal growth factor receptor 2).
HER2 is found in all human cells. It controls cell growth and repair.
But 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 one in five 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, tests will be carried out to check if your cancer is HER2 positive before Herceptin is offered.
Herceptin is given during visits to a hospital or clinic.
It can be given in two ways:
The first time you have Herceptin you'll need to stay in hospital for around six hours so you can be monitored for any side effects. Further treatment sessions usually only require up to two hours in hospital.
If you have breast cancer, you'll have treatment every one or three weeks. Stomach and oesophageal cancer is usually treated once every three weeks.
Early-stage breast cancer will require treatment for a year. For breast, oesophageal or stomach cancer that has spread, treatment is used for as long as it helps.
Herceptin often causes side effects, although many of these will become less severe over time.
The following side effects affect around 1 in 10 people:
Your doctor or care team may be able to provide a full list of possible side effects. Visit Cancer Research UK for more information about the side effects of Herceptin.
Tell your doctor if you experience troublesome side effects, as there may be medicines available to treat them.
Heart problems can sometimes develop while you're on Herceptin and they can be serious.
Your heart will also be regularly checked during treatment.
It's important to tell your doctor if you get any of the following symptoms of a heart problem while on Herceptin:
If you develop a problem with your heart during treatment, it will usually improve if you have a short break from Herceptin.
Herceptin shouldn't be used to treat people with breast, oesophageal or stomach cancer that isn't HER2 positive.
It may also not be suitable if:
Avoid becoming pregnant while taking Herceptin and for at least seven months after treatment stops, as it could harm a developing baby.
Also avoid breastfeeding until at least seven months after treatment stops, as the medicine can get into breast milk and may be harmful for babies.
The Yellow Card Scheme allows you to report suspected side effects from any type of medicine you're taking.
The scheme is run by medicines safety watchdog, the Medicines and Healthcare products Regulatory Agency (MHRA).