Last updated: November 9, 2017 at 16:56 pm
A study has found that breast cancer can return even 15 years after successful treatment.
The New England Journal of Medicine report analysed the progress of more than 60,000 women over a 20-year period.
All had the most common form of breast cancer.
Researchers believe that extending treatment with hormone therapy could lower the risk of recurrence.
This is because the cancer is caused by the hormone oestrogen causing cells to grow.
Each patient was given treatment to block the supply of the hormone the stop the effects, such as aromatase inhibitors or tamoxifen.
Despite the cancer disappearing after five years of treatment, over the next 15 years a number found that cancer spread throughout their bodies.
The highest risk of cancer returning – at 40% – was in women who presented large tumours and affected lymph nodes.
Lead researcher Dr Hongchao Pan, from the University of Oxford, said: “It is remarkable that breast cancer can remain dormant for so long and then spread many years later, with this risk remaining the same year after year and still strongly related to the size of the original cancer and whether it had spread to the (lymph) nodes.”