Pregnancy and radiotherapy

Radiotherapy uses high-energy rays to destroy cancer cells. It is not usually given during pregnancy as even a low dose may harm the developing baby.

If it is needed urgently, it may be given to a part of the body that is not close to the womb. For example if a tumour is causing increased pressure in the brain. But usually if you need radiotherapy you will have it after the baby is born.

Different cancers and radiotherapy

You can find out more about radiotherapy in our information on the type of cancer you have.

Breast cancer and radiotherapy

Radiotherapy is usually given after an operation to remove only the area of the cancer. The delay between surgery and radiotherapy is usually 6 to 8 weeks. If you are diagnosed later in pregnancy, you may be able to delay radiotherapy until after the baby is born.

Many young women with breast cancer also need chemotherapy. You will have chemotherapy before or after surgery, and it can take up to several months to complete the cycles you need. This usually means you will have delivered your baby before radiotherapy starts.

If you are diagnosed in early pregnancy and do not need chemotherapy, it could be more than 6 months after surgery before you have radiotherapy. This delay could increase the risk of the cancer coming back in the breast. So your surgeon may advise you to have the whole of the breast removed (mastectomy). We have more information about having a mastectomy that you might find helpful.

After a mastectomy, some women need radiotherapy to the chest. But this can be safely delayed until after the baby is born.

Cancer of the cervix

Radiotherapy given with chemotherapy (chemoradiation) is the main treatment for cancer of the cervix that is stage 1B2 and above.

If your pregnancy is early and the cancer is at this stage, your doctor may ask you to think about ending the pregnancy. Delaying radiotherapy until after the birth and waiting until you are 14 weeks pregnant to have chemotherapy may be a serious risk to your health.

If you decide to have chemoradiation, your doctor will advise you to end the pregnancy. This can be very distressing. You will be given a lot of support to help you to cope.

If you decide to continue with the pregnancy, your doctors will give you chemotherapy when you reach 14 weeks. If you are over 14 weeks pregnant, you can start chemotherapy straightaway. You can have radiotherapy after the baby is born, usually after a hysterectomy.