Many people who have a breast cancer are completely cured by their initial treatment. But breast cancer is an unpredictable condition and even when it seems that surgery has cleared it completely it is impossible to be certain that it won’t come back.

Unfortunately there are no blood tests, x-rays, scans or other investigations that can be done at the end of treatment that show for sure if the cancer has gone. This is because even the most sensitive tests cannot detect minute, microscopic, traces of cancer.

The fact that your mother's doctors have told her she is 'all clear' could mean one of two things.

Firstly, it is possible that as the operation had taken away all evidence of the cancer your mother's doctors have said that things are 'all clear', meaning there is no obvious sign of anything left behind.

Depending on what the cancer and the lymph glands looked like under the microscope your mother's doctors will be able to estimate the risk of the cancer coming back.

So it may be that there is stronger evidence that her cancer is unlikely to come back. For example, if your mother's cancer was very small, if the appearance of the cancer under the microscope suggested a non-aggressive (low-grade) tumour and if there was no sign of spread of the cancer to the lymph nodes under her arm, then the likelihood of further problems would be very small indeed. So it could be that your mother's doctors have taken these sorts of factors into account when they have given her their reassurance. Not everyone wants to know all the details of the risk of recurrence but if your mother wishes to know the risk she could discuss this with her doctor.