Almost half of breast cancer patients suffer symptoms of post-traumatic stress disorder even years after diagnosis, according to a new study.
The debilitating disorder is often characterised by agitation, anxiety, depression, nightmares, flashbacks, and mood swings.
It is more often associated with soldiers returning from battlefields who have been shell-shocked by their experiences.
But now doctors have found that a similar effect can be found in women told that they have breast cancer.
The researchers behind the study believe that a combination of factors could trigger the condition.
These include the effects of a frightening diagnosis like breast cancer combined with the stress of treatment, such as surgery or chemotherapy, as well as other unexpected consequences, such as patients having to give up work.
Revealingly, the doctors found that even those women whose therapy has been successful and whose cancer has gone into remission can exhibit symptoms of the disorder.
Their study looked at the effects of the disease on 331 women treated in a Greek hospital.
They found that, overall, 45 per cent of the patients showed symptoms of post-traumatic stress disorder (PTSD).
What is more the women reported that they were suffering from the symptoms, and also had a poorer quality of life, three years after their diagnosis and treatment.
The researchers, from the Panteion University of Athens, warn that doctors should watch out for the signs of the condition when they are treating patients with breast cancer.
They warn: "Knowing that breast cancer patients are susceptible to PTSD, it might be necessary for the field of medicine to create a plan in assisting cancer patients that takes into account the entire spectrum of a patient's experience with the illness."
More than 45,000 women in Britain develop breast cancer every year, and one in three of them will go on to die from the disease.
Overall, experts estimate that a woman has a one in nine chance of developing breast cancer over the course of her lifetime.
The findings were presented at the Impakt Breast Cancer Conference in Brussels.
Emma Pennery, from the charity Breast Cancer Care, said: "The principle that women, and men, will have an ongoing risk of anxiety and depression following a diagnosis of breast cancer is well known, and there is a range of national guidance in the UK which covers the role of health care professionals in providing ongoing emotional support to patients. "
Last year doctors reported that having a heart attack could also trigger symptoms of PTSD.
Almost one in six patients, 16 per cent, met the criteria for the condition, while another 18 per cent suffered some symptoms of the disorder.